Gunnison - Paonia Reservoir Sedimentation Study Application

Home Browse Search

. . . Water Supply Reserve Account - Grant Application Form Form Revised October 2006 COLORADO WATER CONSERVATION BOARD WATER SUPPLY RESERVE ACCOUNT 2006-2007 GRANT APPLICATION FORM SEDIMENT A nON MANAGEMENT STUDY FOR P AONIA RESERVOIR OVERVIEW SUPPLEMENT Paonia Reservoir, was commissioned in 1962, with an original capacity of 21 ,000 acre-feet. The reservoir has lost approximately 24% of its total capacity as of the last sediment survey in 2002, and storage losses to sediment continue at an annual rate of about 124 acre-feet. At the historic rate of sedimentation, the storage volume will be completely displaced by sediment within the next 125 years. Nearly all of the dead and inactive pools (storage reserved by the u.S. Federal Government) have presently been depleted due to sedimentation losses and active storage is currently being encroached on. A large sedimentation delta has been forming and moving toward the dam since the reservoir was placed in operation and has migrated downstream over 80 percent of the length of the reservoir to within 3,000 feet of the dam. This delta is expected to reach the dam within the next decade or two. Once that happens the scope of negative impacts is expected to increase. The accumulation of sediment around the outlet's intake structure is expected to adversely affect the reservoir outlet in ways that may harmfully impact the ability to control the reservoir in a manner consistent with historic operation, in accordance with downstream demands for storage releases and in a way which avoids detrimental downstream environmental impacts. The result is that storage water which has historically been used for agriculture and other purposes is being lost and conditions are developing which may jeopardize the ability to judiciously operate the reservoir. In addition to irrigation water, the Paonia Reservoir provides flatwater recreation, fishing, improved late season flows to the North Fork of the Gunnison River, flood control for downstream towns and developments such as the towns of Paonia and Hotchkiss, water for downstream calls (specifically calls placed by Redlands Water and Power Company), water to supplement normal late summer low stream flows and existing as well as potential future augmentation water. All these uses will be curtailed if no solution to the sediment problem is found. Additionally, use of the water to fill present augmentation needs is limited based on the uncertainty of future availability of committed pool volumes. There are no other currently available irrigation options for the farms and ranches in this area that presently rely on water stored in Paonia Reservoir and, without some action, there will be a devastating impact on existing agricultural water users. Unless the storage volume in the reservoir can be maintained or restored, the only alternatives will be to abandon the existing storage rights or to