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2006 Project Viability Assessment

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The 2006 Project Viability Assessment (PVA) represents the current view of the project’s feasibility based on results of various yield, engineering, environmental, and cost analyses through the end of 2006. The studies are designed to address the seven legislative findings required for the project to be implemented; state and federal permitting requirements; issues raised by stakeholders, the Science Review Panel, and other members of the public; and technical feasibility.  Following are the key findings and conclusions of the studies of the 2006 PVA:

Content Note: The information in this section is excerpted from the 2006 Project Viability Assessment. To download the full 154-page report click here.

General Findings:

•  While the analyses are not yet complete, indications are that the project can supply a reliable, firm water supply for SAWS and meet the legislative criteria; however, the studies are based on assumptions. As assumptions are refined, the results of the analyses could change and may affect costs or yield of the project.

• The project would provide more reliable water sources for agricultural users served by LCRA in Colorado, Wharton, and Matagorda counties.

• The studies are generally on time and on projection. Some additional technical work is proposed for the study period based on comments and suggestions received during the public involvement and Science Review Panel processes that may affect the overall cost of the studies.

Specific Findings:

• Model simulations for groundwater and river water availability indicate that the yield from conjunctive use of those sources plus agricultural conservation will be sufficient to meet agricultural needs within the lower Colorado River basin more reliably while still supplying up to 150,000 acre-feet per year of water for the San Antonio area. Operating the LCRA system to meet the lower Colorado River basin demands, project yield, lake levels and environmental flow needs will be challenging; additional modeling will be performed to refine options.

• In keeping with the legislation that allows LCRA to consider this project, the average lake levels are expected to be higher over the life of the project compared to corresponding future conditions without the project. Further evaluation of this issue will continue and an implementation plan consistent with the legislative requirements will be developed.

• Analysis of the delivery systems and on-farm conservation strategies continue to indicate that irrigation demand will be reduced sufficiently so that water supplies for agriculture will be more reliable with the project than without conjunctive use of groundwater.

• Current groundwater production simulations indicate that the average value of the net, or incremental, water level drawdown across each irrigation division could range from about 2 feet in Pierce Ranch to a maximum of 12 feet in the Lakeside Irrigation Division during the model simulation period. Because pumping would vary over the life of the project, with virtually no pumping expected in some years, water level drawdowns are also expected to be temporary. These numbers should be considered preliminary, but suggest that the use of groundwater to help meet agricultural needs is feasible with minimal long-term effects on nearby wells.

• The facility siting identification and evaluation process conducted in 2006 confirms that potential locations for proposed project components such as intake structures, pipelines, and off-channel storage facilities (constructed holding basins for surface water) exist. Detailed evaluations conducted by the project team as well as public comments have revealed specific constraints on potential sites. However, the nature of the facilities and the large study area continue to indicate a feasible site for the necessary facilities should be available.

• The final results of the environmental studies (water quality, river habitat, and bay health) are not complete, but have not yet revealed any effects to date that would preclude the project from being implemented.

• The river water quality modeling to date indicates that dissolved oxygen will be within acceptable ranges after anticipated changes to the flow regime associated with the project. Additional water quality parameters may be modeled during 2007. It is expected that the ongoing studies will identify methods for designing and operating the project to meet environmental flow needs as determined by legislative requirements, agency guidance, and/or permit conditions.

• The aquatic habitat studies have documented a significant amount of information on the blue sucker and other species including migration habits during spawning season and specific habitat preferences. This information will be invaluable for developing site plans and operating procedures sensitive to these species.

• Significant strides were made during 2006 in developing measures to benchmark bay health and productivity, diagramming the interdependencies of those measures, and collecting field data to help refine modeling of the system. Further progress was made in characterizing flow throughout the bay system. The flow has changed over time due to the diversions of the Colorado River and impacts of the Gulf Intracoastal Waterway, and characterizing total volume, onset and duration of flow events, usually experienced each year in the spring and fall. The approach to this study looks at bay health from several perspectives (inflow, habitat, and biology) and seeks to link changes to freshwater inflow to changes in the bay’s habitat that could affect the biological systems or productivity of the bay. This approach is expected to better evaluate possible effects of the project on the bay as the studies continue.
  
  
• The study activities planned for 2007 will support submittal of permit applications in 2008 or 2009, as well as addressing key feasibility, legislative and contractual requirements.