Storms on December 10th and December 15th resulted in 1.7 million gallons and 132,000 gallons, respectively, of mixed sewage and rainwater to be dumped to the estuary, Andrea Pook, a spokesperson for the East Bay Municipal Utility District (EBMUD), told Action Alameda News.
Signs warning people to avoid water contact were present along the estuary last weekend, but they have since been removed, Pook said.
During heavy rains, the amount of water that arrives at the utility’s water treatment plants increases exponentially, Pook said, overwhelming plant capacity and prompting the discharge.
Pook took pains to note that the sewage discharges are heavily diluted, as much as 90 percent to 95 percent rainwater.
The problem, she said, is that pipes in EBMUD’s network, and in the privately owned sewer laterals that connect residences to the network, crack and open up. Heavy rains saturate the ground, and rainwater leaks into the sewer network, overwhelming treatment plants.
“It’s never a good thing,” Pook said. “It’s a problem for a lot of agencies.”
A 2014 settlement agreement called for EBMUD and several East Bay cities to spend some $1.5 billion over 21 years to upgrade sewer systems to prevent such discharges.
Pook said it was unclear if the recent discharges would prompt any repercussions vis-a-vis the settlement agreement, but that the utility had already reported the events to state officials, as required, separately, under state law.
She said that tidal flow should dilute and carry the discharged water out of the estuary, and that the impact was probably limited as fewer people were in the water during the winter. However, the utility was working with a local boat cleaner who gets in the water to do his job.
Pook pointed to the 2011 regional private sewer lateral ordinance as an ongoing mitigation effort, and said that residents interested in taking action to prevent discharges to the San Francisco Bay may want to voluntarily have their private sewer lateral tested and repaired.