2010-11-12_PERMIT FILE - C1981010A (5)

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Doc Date:12/11/2001 ~~ ~~ III IIIIIIIIIIIIIIII 999 2.7.4 Pre-mining Conditions - Surface Water ' This section describes the baseline surface-water regime in the mine-plan area and the adjacent areas, including the Yampa and Williams Fork Rivers. Yield and seasonality of runoff fur the Yampa River valley and the permit area are dis- cussed. Ouality of those wafers is described, and characteristics of the drain- age network in the permit area are presented. The data for the drainages in [he western portion of the area were collected prior to 1981. The eastern portion data was collected beginning in 1984. 2.7.4.1 Water Yield and Uses Quantity and quality of surface water are dependent upon a number of interdepen- dent variabl es. Soil and vegeCation types, topography, climatic regime and ground water interactions are the major variables controlling the mo unt of water in a stream at any time. These parameters are discussed in other sections. The distribution of flows ~i.e., amount of base flow, storm flow and low flow) deter- mines, along with water quality, the uses that can be made of these waters. The amount of wa ter, its seasonal distribution and the uses made of these waters will be discussed for the Yampa River, Williams Fork River and drainages of the pro- posed permit area. The water supplied by the Yampa River depends primarily on melting of winter snuwpacks on the high mountain slopes surrounding the valley. The lower inter- mittent drainages produce only a small part of the total water yield of the basin ~COlOradO Water Conservation Board, 1969). Walton Creek near Steamboat Springs, Colorado, has a mean annual flow of 1.9 cubic feet per second per square mile Steele et al, 1979) which equals 25.8 inches of runoff. Near Craig, Colorado, runoff was measuced at less than one inch per square mile from 1914 to 1965 ~WOndward Clyde, 1977). At the ~ 2-402 X965® FEB 13 '87 ; , 1