By GENEVIEVE BOOKWALTER
Toxic chemicals were found in Tuolumne Utilities District ditch water north of Columbia last weekend and killed about 90 fish at the nearby Matelot Reservoir, forming white, thick, sticky clumps and leaving an oily slick on the water.
However, TUD officials said the chemicals have been neutralized and tap water drawn from that part of the ditch system is safe.
TUD officials are waiting for test results, but General Manager Tim McCullough said someone probably dumped methamphetamine-lab waste into the water.
Originally built in the 1800s, TUD's 56 miles of open ditches provide drinking water for most of the county.
Although Columbia water treatment plant operators noticed a spike Sunday night in the incoming ditch water's pH level, TUD did not release information about the spill until yesterday afternoon.
McCullough said a spike in pH level is not unusual. When the dead fish were discovered Tuesday at the reservoir, district officials realized a contamination problem was likely, he said.
"Thank God we have good instrumentation and were able to detect this stuff," McCullough said. "Columbia is a modern plant I would say the jewel of our system. It has all the whistles and buzzers, and they went off."
Water users who pump directly from the ditch should flush out their systems to prevent contamination, McCullough said. However, most contaminants have probably flowed on by.
While officials haven't pinpointed the exact dumping location, McCullough said chemicals definitely affected the Matelot Ditch below Italian Bar Road.
After learning yesterday about the spill, some TUD board members wondered if more should be done to protect the county's drinking water.
"What does it take? Are they going to wait for someone to get seriously ill and die before they take the water out of these contaminated ditches?" said Director Gary Walter.
A longtime supporter of piping the waterways, Walter said he has seen bathing dogs, dead cats and bloated, decomposing cows in TUD's ditches. Walter recommended saving ditch water for agricultural purposes and piping water to drink.