Oxford Retention Basin


The Oxford Retention Basin is a flood control facility operated by the Los Angeles County Flood Control District. This $14.7 million project is located in the seaside community of Marina del Rey in Los Angeles County, California. This multi-benefit project modernized the 10.7-acre facility to improve local water quality, flood protection, and ecological health. The project involved the construction of a meandering berm to facilitate circulation of local urban runoff and tidal flows through the basin to sustain a habitat for native plants and wildlife, and it added observation areas, educational signage, park benches, walkways with eco-friendly lighting and bike paths to the periphery.


Meaningful stakeholder engagement.
The project team engaged the community and solicited their feedback throughout the project design process. Engaging stakeholders every step of the way and providing ample opportunity for members of the community to learn about the project and provide input fostered strong public support for the project.

Good value for our community and the environment.
The Oxford Retention Basin project emphasizes the importance of incorporating Green Infrastructure (GI)/low impact development (LID) to benefit the community and the environment while also making good financial sense. This project provides a number of climate related benefits, including managing stormwater runoff, reducing urban heat island effects, improving water quality, and providing local residents with additional recreational opportunities. To quantify the benefits of GI/LID in economic terms, the project team utilized a triple bottom-line cost benefit analysis (TBL-CBA) and found the social and environmental Net Present Values of the project to be positive, totaling $68.7 million and $5.5 million, respectively. This result indicates that the Oxford Basin Project provides a net positive financial impact for the community in relation to the total cost of the improvements.

New and improved public space and amenities.
This project includes many features and improvements that add to public space and enhance community livability in a densely-populated area. This project transformed a single-purpose flood control facility into a multi-benefit project complete with recreational amenities, including walking and bike trails, wetland habitat observation areas, benches and seat walls, wayfinding and interpretive signage, and wildlife-friendly lighting.

Twenty-three percent increase in habitat.
Despite the project’s existing site conditions (being bounded by local roads, with a total site area of 10.7 acres), the project was able to significantly increase the area of habitat through restoration and the addition of new, native vegetation. Post-construction, the native vegetation increased from 4.30 acres to 5.28 acres, a 23% gain. In addition, a post-project vegetation survey indicated the average cover of native plant species was 71.5% compared with a pre-project survey showing 56.4%.


“The Oxford Basin Project converted a single-purpose flood control facility into a multi-benefit amenity and community treasure. It addresses a wide range of societal needs while reducing flood risk, improving water quality and enhancing plant and wildlife habitat. It’s a great example of how the County of Los Angeles is reinvesting in its infrastructure to meet the complex needs of the 21st Century,” said Mark Pestrella, PE, Director of Los Angeles County Public Works. 


“Historically, when people thought about the term ‘infrastructure’, they focused on assets like highways, airports, dams, and sewer systems. Often, green infrastructure solutions weren’t considered or were not top-of-mind. Increasingly, however, people understand that we need more natural solutions to address today’s challenges and tomorrow’s threats. Projects like the Oxford Retention Basin Multiuse Enhancement project are so vital as they bring awareness and visibility to the importance of natural solutions and provide a multitude of benefits to both people and the environment,” said Melissa Peneycad, ISI’s managing director.

Envision-verified Project: Oxford Retention Basin Multiuse Enhancement Project
Owner: Los Angeles County Flood Control District
Location: Marina del Rey, Los Angeles County, California
Lead Envision Firm: Los Angeles County Public Works
Envision Rating: Platinum
Award Date: April 20, 2021
Project Phase: Construction Completed

For more information about this project and its sustainability commitments and achievements, visit the following website page. (https://pw.lacounty.gov/swp/oxfordbasin)

Please download the Project Profile announcement

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