Managing Water Supplies


Urban Water Management Plan (UWMP): As required under the California Urban Water Management Planning Act, a UWMP is to be submitted every five years for agencies serving more than 3,000 acre-feet or more than 3,000 connections annually. The UWMP is a significant planning report to ensure long-term water reliability for various categories of water use during normal, single-dry or multiple-dry years. The District completed its last update to the UWMP in 2015. Local sources of water supply for the Central Basin Municipal Water District's service area include: imported water, groundwater and recycled water supplies. Click here to view the UWMP.

Integrated Regional Water Management (IRWM): The District works collaboratively with the Gateway Water Management Authority as part of the Los Angeles Gateway Region Integrated Regional Water Management Joint Powers Authority. The Gateway Authority is Chair for the Lower San Gabriel Sub-Region of the Greater Los Angeles IRWM. These regional planning groups address water resources needs while identifying state and federal funding opportunities to protect and enhance water supply reliability throughout local communities.

Integrated Resources Plan (IRP): The Metropolitan Water District of Southern California developed an IRP along with its 26 member agencies throughout Southern California. The IRP is a planning document for long-term regional water supply reliability to identify overall supply reliability targets for imported water sources and supplies. Central Basin supports these efforts to ensure water supply reliability for the region. Click here to view Metropolitan's IRP.


Water Supply Allocation Plan (WSAP): In response to the statewide drought conditions, Metropolitan Water District worked with its member agencies to develop updates to their WSAP. The WSAP includes specific formulas for calculating member agency supply allocations and implementation elements for administering an allocation when a shortage is declared. In 2015, Central Basin implemented a WSAP in for its retail agencies. The WSAP supersedes Tier 1 Water Budgeting. Included in the WSAP is a conservation model for each agency's Tier 1 level of allocation. This tool is developed to help agencies manage avoiding higher penalty rates for water used in excess of allocated amounts.

State Water Resources Control Board Mandatory Conservation (SWRCB): As a result of statewide water-use restrictions set forth by Governor Brown and the SWRCB, retail agencies with more than 3,000 service connections are required to reduce water use. Each supplier is assigned a conservation standard ranging between 8 - 36%, based on their residential gallons per capita per day (R-GPCD) and are required to report water use each month. Since the mandatory conservation became effective in June 2015, the Central Basin region has surpassed conservation targets each month.

The average conservation target throughout the District's service area was initially established at 16%. In February 2016, the SWRCB adopted a revision that allowed retail water agencies to apply for adjustments to their local conservation standards. In April 2016, the average conservation target throughout the service area was adjusted to 12%. In May 18, 2016, the SWRCB adopted an emergency water conservation regulation to replace the earlier February emergency regulation. The revised regulation became effective June 2016 through January 2017 and requires conservation standards to be based upon local circumstances, thus replacing the prior percentage reduction-based conservation standard with a localized "stress test" approach to ensure a three-year supply for 2017 to 2019.

As a wholesale water agency, Central Basin MWD's source of imported water is from the Metropolitan Water District. Metropolitan and Central Basin MWD will be able to meet all of the District's requested demands for years 2017, 2018 and 2019. For more information on imported water supplies available to retail water agencies, click here.

Imported Water Tier 1 Annual Water Budgets: Central Basin is allowed to purchase a certain amount of imported water from the Metropolitan Water District at the lower Tier 1 rate. As such, Central Basin implemented individual Tier 1 water budgets for its retail agencies as a mechanism to fairly pass on Tier 2 costs, if any, that might be incurred. Through this process, agencies would only be charged Tier 2 prices if Central Basin as a whole exceeds its Tier 1 allocated amount. This program is not in effect if a regional shortage is declared and the District is under a Water Supply Allocation Planning period.