The Environmental Protection Agency and Colorado Department of Public Health announced on Wednesday they were investigating the potential spill of waste from a mine into Left Hand Creek sometime this month.

In a press release, the EPA said that Superfund project managers for the EPA and the state health department were told about discolored water and dead fish in Left Hand Creek downstream from the Captain Jack Mill Superfund site.

According to the EPA, the Captain Jack Mill site is about 1.5 miles south of Ward in Boulder County. It's in a narrow valley called California Gulch. Mining for gold and silver went on from 1860 to 1992 and clean up efforts have been ongoing since 2008.

As of Wednesday, both the state health department and the EPA were looking into whether or not the 100 or so dead fish are related to cleanup activities at Captain Jack Mill.

So far, the Boulder County Health Department, the Boulder County Office of Emergency Management, Colorado Parks and Wildlife and the Left Hand Water District - which has a drinking water intake about 15 miles downstream from the affected area - have been told of the situation.

The EPA said the Left Hand Water District tests raw and treated water continually but as a precautionary measure, the district shut off intake from the creek when first told of the situation. Since then, the EPA said the Water District has reopened intake from the creek after testing the creek's water quality.

Ever since the "historic mining operations" began at the Captain Jack Mill Superfund site in 2008, both the state health department and EPA have been addressing contamination. Both groups said they're going to put in an innovative, in-tunnel water treatment system that will improve the quality of water discharged from the mine.

The EPA and state health department have contractors and coordinators on scene collecting water samples to help with the investigation. More information will be available in the coming days.