A bubbly white substance flowing from a storm drain into the Tuolumne River below the Seventh Street Bridge sparked a flurry of activity Thursday morning by emergency and environmental crews from Modesto, Stanislaus County and the state.
The liquid appeared to be a mixture of milk and cleaning solution from the Foster Farms Dairy plant at 415 Kansas Ave., said Capt. Charles Butler with the Modesto Fire Department's hazardous materials team. The plant is about 2½ miles northwest of the river.
Foster Farms is looking into the incident and has not commented.
Officials are trying to find out how much of the liquid made it into the waterway. By about noon, Foster Farms had blocked the pipe at the source, then city crews attempted to suck out the substance from the line, said Blair Bradley, the senior environmental compliance officer for water quality control for Modesto.
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Officials said they did not know when the spill started.
But it's a challenge to handle the huge volume of water that flows through the pipe's 96-inch diameter, Bradley said.
Foster Farms engineers are trying to figure out where the liquid came from, he said. There was talk Thursday morning of the source being a truck wash at Foster Farms, but Bradley said Thursday evening it was too early to say.
"It could be a (block) in the processing system that goes to the sewage drain," he said. "Our agency and the facility and regional water board staff will be looking at it."
The hazmat team arrived at the river at 9:20 a.m. to find the white liquid spilling into the river, Butler said. Officials from the state's Department of Fish and Game, Stanislaus County's Department of Environmental Resources and Modesto's Public Works Department brainstormed a plan, as they stood in a circle between the graffiti-covered bridge and the nearby railroad trestle.
Investigators also were trying to determine whether milk and cleaner were the only components spilling into the water. The spill extended about 75 feet downstream, Butler said.
Even if the liquid was relatively harmless for humans, it never should have been in the storm drain, Butler said.
Storm and sewage drains are separate systems.
Officials discussed violations Foster Farms could face but said it was too early to make decisions.
Fish and Game and the Department of Environmental Resources will conduct environmental assessments to determine the impact the spill had on wildlife in the river.
"Milk doesn't have a real healthy oxygen value to it," Butler said. "Fish that get caught up in that cluster of milk may suffocate, so it's an issue for the fish."
Bee staff writer Emilie Raguso can be reached at email@example.com or 578-2235.