Water Management Committee Meeting

The Water Management Committee (Water Committee) workshop with the State of Colorado began at 10:00 a.m. in the Board Room of the Denver Water Building in Denver, Colorado. Ann Bleed and Rich Kern participated in the meeting via telephone.

Doug Robotham began the meeting by explaining the purpose of the workshop. The State of Colorado has recommended to the Governance Committee assumptions concerning the monthly distribution of the accretive/depletive effects of sources of supply as set forth in Milestone W8-1 of the Platte River Research Cooperative Agreement (Cooperative Agreement) and in accordance with Attachment III, Appendix A, Tab 3B of the Cooperative Agreement. An interactive spreadsheet tool for Colorado's Plan for Future Depletions was developed to illustrate the cumulative accretive/depletive effects on South Platte River flows from future population growth in the South Platte River Basin of Colorado and from the water supply sources used to meet the water needs associated with that growth. Since the Governance Committee has asked the Water Committee to review and comment on Colorado's Plan for Future Depletions, the State of Colorado sponsored this workshop with the Water Committee to review the interactive spreadsheet tool and the assumptions used to calculate the monthly distribution of the accretive/depletive effects of sources of supply.

John Lawson, Chair of the Water Committee, asked the Water Committee to review and provide comments to him regarding Colorado's assumptions concerning the monthly distribution of the accretive/depletive effects of sources of supply by May 22, 1998. Mr. Lawson will compile the comments received. It is anticipated the Water Committee will further discuss Colorado's assumptions at the June 2 meeting. The Water Committee's recommendations/concerns will be presented to the Governance Committee at their June 3 meeting by the Water Committee Chair.

Mr. Robotham introduced Colorado's consultant, Lee Kozaklis, to the Water Committee and Mr. Kozaklis proceeded to lead the presentation/discussion of Colorado's interactive spreadsheet tool. The spreadsheet tool divides the South Platte River Basin into three Regions: North, Central, and South. Regional mixes of existing and expected water supply sources are subdivided into six categories: transbasin import, native South Platte flow development, nontributary groundwater, in basin agriculture conversion, water conservation, and water reuse. Projected mixes would be verified annually as actual data becomes available. At the end of the five-year period, the mixes would be reviewed and adjusted, if necessary, for the next five-year period.

Mr. Kozaklis reviewed the calculation of the 0.25 acre feet per capita value used in the spreadsheet tool. This value is based on a compilation of reported raw water uses and service populations for the South Platte River Basin water providers (2,574,500 / 638,600 = 0.25). Refer to the enclosed Handout No. 1. An average value for the municipal and industrial consumptive use of 36% was derived from monthly municipal treated water delivery data, assuming indoor and outdoor consumptive use of 5% and 80%, respectively (see enclosed Handout No. 2). The Water Committee members requested the Excel spreadsheet files Handout No. 1 and No. 2 were generated from. Mr. Kozaklis will provide them via Electronic Mail (E-Mail).

Other assumptions are that increases in consumptive use are only tied to population growth, as irrigation is assumed to be stable; water conservation has a net effect of zero with respect to the accretions/depletions; and average climate conditions exist. Tab 3B of the Cooperative Agreement specifies that Colorado will monitor net changes in irrigated agricultural acreage, which can be used to verify the assumption that consumptive use from irrigated acres remains stable over time.

After a lunch break for noon to 1:00 p.m., the workshop resumed with a discussion of the transit loss factors. The transit loss factors currently used in the spreadsheet tool are identified in Attachment III, Appendix A, Tab 3B, page 5, of the Cooperative Agreement. These initial transit loss factors will be replaced by the transit loss factors determined by the Water Committee for the Tracking/Accounting Procedures, as per Milestone W9-1. A distance of 145 miles is used in the spreadsheet tool to represent the weighted average distance between municipal providers in the three Regions to the Julesburg gage.

Mr. Kozaklis then demonstrated how to use the spreadsheet tool by changing some of the input parameters and recomputing the monthly distribution of accretions/depletions.

The workshop adjourned at 3:00 p.m.

Enclosures: (Handout No. 1 and No. 2)