1. Water Quality in the Animas Watershed 1/24/18
Peter Butler, Ph.D.
Animas River Stakeholders Group

2. Initial Notes
Discussion will be limited to high metal concentrations originating from sources in the upper part of the Animas Basin.
All water quality standards are met in Colorado below Bakers Bridge except for the secondary manganese standard for water supply.
Metals in sediments below Bakers Bridge may be an issue but there are no sediment standards, little data, and there don’t appear to be direct impacts to aquatic life related to sediments.
Generally metal water quality standards for aquatic life are more restrictive than for human health.
Many metal standards for aquatic life apply to the dissolved fraction and vary with hardness.

3. Trends in Water Quality
Over the past 26 years, about 60 mine remediation projects have been completed ranging in cost from $10,000 to $2,000,000 apiece.
Water quality in the Animas Basin continually improved throughout the 1990’s into the early 2000’s.
End of 2002, last bulkhead installed in American Tunnel. Gladstone treatment ends in spring of 2004.
After 2004, water quality continues to improve in Animas above Silverton and in Mineral Creek. Water quality gets much worse in Cement Creek, and gets worse below Silverton, worse than early 1990’s.
Water quality appears to have gotten slightly better in the past few years when compared to late 2000’s.

4. Metals of Concern
Zinc: Out of compliance in more locations than any other metal including Bakers Bridge. Lots of historical data. Found at most mine sites.
Cadmium: Usually associated with zinc in mineralized locations. Less compliance issues than zinc.
Copper: High in certain areas, but large reductions due to remediation.
Aluminum: Almost all natural. Toxicity varies in different conditions. Pervasive above Silverton. Out of compliance at Bakers Bridge.
Iron: Mostly natural. Very high concentrations in Mineral and Cement Creeks. Not toxic but smothers. Lowers pH below aquatic life standards.
Manganese: Above standards in some areas, but not as big an issue.

5. Other Metals
Lead: Dissolved lead exceeds aquatic life standards occasionally. Occasional high concentrations of total lead have been seen downstream.
Arsenic: Only detected in certain locations, but not above aquatic life standards.
Lead and arsenic were the two primary metals of concern with the Gold King release. These two metals may be a concern in soils around some mine sites and campgrounds above Silverton.
Silver and Thallium: Have occasionally seen concentrations of concern in certain locations.

6. Gold King
Water Quality Greatly Improved

11. HQ