Environmental restoration is complete in two-thirds of the Kerber Creek watershed, extending from north of Bonanza to San Luis Creek near Villa Grove in the northern San Luis Valley.
Aarón Mohammadi, Kerber Creek Restoration Project coordinator with the U.S. Bureau of Land Management, said the project focused on private land lower reaches of the watershed.
Project success, he said, is the result of collaboration among 40 landowners and 16 entities – including federal, state and local, and nonprofit groups including Collegiate Peaks Chapter of Trout Unlimited and Southwest Conservation Corps.
Kerber Creek is a 19-mile-long waterway contaminated by decades of mining that began in 1880 when prospectors discovered gold and silver in Bonanza Mining District in the northern San Juan Mountains.
Within a few years, tainted runoff began to affect ranchers downstream in the San Luis Valley, and as mining activity increased, so did pollution – toxic metals and sulfuric acid, a by-product of the sulfide ore tailings.
Mine workers eventually installed tailing dams, but after the last mining boom in the 1930s, dams began to fail and mine tailings spread miles downstream, turning the creek orange and contaminating the floodplain.
In 1994, American Smelting and Refining Company initiated cleanup of the main stem of Kerber Creek. By 1998 they had completed riparian restoration of the most heavily contaminated areas in upper segments of the creek.
During the same time, Colorado Department of Public Health and Environment removed three waste piles from the watershed.
Initial cleanup improved water and soil quality in the upper watershed but left 17 miles of contamination in the lower watershed and impaired stream channels throughout the drainage.
In 2005 a collaborative initiative focused efforts on the lower watershed.
The project website, www.kerbercreek.org, indicates goals are to “reduce metal mobility in soils, increase sinuosity, reduce the channel width, improve depth, increase density of aquatic life, increase vegetation cover and stabilize stream banks.”
As recently as 2009, Dr. Carl Ford, bureau toxicologist, recorded acidity levels in the creek 10,000 times higher than pure water. Ford reported extensive zinc contamination in tailings along the creek.
Mohammadi said restoration work involved moving some contaminated soils, but the bulk of the work used phytostabilization to treat contaminants in place.
U.S. Fish and Wildlife Service contaminants specialist Laura Archuleta, also interagency coordinator for the Kerber Creek project, said that type of treatment binds toxic metals to other soil components, minimizing toxicity.
She said the process has been used at sites throughout the West and involves neutralizing acidity with lime and limestone before adding organic material like mushroom and potato compost.
After the soil mellows, workers apply seed and straw mulch and plants do the rest of the work to contain the zinc.
Since 2007, about 72 acres of mine waste along the creek were phytostabilized and partners have raised more than $1.4 million for the work. Additionally, partners and outside groups have donated more than 9,000 volunteer hours since 2007 (www.kerbercreek.org).
Mohammadi said the project has received awards including:
• 2011 American Fisheries Society Riparian Challenge.
• 2010 Public Lands Foundation Landscape Stewardship.
• 2010 Bureau of Land Management Hardrock Mineral Environmental.
• 2010 U.S. Forest Service Water Partner of the Year.
Mohammadi said future plans for Kerber Creek watershed include more restoration in the upper portions of the basin, restoration on a large privately owned parcel and monitoring in and along the creek.
Mohammadi asked that anyone interested in sharing anecdotes or experiences relating to the project do so through the project website, www.kerbercreek.org.