L.A. Adopts Low-flow Diversion Scheme to Abate Runoff

The city of Los Angeles Department of Public Works Bureau of Sanitation announced on March 5 the city's expanded commitment to improve the water quality of Santa Monica Bay.

Using iterative processes to reduce pollutants, the bureau decreased the amount of bacterial pollution and contaminated runoff from streets, sidewalks, yards, and lots. The program was funded by Proposition O, a bond measure that 76 percent of the voters passed in November 2006. The program has reduced bacteria levels by more than 85 percent to protect marine life and the recreational use of the region's beaches.

"Santa Monica Bay and its shorelines are among the nation's most important coastal symbols, and this emphasizes our underlying principle and motivation to protect the bay and ocean," said Cynthia M. Ruiz, president of the Board of Public Works. "To that end, the city of Los Angeles has committed $500 million from the Prop O bond measure."

The cities of Los Angeles and Santa Monica and the county of Los Angeles have installed 23 low-flow diversion structures. These structures divert urban runoff from streets, gutters, canyons, and storm drains into the sewer system and sends untreated water to the Hyperion Wastewater Treatment Plant during the summer dry weather months (April 1 to October 31), the highest time of beach use. The contaminated urban runoff, which includes motor oil, lawn fertilizer, pet droppings, and litter, receives full secondary treatment to meet the designated permit requirements for ocean discharge.

The city of Los Angeles operates eight of 23 low-flow diversion structures at a capital cost of $1 million each, with an average annual operation and maintenance cost of $30,000 to $40,000. The city is currently upgrading low-flow diversion structures along Pacific Coast Highway to increase their capacity and reliability at an additional anticipated cost of more than $35 million.

"Environmental protection underscores our commitment to develop and implement innovative water quality solutions," said Enrique C. Zaldivar, director of the Department of Public Works Bureau of Sanitation. "The city works diligently with regional regulators to comply with water quality requirements and address the regional challenge of urban and stormwater runoff."

The city has incorporated the low-flow diversion structures into the overall strategy to control dry weather runoff pollution. In conjunction with water quality improvement projects in Ballona Creek, Dominguez Channel, Los Angeles River, and Santa Monica Bay among others, more than 20,000 catch basin screen covers and inserts were installed between 2005 and 2007 at a total cost of $27 million. The screens and inserts block and prevent litter from entering the region's waterways and beaches.

The final phase to install the remaining 34,000 catch basin screen covers and inserts throughout the city of Los Angeles is scheduled to begin this spring. The Santa Monica Low Flow Diversion Upgrade project is anticipated to begin in the fall of 2009 along Pacific Coast Highway between Pacific Palisades and the Hyperion Wastewater Treatment Plant.

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