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SB610/SB221 Guidebook and FAQs

Note: A complete Urban Water Management Plan can be a foundational document and source of information for SB 610 Water Supply Assessments and SB 221 Written Verifications of Water Supply. UWMPs serve as a critical source document for cities/counties as they update General Plans. General Plans are a source document as water suppliers update UWMPs. These planning documents are linked and their accuracy and usefulness are interdependent. It is is crucial that cities, counties, and water suppliers work closely when developing and updating these planning documents.

1. What if expected projects, planned for the future, but not formally proposed, were included in an Urban Water Management Plan?

Answer: If the development was included as part of the projected water demand of the current UWMP, the water demand for the proposed development does not need to be separately analyzed as long as water demand for the project has remained substantially the same.

The law (Water Code § 10910(c)(2)) states that if the projected water demand associated with the proposed project was accounted for in the most recently adopted UWMP, the water supplier may incorporate the requested information from the UWMP in preparing the assessment. The Urban Water Management Planning Act (Water Code § 10631) specifies the data necessary to document the existing and projected future water demand during a twenty year projection. The code requires that the projected demands be presented in five-year increments for the twenty year projection. While expected projects can be included in the UWMP, this is not typical practice since projections are usually based on density, use and population, not specific projects.

2. If agricultural users outside the water supplier's boundaries draw from the same groundwater basin, does the assessment or verification need to include agricultural water use?

Answer: Yes. Changes in cropping patterns or agricultural land use may affect demand on the groundwater basin and consequently may affect groundwater availability for various uses. Additionally, identification of agricultural demand is a requirement of both SB 221 and SB 610.

3. Does the clock stop if the water supplier requires additional information?

Answer: Under SB 610, a 30 day extension of the 90 day preparation period is possible. Under SB 221, a water supplier has 90 days to prepare a verification and there is no provision for an extension. To help avoid the need for additional information arising late in the review process, it would be worthwhile for water suppliers and local land use agencies to develop a checklist of information necessary to complete an assessment or verification and to provide this checklist to project applicants.

4. Does SB 610 apply to a specific plan?

Answer: Yes, if the specific plan includes a proposed project as defined by SB 610 (Water Code § 10912 (a) or (b), then the environmental document (Environmental Impact Report or Negative Declaration) must include a water supply assessment.

5. Under SB 610, at what point in the CEQA process does the water supplier need to complete the assessment?

Answer: The assessment must be completed prior to the issuance of a draft Environmental Impact Report or proposed Negative Declaration. The supplier must complete the assessment within 90 days of its receipt of the request for an assessment, plus a possible 30-day extension.

6. When a retail water supplier is served by a wholesale water supplier, which entity is responsible for preparing an assessment or verification?

Answer: The retail water supplier prepares the assessment or verification based, in part, on information about its wholesale water supply.

7. How do you determine how much water conservation decreases demand and, therefore, may result in more water being available or in a decreased water demand?

Answer: This is a local judgment that is determined by the local agencies. Useful information may be found in the applicable Urban Water Management Plan. Additionally, the California Urban Water Conservation Council (CUWCC) has data and methods that may be used to perform this analysis available on their website at

8. Can a consultant/developer prepare the water supply assessment?

Answer: A consultant/developer can prepare and submit material to be used in the water supply assessment, but the water supplier is ultimately responsible for the water supply assessment and must exercise its independent judgment as it considers adoption of the water supply assessment.

9. If a water supplier does not have sufficient supply to provide water for the proposed development, can the developer find a new source of supply?

Answer: Yes, developers may provide a new supply to the water supplier by obtaining and funding alternative water supplies through such activities as: conservation, recycling, water transfers, etc. As it considers adoption of the water supply assessment or verification, the supplier must determine whether these supplies are acceptable as to quality, quantity, and reliability. The city or county shall determine, based on the entire record, whether projected water supplies will be sufficient to satisfy the demands of the project, in addition to existing and planned future uses. If the city or county determines that water supplies will not be sufficient, the city or county shall include that determination in its finding for the project.

10. What is the procedure if the city or county is unable to identify a water supplier?

Answer: If the city or county is not able to identify any public water system that may supply water for the project, the city or county shall prepare the water assessment required by this part after consulting with any entity serving domestic water supplies whose service area includes the project site, the local agency formation commission, and any public water system adjacent to the project site.

11. What if the public water supplier does not provide an assessment or written verification?

Answer: SB 610, (Water Code §10910(g)(3)), provides that a city or county may seek a writ of mandamus to compel the governing body of the public water system to comply with the requirements of the statute. SB 221, (Government Code §66473.7(b)(2)), provides that a city or county, or another interested party, may seek a writ of mandamus to compel the water supplier to comply.

12. Are local agencies permitted to charge a fee for the preparation of water supply assessments and verifications?

Answer: Yes. Public water suppliers and city and county agencies may charge applicants a fee to offset the costs incurred in the preparation of documents related to development applications. Agencies should develop a fee schedule and inform project applicants of all fees prior to commencement of the application process.

13. Must a residential development be at least 500 units before triggering the water supply assessment or verification requirements?

Answer: Both SB 221 and SB 610 apply to a 500 unit residential development OR a project that would increase the number of the public water system's existing service connections by 10%.

Under Water Code § 10912(a)(7), SB 610 would also apply to a "project" that "would demand an amount of water equivalent to, or greater than, the amount of water required by a 500 dwelling unit project." In order to determine whether an assessment will be required under the 500 unit equivalency threshold, the city or county would need to work with the water supplier to determine if the demand associated with a proposed project would be equivalent to or greater than the demand for a 500 unit project in that jurisdiction. This could include a water intensive project of less than 500 residential units, depending on how the local agencies define the typical water demand for a 500-unit residential project.

14. Can my Urban Water Management Plan be rejected or denied?

Answer: The Department of Water Resources does not reject an UWMP filed by an urban water supplier. The Urban Water Management Planning Act requires the Department to review UWMPs to determine whether all of the information required by law has included. If a plan includes all of the required information, it is “complete”. If a plan is not complete, the Department will notify the supplier that they can improve their plan by addressing the provisions identified as “Not Addressed” (highlighted in the Department’s review).