Rio Grande - Alamosa River Watershed Restoration_Application

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e Water Supply Reserve Account - Grant Application Form Form Revised May 2007 6. W ater Availability and Sustainability - this information is needed to assess the viability and effectiveness of the water project or activity. Please provide a description of each water supply source to be utilized for, or the water body to be affected by, the water activity. For water supply sources being utilized, describe its location, yield, extent of development, and water right status. For water bodies being affected, describe its location, extent of development, and the expected effect of the water activity on the water body, in either case, the analysis should take into consideration a reasonable range of hydrologic variation. Alamosa River The Alamosa River watershed comprises 148 square miles in the San Luis Valley of south-central Colorado. The mainstem of the Alamosa River is 51 miles long, extending from near the Continental Divide to east of the City of La Jara. Elevations vary from over 13,000 feet to about 7,600 feet. La Jara Creek, long irrigation ditches, and holding ponds divert a substantial amount of water from the Alamosa River, expanding the drainage area by approximately 15 miles. The river's average bankfull discharge is 650cfs over a 1.5-year interval. The river rights are fully appropriated by private individuals, yet the vast majority of the riparian corridor is undeveloped; ranching and farming reaches to the riverbank only in a few areas. Terrace Reservoir has the upstream water right; when a senior water right holder from downstream on the Alamosa River makes a call, the reservoir will not store the flow. The reservoir allows the river to run as far as US Hwy 285 for about 6 weeks of the season to service a senior water right, typically from early May through mid-June. In general, the stream flows to about County Road 10, April - November. Below County Road 10, the flow continues year 'round due to inflows and springs. Stabilization of the riverbanks will prepare them for saturation, which will add recharge to the aquifer, increasing its levels, and in . turn, increasing the reach and duration of the inflows later into the season. Terrace Reservoir Most of the watershed upstream of Terrace Reservoir is in the Rio Grande National Forest. Another portion is part of the Bureau of Land Management's San Luis Resource Area. The land in the valley below Terrace Reservoir is primarily privately owned and is used for agricultural purposes. Some of Colorado's oldest and predominantly Hispanic communities are located in the Alamosa River watershed, including La Jara and Capulin. The economy of these towns and of Conejos County depends primarily on agriculture. Census figures rank this County among the poorest in the State. Terrace Reservoir (State Dam ID No. 210102) is located on the Alamosa River about 12 stream miles upstream of Capulin. Terrace Reservoir is owned by the DOW and Terrace Irrigation Company (TIC), who operates the reservoir. A portion of the reservoir storage is reserved by the DOW for preserving aquatic habitat and wildlife. The principal purpose of the reservoir is to store water for agricultural uses. There are approximately 30 shareholders and 831-7/8 shares of stock. The TIC sets an annual assessment to be paid by the shareholders. On average, 15,339 acre-feet of water is diverted by the TIC through Terrace Main Canal and the Alamosa Creek Canal during any given year (CWCB, 2004). The reservoir has a storage capacity of about 15,200 acre- feet at normal operating pool (elevation 8,571) and a corresponding footprint of about 300 acres. The reservoir is impounded by a large earth and rockfill dam constructed across a narrow canyon cut down by the river through volcanic rocks. The various phases of the dam construction began in 1903, and construction was completed in 1912. Sustainability The current state of the untreated sections of the Alamosa River are what one might consider the worst case scenario of over-appropriated water use and human intervention in a natural water system. The water system is 100% developed and its water rights are fully appropriated, which has severely affected the flow of the Alamosa e 16