Dozens of fish, including rare steelhead, were killed after a drinking water pipe burst and sent thousands of gallons of chlorinated water rushing into San Mateo Creek, according to an article in the San Mateo Daily Journal.
The San Mateo Creek is just over one mile south of the Burlingame city limit.
The San Mateo Public Utilities Commission discovered the leak Saturday near Crystal Springs Reservoir, part of a drinking water system that serves 2.5 million Bay Area residents, San Mateo officials said.
Officials said they expected at least a couple of hundred fish to die in the incident.
San Mateo Creek flows about five miles from the reservoir to San Francisco Bay. Hillsborough backs up into the resevoir on the west side of town.
The 1932-era pipe that broke was likely corroded, but the official cause of the burst is not yet known, city officials said.
When the pipe burst, it sent chlorinated water at 1,000-gallons per minute down a hillside and into the creek. Crews were able to slow, but not stop, the leak after several hours, and repairs to the pipe was ongoing Tuesday.
Officials said they did not expect a long-term environmental problem there as a result.