File photo of beach closure notice from 2014.

Long Beach and Los Angeles County health officials have issued advisories to avoid beach waters after the first big rainstorm of the season swept through the Southland, washing bacteria, chemicals and debris into local waterways.

“After any significant rainfall, unhealthy conditions may result from increased runoff from storm drain outlets and rivers, which eventually reach the City’s beaches,” city health officer Dr. Anissa Davis said in a news release.

The Long Beach advisory is an extension of a closure order Davis issued on Saturday after an approximate 50,000 gallons of sewage spilled into the Los Cerritos Channel. Health officials said the spill was caused by a pump station malfunction from the county sewer system after it lost power that day. The beaches will remain closed until the water quality meets state requirements, officials said.

All recreational swimming areas should be avoided for at least three days after the end of a rainstorm, but the closures will be extended if the rain continues for both city and county beaches. County health officer Dr. Muntu Davis said the trash, bacteria and other public health hazards from city streets will likely contaminate ocean waters through storm drains and rivers after heavy rainfall.

“Individuals who enter the water in these areas could become ill,” he said.

Editor’s note: This story has been updated to add the cause for the sewage spill.

Valerie Osier is the Social Media & Newsletter Manager for the Long Beach Post. Reach her at [email protected] or on Twitter @ValerieOsier