WATER QUALITY AND PRODUCTIVITY ENHANCEMENT IN AN IRRIGATED RIVER BASIN THROUGH PARTICIPATORY CONSERVATION PLANNING AND ANALYSIS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: OTHER GRANTS
• Reporting Frequency: Annual
• Accession No.: 1004433
• Grant No.: 2014-51130-22491
• Cumulative Award Amt.: $659,954.00
• Proposal No.: 2014-08224
• Project Start Date: Sep 1, 2014
• Project End Date: May 31, 2019
• Grant Year: 2014
• Program Code: [110.J]- Farm, Landscape and Watershed Scale Projects

Recipient Organization
COLORADO STATE UNIVERSITY
(N/A)
FORT COLLINS,CO 80523

Performing Department
Civil & Environmental Engr

Non Technical Summary
Two great challenges to the nation's highly productive irrigated lands are salt and pollutant build-up in surface and groundwater, with consequent damage to crop yields and the environment, and growing urban competition for water supplies. Improved conservation practices, including schemes such as rotational lease-fallowing for preventing permanent dry-up of irrigated lands, can sustain productivity and benefit the environment by lowering return flows and pollutant loads to streams and aquifers while allowing continued access to irrigation water. A major obstacle to using these methods in western irrigated river valleys is the requirement that altered stream flow patterns cannot violate water rights or interstate river compacts. Finding river-reservoir system management schemes and economical ways to enhance water quality, boost productivity, and conserve water while complying with water law, requires collaborating with water users and agencies to implement computational tools built upon comprehensive data. This project's goal is to identify and rank conservation practices, with extensive advisory stakeholder and student participation in model building and application processes, for sustaining the valuable agriculture sector in Colorado's Lower Arkansas River Basin by reducing salinity and selenium, increasing the productivity and economic viability of the land and its rural communities, and maintaining access to irrigation water. Calibrated regional and basin scale models are used to find effective conservation scenarios in a characteristic irrigated basin that satisfy socioeconomic and institutional constraints. Access through a web-based platform, documents and conference presentations, and course material will promote a vehicle for regional interaction and dissemination of findings nationally.

Animal Health Component

80%

Research Effort Categories

Basic

(N/A)

Applied

80%

Developmental

20%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
112	0310	2020	20%
103	0210	2050	10%
111	0210	2020	20%
601	0210	3010	20%
133	0210	2020	30%

Knowledge Area
601 - Economics of Agricultural Production and Farm Management; 103 - Management of Saline and Sodic Soils and Salinity; 133 - Pollution Prevention and Mitigation; 112 - Watershed Protection and Management; 111 - Conservation and Efficient Use of Water;

Subject Of Investigation
0310 - River basins; 0210 - Water resources;

Field Of Science
2020 - Engineering; 2050 - Hydrology; 3010 - Economics;

Keywords

agriculture

watersheds

collaborative modeling

nonpoint source pollution

salinity

irrigation eff

Goals / Objectives
This proposed effort seeks to demonstrate that through participatory basin-wide planning and analysis, conservation practices can be identified and evaluated to economically improve water quality, boost agricultural productivity, and save water in an irrigated river basin, while assuring compliance with legal-institutional constraints. Specific objectives related to research, extension, and education are:(1) Identify conservation practices and describe their impact in improving water quality, boosting agricultural productivity, and saving water in the irrigated stream-aquifer system of the Lower Arkansas River (LAR) Basin in Colorado.(2)Identify river-reservoir system operation strategies at the basin-scale that permit implementation of conservation practices in the LAR Basin so as to comply with State water law and the interstate Compact.(3)Measure the economic standing of alternative conservation practices and river-reservoir operation/flow augmentation options.(4)Incorporate data and impacts of conservation practices and river operation/flow augmentation options into a platform that invites participation by interested stakeholders and educates policy makers as to the benefits of integrated basin-wide water management.(5) Evaluate, through participation with water users and agencies, the technical, socio-economic, and administrative viability of alternative conservation practices and river-reservoir operation/flow augmentation options and determine a recommended set of best options. (6)Broaden the understanding of local water users in the water quality and productivity implications resulting from irrigation practices, reservoir operations, and compact compliance issues.(7)Improve education and involvement of water users, agencies, and students in participatory identification, evaluation, and administrative enablement of conservation practices using data and models.(8) Provide active participation opportunities for graduate and undergraduate students to engage in the proposed research, education, and extension activities.(9)Develop and disseminate the results of this research as undergraduate and graduate level course material related to conservation of water resources at the river basin scale.

Project Methods
Task 1. Formation and Preliminary Planning with Stakeholder Advisory Group. Form a stakeholder advisory group and conduct preliminary interviews with stakeholders to describe problems in the LAR Basin and to suggest improvements. A defining feature of the extension methodology of the project will be the periodic convening of a local advisory group to serve as partners in the development of viable scenarios that meet the constraints and objectives.Evaluation Plan for Task 1. The value of this two-way contribution will be appraised through a means of a longitudinal set of surveys, conducted through the course of the project to quantify the increased level of knowledge by program participants. Evaluation metrics will be designed to measure knowledge gained, likelihood of behavioral change, and consideration of solutions.Task 2. Regional-Scale Analysis of Alternative Conservation Practices. Refine and apply regional-scale groundwater and surface water models to predict the effectiveness of alternative conservation measures in meeting performance criteria and their impacts on return flows to the river system. Numerical models will be used for both the USR and DSR to evaluate the effectiveness of alternative conservation practices at the regional scale. These results then will be up-scaled to the basin scale using methods described in Task 3.Evaluation Plan for Task 2. Progress of Task 2 activities will be evaluated by the project senior personnel (PI, Co-PIs) and by the stakeholder advisory group. Items of evaluation include model performance assessment and assuring that model simulation scenarios are being completed in a timely manner. Evaluations will occur at monthly to bi-monthly project senior personnel meetings, at meetings between senior project personnel and graduate students, and at meetings between senior project personnel and stakeholders and will be documented in bi-annual reports for the first two years.Task 3. Basin-scale Analysis of Flow Augmentation and River-Reservoir Operations. Extend and apply basin scale river flow administration model to investigate ways of implementing regional scale conservation practices that protect Colorado water rights and comply with the Colorado-Kansas Interstate Compact.Using the appropriate machine learning method for this study, reservoir optimization will be conducted in conjunction with flow simulation in River GeoDSS for a wide range of conservation scenarios as developed from the updated and improved regional-scale modeling. This will act as a screening process to determine the set of scenarios for which reservoir operational rules can be found that provide compliance with the Arkansas River Compact, while maintaining LAR Basin water right priorities.Evaluation Plan for Task 3. As stated in Brown and Caldwell (2011), modeling tools such as those described herein, "cannot replace or supersede" the Hydrologic-Institutional (H-I) Model stipulated by Supreme Court ruling or its findings regarding compliance with the Arkansas River Compact. Evaluation of the effectiveness and success of this task must ultimately be based on consistency of River GeoDSS calculated river flows at the Colorado-Kansas stateline under various conservation scenarios with results from the H-I model as configured to simulate implementation of these same scenarios determined from the regional scale modeling.Task 4. Economic Analysis of Alternative Improvements. Apply methods of economic valuation to alternative conservation practices and methods of administrative compliance.This task determines the economic consequences associated with implementing alternative improvements. Economic analysis will involve calculating the costs of implementing each conservation practice and river-reservoir operation/flow augmentation measure using information gathered in consultation with stakeholders, as outlined in Task 1, and secondary data where appropriate. These cost estimates will be used in conjunction with the predicted modeling outcomes (e.g. reductions in salt and Se loads and concentrations and increased productivity) to develop economic efficiency measures for each potential practice. In Tasks 5 and 6, results will be presented to the stakeholder advisory group using a participatory platform for continuous updating.Evaluation Plan for Task 4. As described for Task 1, a longitudinal set of surveys of increased awareness of costs and benefits will be conducted with evaluation metrics designed to measure knowledge gained, likelihood of behavioral change, and consideration of solutions.Task 5. Collaborative Examination and Assessment of Improvement Alternatives. Interact with stakeholder advisory group to provide information about the likely impacts and costs of improvement alternatives, and to assess and refine the alternatives for a final analysis.As mentioned in Task 1, this project will rely on participatory research with a stakeholder advisory group through informal direct interaction and a series of participatory decision support sessions. Stakeholders will be the primary source for determining the specifics of research questions, such as which conservation practices are considered, where and when they are considered, and which results need to be pursued further.Interaction with stakeholders in participatory decision support sessions around the likely impacts and costs of alternative improvements will be enhanced through the use of eRAMS. eRAMS will be used to store and retrieve geospatial data, hydrologic and water quality time series data, and modeling results that correspond both to current baseline conditions and to alternative scenarios of conservation practice and river-reservoir operation/flow augmentation.Evaluation Plan for Task 5. A final longitudinal set of surveys of increased awareness of the likely benefits and desirability of improvement alternatives will be conducted with evaluation metrics designed to measure knowledge gained, likelihood of behavioral change, and consideration of solutions.Task 6. Recommended Ranking of Improvement Alternatives. Survey and interact with stakeholders to rank alternative conservation practices and methods of administrative compliance. The last step required before dissemination of information can occur is to rank the considered improvement alternatives. Stakeholders will have worked with the research team to accumulate the kind of information that they need to make decisions about how they can improve conservation, enhance water quality, and meet institutional constraints while maintaining or increasing profits.Based on survey information from the stakeholder advisory group and other selected stakeholders, multicriteria evaluation tables will be prepared to allow application of the methods of multicriteria decision analysis (MCDA) to rank the alternative improvement scenarios with respect to all relevant criteria. Tradeoffs between productivity and profitability objectives and environmental objectives will be considered in the analysis. The most appropriate MCDA methods will be selected for this task, with more than one method utilized to provide a comparative evaluation of rankings.Evaluation Plan for Task 6. A final longitudinal set of surveys of increased awareness of the likely benefits and desirability of improvement alternatives will be administered to the stakeholder group with evaluation metrics designed to measure knowledge gained, likelihood of behavioral change, and consideration of solutions.Task 7. Dissemination of Findings. Project findings will be communicated to selected audiences through documents and internet platforms and incorporated into academic curricula focusing on basin-wide conservation planning and integrated river basin water management.

Progress 09/01/14 to 05/31/19

Outputs
Target Audience:Water resources and irrigation professionals, farmers and irrigators, canal companies, water conservancy districts, state and federal water agencies, general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Five MS graduate students and two PhD graduate students were trained and mentored in developing, calibrating, and applying computational models for simulating the impact of alternative BMPs on groundwater and stream water quality, irrigated crop production, and water savings. Model development included intensive computer programming, de-bugging, and the use of GIS pre-processing tools. Besides developing and enhancing computational algorithms, graduate students learned about model coupling and code parallelization for enhancing model run-time. Three MS graduate students successfully published their MS theses, while two others are nearing completion of their degrees. Three PhD graduate students have successfully defended their PhD dissertations. One MS graduate student has co-authored two refereed journal articles, and two have co-authored one; one PhD student has co-authored two refereed journal articles, a second PhD student has co-authored one refereed journal article, and a third has prepared two for review. Multiple graduate students have made presentations at professional conferences. Two undergraduate students were actively engaged in analyzing data and model results, and maintaining the ARMAC website. Faculty members enhanced their expertise in modeling of irrigated stream-aquifer systems, socio-economic analysis of BMPs, and in participatory planning and analysis for enhancing irrigated crop productivity and the environment. How have the results been disseminated to communities of interest?Project results have been presented to shareholders at the Arkansas River Basin Water Forum, in meetings with the ARMAC, in meetings with LAVWCD and CDPHE personnel, at professional conferences, in reports and magazine articles, in six graduate theses, and in seven refereed journal articles. The ARMAC website was used as a platform for data and information exchange. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? This project has developed and applied tools and methods for preserving and enhancing productive irrigated lands by (1) reducing salt and pollutant build-up in groundwater and streams, with consequent damage to crop yields and the environment, and (2) conserving water by decreasing non-beneficial consumption. The project prepared models to find best management practices (BMPs) to lower salinity, selenium, and nitrate in groundwater and streams in Colorado's Lower Arkansas River Valley (LARV), developed and applied a model for assessing how BMPs affect compliance with the Arkansas River Compact and water rights, engaged with stakeholder groups of water users and agencies to gain insight into practicable and cost-effective alternative BMPs, published an economic assessment of alternative BMPs, incorporated findings into academic courses at CSU, and prepared papers,presentations, and reports of findings. Accomplishments under the nine project objectives are summarized as follows: (1) Regional-scale models of flow and water quality in the LARV were developed and applied for evaluating alternative BMPs identified by the Arkansas River Management Action Committee (ARMAC) (about 10 farmers and 17 other water stakeholders) and the CSU research team: • The development, calibration, testing, and application of linked groundwater (MODFLOW-UZF, UZF-RT3D) and surface water (SFR, OTIS-QUAL2E) flow and solute transport models of the upstream study region (USR) of the LARV were documented in three refereed journal articles, an MS thesis, and a popular water news magazine. The coupled model was used to explore the prospect for alternative BMPs to lower selenium and nitrate concentrations in the USR toward compliance with regulatory standards. Results reveal the potential to reduce average concentrations along the Arkansas River by as much as about 50% for selenium and about 30% for nitrate by applying water BMPs that also include ERB and RF. • The coupled RT3D-OTIS model was calibrated, tested, and initially applied for predicting selenium and nitrogen concentrations in the groundwater and stream network of the downstream study region (DSR) under baseline and BMP conditions and published in an MS thesis. A river mass balance analysis estimated nonpoint source return flows and solute loads to the river and was documented in a journal article. • A 3D coupled groundwater reactive transport and equilibrium chemistry model was developed to simulate salt ion fate and transport in irrigated agricultural watersheds. The finite-difference model, UZF-RT3D/SEC simulates transport of the major salt ions and accounts for crop uptake, soil organic matter decomposition, mineralization/immobilization, and oxidation/reduction reactions, as well as precipitation/dissolution of salt minerals, complexation, and cation exchange. Model calibration was completed to meet targets for total dissolved solids (TDS) in the unsaturated zone; TDS and major salt ion concentrations in the saturated zone; and sulfate and TDS loading to the Arkansas River and tributaries. The model was applied for initial evaluation of BMP impacts in the USR on groundwater and soil salinity, with impacts on crop yield. Two related refereed journal articleswere published. • Work was initiated on calibrating and testing a coupled UZF-RT3D/SEC groundwater model and stream flow and water quality model (SFR, OTIS-QUAL2E) for an evaluation of salinity in the LARV DSR, to be published in an MS thesis. The model will be refined and applied to explore BMPs for lowering salinity and boosting crop yields in the DSR and the USR. • Lower Arkansas Valley Water Conservancy District (LAVWCD) was funded by the Colorado Department of Public Health and Environment (CDPHE) to launch a pilot implementation project to begin testing the BMPs recommended by our project in a region west of Lamar, CO. (2) The LARV basin-scale model (River GeoDSS) was developed and applied to examine ways to implement BMPs without harming Colorado water rights or violating the Arkansas River Compact with Kansas. Artificial neural networks (ANN) were used to emulate MODFLOW models, leveraging the well-calibrated regional flow models in the USR and DSR into a larger basin-scale model without a need to create a basin-wide MODFLOW model. The River GeoDSS model showed that operation of a new storage account in John Martin Reservoir would allow water BMP implementation without violating water law. This was documented in a magazine article, and two journal articles are in preparation. (3) An assessement was made of the basic economic and institutional factors a farmer must consider when switching to more efficient irrigation practices which lead to improved water quality. Budgets also were developed to describe costs of sealing canals, which occurs off the farm. A regional linear programming (LP) model was developed with an objective function that maximizes net income for the region, while meeting constraints regarding environmental and physical conditions, water availability and use, and institutions. Pollution outputs are simulated by flow and solute transport models for each scenario, providing information about the tradeoffs between net income, soil salinity reduction, and river selenium and nitrogen reduction for the baseline and each considered BMP. This work was documented in two journal articles, an MS thesis, and a magazine article. (4) A website was used for exchange of information about the project, including access to GISbased data and model results . The website provided information to stakeholders and water specialists for evaluation of the pros and cons of land and water BMP options. (5) Multiple meetings and interactive sessions were held with the ARMAC and other interested stakeholders regarding the assessment and potential implementation of BMPs. The interactive dialogue focused on stakeholder opinions about tradeoffs between economic returns, soil salinity, and selenium and nitrogen pollution in the Arkansas River. A survey was sent to 400 LARV farmers to establish a baseline about awareness and actions toward BMPs related to salinity, selenium, and nitrogen. About 30% responded, with results indicating more awareness about salinity and nitrogen problems than about selenium problems. Farmers are split as to whether they would be willing to incur costs to adopt BMPs, but would implement them to avoid regulations. They are united in feeling that if they do not change their practices then both water quality and quantity will be at risk in the future. (6) Data, modeling results, and economic analysis related to these issues were presented and discussed at several ARMAC meetings, at the Arkansas River Basin Water Forum, and at two Sprinkler Irrigation workshops. They also were discussed on local radio interviews and posted on the ARMAC website. (7) Dialogue occurred between CSU researchers and personnel from the LAVWCD and CDPHE regarding a pilot field study of BMPs to improve water quality. Recommendations for the pilot study were made in light of project findings. (8) Five MS graduate students and three PhD graduate students have been trained in developing and applying computational models for simulating baseline conditions and the impact of alternative BMPs and in their socio-economic analysis and ranking. Undergraduate students have been active in maintaining the ARMAC website, analyzing data and modeling results, and making them accessible to stakeholders. (9) The tradeoff between water quantity and quality goals in the LARV were highlighted in the CSU course AREC 478, a capstone course on agricultural policy. Elements of computational modeling of flow and solute transport in irrigated stream-aquifer systems were incorportated into CIVE 542 on water quality modeling. Results are expected to be incorported into groundwater modeling courses, CIVE 531 and and CIVE 423, and perhaps systems courses, ENGR 520 and CIVE 645.

Publications

• Type: Journal Articles Status: Published Year Published: 2016 Citation: Sharp, M.D., Hoag, D.L.K, Bailey, R.T., Romero, E.C., and T.K. Gates. 2016. Institutional Constraints on Cost-Effective Water Management: Selenium Contamination in Colorados Lower Arkansas River Valley. Journal of the American Water Resources Association 52(6), 1420-1432.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Tavakoli-Kivi, S., and Bailey, R. T. 2017. Modeling sulfur cycling and sulfate reactive transport in an agricultural groundwater system. Agric. Water Mgmt., 185, 78 - 92.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Shultz, C. D., Bailey, R. T., Gates, T. K., Heesemann, B. E. , and Morway, E. D. 2018. Simulating selenium and nitrogen fate and transport in coupled stream-aquifer systems of irrigated regions. J. Hydrology, 560, 512  529.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Shultz, C. D., Gates, T. K., and Bailey, R. T. 2018. Evaluating best management practices to lower selenium and nitrate in groundwater and streams in an irrigated river valley using a calibrated fate and reactive transport model. J. Hydrology, 566, 299  312.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Gates, T. K., Cox, J. T., and Morse, K. C. 2018. Uncertainty in mass-balance estimates of regional irrigation-induced return flows and pollutant loads to a river. J. Hydrology: Regional Studies, 19, 193  210.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Hoag D., Goemans, C., and Orlando, T. 2018. Sustainable policies that align irrigation and water quality. Special Issue: The Future of Water in the West, Western Economic Forum, 16(1), 54 - 61.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Tavakoli-Kivi, S., Bailey, R. T., and Gates, T. K. 2019. A salinity reactive transport and equilibrium chemistry model for regional-scale agricultural groundwater systems. J. Hydrology, 274 - 293.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Rohmat, F., Labadie, J. W., and Gates, T. K. 2019. Deep learning for compute-efficient modeling of BMP impacts on stream-aquifer exchange and water law compliance in an irrigated river basin. J. Environ. Model. Software (in revision and re-review).
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Tavakoli, S., Bailey, R. T., and Gates, T. K. 2015. Simulating coupled salinity transport model in an agricultural groundwater system. National Ground Water Association Upper Great Plains Groundwater Conference, September 22-23, 2015, Cheyenne, Wyoming.
• Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: Rohmat, F., Labadie, J. W., and Gates, T. K. 2016. Artificial neural network database development for modeling stream-aquifer interactions in the Lower Arkansas River Basin of Colorado. Hydrology Days 2016, Fort Collins, CO.
• Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: Shultz, C. D., Gates, T. K., and Bailey, R. T. 2016. Finding land and water management practices to lessen river pollutant concentrations in irrigated regions. Hydrology Days 2016, Fort Collins, CO.
• Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: Tavakoli-Kivi, S., Bailey, R. T., and Gates, T. K. 2016. Simulating Salt Movement and Transformation using a Coupled Salinity Reactive Transport Model in Variably-Saturated Groundwater Systems. American Geophysical Union Fall Conference.
• Type: Conference Papers and Presentations Status: Other Year Published: 2017 Citation: Shultz, C. D., Gates, T. K., and Bailey, R. T. 2017. Using MODFLOW and a Coupled RT3D-OTIS Model to Simulate Best Management Practices for Water Quality Improvement in an Irrigated Agricultural River Valley. MODFLOW and More 2017, Golden, CO.
• Type: Conference Papers and Presentations Status: Other Year Published: 2017 Citation: Rohmat, F., Labadie, J. W., and Gates, T. K. 2017. Application of Neural Networks to Development of a Computationally Efficient Surrogate to the MODFLOW Model: Application to the Stream-aquifer System of the Lower Arkansas River Basin in Colorado. 2017 UCOWR/NIWR Annual Conference.
• Type: Conference Papers and Presentations Status: Other Year Published: 2017 Citation: Orlando, T., Hoag, D., and Gates, T. K. 2017. Barriers to Sprinkler Irrigation Adoption in Colorados Lower Arkansas River Valley: Facts, Fiction, and Water Quality Impacts. Hydrology Days 2017, Colo. State Univ., Fort Collins, CO.
• Type: Conference Papers and Presentations Status: Other Year Published: 2017 Citation: Cox, J. T., and Gates, T. K. 2017. Stochastic Estimation of Groundwater Nonpoint-Source Return Flows and Pollutant Mass Loading to Two Reaches of the Arkansas River in Colorado. Hydrology Days 2017, Colo. State Univ., Fort Collins, CO.
• Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Cox, J. T., Qurban, I. A., Gates, T. K., and Bailey, R. T. 2018. Modeling the Fate and Transport of Nitrate, Selenium, and Uranium Using a Coupled Stream-Aquifer Reactive Transport Model.Inter. Environ. Model. Software Soc. Conf. 2018, Fort Collins, CO.
• Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Rohmat, F., Labadie, J. W., and Gates, T. K. 2018. Computationally Efficient ANN as a Realistic Surrogate of MODFLOW-UZF for Integration with the GeoMODSIM River Basin Management Model. Inter. Environ. Model. Software Soc. Conf. 2018, Fort Collins, CO.
• Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Tavakoli-Kivi, S., Bailey, R. T., and Gates, T. K. 2018. A Coupled Reactive Transport and Equilibrium Chemistry Model for Assessment of Salinity in Regional- Scale Groundwater Systems.Inter. Environ. Model. Software Soc. Conf. 2018, Fort Collins, CO.
• Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Underwood, E. N., Gates, T. K., and Cox, J. T. 2019. Modeling to Characterize and Mitigate Uranium Pollution in an Irrigated River Valley. Hydrology Days 2019, Colo. State Univ., Fort Collins, CO.
• Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Bin Javed, A., Gates, T. K., Bailey, R. T., and Tavakoli Kivi, S. 2019. Modelling the Distribution of Major Salt Ions in Agricultural Stream and Groundwater Systems. Hydrology Days 2019, Colo. State Univ., Fort Collins, CO.
• Type: Other Status: Published Year Published: 2018 Citation: Hoag, D. L, Gates, T. K., Bailey, R. T., Shultz, C. D., and Orlando, A. 2018. Keeping irrigated agriculture productive and the environment healthy in Colorado's Lower Arkansas River Valley. Colorado Water. Water Center, Colorado State University, Fort Collins, Colo., Mar/Apr.
• Type: Other Status: Published Year Published: 2019 Citation: Rohmat, F., Labadie, J. W., and Gates, T. K. 2019. Improving water quality without injuring water rights in the Lower Arkansas River Valley. Colorado Water. Water Center, Colorado State University, Fort Collins, Colo., Mar/Apr.
• Type: Other Status: Published Year Published: 2017 Citation: Osborn, B., Orlando, A. S., Hoag, D. L., Gates, T. K., and Valliant, J. C. 2017. The economics of irrigation in Colorados Lower Arkansas River Valley. Colorado Water Institute Special Report No. 32, Colorado State Univ., Fort Collins, Colo.
• Type: Theses/Dissertations Status: Published Year Published: 2017 Citation: Sharp, M. 2017. Three essays on institutional design for voluntary water conservation. PhD dissertation, Dept. Agric. Resour. Econ., Colorado State Univ., Fort Collins.
• Type: Theses/Dissertations Status: Published Year Published: 2018 Citation: Tavakoli Kivi, S. 2018. Simulating the Fate and Transport of Salinity Species in a Semi-Arid Agricultural Groundwater System: Model Development and Application. PhD dissertation, Dept. Civil and Environ. Engrg., Colorado State Univ., Fort Collins.
• Type: Theses/Dissertations Status: Published Year Published: 2019 Citation: Rohmant, F. 2019. Machine Learning Methods to Facilitate Optimal Water Allocation and Management in Irrigated River Basins to Comply with Water Law. PhD dissertation, Dept. Civil and Environ. Engrg., Colorado State Univ., Fort Collins.
• Type: Theses/Dissertations Status: Published Year Published: 2017 Citation: Shultz, C. D. 2017. Finding Land and Water Management Practices to Reduce Selenium and Nitrate Concentrations in an Agricultural River Valley Applying a Regional-Scale Stream-Aquifer Model. MS thesis, Dept. Civil and Environ. Engrg., Colorado State Univ., Fort Collins.
• Type: Theses/Dissertations Status: Published Year Published: 2018 Citation: Qurban, I. 2018. Finding Water Management Practices to Reduce Selenium and Nitrate Concentrations in the Irrigated Stream-Aquifer System Along the Lower Reach of Colorados Arkansas River Valley.MS thesis, Dept. Civil and Environ. Engrg., Colorado State Univ., Fort Collins.
• Type: Theses/Dissertations Status: Published Year Published: 2017 Citation: Orlando, A. 2017. Economic and Environmental Trade-Offs of Irrigation Best Management Practices in the Lower Arkansas River Valley. MS thesis, Dept. Agric. Resour. Econ., Colorado State Univ., Fort Collins.

Progress 09/01/17 to 08/31/18

Outputs
Target Audience:Water resources and irrigation professionals, farmers and irrigators, canal companies, water conservancy districts, state and federal water agencies, general public Changes/Problems:Development, calibration, and application of the DSR regional-scale model and the basin-scale model to assess impact of considered BMPs are taking longer than originally expected. Evaluation of the feasibility of being able to incorporate alternative reservoir management options for offsetting impacts on state line flows is essential but taking longer than expected. What opportunities for training and professional development has the project provided?Two MS graduate students and two PhD graduate students were trained and mentored in developing, calibrating, and applying computational models for simulating the impact of alternative BMPs on groundwater and stream water quality, irrigated crop production, and water savings. Model development includes intensive computer programming, de-bugging, and the use of GIS pre-processing tools. Besides developing and enhancing computational algorithms, graduate students have learned about model coupling and code parallelization for enhancing model run-time. Two MS graduate students successfully published their MS theses. The first was entitled "Finding Land and Water Management Practices to Reduce Selenium and Nitrate Concentrations in an Agricultural River Valley Applying a Regional-Scale Stream-Aquifer Model", and the second was entitled "Finding Water Management Practices to Reduce Selenium and Nitrate Concentrations in the Irrigated Stream-Aquifer System Along the Lower Reach of Colorado's Arkansas River Valley." A PhD graduate student successfully defended his PhD dissertation, entitled "Simulating the Fate and Transport of Salinity Species in a Semi-Arid Agricultural Groundwater System: Model Development and Application." One MS graduate student co-authored a journal article published in the Journal of Hydrology. Three students made presentations at the Environmental Modeling and Software Conference at CSU in June 2018. Two undergraduate students were actively engaged in analyzing data and model results, and maintaining the ARMAC website. Faculty members enhanced their expertise in modeling of irrigated stream-aquifer systems, socio-economic analysis of BMPs, and in participatory planning and analysis for enhancing irrigated crop productivity and the environment. How have the results been disseminated to communities of interest?Results have been presented to shareholders at the Arkansas River Basin Water Forum, in meetings with personnel from the LAVWCD and CDPHE, at a professional conference, and in a refereed journal article. The ARMAC website is being used as a platform for data and information exchange. What do you plan to do during the next reporting period to accomplish the goals?Plans for the next reporting period are summarized under each of the nine project objectives as follows: (1) A number of actions are planned: The coupled RT3D/SEC-OTIS-QUAL2E salt transport and equilibrium chemistry model will be enhanced to include the effect of salinity on evapotranspiration and will be applied to examine the impact of additional BMP alternatives on subsurface dissolved salts and crop yield impacts in the USR. The coupled RT3D/SEC-OTIS-QUAL2E salt transport and equilibrium chemistry model will be calibrated, tested, and applied to simulate subsurface dissolved salts, river salt concentrations, and crop yield impacts in the DSR under baseline conditions. Additional journal articles will be published and submitted for review that address the characterization and analysis of salt, selenium, and nitrate pollution under baseline and BMP conditions. (2) The River GeoDSS model with enhanced ANNs will be used to evaluate the compliance of potential BMPs with Colorado water law and the Arkansas River Compact. Work will continue on incorporating storage accounts in John Martin Reservoir, and possibly Pueblo Reservoir, for capturing and storing additional Arkansas River flows resulting from reduced diversions as a consequence of BMP implementation, into the River GeoDSS model. This will allow simulation of flow releases from the reservoirs to offset depletions to the river and thereby facilitate implementation of BMP strategies. (3) Additional economic assessment activities are not planned for the remainder of the project. (4) Efforts will continue to provide access to field data, model simulations, and socio-economic analysis through the ARMAC website and linked eRAMS platform. (5) Additional conference presentations and informal meetings with stakeholders may be conducted to disseminate research findings and assist stakeholders to assist with their implementation plans. (6) The CSU research team will continue to apply regional-scale and basin-scale simulation models to evaluate BMPs recommended for consideration by LARV stakeholders with a special focus on the DSR. Expanded attention also will be given to basin-wide impacts. Results will be reported in appropriate forums and on the ARMAC website. A printed article on insuring compliance with state and interstate water rights under implementation of BMPs will appear in the March-April 2019 edition of Colorado Water, a widely-read magazine focusing on water issues in Colorado. (7) Where possible, appropriate forums will be used for communicating the rationale and methods for identifying, evaluating, and providing administrative support for promising BMPs using data and models. Two journal articles will appear in print, and two journal articles are expected to be submitted, describing the calibration and application of the coupled RT3D-OTIS-QUAL2E groundwater-surface water models for evaluating baseline conditions and the impact of BMPs on loads and concentrations of salt, selenium, and nitrogen in groundwater, soils, and streams. A journal article is expected to be submitted describing the development and application of the River GeoDSS model to examine the impact of proposed BMPs on flows within the LARV in Colorado and crossing the state line into Kansas. One article is expected to be submitted describing the socio-economic evaluation of the alternative BMPs for enhancing the LARV environment and sustaining crop productivity. Results of the project are expected to be presented at CSU Hydrology Days (March 2019) and at the World Environmental and Water Resources Conference. (8) Faculty will continue to mentor graduate and undergraduate students in data assessment, model development and application, and participatory evaluation of the feasibility and practicability of alternative BMPs. (9) Descriptions of the development and application of flow and solute transport models and of socio-economic analyses of BMPs will be incorporated into the syllabus of selected courses at CSU for spring and fall semesters, 2019.

Impacts
What was accomplished under these goals? This project is developing and applying tools and methods that are expected to contribute to the solution of two great challenges to preserving and enhancing productive irrigated lands: (1) salt and pollutant build-up in surface and groundwater, with consequent damage to crop yields and the environment, and (2) growing urban competition for water supplies. The fourth year of the project focused on applying a calibrated model to find Best Management Practices (BMPs) to lower selenium and nitrate in groundwater and streams in Colorado's Lower Arkansas River Valley (LARV), completing the development of a model for simulating salinization and its impacts on irrigated agriculture in the LARV, expanding and refining a model for assessing how BMPs affect compliance with the Arkansas River Compact, engaging with stakeholder groups of water users and agencies to gain insight into practicable and cost-effective alternative BMPs, refining economic assessment of alternative BMPs, and preparing articles and reports of findings to date. The goal of BMP implementation is to improve water quality, enhance crop productivity, and conserving water in the LARV. Accomplishments under each of the nine project objectives, as described above, are summarized as follows: (1) Regional-scale models of flow and water quality in the LARV were further enhanced and applied for evaluating alternative BMPs identified by the Arkansas River Management Action Committee (ARMAC) and the CSU research team: The development, calibration, testing, and application of linked groundwater (MODFLOW-UZF, UZF-RT3D) and surface water (SFR, OTIS-QUAL2E) flow and solute transport models of the upstream study region (USR) of the LARV were documented in a refereed journal article (March 2018) and in an MS thesis. Application of the coupled model to explore the potential for alternative BMPs to lower selenium and nitrate concentrations in the USR toward compliance with regulatory standards was submitted for publication in another refereed journal article, was published in an MS thesis, and was published in a popular water news magazine. The coupled RT3D-OTIS model was calibrated, tested, and initially applied for predicting selenium and nitrogen concentrations in the groundwater and stream network of the DSR under baseline and BMP conditions. This work was documented in an MS thesis. Initial development was completed of a three dimensional coupled groundwater reactive transport and equilibrium chemistry model to simulate salt ion fate and transport in irrigated agricultural watersheds. The model, UZF-RT3D/SEC uses the finite-difference method to simulate transport of the major salt ions sulfate, calcium, magnesium, sodium, chloride, and bicarbonate. It accounts for crop uptake, soil organic matter decomposition, mineralization/immobilization, and oxidation-reduction reactions in the transport module, as well as equilibrium chemical reactions such as precipitation/dissolution of salt minerals, complexation, and cation exchange. Calibration and testing of the model was completed to meet targets for total dissolved solids (TDS) in the unsaturated zone; TDS and major salt ion concentrations in the saturated zone; and sulfate and TDS loading to the Arkansas River and its tributaries. The model was applied for initial evaluation impacts of several selected BMPs in the USR on groundwater and soil salinity, with consequent impacts on crop yield. A refereed journal article documenting the development and application of the UZF-RT3D/SEC model to the USR was submitted for possible publication. Work was initiated on coupling the UZF-RT3D/SEC groundwater model with the stream flow and water quality models (SFR, OTIS-QUAL2E) in application to an evaluation of salinity in the downstream study region (DSR) of the LARV. The model will be calibrated, tested, and applied to explore BMPs for lowering salinity and boosting crop yields in the DSR, with eventual extension to the USR. (2) The LARV basin-scale model (River GeoDSS) was further enhanced to examine ways to implement BMPs without harming Colorado water rights or violating the Arkansas River Compact with Kansas. Artificial neural networks (ANN) were refined to act as a surrogate to a MODFLOW model of the LARV, leveraging the highly well-calibrated regional flow models in the USR and DSR into a larger basin-scale model without a need to create a basin-wide MODFLOW model. The River GeoDSS model was initially applied to examine BMP impacts on river flows and water rights within Colorado and on river flows crossing the state line into Kansas. (3) A report entitled "The Economics of Irrigation in Colorado's Lower Arkansas River Basin", was published in November 2017. The report documents the basic economic factors a farmer must consider at the field level, as well as institutional hurdles to be addressed, when switching to more efficient irrigation practices which lead to improved water quality. The report includes information about water management beyond the farm gate. Budgets were developed to describe costs of lining canals, which occurs off the farm. (4) A website (www.coloradoarmac.org) was used for exchange of information about the project, including access to GIS-based data and model results through the Environmental Risk Assessment and Management System (eRAMs) platform. The website facilitates information exchange between stakeholders and water specialists and evaluation of the pros and cons of available land and water management options. (5) As described above, progress has been made in refining groundwater and stream models for assessing the technical performance of proposed BMPs. A session entitled "Tackling Water Quality Problems while Keeping Agriculture Productive" was held at the Arkansas River Basin Water Forum in April 2018 where technical and economic aspects of BMP implementation were presented. As part of the session, CSU researchers conducted an interactive dialogue that allowed responses from stakeholders using their smartphones via the internet. The interactive dialogue focused on stakeholder opinions about tradeoffs between economic returns, soil salinity, and selenium and nitrogen pollution in the Arkansas River. (6) Data, modeling results, and economic analysis related to these issues were presented and discussed at a session of the Arkansas River Basin Water Forum in April 2018 and are posted on the ARMAC website. A Sprinkler Irrigation Workshop was conducted in La Junta, Colorado and in Lamar, Colorado in January 2018. Sessions addressed agronomic, engineering, installation, management and economic factors associated with adoption of center pivot irrigation to promote irrigation efficiency with improved water quality. Representatives from the Natural Resource Conservation Service and the Lower Arkansas Valley Water Conservancy District (LAVWCD) were on-hand to explain available cost sharing strategies and options and the Colorado Rule 10 Plan process for irrigation system improvements. (7) Dialogue occurred between CSU researchers and personnel from the LAVWCD and the Colorado Department of Public Health and Environment (CDPHE) regarding pilot field implementation of BMPs to improve water quality. Recommendations for the pilot study were made in light of project findings. (8) Graduate students have been trained in developing and applying computational models for simulating baseline conditions and the impact of alternative BMPs and in their socio-economic analysis and ranking. Undergraduate students have been active in maintaining the ARMAC website, analyzing data and modeling results, and making them accessible to stakeholders. (9) Nothing has been accomplished to date under this objective.

Publications

• Type: Journal Articles Status: Published Year Published: 2018 Citation: Shultz, C. D. , Bailey, R. T., Gates, T. K., Heesemann, B. E., and Morway, E. D. 2018. Simulating selenium and nitrogen fate and transport in coupled stream-aquifer systems of irrigated regions. J. Hydrology, 560, 512  529
• Type: Journal Articles Status: Accepted Year Published: 2018 Citation: Shultz, C. D., Gates, T. K., and Bailey, R. T. 2018. Evaluating best management practices to lower selenium and nitrate in groundwater and streams in an irrigated river valley using a calibrated fate and reactive transport model. J. Hydrology, 566, 299  312.
• Type: Journal Articles Status: Submitted Year Published: 2018 Citation: Gates, T. K., Cox, J. T. , and Morse, K. C. 2018. Uncertainty in mass-balance estimates of regional irrigation-induced return flows and pollutant loads to a river. J. Hydrology: Regional Studies, 19, 193  210.
• Type: Other Status: Published Year Published: 2017 Citation: Osborn, B., Orlando, A. S., Hoag, D. L., Gates, T. K., and Valliant, J. C. 2017. The economics of irrigation in Colorados Lower Arkansas River Valley. Colorado Water Institute Special Report No. 32, Colorado State Univ., Fort Collins, Colo.
• Type: Other Status: Published Year Published: 2018 Citation: Hoag, D. L, Gates, T. K., Bailey, R. T., Shultz, C. D., and Orlando, A. 2018. "Keeping irrigated agriculture productive and the environment health in Colorado's Lower Arkansas River Valley." Colorado Water. Water Center, Colorado State University, Fort Collins, Colo., Mar/Apr.

Progress 09/01/16 to 08/31/17

Outputs
Target Audience:Water resources and irrigation professionals, farmers and irrigators, canal companies, water conservancy districts, state and federal water agencies, general public Changes/Problems:Development, calibration, and application of the DSR regional-scale model and the basin-scale model to assess impact of considered BMPs are taking longer than originally expected. We are particularly concerned about the feasibility of being able to incorporate alternative reservoir management options for offsetting impacts on state line flows. What opportunities for training and professional development has the project provided?Two MS graduate students and two PhD graduate students were trained and mentored in developing, calibrating, and applying computational models for simulating the impact of alternative BMPs on groundwater and stream water quality, irrigated crop production, and water savings. Model development includes intensive FORTRAN and MATLAB programming, de-bugging, and the use of GIS pre-processing tools. Besides developing and enhancing computational algorithms, graduate students have learned about model coupling and code parallelization for enhancing model run-time. One graduate student successfully defended his MS thesis, entitled "Finding Land and Water Management Practices to Reduce Selenium and Nitrate Concentrations in an Agricultural River Valley Applying a Regional-Scale Stream-Aquifer Model." One MS graduate student was trained and mentored in the socio-economic analysis and ranking of alternative BMPs and successfully defended his thesis, entitled "Economic and Environmental Trade-offs of Irrigation Practices in the Lower Arkansas River Valley". Three MS graduate student and one PhD student presented preliminary modeling results at three professional conferences. One PhD graduate student co-authored a journal article published in Agricultural Water Management. Two undergraduate students have been actively engaged in analyzing data and model results, maintaining the ARMAC website, and making data and modeling results accessible to ARMAC members and the interested public through the eRAMS platform. Faculty members are enhancing their expertise in modeling of irrigated stream-aquifer systems, socio-economic analysis of BMPs, and in participatory planning and analysis for enhancing irrigated crop productivity and the environment. How have the results been disseminated to communities of interest?Results have been presented to shareholders at ARMAC meetings, to a board meeting of the Lower Arkansas Valley Water Conservancy District (a key agency for preservation of agricultural water resources in the LARV), in newspaper articles in the LARV, in a radio interview in the LARV, at three professional conferences, and in two refereed journal articles. The ARMAC website is being used as a platform for data and information exchange. What do you plan to do during the next reporting period to accomplish the goals?Plans for the next reporting period are summarized under each of the nine project objectives as follows: A number of actions are planned: The coupled RT3D-OTIS-QUAL2E model will be further calibrated and tested for predicting selenium and nitrogen concentrations in the groundwater and stream network of the DSR under baseline conditions.The coupled RT3D-salt transport and equilibrium chemistry model will be applied to simulate subsurface dissolved salts and crop yield impacts in the USR under alternative BMPs.The coupled RT3D-salt transport and equilibrium chemistry model will be calibrated and tested in the DSR against field data on soil water content, soil salinity, groundwater salt ion concentrations, and salt ion mass loading to the Arkansas River.Work will commence on developing and calibrating an RT3D-OTIS-QUAL2E groundwater-surface water model for simulating the loading and transport of salt ions in the Arkansas River and its tributaries in the USR and DSR. A discussion will be facilitated between ARMAC committee members and the broader water management community to refine and rank BMPs and to plan for their implementation. The River GeoDSS model with enhanced ANNs will be used to evaluate the compliance of potential BMPs with Colorado water law and the Arkansas River Compact. River GeoDSS and the H-I model simulations will be compared to ensure that the Colorado-Kansas interstate compact can be met and that all basin water rights can be satisfied. Work will begin on incorporating storage accounts in John Martin Reservoir, and possibly Pueblo Reservoir, for capturing and storing additional Arkansas River flows resulting from reduced diversions as a consequence of BMP implementation, into the River GeoDSS model. This will allow simulation of flow releases from the reservoirs to offset depletions to the river. Work will commence on use of the River GeoDSS model to examine preliminary strategies for integrated, basin-scale river-reservoir system management to facilitate implementation of BMP strategies. The report on "The Economics of Irrigation in Colorado's Lower Arkansas River Valley", reviewed by selected stakeholders in the LARV, will be published by the Colorado Water Institute and posted on their website. The ARMAC will provide refined input on the evaluation and ranking of BMPs for eventual implementation based upon simulated outcomes for salinity, selenium, and nitrogen concentrations; net economic returns; and water savings. The goal will be to compare economic and environmental outcomes of a given land and water management practice at the regional level. Models also will be used to evaluate various policy options that can help LARV residents to better manage their resources. Estimates of costs to implement alternative BMPs, including collective augmentation of depleted return flows, will be refined. To the extent possible, benefits of water quality improvement and enhancement to crop productivity brought about by alternative BMPs also will be estimated. Efforts will continue to enhance access to field data, model simulations, and socio-economic analysis through the ARMAC website and linked eRAMS platform. A major forum of interaction between the CSU research team, ARMAC committee members, and the broader water management community is planned for the Arkansas River Basin Water Forum to be held 11 - 12 April 2018 in La Junta, CO. Findings on the most promising BMPs for economic return, crop productivity enhancement, and river pollution mitigation will be presented. A facilitator will be engaged to guide ARMAC members and the water community to discuss, debate, and rank alternative BMPs to be targeted for implementation. Follow up meetings may be held between CSU researchers and stakeholders to assist with their implementation plans. The CSU research team will continue to apply regional-scale and basin-scale simulation models and socio-economic analysis tools to evaluate BMPs recommended for consideration by the ARMAC with a special focus on the DSR. Expanded attention also will be given to basin-wide impacts. Results will be reported at the Arkansas River Basin Water Forum and on the ARMAC website. Newspaper articles and local radio, along with other appropriate media, also will be used to provide updates on project progress to the general public in the LARV. A printed article on major findings and top-ranking BMPs recommended for consideration is planned for the February or April edition of Colorado Water, a widely-read magazine focusing on water issues in Colorado. The Arkansas River Basin Water Forum and ARMAC website will be used as media for communicating the rationale and methods for identifying, evaluating, and providing administrative support for promising BMPs using data and models. Three to four journal articles are expected to be submitted, describing the calibration and application of the coupled RT3D-OTIS-QUAL2E groundwater-surface water models for evaluating baseline conditions and the impact of BMPs on loads and concentrations of selenium and nitrogen in streams. Two journal articles are expected to be submitted, describing the calibration and application of the coupled RT3D salt transport and chemical equilibrium model for evaluating baseline conditions and the impact of BMPs on soil and groundwater salinity and crop productivity. One to two journal articles are expected to be submitted describing the development and application of the River GeoDSS model to examine the impact of proposed BMPs on flows within the LARV in Colorado and crossing the state line into Kansas. One article is expected to be submitted describing the socio-economic evaluation of the alternative BMPs for enhancing the LARV environment and sustaining crop productivity. Results of the project will be presented at CSU Hydrology Days (March 2018) and at three national or four national conferences. Faculty will continue to mentor graduate and undergraduate students in data assessment, model development and application, and participatory evaluation of the feasibility and practicability of alternative BMPs. Graduate students will continue to interact with shareholders in the LARV. Descriptions of the development and application of flow and solute transport models and of socio-economic analyses of BMPs will be incorporated into the syllabus of selected courses at CSU for spring and fall semesters, 2018.

Impacts
What was accomplished under these goals? Accomplishments under each of the nine project objectives, as described above, are summarized as follows: The ARMAC, made up of about 10 farmers and 17 other water stakeholders in the LARV, met three times to assess results and provide guidance on best management practices (BMPs) that are practicable as well as effective.Regional-scale models of water flow and quality in the LARV were further enhanced and applied for evaluating alternative BMPs identified by the ARMAC and the CSU research team:. Groundwater (MODFLOW-UZF, UZF-RT3D) and surface water (SFR, OTIS-QUAL2E) flow and solute transport models have been successfully linked and their calibration and testing, using field data from the upstream study region (USR) in the LARV, was completed. The linked models were were applied to explore the potential for alternative best management practices (BMPs) to lower selenium and nitrate concentrations in the USR toward compliance with regulatory standards. A total of 67 water and land BMPs, including 39 combination scenarios, were examined. The BMPs included reduced irrigation application (RI); canal sealing to reduce seepage (CS); rotational lease-fallowing of irrigated land (LF); reduced fertilizer application (RF); enhanced riparian buffers (ERB); and their various combinations, at basic, intermediate, and aggressive levels. Results reveal the potential to reduce average concentrations along the Arkansas River within the region by as much as about 50% for selenium and about 30% for nitrate by applying BMPs that include ERB and RF. If implementing water BMPs alone, the most effective combinations include RI, LF, and CS which were predicted to achieve up to about a 20% reduction of selenium but result in increased nitrate concentrations if not coupled with ERB and RF land BMPs. Progress was made in application of the models to examine BMPs for a downstream study region (DSR) in the LARV. A three dimensional coupled groundwater reactive transport and equilibrium chemistry model has been developed to simulate salt ion fate and transport in irrigated agricultural watersheds. The model uses the finite-difference method to simulate transport of the major salt ions sulfate, calcium, magnesium, sodium, chloride, and bicarbonate. It accounts for crop uptake, soil organic matter decomposition, mineralization/immobilization, and oxidation-reduction reactions in the transport module, as well as equilibrium chemical reactions such as precipitation/dissolution of salt minerals, complexation, and cation exchange. Calibration was conducted to meet targets for total dissolved solids (TDS) in the unsaturated zone; TDS and major salt ion concentrations in the saturated zone; and sulfate and TDS loading to the Arkansas River and its tributaries. The model will be applied to evaluate BMP impacts on groundwater and soil salinity, with consequent impacts on crop yield. The LARV basin-scale model (River GeoDSS) was enhanced to examine ways to implement BMPs without harming Colorado water rights or violating the Arkansas River Compact with Kansas. Artificial neural networks (ANN) were refined to act as a surrogate to a MODFLOW model of the LARV, leveraging the highly well-calibrated regional flow models in the USR and DSR into a larger basin-scale model without a need to create a basin-wide MODLOW model. The output of the ANN surrogate model was coupled with the MODSIM generalized surface water model used in this project to simulate basin-wide streamflow. The basin-wide model is calibrated to available stream gauge data and applied to examine BMP impacts on flows within Colorado and crossing the state line into Kansas. A report entitled "The Economics of Irrigation in Colorado's Lower Arkansas River Basin", was completed and is awaiting publication. The report documents the basic economic factors a farmer must consider at the field level as well as institutional hurdles to be addressed when switching to more efficient irrigation practices. The report includes information about water management beyond the farm gate. Budgets were developed to describe costs of lining canals, which occurs off the farm.This basic economic information was combined with data and modeling results to determine economic and environmental tradeoffs for different BMP strategies in the LARV. A regional linear programming (LP) model was developed with an objective function that maximizes net income for the region, while meeting several constraints regarding environmental and physical conditions, water availability and use, and institutions. Net returns include income over variable costs for crops produced, increased yields when salinity is reduced, reduced yields when fertilizer is reduced, and canal sealing costs, including buying replacement water. The baseline was furrow or flood irrigation. RI and RF BMPs were applied at 10, 20, and 30 percent levels of reduction and LF BMPs were applied at 10, 20 and 30 percent of irrigated acreage. CS BMPs were applied at 20, 40, 60 and 80 levels of seepage reduction over all six major canals. Pollution outputs are simulated by flow and solute transport models for each scenario, thus providing information about the tradeoffs between four outcomes: net income, soil salinity reduction, river selenium concentration reduction, and river nitrogen concentration reduction for the baseline and for each of the considered BMPs. While no single BMP or combination provides an across the board win; however, four provide high results for all four outcomes: RI30%+RF30%+CS80%, LF30%+RF30%+CS80%, RI30%+LF30%+CS80%, and all BMPs at aggressive levels. A website (www.coloradoarmac.org) is used for exchange of information about the project, including access to GIS-based data and model results through the Environmental Risk Assessment and Management System (eRAMs) platform. The website facilitates information exchange between stakeholders and water specialists and evaluation of the pros and cons of available land and water management options. As described above, progress has been made in refining groundwater and stream models for assessing the technical performance of proposed BMPs. Three meetings were held with the ARMAC, culminating in a meeting in August to present results for the USR in a way that lets users interact with researchers about tradeoffs between economic returns, soil salinity, and selenium and nitrogen pollution in the Arkansas River. A format was used that allows local stakeholders to decide how they want to move forward and to guide their local projects and planning efforts. We also met with a smaller set of local water managers about coordinating their pilot programs to feature water management options and to further investigate how they might impact the river and ground water. Data, modeling results, and economic analysis related to these issues were presented and discussed at ARMAC meetings and are posted on the ARMAC website. Refined model predictions of BMP impacts on water table depth, groundwater solute concentrations, and stream concentrations have been presented to the ARMAC. Project graduate students have attended the ARMAC meetings. Refined model results will be made accessible via the eRAMS platform link within the ARMAC website. Plans are being made for a meeting in April 2018 that will be targeted at all stakeholders in the region. That effort includes a media campaign, a publication in a widely read Colorado water publication, and a community meeting. Graduate students have been trained in developing and applying computational models for simulating baseline conditions and the impact of alternative BMPs and in their socio-economic analysis and ranking. Undergraduate students have been active in maintaining the ARMAC website, analyzing data and modeling results, and making them accessible to ARMAC members and the interested public through the eRAMS platform. Nothing has been accomplished to date under this objective.

Publications

• Type: Journal Articles Status: Published Year Published: 2017 Citation: Tavakoli Kivi, S., and Bailey, R. T. 2017. "Modeling sulfur cycling and sulfate reactive transport in an agricultural groundwater system." Agricultural Water Management, 185, 78 - 92.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Sharp, M., Hoag, D., Bailey, R. T., Romero, E. C., and Gates, T. K. 2016. Institutional constraints on cost-effective water management: Selenium contamination in Colorados Lower Arkansas River Valley. Journal American Water Resources Association, 52(6), 1420  1432.
• Type: Other Status: Awaiting Publication Year Published: 2017 Citation: Osborn, B., Orlando, A. S., Hoag, D. L., Gates, T. K., and Valliant, J. C. 2017. The economics of irrigation in Colorados Lower Arkansas River Valley. Colorado Water Institute Special Report No. 32, Colorado State Univ., Fort Collins, Colo.

Progress 09/01/15 to 08/31/16

Outputs
Target Audience:Water resources and irrigation professionals, farmers and irrigators, canal companies, water conservancy districts, state water agencies, federal water agencies, general public. Changes/Problems:Request for a one-year no-cost project extension is expected to be submitted in order to adequately complete project goals. Development, calibration, and application of regional-scale and basin-scale models to assess impact of considered BMPs is taking longer than originally expected. What opportunities for training and professional development has the project provided?Two MS graduate students and two PhD graduate students are being trained and mentored in developing, calibrating, and applying computational models for simulating the impact of alternative BMPs on groundwater and stream water quality, irrigated crop production, and water savings. Model development includes intensive FORTRAN and MATLAB programming, de-bugging, and the use of GIS pre-processing tools. Besides developing and enhancing computational algorithms, graduate students have learned about model coupling and code parallelization for enhancing model run-time. One MS graduate student is being trained and mentored in the socio-economic analysis and ranking of alternative BMPs. One MS graduate student and one PhD student presented preliminary modeling results at a professional conference. Four undergraduate students have been actively engaged in analyzing data and model results, developing the ARMAC website, and making data and modeling results accessible to ARMAC members and the interested public through the eRAMS platform. Faculty members are enhancing their expertise in modeling of irrigated stream-aquifer systems, socio-economic analysis of BMPs, and in participatory planning and analysis for enhancing irrigated crop productivity and the environment. How have the results been disseminated to communities of interest?Results have been presented to shareholders at ARMAC meetings, to a board meeting of the Lower Arkansas Valley Water Conservancy District (a key agency for preservation of agricultural water resources in the LARV), in newspaper articles in the LARV, in two radio interviews in the LARV, and at a professional conference. The ARMAC website is being used as a platform for data and information exchange. What do you plan to do during the next reporting period to accomplish the goals?Plans for the next reporting period are summarized under each of the nine project objectives as follows: 1. A number of actions are planned: Continued guidance from the ARMAC committee members and other interested parties will be sought to refine the definition of feasible and practicable BMPs for consideration, and their evaluation and ranking. The coupled RT3D-OTIS-QUAL2E model will be further calibrated for predicting selenium and nitrogen concentrations in the groundwater and stream network of both the Upstream Study Region (USR) and the Downstream Study Region (DSR) under baseline conditions. The coupled RT3D-salt equilibrium model will be calibrated and tested to simulate subsurface dissolved salts in (1) the soil profiles in Rocky Ford, CO, and (2) the USR and the DSR. Testing data will include soil water content, soil salinity, groundwater salt ion concentrations, and salt ion mass loading to the Arkansas River. Work will begin on using crop production functions to estimate the effects of altered soil water and salinity under considered BMPs on relative crop yield. Work will commence on developing and calibrating an RT3D-OTIS-QUAL2E groundwater-surface water model for simulating the loading and transport of salt ions in the Arkansas River and its tributaries. Calibrated models will be applied for simulating salt ions, selenium, and nitrogen will be used to estimate the likely impact of BMPs, defined by the ARMAC, on groundwater and surface water quality, irrigated crop productivity, and water savings in both the USR and DSR. 2. Work will be completed on the enhancement of ANNs for predicting return flows to the Arkansas River under considered BMPs for both the USR and DSR. The River GeoDSS model with enhanced ANNs will be used to evaluate the compliance of potential BMPs with water law and the Arkansas River Compact. River GeoDSS and the H-I model simulations will be compared to ensure that the Colorado-Kansas interstate compact can be met and that all basin water rights can be satisfied. Use of storage accounts in John Martin Reservoir, and possibly Pueblo Reservoir, for capturing and storing additional Arkansas River flows resulting from reduced diversions as a consequence of BMP implementation, will be incorporated into the River GeoDSS model. This will allow simulation of flow releases from the reservoirs to offset depletions to the river. Work will commence on use of the River GeoDSS model to examine preliminary strategies for integrated, basin-scale river-reservoir system management to facilitate implementation of BMP strategies. 3. Review of the draft report on "The Economics of Irrigation in Colorado's Lower Arkansas River Valley" by key stakeholders in the LARV will be completed and the report will be published and distributed. The ARMAC will provide input on the evaluation and ranking of BMPs for eventual implementation. Information will be integrated about farm-level economics with regional models outcomes for salinity, selenium, and nitrogen concentrations; irrigated crop productivity; and water savings. The goal will be to compare economic and environmental outcomes of a given land and water management practice at the regional level. Models also will be used to evaluate various policy options that can help LARV residents to better manage their resources. Estimates of costs to implement alternative BMPs, including collective augmentation of depleted return flows, will be refined. To the extent possible, benefits of water quality improvement and enhancement to crop productivity brought about by alternative BMPs also will be estimated. 4. Efforts will continue to enhance access to field data, model simulations, and socio-economic analysis through the ARMAC website and linked eRAMS platform. 5. Results of the completed survey of farmers regarding current knowledge, attitudes, and practices related to crop production, water management, and potential water pollution will be published. Results will guide on-going discussions at ARMAC meetings and via the website regarding feasible and practicable BMPs for consideration. The survey will be repeated at project end to assess the project impact on knowledge, attitudes, and most importantly water management practices in the region. Three to four ARMAC meetings are planned.Interactions with the ARMAC will be tracked on an ongoing basis.Meeting agendas will be jointly agreed-upon by the ARMAC and the CSU research team.The purpose of each meeting will be recorded and three major questions will be asked at the end of each meeting:1) "What is the need?", 2) "Are our current efforts addressing these needs?", and (3) "What are the next steps?". Feedback from the meetings and from exchange of information via the website will be used to refine the analysis and evaluation of BMPs for further consideration by the ARMAC in determining ranked preferences. 6. The CSU research team will continue to apply regional-scale and basin-scale simulation models and socio-economic analysis tools to evaluate BMPs recommended for consideration by the ARMAC. Expanded attention will be given to basin-wide impacts. Results will be reported at three to four ARMAC meetings and on the ARMAC website. Newspaper articles and local radio, along with other appropriate media, also will be used to provide updates on project progress to the general public in the LARV. 7. ARMAC meetings and the ARMAC website will continue to be used as media for communicating the rationale and methods for identifying, evaluating, and providing administrative support for promising BMPs using data and models.At least one journal article is expected to be submitted, describing the development and testing of the coupled RT3D-chemical equilibrium model for evaluating baseline conditions and the impact of BMPs on soil and groundwater salinity and crop productivity.Two journal articles are expected to be submitted, describing the development and testing of the coupled RT3D-OTIS-QUAL2E groundwater-surface water models for evaluating baseline conditions and the impact of BMPs on loads and concentrations of selenium and nitrogen in streams. Results of the project will be presented at CSU Hydrology Days (March 2017) and at two to three national conferences. 8. Faculty will continue to mentor graduate and undergraduate students in data assessment, model development and application, and participatory evaluation of the feasibility and practicability of alternative BMPs. Graduate students will continue to attend ARMAC meetings and increasingly will interact with shareholders in the LARV. 9. Descriptions of the development and application of flow and solute transport models and of socio-economic analyses of BMPs will be incorporated into the syllabus of selected courses at CSU for fall semester, 2017.

Impacts
What was accomplished under these goals? Methods and tools developed in this project are expected to contribute to the solution of two great challenges to preserving and enhancing productive irrigated lands: (1) salt and pollutant build-up in surface and groundwater, with consequent damage to crop yields and the environment, and (2) growing urban competition for water supplies. The second year of the project focused on engaging with the Arkansas River Management Action Committee (ARMAC) stakeholder group of water users and agencies in Colorado's Lower Arkansas River Valley (LARV) to gain insight into practicable and cost-effective alternative Best Management Practices (BMPs) in the LARV, conducting and interpreting a broad survey of representative stakeholders in the LARV, calibrating and applying models to assess the effectiveness of alternative BMPs in the LARV, gathering information to measure the socio-economic impact of BMPs, and preparing a report on the economics of irrigation in the LARV. Accomplishments under each of the nine project objectives, as described above, are summarized as follows: 1. The ARMAC, made up of about 10 farmers and 17 other water stakeholders in the LARV, met three times to assess study results and provide guidance in the search for BMPs that are practicable as well as effective. Regional-scale models of groundwater and surace water flow and quality in the LARV have been enhanced and applied for evaluating the alternative BMPs identified by the ARMAC and the CSU team: Groundwater (MODFLOW-UZF, UZF-RT3D) and surface water (SFR, OTIS-QUAL2E) flow and solute transport models have been successfully linked and initially calibrated and tested using extensive field data from a region in the LARV. The linked models have been used to simulate groundwater concentrations, loading rates to streams, and concentrations in streams for selenium and nitrogen under baseline conditions over the period 1999 - 2009. They have been applied to explore the potential for alternative best management practices (BMPs) to lower concentrations in the region toward compliance with regulatory standards and performance goals. The following BMPs have been examined so far: reduced fertilizer application by 30% (RF30); reduced irrigation application by 30% (RI30); canal sealing to reduce seepage by 80% (CS80); rotational lease-fallowing of irrigated land by 25% (LF25); combination of RF30 and CS80; and combination of RF30, CS80, and RI30. Preliminary results indicate the potential to reduce average concentrations along the Arkansas River within the region by as much as about 9% for nitrate and 11% for selenium. Additional BMPs, both single and combined, are being considered. Application of the models to examine BMPs for another LARV region located further downstream has been initiated. The groundwater models were revised to include the transport and equilibrium chemical reactions of all major dissolved inorganic ions that make up salinity. Preliminary simulations have been completed, including a comparison to observed sulfate concentrations in the study region for baseline conditions. Calibration and testing activities are underway, leading to model applications to evaluate the impact of several alternative BMPs on groundwater salinity and soil salinity, with consequent impacts on crop yield. Preliminary assessment of a few BMPs indicates potential for substantial decrease in salt loading to the Arkansas River. 2. The LARV basin-scale model (River GeoDSS) is being revised to examine ways to implement BMPs without harming Colorado water rights or violating the Arkansas River Compact. Results from regional-scale modeling are being incorporated, using artificial neural networks (ANN), to estimate how irrigation return flow and in-stream flow will be impacted by BMPs and to explore different operational schemes for mitigating impacts. Work was conducted on refining the existing ANNs to enhance accuracy and extended application along the LARV. The River GeoDSS model employs a hydro-administrative component and considers up-to-date spatial features, stream gauge measurements, rainfall measurements, groundwater return flow model, water rights and storage accounts in the LARV. A meeting was held with personnel from the Colorado Division of Water Resources to discuss options for setting up reservoir storage accounts and altering river operations to meet Compact requirements. 3. A report entitled "The Economics of Irrigation in Colorado's Lower Arkansas River Basin", has been drafted for publication through the Colorado Water Institute. The report documents the basic economic factors a farmer must consider at the field level as well as institutional hurdles to be addressed when switching to a more efficient irrigation practice. The report is based on extensive interviews of farmers and other stakeholders in the LARV, and includes information about water management beyond the farm gate. Budgets also have been developed to describe costs of lining canals, which occurs off the farm. This basic economic information will be combined with data and modeling results to determine economic and environmental tradeoffs for different BMP strategies in the LARV, then communicated to the ARMAC at the end of the project. 4. A website (www.coloradoarmac.org) was set up for exchange of information about the project, including access to GIS-based data and model results through the eRAMs platform. The website facilitates interaction between stakeholders and water specialists and evaluation of the pros and cons of available land and water management options. eRAMs provides access to field data and modeling results. 5. Progress has been made in refining groundwater and stream models for assessing the technical performance of proposed BMPs. Input has been provided by the ARMAC on additional BMPs for consideration. A survey was sent to 400 LARV farmers to establish a baseline about farmers' awareness and actions toward BMPs related to salinity, selenium and nitrogen. A similar survey is planned at the end of the project to determine if attitudes and/or practices have changed. About 30% responded, nearly 50% when you exclude surveys sent to farmers that no longer irrigate. Early results suggest that producers are more aware about salinity and nitrogen problems than about selenium problems. They are split as to whether they would be willing to incur costs to adopt BMPs, but would implement them to avoid regulations. They are united in feeling that if they do not change their practices then both water quality and quantity will be at risk in the future. The final evaluation and ranking of a refined set of BMPs, to be recommended by the ARMAC for consideration, has not yet been conducted. 6. Data, modeling results, and economic analysis related to these issues were presented and discussed at ARMAC meetings and are posted on the ARMAC website. 7. Refined model predictions of BMP impacts on water table depth, groundwater solute concentrations, and stream concentrations have been presented to the ARMAC. Project graduate students have attended the ARMAC meetings. Refined model results will be made accessible via the Environmental Risk Assessment and Management System (eRAMS) platform link within the ARMAC website. Discussions have begun with stakeholders to encourage active participation in assessing BMPs under current consideration and proposing new BMPs for consideration. 8. Graduate students have been trained in developing, calibrating, and applying computational models for simulating baseline conditions and the impact of alternative BMPs and in their socio-economic analysis and ranking. Undergraduate students have been active in developing the ARMAC website, analyzing data and modeling results, and making them accessible to ARMAC members and the interested public through the eRAMS platform. 9. Nothing has been accomplished to date under this objective.

Publications

• Type: Journal Articles Status: Published Year Published: 2016 Citation: Sharp, M., Hoag, D., Bailey, R. T., Romero, E. C., and Gates, T. K. 2016. Institutional constraints on cost-effective water management: Selenium contamination in Colorados Lower Arkansas River Valley. J. Amer. Water Resour. Assoc., Published online Sept 2016.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Rohmat, F., Labadie, J. W., and Gates, T. K. 2016. "Artificial neural network database development for modeling stream-aquifer interactions in the Lower Arkansas River Basin of Colorado." Hydrology Days 2016, Fort Collins, CO.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Shultz, C. D., Gates, T. K., and Bailey, R. T. 2016. "Finding land and water management practices to lessen river pollutant concentrations in irrigated regions." Hydrology Days 2016, Fort Collins, CO.

Progress 09/01/14 to 08/31/15

Outputs
Target Audience:Water resources and irrigation professionals, farmers and irrigators, canal companies, water conservancy districts, state water agencies, federal water agencies, general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Two MS graduate students and two PhD graduate students are being trained and mentored in developing, calibrating, and applying computational models for simulating the impact of alternative BMPs on groundwater and stream water quality, irrigated crop production, and water savings. Model development includes intensive FORTRAN and MATLAB programming, de-bugging, and the use of GIS pre-processing tools. Besides developing and enhancing computational algorithms, graduate students have learned about model coupling and code parallelization for enhancing model run-time. One MS graduate student and one PhD student are being trained in the socio-economic analysis and ranking of alternative BMPs. One PhD graduate student has presented preliminary modeling results at a professional conference. Two undergraduate students have been actively engaged in developing the ARMAC website and making data and modeling results accessible to ARMAC members and the interested public through the eRAMS platform. Faculty members are enhancing their expertise in modeling of irrigated stream-aquifer systems, socio-economic analysis of BMPs, and in participatory planning and analysis for enhancing irrigated crop productivity and the environment. How have the results been disseminated to communities of interest?As described above, results have been presented to shareholders at ARMAC meetings, in newspaper articles in the LARV, and at a professional conference. The ARMAC website also has been developed as a platform for data and information exchange. What do you plan to do during the next reporting period to accomplish the goals?Plans for the next reporting period are summarized under each of the nine project objectives as follows: (1)A number of actions are planned: Guidance from the ARMAC committee members and other interested parties will be sought to refine the definition of feasible and practicable BMPs for consideration. All major anions and cations will be included in the standard RT3D to provide an accurate coupling with the salt equilibrium module. The coupled RT3D-salt equilibrium model will be calibrated and tested to simulate subsurface dissolved salts in (1) the soil profiles in Rocky Ford, CO, and (2) the USR and the DSR. Testing data will include soil water content, soil salinity, groundwater salt ion concentrations, and salt ion mass loading to the Arkansas River. Work will begin on using crop production functions to estimate the effects of altered soil water and salinity under considered BMPs on relative crop yield. Work will commence on developing and calibrating an RT3D-OTIS-QUAL2E groundwater-surface water model for simulating the loading and transport of salt ions in the Arkansas River and its tributaries. The coupled RT3D-OTIS-QUAL2E model will be further calibrated for predicting Se and nitrogen concentrations in both the USR and DSR using sensitivity analysis and the Parameter ESTimation (PEST) software. Calibrated models for simulating salt ions, Se, and nitrogen will be used to estimate the likely impact of BMPs, defined by the ARMAC, on groundwater and surface water quality, irrigated crop productivity, and water savings. (2)Compliance of potential BMPs with water law and the Arkansas River Compact will be assessed using the ANN-enriched River GeoDSS model. Since the ANN has only been trained for the USR, work will commence to apply it to the DSR and determine if separate ANNs are required for each region, or if a composite ANN is possible. River GeoDSS and the H-I model simulations will be compared to ensure that the Colorado-Kansas interstate compact can be met and that all basin water rights can be satisfied. Meetings will be set up with CDWR to discuss the possibility of establishing storage accounts in John Martin Reservoir, and possibly Pueblo Reservoir, for capturing and storing additional Arkansas River flows resulting from reduced diversions as a consequence of BMP implementation. Preliminary indications are that such accounts are feasible, but require extensive investigation of legal and administrative ramifications. Preliminary strategies for integrated, basin-scale river-reservoir system management will be developed and tested for a wide variety of conservation scenarios. In addition, an attempt will be made to transform River GeoDSS into a collaborative decision support system that allows stakeholders to play an active role in the development and implementation of BMP strategies. (3)Economic analysis will progress in three major phases. In Phase 1, to be completed by June 2016, detailed partial enterprise budgets will be developed for the land and water management practices examined in the BMP modelling efforts. The ARMAC will help in choosing which land and water management practices should be considered. Existing crop enterprise budgets for the region for major crops will be identified, which will serve as a baseline for all costs except irrigation. Irrigation activities will be divided into conveyance and application activities. With the assistance of local extension contacts and water groups this information will be assembled in an extension publication to guide farmers through decisions to alter their irrigation existing systems. Phase 2, to begin in late summer or early fall 2016, will involve integrating information about farm-level economics with regional models outcomes for salinity, Se, and nitrogen concentrations; irrigated crop productivity; and water savings. The goal will be to compare economic and environmental outcomes of a given land and water management practice at the regional level. Models also will be used to evaluate various policy options that can help LARV residents to better manage their resources. To the extent possible, welfare analysis will be included by valuing water quality losses. Phase 3, to begin in spring 2017, will involve cooperating with all members of the project to develop tools that the ARMAC and others can use to help make informed decisions about how to manage land and water in the LARV in a sustainable way. (4)Efforts will continue to enhance access to field data, model simulations, and socio-economic analysis through the ARMAC website and linked eRAMS platform. (5)A longitudinal survey of 400 LARV farmers will be administered to assess current knowledge, attitudes, and practices related to crop production, water management, and potential water pollution. Results will guide on-going discussions at ARMAC meetings and via the website regarding feasible and practicable BMPs for consideration. The survey will be repeated at project end to assess the project impact on knowledge, attitudes, and most importantly water management practices in the region. Three to four ARMAC meetings will be held. Interactions with the ARMAC will be tracked on an ongoing basis. Meeting agendas will be jointly agreed-upon by the ARMAC and the CSU research team. The purpose of each meeting will be recorded and three major questions will be asked at the end of each meeting: 1) "What is the need?", 2) "Are our current efforts addressing these needs?", and (3) "What are the next steps?". Feedback from the meetings and from exchange of information via the website will be used to refine the analysis and evaluation of BMPs for further consideration by the ARMAC in determining ranked preferences. (6)The CSU research team will apply regional-scale and basin-scale simulation models and socio-economic analysis tools to evaluate BMPs recommended for consideration by the ARMAC. Results will be reported at three to four ARMAC meetings and on the ARMAC website. Newspaper articles and local radio, along with other appropriate media, also will be used to provide updates on project progress to the general public in the LARV. (7)ARMAC meetings and the ARMAC website will continue to be used as media for communicating the rationale and methods for identifying, evaluating, and providing administrative support for promising BMPs using data and models. Two to three journal articles will be submitted, describing the development and testing of the coupled RT3D-chemical equilibrium model for evaluating the impact of BMPs on soil and groundwater salinity and crop productivity. One to two journal articles will be submitted, describing the development and testing of the coupled RT3D-OTIS-QUAL2E groundwater-surface water models for evaluating the impact of BMPs on loads and concentrations of salt, Se, and nitrogen in streams. Results of the project will be presented at CSU Hydrology Days (March 2016) and at two to three national conferences. (8)Faculty will continue to mentor graduate and undergraduate students in data assessment, model development and application, and participatory evaluation of the feasibility and practicability of alternative BMPs. Graduate students will continue to attend ARMAC meetings and increasingly will interact with shareholders in the LARV. (9)Descriptions of the development and application of flow and solute transport models and of socio-economic analyses of BMPs will be incorporated into the syllabus of selected courses at CSU for fall semester, 2016.

Impacts
What was accomplished under these goals? Methods and tools developed in this project are expected to contribute to the solution of two great challenges to highly productive irrigated lands: (1) salt and pollutant build-up in surface and groundwater, with consequent damage to crop yields and the environment, and (2) growing urban competition for water supplies. The first year focused on assembling and building rapport with a stakeholder group of water users and agencies in Colorado's Lower Arkansas River Valley (LARV), refining data and models to assess the effectiveness of alternative Best Management Practices (BMPs) in the LARV, constructing survey tools, and gathering information to measure the socio-economic impact of BMPs. A committee of stakeholders, called the Arkansas River Management Action Committee (ARMAC), was formed and consists of nine farmers and thirteen representatives of local and state water agencies. The aim of the ARMAC is to cooperate with the Colorado State University (CSU) research team to evaluate alternative BMPs to improve water quality, enhance crop productivity, and save water in the LARV. This will involve evaluation of the technical, socioeconomic, and administrative viability of alternative management actions. Accomplishments under each of the nine project objectives, as described above, are summarized as follows: (1)Two meetings were held to brief the ARMAC on data and modeling results regarding current water quality, crop productivity, and water use conditions and on preliminary BMPs. A broad survey of farmers was designed for discovering views and preferences regarding the severity of these problems and the most practicable ways to address them. ARMAC members agreed to share their experience and expert opinions in identification and evaluation of additional prospective BMPs. Regional-scale models of groundwater and surface water flow and quality in the LARV have been enhanced for evaluating the alternative BMPs identified by the ARMAC and the CSU team: A module accounting for salt ion equilibrium chemistry and chemical precipitation/dissolution in groundwater has been developed and tested against benchmark data. Numerical methods have been used to optimize calculations. The salt equilibrium module has been coupled with a modified version of the RT3D (Reactive Transport in 3 Dimensions) solute transport model, to better characterize salt ion fate and transport in LARV groundwater systems. The modified RT3D currently simulates the fate and transport of nitrogen, carbon, selenium (Se), and sulfur species. Additional field data (from a companion project) on salt ion concentrations were collected from 3 soil profiles in an irrigated field at the CSU Arkansas Valley Research Center in Rocky Ford, CO. Data will be used to test the salt equilibrium module. The coupled RT3D-equilibrium model currently is being applied to the Upstream Study Region (USR) of the LARV, in the vicinity of La Junta, Colorado. Results look promising in comparison with observed salt concentrations in groundwater. Groundwater-surface water interaction has been modeled using the USGS MODFLOW model with the Stream Flow Routing (SFR) package and RT3D has been used to simulate groundwater solute transport, along with an embedded OTIS-QUAL2E model of reactive transport in the streams. This combined model had been implemented in the USR for simulating Se and nitrogen in the Arkansas River system. Comparison of simulated and observed in-stream Se concentrations led to adjustment of model parameters. Examination of simulated nitrate concentrations indicates an acceptable match with field data. (2)Activities under this objective are described as follows: A meeting was held with the Lead Modeler of the CDWR to discuss options for setting up reservoir storage accounts to permit releases to offset stream depletion due to changes in return flows from BMP implementation. Such augmentation is required to fulfill Colorado's obligations of flow to Kansas under the Arkansas River Compact. A copy of the Hydrologic Institutional (HI) model was acquired and examined, along with associated data sets for running the model, to insure that results from the basin-scale River GeoDSS modeling system do not violate the court-approved flow simulations of the HI model. Although groundwater-surface water interactions have been modeled using the MODFLOW/SFR package, and can be interconnected with River GeoDSS, this modeling is restricted to the USR and the Downstream Study Region (DSR), near Lamar, CO, where extensive data for calibration and testing are available. Unfortunately, such data are lacking in regions above the USR and between the USR and the DSR. An artificial neural network (ANN) has been trained using MODFLOW output under various BMP scenarios in the USR. Inputs to the ANN include various explanatory variables, believed to be correlated with stream-aquifer responses, that can be measured in the basin regions lacking extensive data and. The trained ANN can then be applied to these data-poor areas and incorporated into the River GeoDSS for modeling the river-reservoir system network with inclusion of stream-aquifer interactions. Extensive work has been done in coding the ANN structure for incorporation into River GeoDSS, including development of an application-programming interface for extracting information from the input data sets needed by the ANN. Effort has been directed towards updating the database for River GeoDSS, with particular emphasis on canal diversion data. (3)An graduate student was recruited to focus on economic analysis of alternative BMPs. Initial plans were formulated for developing detailed partial enterprise budgets, in coordination with the ARMAC, for land and water management practices to be examined in the BMP modeling efforts. (4)Work was done on developing a website for the ARMAC (www.coloradoarmac.org) to provide a platform for information exchange, including field data and modeling results, about the potential benefits of alternative BMPs. The website facilitates interaction between stakeholders and water specialists and evaluation of the pros and cons of available land and water management options. (5)Progress has been made in refining groundwater and stream models for assessing the technical performance of proposed BMPs. However, the evaluation and ranking of a refined set of BMPs, to be recommended by the ARMAC for consideration, has not yet been conducted. (6)Data and modeling results related to these issues were presented and discussed at ARMAC meetings in March and June 2015 and are now posted on the ARMAC website. (7)An initial set of BMPs (increased irrigation application efficiency, reduced canal seepage, reduced fertilization, lease-fallowing of irrigated land, and enhanced riparian buffer zones) has been discussed with the ARMAC. Initial model predictions of BMP impacts on water table depth, groundwater solute concentrations, and solute loading rates to the stream system have been presented. Project graduate students have attended the ARMAC meetings. Work is underway to make these and similar model results accessible via the Environmental Risk Assessment and Management System (eRAMS) platform link within the ARMAC website. Discussions have begun with stakeholders to encourage active participation in assessing BMPs under current consideration and proposing new BMPs for consideration. (8)Graduate students were trained in developing, calibrating, and applying computational models for simulating baseline conditions and the impact of alternative BMPs and in their socio-economic analysis and ranking. Undergraduate students have been active in developing the ARMAC website and making data and modeling results accessible to ARMAC members and the interested public through the eRAMS platform. (9)Nothing has been accomplished to date under this objective.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Tavakoli, S., Bailey, R. T., and Gates, T. K. 2015. "Simulating coupled salinity transport model in an agricultural groundwater system." National Ground Water Association Upper Great Plains Groundwater Conference, September 22-23, 2015, Cheyenne, Wyoming.