Los Angeles River and Arroyo Seco Low Flow Diversion

The Department of Public Works Bureau of Engineering is proposing to design and construct five (5) Low Flow Diversion (LFD) systems: two (2) LFD systems to divert dry-weather flows which would discharge to the Arroyo Seco and three (3) LFD systems to divert the dry-weather flows which would discharge to an area known as Reach 2 of the Los Angeles River (LA River), which runs upstream to downstream from Figueroa Street, Los Angeles to Carson Street, Long Beach. Thus, the Los Angeles River and Arroyo Seco Low Flow Diversion Project (Project) will capture dry-weather flows from the prioritized stormwater outfalls before discharge into adjacent water bodies and divert the dry-weather flows to sanitary sewers for treatment at the Hyperion Water Reclamation Plant (HWRP). Project construction consists of installing storm drain diversions and pipelines, trash collection structures, maintenance holes, junction structures, diversion structures with weirs, pretreatment units, pump stations, pressurized pipes, valve and meter vaults, power supplies for pump stations, a supervisory control and data acquisition (SCADA) system, and instrumentation.

The intent of the Project is to help improve water quality of the Los Angeles River and its tributaries (including the Arroyo Seco) by reducing the dry-weather flows, which have been identified to have high level of bacteria. Construction of the Project would last for approximately 18 months beginning Winter 2021 and concluding in Fall 2022. 

The Project consists of five (5) distinct Project sites in the City of Los Angeles and are generally categorized as being adjacent to the Arroyo Seco or Los Angeles River. The following describes the location and setting of the five Project sites:

• Figueroa Street LFD: This LFD system will divert dry-weather flows which would discharge to the Arroyo Seco river. The Project is adjacent to the City’s Sycamore Grove Park at the southeast corner of N. Figueroa Street and S. Avenue 49 in the Highland Park area of the Northeast Los Angeles Community Plan Area. The Project site is a currently an unpaved access road that is gated to restrict vehicular access. 
• Via Marisol LFD: This LFD system will divert dry-weather flows which would discharge to the Arroyo Seco river. The Project is in the public right-of-way on the northside Via Marisol between Monterey Road and the SR 110. The Project is in the Highland Park area of the Northeast Los Angeles Community Plan
• Rose Street LFD: This LFD system will divert dry-weather flows which would discharge to the Reach 2 of the LA River. The Project site is in the public right-of-way on the northside of 2nd Street between Alameda Street and Rose Street in the Artists-in-Residence District, also known as the “Arts District”, of the Central City North Community Plan Area.
• Mission Road LFD: This LFD system will divert dry-weather flows which would discharge to the Reach 2 of the LA River. The Project site is in the public right-of-way on Mission Road between Cesar Chavez Avenue and the US-101 freeway ramps in the Boyle Heights Community Plan Area. 
• Palmetto Street LFD: This LFD system will divert dry-weather flows which would discharge to the Reach 2 of the LA River. The Project site is at the intersection of Palmetto Street and Santa Fe Avenue within the public right-of-way in the “Arts District” area of the Central City North Community Plan Area.

The Department of Public Works Bureau of Engineering has prepared a draft Initial Study/Mitigated Negative Declaration (IS/MND) for the Project. The IS/MND will be circulated for a twenty (20) day public review period, beginning on June 25, 2020 and ending on July 14, 2020.

The Final IS/MND and project approval are pending scheduling to be heard before the Board of Public Works for consideration and recommendation to the Los Angeles City Council. The hearing date is to be determined. Agendas for upcoming meetings of the Board of Public Works are available at this webpage: https://boe.lacity.org/dpw/ebreports/

Please note that the dates, time, and location of the meeting(s) at which these items will be considered are subject to change. 

The Final IS/MND will be considered by the City Council after the hearing by the Board of Public Works (date to be determined). The calendar and agendas for the meetings of the Los Angeles City Council and Council Committees can be viewed at: https://www.lacity.org/government/meeting-calendars/city-council-meetingsagendas