Annual Water Supply and Demand Assessment

Drought is a recurring feature of California’s climate.

In 2018, the California Legislature enacted into law new requirements for urban water suppliers to increase drought resilience and to improve communication of water shortage response actions. Each urban water supplier is required to prepare an Annual Water Supply and Demand Assessment (Annual Assessment) and submit an Annual Water Shortage Assessment Report (Annual Shortage Report) to DWR on or before July 1, 2022, and every year thereafter. 

Annual Shortage Reports must be submitted to DWR as follows:

Suppliers are responsible for providing a reliable supply of water for their customers, evaluating their water supply status on a regular basis and, in the case of anticipated water shortages, preparing mitigation actions.

The results of these evaluations are included in the following suppliers’ plans and reports:

  • Urban Water Management Plan (UWMP), specifically the
    • Water Shortage Contingency Plan (WSCP)
    • Drought Risk Assessment (DRA)
  • Annual Shortage Report

The requirements for Annual Assessments and the resulting Annual Shortage Reports are found in Section 10632 of California Water Code (CWC). Every Supplier that either provides over 3,000 acre-feet of water annually or serves more than 3,000 urban connections is required to perform an Annual Assessment and submit an Annual Shortage Report to DWR every year beginning July 1, 2022. A supplier that relies on imported water from the State Water Project or the Bureau of Reclamation shall submit its annual water supply and demand assessment within 14 days of receiving its final allocations, or by July 1 of each year, whichever is later.

The Annual Shortage Report includes information on anticipated shortage, triggered shortage response actions, compliance and enforcement actions, and communication actions as described in each Supplier’s WSCP.


Suppliers’ assessments and reports are important for drought response as these exercises help proactively prepare for anticipated water shortages in the coming year. The tools a supplier selects to mitigate shortages are called Response Actions and are ideally locally appropriate and effective. The Response Actions can focus on increasing supply in the near term or reducing demand temporarily, making operational changes, implementing water use prohibitions, imposing emergency rates, rationing, and other methods.

Annual Water Supply and Demand Assessments Summary Report