Oros Green Street and Steelhead Park

Project Description

The Oros Green Street project exemplifies North East Trees’ commitment to transform the urban infrastructure from “gray” to “green”. The first Green Street in Los Angeles, this pilot project re-designed a residential street and park to manage storm and dry weather urban runoff in an environmentally sustainable way. This project demonstrates that best management practices (BMPs) based on biological treatment and filtration processes can be used to meet water quality objectives. 

Project Information

Project Funded by:

State of California Proposition 13 Grant

Federal Clean Water Act 319(h) Grant

City of Los Angeles Prop. O funds


Best Management Practices (BMP) :

Infiltration types of BMPS that were employed include:

1. Infiltration galleries between the street and private property line. These were designed to capture runoff from private residences. These galleries include perforated pipes and a gravel filter buried beneath the sidewalks.

2. An infiltration gallery below NET’s Steelhead Park at the end of the street, designed to capture all street and private property run off. After the project, 90% of the polluted runoff that would have reached the river from Oros Street was diverted to the multi-purpose BMP for filtration and infiltration.

How It's Done

Installation of infiltration galleries between street and property lines with french drains across their driveways to capture runoff from residential properties to let it soak into ground. Sustainable, low water use gardens were planted over these galleries.

Construction of infiltration galleries below Steelhead Park, designed to capture remaining runoff from the end of Oros Street.

Plantings above the subsurface infiltration galleries include native grasses and other low-water and native plants. Infiltration serves to pull pollutants from the water. Trench drains across driveways provide a place for water to enter the infiltration galleries. 

The infiltration gallery in Steelhead Park is not apparent in the completed park. Water diverted into it is cleaned before it flows into the Los Angeles River. Water monitoring performed by North East Trees
demonstrated that 90% of the pollutants are filtered by the soil, preventing it from entering the River.

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