Fueled by summer heat, algae blooms persist in renovated Oxford Basin
By Gary Walker
The renovated Oxford Basin in Marina del Rey, which opened to great fanfare last year, is arguably an aesthetic improvement over the long-neglected flood control and storm water capture system of past years.
But among the new array of colorful drought-tolerant plants and 750 native trees, one less than appealing visual has been an unsightly veneer of green coating across the surface of the basin’s lagoon.
That unwelcome visitor is algae, which county officials hope to eradicate in order to maintain the visual appeal of the basin’s $14.5-million renovation into a recreation area for residents and haven for seabirds.
The humid and excessively hot summer months could have played a role in creating the algae bloom, which has lingered for several months but appears to be declining, said Los Angeles County Strategic Communications Manager Kerjon Lee.
“Early indications show a correlation between days of intense summer heat and algal growth, but we’re still studying the issue,” Lee said. “The goal is to better understand the cause and determine whether the problem is ephemeral and naturally declining, or indicative of a persistent issue.”
Loyola Marymount University marine biology professor John Dorsey agrees that weather can be a factor in algae growth and doesn’t see it as a long-term problem in Oxford Basin Lagoon.
“This type of algae can be more common in back bays and wetlands. It is not as harmful as the type of algae blooms that we see in the Santa Monica Bay, where toxins produced the algal blooms can be ingested by shellfish and if eaten can be fatal in some cases to humans,” Dorsey said.
Lee said the county officials who are charged with maintaining the basin’s health have been consulting with the Southern California Coastal Water Research Project’s algae expert.
“We’re performing maintenance every two weeks and as needed at the basin,” Lee said.
The county’s most recent effort to remove algae from the basin was in September, and the bloom has been dissipating since the end of summer.
County officials say a recent analysis of the basin’s water continues to show significantly increased water circulation between the basin and the marina, which is one of the project’s goals during its year-plus renovation last year.
Lack of water circulation led to poor water quality in the lagoon before workers dredged out 10,000 cubic yards of contaminated sentiment from the basin last year.
Dorsey noted that urban runoff is another catalyst for algae. Hotels border the basin to the south and the residential Oxford Triangle neighborhood is directly east.
“Nutrients from dry weather runoff and perhaps poor water circulation can make a great recipe for algal growth,” Dorsey said.
A group of environmentally conscious residents who were angered by the removal of over 600 trees to make way for the basin’s refurbishment have suggested the presence of algae has more insidious origins — namely a lack of scientific analysis during the refurbishing process.
Although the lagoon’s water was much clearer in late September than it was in summer, Lee said county officials will continue to monitor basin water quality and take measures to deter algae growth. These include reversing the direction of water flow by manually operating tide gates, removing algae more regularly, utilizing new algae control equipment and conducting weekly visual inspections with photo documentation of algae growth.
Lee said that if residents see new algae or have concerns about the basin, they can call the county’s 24-hour phone number, (800) 675-HELP.