GENERAL34738 - Laserfiche WebLink

Home Browse Search

The Seneca II-W Mine permit area lies on the western flank of the Sage Creek Anticline, a local structure located within the more regional Sand Wash Basin. The Sage Creek Anticline is thought to control local ground water flow, as artesian head increases with distance from the anticlinal axis. Ground water occurs in the alluvium associated with Hubberson Gulch within and adjacent to the permit boundary. Quality of this water prohibits its use for drinking and seve~rei~ limits its use ~~ irrigation. Drinking water and irrigation standards were exceeded for TDS` C¢nductiviry and ~ M~rtganese. U Surface Water The mine permit boundary encompasses two surface watersheds. Most of the mine site and the major portion of the disturbed azea will drain into Hubberson Gulch and an unnamed tributary to Dry Creek. A small azea on the eastern edge of the permit boundary drains to Sage Creek. Flows on Sage Creek range from intermittent to perennial, depending on location and precipitation patterns. At the Seneca II-W monitoring sites, Sage Creek can be classified as perennial during years at or above average precipitation, and intermittent in yeazs below average. The numerous small drainages which are tributary to Dry Creek are ephemeral in nature. Hubberson Gulch, downstream of the mine site to its confluence with Dry Creek, is intermittent. Dry Creek, like Sage Creek, can be classified as perennial most years, and intermittent during years with below average precipitation. Both Sage Creek and Dry Creek are confluent with the Yampa River near Hayden, Colorado. Water in Hubberson Gulch is a MgCa-SO< type. Surface water total dissolved solids (TDS) averages 820 mg/l. The water is hard, and is characterized as slightly alkaline (average pH 8.10). It is suitable for livestock watering and irrigation of salt-tolerant crops grown in well drained soils. Water quality in Sage Creek is a CaMg-HCO3 type. Samples from baseline monitoring points indicate the water is slightly alkaline with a pH ranging between 7.0 and 8.0. The water has a TDS level of less than 500 mg/I, but is characterized as very hard. It is suitable for livestock and irrigation, however, flow is generally inadequate for irrigation. Dry Creek water quality is categorized as brackish, since TDS averages greater than 1000 mg/1 (1048 mg/I) neaz the confluence with Hubberson Gulch. Water quality degrades further downstream. With an average pH of 8.3, the water is slightly alkaline. Hardness averages 796 mg/1, and is considered very hard. Climate The average annual precipitation at the mine site is approximately 16 inches. The precipitation is consistent throughout the year with no significant dry periods. The mean annual temperature Seneca II-W Findings Document 7 November 3, 1999