ACWD’s Water Sources & Supplies

Sources & Supplies

ACWD currently has three primary sources of water supply:

The SWP and SF supplies are imported into the District service area through the South Bay Aqueduct and Hetch-Hetchy Aqueduct, respectively. Local supplies include fresh groundwater from the Niles Cone Groundwater Basin (underlying the District service area), desalinated brackish groundwater from portions of the groundwater basin previously impacted by seawater intrusion, and surface water from the Del Valle Reservoir.

The primary source of recharge for the Niles Cone Groundwater Basin is from percolation of runoff from the Alameda Creek watershed. To a lesser degree, a portion of ACWD's SWP supplies are also used for local groundwater percolation. Infiltration of rainfall and applied water also contribute to local groundwater recharge.

Water Supply Planning

The District develops comprehensive, long-term planning documents to manage our water supply and ensure we meet current and future demands.

Integrated Resources Plan (PDF)
Urban Water Management Plan
Water Supply Reliability Fact Sheet (PDF)

Regional Water Supply Efforts

The Bay Area Regional Reliability (BARR) Partners include the following:

  • Alameda County Water District
  • Bay Area Water Supply and Conservation Agency
  • Contra Costa Water District
  • East Bay Municipal Utility District
  • Marin Municipal Water District
  • San Francisco Public Utilities Commission
  • Santa Clara Valley Water District
  • Zone 7 Water Agency.

The BARR Partners have joined forces to leverage existing facilities and, if needed, build new ones to bolster regional water supply reliability.
BARR website


Before being supplied to ACWD's customers, the source water supplies are treated to meet and surpass all state and federal drinking water standards. ACWD operates one surface water treatment plant that treats SWP and local surface water from Del Valle Reservoir. The Newark Desalination Facility treats brackish groundwater to remove salts and other impurities, and the Blending Facility blends San Francisco water with local fresh groundwater (with higher hardness) to provide a blended supply with lower overall hardness.

Meeting Demands

ACWD’s diverse water supply portfolio helps the District to provide water supply reliability. During a typical year, the District receives water from:

San Francisco Regional System (imported)- 20%*

State Water Project (imported) – 40%*

Alameda Creek Watershed (local) – 40%*


*Amounts are approximate