Region 8
Serving Colorado, Montana, North Dakota, South Dakota, Utah, Wyoming and 27 Tribal Nations
EPA Region 8 - California Gulch Superfund Site
Gaw Shaft Sample Results
On February 28, EPA began pumping water from the Gaw Shaft in response to issues related to the Leadville Mine Drainage Tunnel. EPA is monitoring the water being pumped from the Gaw Shaft and discharged into California Gulch.Map of the Cal Gulch area, including the Gaw Shaft (2,900 KB)
Q: Where is the Gaw Shaft?
A: The Gaw Shaft is located in Lower California Gulch.
Q: How are samples from the Gaw Shaft taken?
EPA will sample the water being pumped from the Gaw Shaft and discharged into California Gulch. EPA will monitor pH (a measure of acidity), flow, and water levels on at least a daily or more frequent basis. Dissolved metals samples will be collected once a week and sent to the EPA lab for analysis. The lab will report the results and after a quality control review, we will post the sample results on a link to this web page.
Q: What is the current water quality?
The water analysis from the Gaw Shaft shows non-detect levels of cadmium and a small amount of zinc, indicating little to no adverse impact on Arkansas River water quality. EPA will evaluate the water quality data on a regular basis and take appropriate action should water quality become an issue. Analytical results can be found in the PDF documents below: