9596 - Laserfiche WebLink

Home Browse Search

2 I I I I I I I I I I I I I I I I I I I 2. BACKGROUND 2.1. Overview of Basin Hydrology and Water Uses The Yampa River Basin encompasses about 8,000 square miles in northwestern Colorado and southern Wyoming, ranging in elevation from more than 12,000 feet along its eastern divide to about 5,000 feet at its confluence with the Green River. The basin is divided into an arid zone in the west and a high alpine zone in the south and east. The arid zone produces minor amounts of precipitation, while the high alpine area averages 40 inches of precipitation annually. Melting snowpack from higher elevations produces most of the yield of the Yampa River Basin. About 64 percent of the 1.13 million acre-foot (mat) average annual discharge of the Yampa River at the Maybell gage occurs in the months of May and June. Summer precipitation augments the water supply in minimal amounts. As a result, flows in the Yampa River are characterized by seasonal extremes, ranging from average spring peaks of 14,300 cubic feet per second (cfs) to average late summer flows of 350 cfs at the Maybell gage. In dry years, flows approach zero cfs in several river reaches immediately downstream from water diversion dams. The Yampa River originates along the northeastern edge of the White River Plateau. Numerous small tributaries also drain adjoining areas of the plateau and western slopes of the Sierra Madre, Park, and Gore Ranges along the Continental Divide (Figure 1). In its upper reaches, the Yampa is a high-gradient stream descending through narrow mountain canyons. After emerging from the foothills, the Yampa flows north to Steamboat Springs, then west past the towns of Hayden and Craig through rolling open terrain. Downstream from Craig the river descends through a series of narrow canyons formed by Juniper Mountain and Cross Mountain. The Little Snake River, the largest tributary to the Yampa, enters the Yampa just downstream from Cross Mountain Canyon and upstream from Dinosaur National Monument. It contributes about 28 percent (430,000 acre-feet) of the average annual flow of the Yampa at Deerlodge Park. Downstream from Deerlodge Park the Yampa flows through deeply incised Yampa Canyon within Dinosaur National Monument to its confluence with the Green River at Echo Park. 2.1.1. Water Uses Most water development in the Yampa River Basin consists of irrigation diversions constructed beginning late in the 19th century. There are hundreds of ditches scattered throughout the basin that divert water from the Yampa River and its tributaries. Most of the diversions take only a few cfs, but several larger ditches divert more than 10 cfs. Individuals and private ditch companies have developed most of these ditches. Many of the ditches incorporate small reservoirs and stock ponds. There are about 150 reservoirs in the basin with volumes larger than 10 acre-feet (at). Total capacity of all reservoirs in the basin is approximately 125,000 af. Five of these reservoirs have capacities greater than 7,500 af. They are Yamcolo Reservoir, Stagecoach Reservoir, Lake Catamount, Steamboat Lake, and Elkhead Reservoir (Figure 1). Yamcolo and Stagecoach Reservoirs provide water for agricultural and municipal purposes, as well as cooling water for the Craig electric generating station. Stagecoach also is used to generate hydropower. Elkhead is used for recreation and provides cooling water for the Craig station. Lake Catamount and Steamboat Lake are used for recreation. In addition, the Hayden station owns 5,000 af of cooling water in Steamboat Lake, and the USFWS leases up to 3,300 af of Steamboat Lake water from the State of Colorado to benefit the endangered fishes. This volume has been decreed for instream use. The current term of the lease extends through September 30, 2000, subject to renewal for a lease term and price to be negotiated.