1:31pm | Consumers in portions of four Southern California counties may notice a musty taste and odor in their tap water, but it is an aesthetic problem and not a health hazard, according to water quality experts.
“The earthy taste and smell stem from an especially large and persistent algae bloom in the east branch of the State Water Project,” said Jim Green, the Metropolitan Water District of Southern California’s manager of water system operations.
“Metropolitan receives a major portion of its water through the SWP’s east branch, which includes Silverwood Lake in the San Bernardino Mountains, and we are working with the state Department of Water Resources—which owns and operates the state system—to address the situation,” Green said.
“Consumers, however, can be assured that the taste-and-odor issues they may be experiencing in their tap water do not pose any health risks,” he said.
Green suggested consumers may consider refrigerating drinking water to help improve its taste until the problem diminishes. He cautioned, however, that the problem may persist for a few more weeks.
For the third time in three weeks, DWR water quality experts Thursday applied copper sulfate to control the algae bloom. Officials stressed that the treated water will be safe for consumers as well as boaters and swimmers at Silverwood and downstream at the state’s Lake Perris. Fish and wildlife also will not be impacted.
In response, Metropolitan also has reduced deliveries from Silverwood Lake, which supplies the district’s F.E. Weymouth Water Treatment Plant in La Verne and Robert B. Diemer plant in Yorba Linda. The two plants provide treated drinking water to about 7 million people in the affected areas.
The cause has been identified as 2-methylisoborneal, or MIB. The nuisance compound MIB is produced from the growth of certain algae in freshwaters throughout the world. Typically, MIB levels increase when warmer weather accelerates the growth of algae, Green said.
“Unfortunately, MIB is a noticeable needle in the haystack,” he added. “People with sensitive taste and smell can detect the compound in water levels as low as 5 parts-per-trillion. However, water from two treatment plants have experienced MIB concentrations as high as 20 parts-per-trillion.
“By comparison, one part-per-trillion is equivalent to just 10 drops of MIB in enough water to fill the Rose Bowl,” Green said.
According to to an email from Councilwoman Gerrie Schipske, several Fifth District residents have contacted her office to report noticing the musty taste and odor in their drinking water.
Consumers interested in receiving additional information about the quality of Metropolitan’s drinking water supplies can visit the district’s website, www.mwdh2o.com, for the district’s annual water quality report and other related materials.