Water Availability Information

Why Water Availability Analysis?

A Water Availability Analysis (WAA) is required by the California Water Code.  Pertinent provisions of the Water Code are summarized below:

  • Every water right application submitted to the State Water Board must include "sufficient information to demonstrate a reasonable likelihood that unappropriated water is available for appropriation." (Water Code section 1260(k))
  • "...In determining the amount of water availability for appropriation, the State Water Board shall take into account, whenever it is in the public interest, the amounts of water needed to remain in the source for protection of beneficial uses..." Instream beneficial uses include, but are not limited to, recreation and the preservation of fish and wildlife habitat. (Water Code section 1243)
  • Before the State Water Board can grant a water right permit, it must find that there is "unappropriated water available to supply the applicant." (Water Code section 1375(d))

How to Prepare a Water Availability Analysis

Before preparing a WAA, consult with the Division of Water Rights permitting staff contact assigned to your project in eWRIMS. For more information about accessing eWRIMS to view the assigned staff contact, please refer to the Guide for the eWRIMS Public Database.

Projects located in the North Coast Instream Flow Policy Area

WAAs prepared for projects located within the geographic scope of the Policy for Maintaining Instream Flows in Northern California Coastal Streams (North Coast Instream Flow Policy or Policy) should adhere to specific requirements set forth in the Policy. If the WAA was completed prior to the adoption of the Policy, see Policy Section 3.3.1.

The Policy prescribes measures that protect native fish populations, with particular focus on anadromous salmonids and requires that a WAA include (1) a water supply report that quantifies the amount of water remaining instream after senior diverters are accounted for, and (2) a cumulative diversion analysis to evaluate the effects of the proposed project, in combination with existing diversions, on instream flows needed for fishery resources protection. Applicants may use regional criteria, site-specific criteria, or a combination of the two in the cumulative diversion analysis for assessing whether the proposed diversion affects the instream flows needed for fishery resources. Exceptions to diversion criteria may be granted for certain projects involving an application coupled with a reduction of existing diversion under another basis of right.

The Policy exempts projects located on flow-regulated mainstem rivers from the regionally protective instream flow criteria and the cumulative diversion analysis requirements.  However, such projects must still comply with the rest of the Policy, including the policy principles and regionally protective criteria pertaining to onstream dams. The Policy defines flow regulated rivers as a river or stream in which scheduled releases from storage are made to meet minimum instream flow requirements established by State Water Board Order or Decision. Division staff have developed a methodology for evaluating water availability on the mainstem Russian River and Dry Creek below Lake Sonoma—both flow-regulated mainstem rivers—that is separate from the water supply report and cumulative diversion analysis pathway. If you have a pending application on the mainstem Russian River or Dry Creek and would like to discuss this WAA methodology, please reach out to the staff contact assigned to your application. If you are interested in evaluating the feasibility of a potential project using this WAA methodology, please contact Division staff at dwr-applications@waterboards.ca.gov. To read more about the WAA methodology and the Russian River WAA Tool, please review the Water Availability Analysis Methodology for Pending Applications on The Mainstem Russian River in Mendocino and Sonoma Counties and Dry Creek Downstream of Lake Sonoma in Sonoma County.

The Policy also includes an alternative WAA pathway applicable to certain Class II and III onstream reservoirs. The Volume Depletion Approach webpage has additional information regarding this pathway.

Projects located outside of the North Coast Instream Flow Policy Area

WAAs prepared for projects located outside of the geographic scope of the North Coast Instream Flow Policy need to provide information required under the California Water Code to demonstrate whether water is available for appropriation, including whenever it is in the public interest, the amounts of water required for recreation, and the preservation and enhancement of fish and wildlife resources.

For projects located outside of the geographic scope of the Policy there is no set methodology for conducting a WAA. Applicants should consult with their assigned permitting staff lead to develop their proposed approach.

Since it provides a general methodology for evaluating the senior diverter demand component of water availability, applicants may be able to rely on guidelines for the water supply report component of the Policy to prepare WAAs even if their project is located outside of the Policy area. While the applicant can demonstrate through a water supply report or a similar type of an analysis that there is unappropriated water to supply the proposed project, there could still be impacts to instream beneficial uses caused by the proposed project in combination with senior diverters. In select watersheds, instream flow requirements have been established and could be considered. Most watersheds do not have such instream flow requirements established yet, and applicants will need to develop and/or rely on a site specific approach.

Water Availability Analysis Resources

Examples of Water Availity Analyses. Applicants with pending applications should contact the permitting staff lead assigned to their project to obtain examples of recent Water Availability Analyses conducted in the general geographic location of their proposed project.

State Filed Applications

Water Rights and Climate Change (useful information for evaluation of climate change impacts on proposed projects in order to improve the long-term feasibility of new water rights)

Hydrologic Information

2002 Water Availbility Peer Review

Still have questions?

Contact the Division of Water Rights permitting supervisor responsible for the area in which your project is located.