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How Los Angeles County is capturing, treating and storing water

  • Morris Dam. Photo by Phoenix Tso.

  • Peck Water Conservation Park, a project that could be funded by L.A. County's Safe Clean Water Program. The program was approved by L.A. County voters during the Nov. 6 election. Photo by Phoenix Tso.


Alhambra , CA United States

The Los Angeles County Department of Public Works controls 14 dams, 27 spreading grounds and 500 miles of open channel.

All of these structures are designed to move stormwater to the ocean in order to prevent flooding. But L.A. County needs to capture and treat stormwater, which is why it’s pushing a stormwater tax measure, which the L.A. County Board of Supervisors will consider putting on the November ballot during the July 10 meeting.

L.A. County’s flood control infrastructure, which was mainly built in the 1930s, is aging, while residents depend primarily on outside sources for their drinking water. Trash, pesticides and other sources of pollution contaminate stormwater, which flows to different bodies of water throughout the county. With climate change and a five-year drought that cost the state billions of dollars, it’s time for L.A. County to become more water-independent.

Edel Vizcarra, a government relations official with LADPW, explained the purpose of this measure at the site of the Morris Dam, near Azusa in the San Gabriel Valley. “What we’re trying to do is get this system here and optimize it, bring it down to the neighborhood level, bring it down to your community,” he said.

These neighborhood-level projects would include green streets, which uses vegetation to capture and treat stormwater, as well as stormwater infiltration galleries under parks and schools. The measure would raise about $300 million every year, said Kerjon Lee, strategic communications manager for LADPW. The measure would apply 2.5 cents per square foot of impermeable surface area of a person’s private property, which would amount to an estimated annual median cost of $83 per residential property owner.

Forty percent of revenue would go to large-scale regional stormwater projects, while 10 percent would go to L.A. County’s flood control district to fund administration and education. The remaining 40 percent would go to local projects in 85 L.A. County cities. This would be an exciting opportunity for cities like Alhambra to increase their stormwater capture and treatment.

LADPW officials took reporters on a tour of three current stormwater facilities in the San Gabriel Valley. Below is an introduction to all of them, with explanations as to how the proposed measure would enhance their capabilities.

Morris Dam

Morris Dam was built in the 1930s and is important for flood control and groundwater recharge. It’s one of 14 dams that the L.A. County Department of Public Works built after a devastating flood in 1914. With the proposed parcel tax, LADPW is getting away from building large projects like these and aim to focus on community-level initiatives that capture and treat stormwater, rather than moving it towards the ocean.

San Gabriel Coastal Spreading Grounds

Located in Pico Rivera, the San Gabriel Coastal Spreading Grounds collects the county’s water for groundwater replenishment. The water, which comes from imported sources, the San Gabriel Canyon and a couple of nearby dams, can then be pumped for use throughout the county. The San Gabriel Coastal Spreading Grounds lies to the west of the San Gabriel River and is one of of 27 LADPW spreading grounds. These spreading grounds are an example of a project that the proposed tax measure would fund.

Peck Water Conservation Park

Located in Arcadia, Peck Water Conservation Park is a five-acre park with a spreading basin that receives water from the Santa Anita Wash and the Sawpit Wash to recharge groundwater. The basin can also conserve stormwater, but its capability to do so is limited due to lack of funding. In addition, the water is polluted with pesticides, bacteria and other contaminants. The proposed tax measure could help with an LADPW project to divert water from the Arcadia Wash into Peck’s stormwater basin, explained Aracely Lasso, a LADPW engineer. Another project would convert the commercial area north of the park into engineered treatment wetlands that stormwater would meander through, before flowing into the groundwater recharge basin.

“We are creating wetlands for additional habitats in the park, but potentially we are also cleaning up the water that is in the lake itself,” Lasso said.

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