Water Quality in the Animas Watershed 12418 Peter

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

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.

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 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.

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 p. H below aquatic life standards. • Manganese: Above standards in some areas, but not as big an issue.

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.

Water Quality Greatly Improved Gold King

Dis. Zn Conc. at M 34 700 85 th d. Zn 1991 -mid 1996 85 th d. Zn 2007 -2011 600 Zn Standard 2012 -2016 Dis Zn (ug/l) 500 85 th d. Zn 2012 -2016 400 300 200 100 0 Jan. Feb Mar Apr May June July Aug Sept Oct Nov Dec

Trec Al Conc. At M 34 6000 50 th Trec Al 1998 -2001 5000 50 th Trec Al 2007 -2011 50 th Trec Al 2012 -2016 Site Spec Al Std 2012 -2016 Trec Al (ug/l) 4000 3000 2000 1000 0 Jan. Feb Mar Apr May June July Aug Sept Oct Nov Dec

Dis Zn Conc. At CC 48 4500 85 th d. Zn 2007 -2011 4000 85 th d. Zn 1991 -mid 1996 85 th d. Zn 1998 -2001 Dissolved Zinc (ug/l) 3500 85 th d. Zn 2012 -2016 3000 2500 2000 1500 1000 500 0 Jan. Feb Mar Apr May June July Aug Sept Oct Nov Dec

Dis Zn Conc. at A 72 1200 85 th d. Zn 2007 -2011 85 th d. Zn 2012 -2016 1000 85 th d. Zn 1991 -mid 1996 Table Value Std 2012 -2016 Dis Zn (ug/l) 800 600 400 200 0 Jan. Feb Mar Apr May June July Aug Sept Oct Nov Dec

HQ Ave. Dis Zn Conc/TVS (A 72) 4, 00 3, 50 Ave Zn/TVS 2012 -2016 Ave. Zn/TVS 1998 -2001 3, 00 2, 50 2, 00 1, 50 1, 00 0, 50 0, 00 Jan. Feb Mar Apr May June July Aug Sept Oct Nov Dec