skip to Main Content

Promote healthy, safe, clean water.

The mouth of the LA River in Long Beach at river mile 0.
OLIN, 2018.

The LA River is a water body with multiple beneficial uses, impairments, and regulated pollutants.

While over 800 water quality improvement projects are planned, in development, or have been completed within the river’s watershed, additional efforts are needed to meet established water quality targets. In many locations there are projects proposed or constructed to meet the river’s water quality requirements. However, there are many challenges in funding and implementation of the proposed projects to keep pace with approved regulatory milestones. In 2018, the County passed Measure W, the Safe Clean Water Program, to provide a new source of funding to help implement local and regional water quality projects that also help address water supply, community investments, and nature-based solutions. Since implementation, over $250 million dollars has been allocated to 30 Regional Program projects throughout the LA River watershed, with $42 million towards seven Infrastructure Program projects in the Lower Los Angeles River watershed and $214 million towards 23 Infrastructure Program projects in the Upper Los Angeles River watershed.


Steps that should be taken to achieve the goal

LA River Water Quality Need
LA County Water Quality Need Ruler.
OLIN, 2019.

Needs: Water Quality

Water picks up pollutants and absorbs heat as it drains more impervious paved areas on its way to the LA River, impairing water quality and adversely impacting the beneficial uses water provides.

The LA River is an impaired water body with multiple pollutants concentrations detected above federally established water quality standards. In an effort to restore impaired water bodies, Section 303(d) of the Clean Water Act established Total Daily Maximum Loads (TMDLs), a regulatory item that sets the maximum pollutant allowed to be discharged into an impaired water body. The LA River is subject to five TMDLs that collectively regulate discharges of 13 pollutants.

Pollutant reduction targets can be achieved through a combination of water quality improvement projects with varying sizes, target pollutants and treatment methods. They range from local bioretention planters sized to capture and treat stormwater generated on a single parcel to regional stormwater retention facilities that divert from existing culverts, storm drains and can treat up to hundreds of acres of tributary area. A few additional examples of BMPs are rain grading, wetlands, bioswales, and green streets.

Water quality improvements were evaluated for sub-watersheds within the LA River watershed that directly drain to the LA River (not its tributaries). The current water quality conditions at the sub-watersheds were compared with planned efforts to identify additional improvements needed to comply with water quality regulations.
LA County Map
LA River Watershed Water Quality Need.
LA County Public Works LSPC Model Input, 2012; Geosyntec, 2018.
The EWMP/WMP score reflects the weighted difference of target BMP volume (75% weight) versus planned BMP volume (25% weight) for areas in the Upper LA River EWMP (2016), LA River Upper Reach 2 WMP (2015), and Lower LA River WMP (2017) to comply with water quality regulations. The percentage weighting of the data accounts for uncertainty in future implementation. Areas with high EWMP/WMP scores were considered to have a very high need for water quality improvements while areas with a low score were considered to have a general need.
Water quality priority represents an integrated evaluation of dry- and wet weather runoff quality based on receiving water body impairments, identified beneficial uses, and land-use-based pollutant loading within the direct drainage. A higher score indicates a higher water quality need.
Back To Top