Guidance Document Part 1B: Conjunctive Management of Surface and Groundwater in the Rio Grande Basin



Rast, Walter
Roberts, Susan V.

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The Rio Grande basin of the southwestern U.S. has known, demonstrable, and complex water issues, including water shortages, flooding, non-flows along several riverbed segments, and water quality challenges. While each broad category of water issues has issues across the basin, perhaps none are as long-lasting as water supply concerns. This report and a previous report (Evaluation Report) prepared under the EPA Geography and Water grant program, focus on conjunctive management as a viable option for water supply. The Evaluation Report provided information about conjunctive use and conjunctive management in general in addition to data and information about programs that are examples of the differential development of conjunctive management. General background information and data were also provided as a context in which to understand conjunctive management. Surveys and interviews about conjunctive management and its applicability were reported. The results strongly indicate that a clear definition of conjunctive management is the basis for understanding its potential as a water management tool. In this document, each work task addresses the basic components of physical water systems, economic factors, legal frameworks, and a societal understanding of conjunctive water management. Physical water systems and economic factors are evaluated through in-depth assessment of published models and programs, with a resulting output of common parameters and data ranges. A review of state water laws provides insights into legal impacts on conjunctive strategies. Research, analysis, and interviews consistently emphasize that there is no single criteria or model that sufficiently defines conjunctive management, and that its flexibility requires a broad approach rather than a single model or narrow set of data by which to rank conjunctive strategies. An in-depth evaluation of major components allows formulation of a conceptual model, criteria, and a decision matrix for planning. The framework is founded upon the four components noted above and then expanded to address critical questions about future water management approaches and issues. The conceptual model and criteria are presented as guidance and as a framework in which future programs can be designed and critiqued. As discussed in the previous Evaluation Report, conjunctive management programs have been developed in certain areas of the Rio Grande basin. The report reviews those programs and summarizes known water management goals of conjunctive strategies, as well as geographic locations that demonstrate water-stress characteristics that conjunctive management may suitably address. To demonstrate the applicability of the conjunctive strategy framework, the criteria and matrix are applied to the water planning region at the lower region of the Rio Grande basin. In summary, research for this document and many other research studies and active conjunctive programs demonstrate the many strengths of conjunctive management. It can be considered a viable, cost-effective management tool, as a stand-alone and supplemental water supply approach, that is worth the consideration and detailed evaluation of many communities in the Rio Grande basin.



water quality, conjunctive water systems, Rio Grande Basin, surface water, groundwater


Rast, W., & Roberts, S. V. (2010). Guidance document part 1B: Conjunctive management of surface and groundwater in the Rio Grande Basin (Report No. 2010-07). Texas State University-San Marcos, San Marcos, Texas.


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