Sewage spill tests show contaminated waters

February 1, 2008 12:00:00 AM PST
Warnings of potential contamination are posted at some beaches after 2.7 million gallons of partially treated sewage leaks from a Mill Valley treatment plant.

The first tests following Thursday's sewage spill have found significant e-Coli contamination. The highest concentrations were found to the north and south of the plant in amounts well above state limits.

However, areas tested further away from the spill are showing safe levels. Nevertheless, warning signs remain on beaches and waterfronts in Marin County and San Francisco.

The two contaminated samples were collected at Shelter Bay and Bayfront Office Park, just upstream from the Sewage Agency of Southern Marin.

The flow of the tides can push the water back past the plant. The two samples tested had fecal coli forms at four times the level deemed safe by the state.

Consequently, people continue to be warned to stay off the Marin County shoreline and several San Francisco beaches.

Keep in mind, there is a dog park near the testing site so health officials are unclear weather the nature of the ground and rainwater is contributing to the high contamination numbers. With all this rain, the sewage plant is on alert to prevent another spill.

"We're going to just staff up this evening. We are not going to wait for an alarm to do anything. Conditions are similar to Thursday evening. We have a light rain right now, but the radar says we're supposed to get a lot more this evening. That's one of the things that threw us off Thursday evening, that caused us to have an operational error. We are anticipating much less rainfall."

The operational error was when two of the six pumps were operating when there should have been four. The Health Department will continue to test thpae waters until the storms pass and will not take down the warning signs until all tests end up clear.

The next wave of showers should help dilute and cleanse the contaminated waters in the bay.

Warnings about swimming were posted from Southern Marin to San Francisco, and include the following beaches:

-Crissy Field
-Baker Beach
-China Beach
-Aquatic Park.