Stormwater Engineering Projects

Picture of Pacoima Spreading Grounds


Pacoima Spreading Grounds was built in the 1930s and is one of the major water conservation facilities that provide groundwater recharge for the San Fernando Groundwater Basin. Currently, the spreading grounds' percolation rate is reduced due to a low permeable clay layer underlying the spreading basins. The proposed project will increase the spreading grounds' storage capacity and percolation rate and simplify operations by combining basins and constructing new interbasin structures.

The proposed project will result in increased groundwater recharge in the San Fernando Groundwater Basin. Primary project objectives include:

  • Increasing the percolation rate from 65 to 140 cfs by removing the underlying clay layers in the spreading basins;
  • Expanding the storage capacity of the spreading basins from 530 to 1,200 acre-feet by combining and deepening the spreading basins;
  • Modifying the intake structure between the channel and the spreading basins to enhance operations;
  • Installing tubular perimeter fencing; and
  • Constructing a new bike path along Pacoima Diversion Channel, between Devonshire Street and Filmore Street to improve neighborhood connectivity.

This project is funded by the State Proposition 84 grant through the Intergrated Regional Water Management Plan (IRWMP), the Los Angeles Department of Water and Power, and the Los Angeles County Flood Control District.


Los Angeles County Board of Supervisors adopted the project and its Recirculated

Mitigated Negative Declaration on March 9, 2021. Construction of the project is scheduled to begin in Summer 2021 and last nearly 3 years. Excavated material will be transported to Sunshine Canyon Landfill in Sylmar and Cal-Mat Pit in Sun Valley.

Construction activities will take place from Monday through Friday, between 9 a.m. - 5:30 p.m. Access to residents will not be impacted during construction. Low emission trucks will be used for the transportation of material. LA County will implement measures for noise and dust suppression during construction.



For more information on the project or to be added to the project mailing list, please contact

Updated on: 06/01/2021