Water Availability Information
- Why Water Availability Analysis?
- How to Prepare a Water Availability Analysis
- Water Availability Analysis Resources
- Still Have Questions?
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
- "...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))
Before preparing a WAA, consult with the Division of Water Rights permitting staff lead assigned to your project. If you need assistance determining who to contact, consult with the permitting supervisor responsible for the area in which your project is located.
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 Volume Depletion Approach is an alternative to the water supply report and cumulative diversion analysis applicable to certain Class II and III onstream reservoirs.
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.
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.
2002 Water Availbility Peer Review
- Methods to Estimate Streamflow and Water Availability (State Water Board Staff Presentation, 2002)
- Evaluation of Methods Used for Estimating Selected Streamflow Statistics, and Flood Frequency and Magnitude, for Small Basins in North Coastal California (USGS Scientific Investigations Report, 2004)
- Streamflow and Water Availability Estimates in Ungauged Streams Workshop (State Water Board, CWEMF, 2002)
- Evaluation of the State Water Board’s Water Availability Analysis (MBK Engineers Report, 2001)
Still have questions?
Contact the Division of Water Rights permitting supervisor responsible for the area in which your project is located.