PUB00118 - Laserfiche WebLink

Home Browse Search

Arkansas River Water Needs Assessment - Section 1. Executive Summary water users and the natural environment. However, all of these opportunities involve numerous issues and concerns, affected parties, and legal constraints. These opportunities include: Modified management of existing storage and conveyance facilities Expanded or new storage capacity Construction of a southern delivery system for Colorado Springs Utilities Temporary water transfers - Arrangements with municipal water providers Expanded season of exchanges Increased watet imports Agreements regarding upstream irrigation water rights Most of the water users in the basin have agteed that to better meet water needs, improved storage management should be thoroughly investigated and tried before other options are explored and imple- mented. To this end, Southeastern Colorado Water Conservancy District is coordinating a study of storage needs and storage management within the basin. Summary of the Hydrologic Analysis of Changes in Arkansas River Flows Since 1889 The hydrologic analysis of flows was divided into three time periods to reflect major changes in rivet management. The first designated time period, 1889-1910, reflects the earliest date for which continuous flow records are available, and repre- sents a fairly natural, unregulated system before 1900. Between 1900 and 1910, the system began to experience the effects of limited water imports and the construction of Clear Creek, Twin Lakes, and Sugarloaf Reservoirs in the upper basin. The second designated time period, 1911- L960, reflects a time period when water management was fairly stable, without any major new water management facilities. Transbasin diversions, overall storage capacity, and active storage management increased incrementally, but did not dictate extensive alter- ations in how the river was managed. The third period, 1982-1995, reflects a period when the Fryingpan-Arkansas Project was coming online, along with associated institutional changes in how water was managed and allocated. The 1961 to 1981 period was not analyzed because the timing and magnitude of flows fluctuated as new water storage and import systems came online. The overall net effects of water management changes from 1889-1910 are a slight reduction in November-April flows, a reduction in spring runoff flows (May-June), and an increase in August- September flows. These effects are predominantly the result of upper basin storage put into service after 1900. Mean flows for November-April prior to 1901 were approximately 420 cfs, while mean flows for November-April post-1901 were approxi- mately 350 cfs. Mean daily flow befote 1901 for the August 1-15 period was 680 cfs, while after 1901, but before 1911, the mean daily flow for the August 1-15 period was 740 cfs. Flows during the 1911-1960' period were approxi- mately the same as the 1889-1910 period during fall, winter, and spring. However, due to the release of imported water that was stored on the east slope during runoff, July and August flows increased significantly. The mean daily flow for August I-August 15 for the 1911-1960 period was approximately 1,000 cfs, compared to 740 cfs from 1901-1910. This is an increase of 230 cfs from the 1901-1910 period, and is almost completely attributable to transbasin imported water. Flow analysis during the 1982-1995 period is complicated by several factors. Completion of the Ftyingpan-Arkansas Project created tremendous flexi- bility in the process of water storage and movement. In addition, the wettest period on record was from 1982-1987, 1989-1992 was extremely dty, and 1995 was the wettest year on record. Finally, an annual Summary of the Hydrologic Analysis of Changes in Arkansas River Flows Since 1889 -1-7