GENERAL45645 - Laserfiche WebLink

Home Browse Search

could also occur if fault zones are encountered. However, as the base of the B coal seam in the vicinity of both Trout Creek Sandstone wells is above the current potentiometric level in these two we:Lls, it is not likely that the fluctuations in potentiometric levels in the 'Grout Creek Sandstone are related to mine dewatering in the overlying 8 coal seam. Surface water Surface Water Occurrence The area of the Bogle No. 5 and No. 9 Mines is drained by the Yampa River and the Williams Fork River, both perennial rivers which join within the permit boundary. The Williams Fork River is a major tributary to the Yampa. It flows in a northerly direction within the permit boundaries to the confluence with the Yampa River. The Yampa River i'.lowe in a south- westerly direction across the permit area. Flow in the Yampa River depends primarily on snowmelt from the winter snowpack on the high mountain elopes surrounding the drainage basin. The lower intermittent and ephemeral drainages produce only a small part of the total water yield of the basin (Colorado Water Conservation Board, 1969). About 64 percent of the flow occurs in May and June with up to 84 percent occurring from April to July at selected gaging stations within the drainage basin (Steele, et al ., 1979). Minimum £lowe generally occur from August through February. Irons, et al. (1965) reported that summertime flows in streams of the basin from July through October generally include a large component of ground water discharge. Extremes recorded at the Maybell Gaging Station are a maximum flow of 17,900 cfe on May 19, 1917, and a minimum of 2.0 cfe on July 17-19, 1934. Annual variation in yield may also be great. Historical annual yield has varied from 345,000 acre-feet in 1977 to 2,135,000 acre-feet for the Yampa River in 1917. Average annual yield amounts to 1,116,000 acre-feet. The Williams Fork River is a major tributary to the Yavrpa River and enters the Yampa River within the permit area of the Bogle Mines. It drains approximately 350 square miles, or ten percent of the Yampa River Valley, and shows many of the same characteristics as the Yampa River, except that the Williams Fork is more dependent on snowmelt, and th~are ie less ground water discharge to sustain the flows of the river during low flow periods. In addition to yield,~water quality also varies seasona:Lly. Total suspended sediment loads are at a maximum during peak flows associated with spring runoff. Steele et al. (1979) reports that up to 90 percent of the annual sediment load of the Yampa River at the Maybell Station is discharged during the period of snowmelt runoff. Total suspended sediment loads increase with increased discharges (flows) in the rivers. Dissolved solids loads show an inverse relationship with stream discharges. High quality snowmelt runoff contains relatively low levels of total dissolved solids (TDS). Therefore, concentrations of TDS decrease during peak flow periods. In the summer, when ground water discharge makes up a larger percentage of the flow in the rivers, TDS values increase. The Colorado Y7ater Conservation Board (1969) reports that intermittent (and ephemeral) drainages at lower elevations contribute most of the dissolved and suspended solids that leave the basin. The dominant cations in the Yampa and Williams Fork Rive~re include calcium, sodium, and magnesium, while dominant anions are bicarbonate and sulfate with some chloride present. The total dissolved solids (TDS) load in the Yampa River ie increased by discharges from the Williams; Fork River. In 25