Residents are being urged to stay out of Matson Creek and Wolf Creek in Grass Valley for at least two weeks after 500 gallons of raw sewage flowed into the waterways Monday night.

As of late Tuesday, however, the area had not been posted to warn passersby.

Grass Valley city officials issued a warning early Tuesday to "avoid all contact with the water" until bacterial testing can be completed to deem it safe.

The warning came after a miscommunication between the city and county about the spill, according to County Environmental Health Director Wesley Nicks. Grass Valley Deputy Director of Public Works Rick Beckley said he was surprised the county didn't ask for a safety warning be posted about the stream right away.

An Environmental Health Department worker, Gabriel Herrera, responded to the spill, Nicks said.

"He was under the impression there was no other spillage other than what was in the street," Nicks said. Herrera deferred to Nicks for comment.

Thinking there was no other public exposure, Herrera did not order any other procedures, Nicks said.

"There may have been a little slip there," Nicks said. "We're reviewing our procedures with Grass Valley."

Even if Herrera had known about the creek spillage, the 500 gallons of sewage was not enough to trigger an automatic alert, Nicks said.

Regulations call for a sewage spill going into a stream to be 1,000 gallons or more before it has to be posted, Hicks said. Proposed state legislation would reduce the amount to 500 gallons, he added.

A blocked manhole caused the overflow about 6 p.m. Monday on West Berryhill Drive.

The area was washed down and sprayed with betadyne, a disinfectant that does not harm fish, Beckley said. No water samples were taken Monday night, Beckley said.

"The health department usually shows up and usually directs us to post," Beckley said. "They said not to last night."

The city issued the e-mail warning at 9 a.m. Tuesday as a courtesy to Wolf Creek Community Alliance members and others in the community who seek information quickly after spills, Beckley said.

After contacting official agencies about the spill Monday night, the city had difficulty getting the community e-mail notices out until the next morning, he said.

Another notice will be issued when the creek is determined to be safe, said Linda Quinn of the city's public works department. Water testing results to determine the safety will take until at least April 1 to process, Quinn said.

To contact Senior Staff Writer Dave Moller, e-mail dmoller@theunion.com or call 477-4237.