Gross: overnight rains caused several leaky manholes to overflow along the Great Highway at Ocean Beach last night, prompting the SF Public Utilities Commission to temporarily shut down parts of the pedestrian path and the beach itself.

The first (ahem) manhole discharge happened just before 1 a.m. this morning near Lake Merced. Less than half an hour later, two other manholes spilled over at Vincente Street and Lincoln Way, Ocean Beach Bulletin reports. Around the same time another manhole overflowed on the North end of Ocean Beach near Balboa Street.

Although the SF PUC says the discharge is 90% rainwater, the promenade along Great Highway and the beach itself are both closed and signs warning pedestrians have been put in place. The Department of Public Works was on the scene cleaning up and hosing down the sidewalk this morning, but because a portion of the spillage seeped into the sand, the beach won't reopen to public access until the cleanup crews can test for bacteria levels. The beach will likely re-open tomorrow at the earliest.

According to Ocean Beach Bulletin, this occasionally happens after heavy rains like we've had this week because San Francisco's waste treatment system mixes rainwater with wastewater from homes and businesses. Normally that means runoff from the gutters and street drains gets treated before being dumped out into the Pacific, but after heavy rains the city's system overflows and partially treated wastewater spills over.

Anyhow, if you were hoping to take a Thanksgiving stroll along the Pacific, it would be a good idea to check the Water Quality Report right here.