Lower South Platte River Study

• Contractor Name: Colorado Water Conservation Board
• Loan Projects - Doc Type: Feasibility Study

Lower South Platte River Study
Colorado Water Conservation Board
' December 2001
offset the effects of existing and new water-related activities in the Platte
River Basin, help prevent further ESA listing, and mitigate new water-related
activities in a state so as not to increase mitigation responsibilities of the other
states
' - Establishment of a governance structure to ensure appropriate government and
stakeholders involvement in the overall process
• The CA includes several provisions, which may need to be considered in regard to a
' potential water project in the Lower South Platte Basin. The CA describes/defines
the term"water related activities" and establishes processes for handling"water
related activities." These processes are different for activities that occur during the
' term of the CA versus the first increment of the proposed program (see the July 1997
CA for additional details).
' For the purposes of this report, it is assumed that the implementation of any water
project will most likely be at the termination of the CA(June 30, 2003). Therefore,
' this discussion will focus on the requirements discussed in the proposed program.
Under the proposed program new"water related activities" are expected to be
1 mitigated if they impact USFWS species-specific target flows. However, water
projects can develop water that is in excess of these flows. As indicated in Section 2,
the water availability analyses used in the reconnaissance studies are based on this
' condition. Water development in excess of species target flows should also consider
USFWS peak flow recommendations.
At this time, the specific beneficial uses and purposes for a potential water storage
project have not yet been identified. Once the specific beneficial uses are identified, a
' more-detailed analysis of any effects on the timing and quantity of South Platte flows
may need to be completed. It is highly plausible that one use of the potential storage
projects would be as an alternate source of water for existing uses, which pre-date the
CA. Consequently, the project, or a portion of the project, may not be considered a
new"water related activity." In addition, if the potential project is used for
' environmental beneficial uses within Colorado, then most of the water use would be
nonconsumptive, except for evaporation.
' Nevertheless, it is recognized that the storage pattern for the potential project could
have an influence on the timing of South Platte flows. To be conservative, the water
availability analysis only assumed that water would be stored under the following
conditions: when Colorado senior water rights were met; when the conditions of the
South Platte Compact were met; and when the USFWS species specific target flows
' were met.
GEI Consultants, Inc. 3-4 01002 Dec 2001 Lower South Platte River Study