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Tuolumne County Profile Watershed Quality

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Sonora, Ca — Today we will examine Watershed Quality in our ongoing series on the Tuolumne County Profile, Community Indicators Project.

The following was published by the Sonora Area Foundation:

Why is this important?

High-quality water in the region´s watersheds is critical for ecosystem health, and for public use and enjoyment of local water bodies. Low-quality water in streams and lakes results in reduced fish and wildlife populations, increased algal blooms and drinking water treatment costs, as well as sediment-related problems including flooding and loss of carrying and storage capacity in the local streams and lakes.

What is the measure?

Watershed water quality is measured by sampling local creeks and lakes for levels of turbidity, and chemical and biological contaminants such as fecal coliform bacteria colonies.

The current United States Environmental Protection Agency (EPA) recommendations for fecal coliform bacteria colonies are:

body-contact recreation – fewer than 200 colonies/100 ml

fishing and boating – fewer than 1000 colonies/100 ml

domestic water supply for treatment – fewer than 2000 colonies/100 ml

drinking water standard – less than 1 colony/ 100 ml

How are we doing?

The water quality in the ditches, lakes and streams located upstream of populated areas of the county is generally contaminant-free and of very high quality. However, as the water flows downhill through the populated areas, fecal coliform and turbidity levels of these water sources increase significantly. Identified sources of fecal coliform include failing septic systems, urban stormwater runoff, agricultural livestock operations, and wildlife.

Based on available data and USEPA recommendations, the following sampled creeks may be unsafe for:

Body-Contact Recreation? Groveland Creek (not shown in chart), Sullivan Creek, Woods Creek, Curtis Creek, Turnback Creek, Mormon Creek

Fishing and Boating? Groveland Creek, (not shown in chart), Sullivan Creek, Woods Creek, Curtis Creek, Turnback Creek

Domestic Water Supply (even after treatment) ? Woods Creek

Click Community Indicators Project for the complete 2008 Tuolumne County Community Profile.

Written by BJ Hansen