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The North Fork of the Gunnison River is the major drainage for the mine site. Streams on the northern portion of the permit area drain directly into the North Fork near Somerset. The Minnesota Creek basin is a significant drainage system occurring outside of the 5-year permit boundary. Minnesota Creek and its tributaries draw the southern portion of the coal lease area. Minnesota Creek enters the North Fork near Paonia. The North Fork has an annual streamflow at Somerset of approximately 313,200 acre feet per year (1933-1982). The flow is regulated by the Paonia Reservoir 5 miles upstream, which became operational in 1962. Flows during that period have ranged from a high of 451,300 acre-feet per year in Water Year 1962 to a low of 82,270 acre-feet in Water Year 1977. Annual streamflow for water years 1983-1985 was significantly higher averaging 580,800 acre-feet per year. Annual streamflow was highest in 1984 with 601,800 acre-feet per year. A number of separate drainages have their headwaters in the mine environmental study area. Sylvester Gulch and Lone Pine Gulch are ephemeral streams which drain the northern portion of the area. They flow directly into the North Fork. There are five tributaries which drain into the main flow of Minnesota Creek. Characteristics of the drainages are given in Table 2. No flow was observed in Lone Pine Gulch fora period of years thus, it was omitted from the study. Sylvester Gulch is an ephemeral stream and has a drainage area of 4.25 square miles. It is important to note that the major portion of the surface facilities will be located near this drainage in the valley adjacent to the North Fork. The hydrologic yield of Sylvester Gulch is low compared to the other watersheds. This is due to the fact that it drains a lower elevation area with more gentle slopes. Horse Creek, South Prong, Lick Creek, Dry Fork, and East Fork drain into Minnesota Creek. Their slopes are generally more steep and the watersheds are at higher elevations than those tributary to the North Fork. Based upon streamflows measured in water year 1978, the water yields from these drainages are nearly an order of magnitude greater than that of Sylvester Gulch. streamflow in Sylvester Gulch during 1982-86 was approximately two to three times greater than for water year 1978 and was comparable to the flow of streams in the Minnesota Creek drainage basin. There are numerous springs located throughout the permit and life of mine area. Measurements indicate the spring flows generally decrease from a high in the early summer to a low point in the fall. A number of the springs dry up in the winter, indicating that their source is most likely a small localized ground water table. 31