Countywide : Algae Suspected as Cause of Water Tasting ‘Swampy’

Some county residents discovered that their tap water had a bad taste and smelled musty Tuesday and Wednesday. This may have been caused by the proliferation of algae in a Riverside County reservoir, San Diego’s sole source of treated water from the Metropolitan Water District, an MWD spokesman said Wednesday.

Engineers bypassed the Lake Skinner reservoir Wednesday after officials determined that the problem water was most probably coming from MWD-treated water in the reservoir and not from locally treated water.

The supply going to Lake Skinner, a combination of water from Northern California and the Colorado River, will be rerouted directly to an adjacent treatment plant until tests can determine what exactly caused the “swampy” taste and smell, said Bob Gomperz, an MWD spokesman.

Even though the water department is fairly certain that a blue-green algae that secretes a substance called 2-methylifoborneol is the culprit, officials say there is a slight chance that chloramine, the new water additive substituted for chlorine, may also be to blame.

“Unfortunately it’s (algae growth) a seasonal problem, but it’s an extremely acute problem right now because of the warmer weather,” Gomperz said.

Despite the unusual smell and taste, the algae is not harmful, Gomperz said.

“It is an extremely fast-growing plant,” he said. “One thimble full in a football field-sized area of water will cause the water to smell and taste funny to a sensitive person.”

Local water departments and the MWD first began receiving complaints Tuesday and “they’ve been coming hot and heavy ever since,” Gomperz said Wednesday.

The water bypassing the Lake Skinner reservoir will first be chlorinated, then processed with chloramine, a combination of chlorine and a small amount ammonia, while testing is carried out on water in the reservoir.

Gomperz said chloramine does not oxidize as rapidly as chlorine and therefore may allow the algae to continue to grow. Meanwhile, the algae-ridden water that remains in the reservoir will be diluted with fresh water until the algae is eradicated, he said.