Animas Watershed Plan - Laserfiche WebLink

Home Browse Search

(exceeding 1000 pages, not including the database) is available by contacting Bill Simon at (970) 385-4138 or email: ~vsimon(cr~,frontier.net. In 2002 the WQCD adopted 29 Total Maximum Daily Load limits for streams throughout the Upper Animas watershed above Baker's Bridge, which is located 12 miles north of Durango. The TMDL's were developed from the calculations provided in the Animas UAA, Chapters X and Xl. II. PROBLEM DESCRIPTION: CAIISE AND SOIIRCE IDENTIFICATION This Plan has been specifically written for the Animas River and its tn~utaries above Baker's Bridge. A map of the area is provided as Figure 1. Major tributaries to this upper portion of the Animas include, Cascade, Needle, Elk, Mmerai, and Ceme~ Creeks_ Below Baker's Bridge the Animas River flows to its confluence with the San Juan River in northern New Mexico. Metals and acids that arise from the Upper Animas Basin at and above Silverton impact this portion of the watershed_ This is an area of approximately 186 square miles, dominated by the Silverton caldera and its associated, highly mineralized geology. Both historic mine sites and natural geological processes contribute significant metals and acid to the streams. As one proceeds downstream from Silverton, beyond the caldera, tributaries dilute the metal rich water of the Animas. Nevertheless, until recently, fish were unable to reproduce throughout most of the Animas main stem_ Recent water quality improvements appear to have provided trout sustainability in the lower parts of the Animas. The Upper Basin contains over 1500 abandoned mine sites. Many of these are small and have little or minimal disturbances. However approximately 174 draining edits and over 159 mine waste sites were considered to have potential as significant polluters to the watershed_ These were characterized in detail and a feasibility analysis for remediation developed for each. III, RFMFDIATION METHODS, RANIONG, AND PRIORITIZ~-TION (COPIED AND MODIFIED FROM CHAPTER X OF THE ANIMAS UAA) This section discusses what can be done to eliminate or reduce the mino-related loading sources. It also describes a prioritization process that ARSG has conducted for targeting sources in order to get the "biggest bang for the bucl~' in metal reduction_ Remediation can be classified into two broad categories: preventative measures and treatment. Preventive measures are designed to minimise the chemical, physical and biological processes that cause metal loading and increase acidity. The main method, called hydrologic modification, is to try to keep water, oxygen, and acid generating material separate_ Other remediation efforts involve treatment of water that is already acidic and/or caries high concentrations of metals. Treatmem can be passive where the treatment processes need only periodic maintenance or active where the processes need frequent maintenance and supervision. e~ 4 _~~~ -