Arroyo Seco Water Reuse Project

San Rafael Site:
Lower Arroyo Seco southwest of the San Rafael Avenue overpass of the Arroyo Seco Channel at the southern border of the City of Pasadena; and

San Pascual Site:
Lower Arroyo Seco southeast of the San Pascual Avenue overpass of the Arroyo Seco Channel between the channel and Stoney Drive in the Cities of South Pasadena and Los Angeles.


The applicant, City of Pasadena Department of Public Works as Lead Agency, is proposing to construct a stormwater capture project. The proposed Project consists of two regional stormwater capture and treatment facilities, also referred to as Best Management Practices (BMPs), located within existing underutilized open space areas near the Arroyo Seco Channel. The Project would provide water quality benefits for multiple jurisdictions within the 5,005-acre drainage area of the two BMP sites.

The Project sites are located within the Upper Los Angeles River (ULAR) Watershed. Runoff from this watershed drains to over 50 linear miles of the Los Angeles River and then to the Pacific Ocean. The Arroyo Seco Channel is a major tributary to the Los Angeles River. On July 9, 2010, the Los Angeles Regional Water Quality Control Board (RWQCB) adopted resolution No. R10-007 incorporating a total maximum daily load (TMDL) for indicator bacteria in the Los Angeles River watershed. A TMDL is the calculation of the maximum amount of a pollutant allowed to enter a waterbody so that the waterbody will meet and continue to meet water quality standards.

Outfalls along the Arroyo Seco Channel were modeled for indicator bacteria and the San Rafael Creek outfall was identified as a priority outfall having bacteria levels which consistently exceed allowed limits. A Load Reduction Strategy (LRS) was developed for the watershed and the proposed LRS for the two locations in the Arroyo Seco Channel is to remove 100% of the dry weather flows for treatment. Runoff in San Rafael Creek would be diverted into the San Rafael project site, treated, and a portion infiltrated for groundwater recharge. Treated runoff would then be discharged into the Arroyo Seco Channel and diverted into the San Pascual project site. The runoff would go through additional treatment and a portion would be stored and reused for irrigation of South Pasadena’s Arroyo Seco Golf Course located approximately 1,000 feet south of the San Pascual site.

In addition to fulfilling regulatory obligations to provide cleaner water in the Arroyo Seco and Los Angeles River channels, other Project benefits include increased habitat and reestablishment of natural plant communities, improved trails and public access to open space areas, and educational opportunities utilizing interpretive materials focused on hydrology and native habitat.



An initial environmental study recommending a Negative Declaration with mitigation measures (Mitigated Negative Declaration) has been prepared. Possible impacts identified in the Initial Study include those related to Biological Resources, Cultural Resources, Geology and Soils, and Tribal Cultural Resources. With implementation of mitigation measures, all potential impacts would be less than significant.



A public Scoping Meeting will be held to share information regarding the Project, the environmental review process, and to receive written comments about the scope and content of the environmental analysis to be addressed in the Draft Initial Study/Mitigated Negative Declaration (IS/MND). The Scoping Meeting is an information-gathering meeting, not a public hearing, and no public testimony or recordation of the meeting will occur. Attendees are encouraged to submit all comments in writing, which will be reviewed and considered by the Department of Public Works as part of the environmental analysis of the Project. No decisions about the Project will be made at the Scoping Meeting. A separate public hearing for entitlement requests and consideration of certification of the IS/MND will be scheduled after the completion of the final IS/MND which will include all public comments received during public review of the draft IS/MND and the City’s corresponding responses. The date, time, and location of the public Scoping Meeting are as follows:

Date: Thursday, December 14, 2023
Time: 6:00 - 8:00 P.M.
Location: La Casita Del Arroyo, 177 South Arroyo Boulevard, Pasadena, CA 91105


The Notice of Intent and Initial Study/Mitigated Negative Declaration and technical reports can be viewed during regular business hours at the City of Pasadena Permit Center, 175 North Garfield Avenue, Pasadena, California, 91101; the San Rafael Library, 1240 Nithsdale Road, Pasadena, California, 91105; the South Pasadena Public Library, 1100 Oxley Street, South Pasadena, California 91030, or online on the City of Pasadena’s Environmental Notices webpage at:

The City will consider all written comments regarding the potential environmental effects of the Project received during the public review period. Written comments, including emails, must be submitted in writing by 5:00 P.M., January 15, 2024. Written comments will also be accepted at the Scoping Meeting described above.

Please direct your written comments via email and/or postal service to:

Christina Monde, P.E.
City of Pasadena Department of Public
100 North Garfield Avenue, Suite N306
Pasadena, California 91101

CASE MANAGER: Christina Monde, P.E.