§ 842.Service of Initial Disclosure

Title 10. Actions In Particular Cases · Chapter 7. Actions Relating to Groundwater Rights · Article 9. Initial Disclosures · Last amended 2026 · Last verified July 28, 2026

In one sentenceSection 842 requires each party in a comprehensive adjudication to serve, within six months of appearing, a sworn initial disclosure covering their historical extraction, water right claims, land and crop use, future claims, replenishment activities, and supporting witnesses, subject to a rebuttable presumption for small extractors and a duty to supplement.

Full Text of § 842

Text sizeJump to: (a) (b) (c) (d) (e) (f) (g) (h)

(a) Except as otherwise stipulated by the parties or ordered by the court, within six months of appearing in a comprehensive adjudication, a party shall serve on the other parties and the special master, if one is appointed, an initial disclosure that includes all of the following information:

(1) The name, address, telephone number, and email address of the party and, if applicable, the party's attorney.

(2) The quantity of any groundwater extracted from the basin by the party and the method of measurement used by the party or the party's predecessor in interest for each of the previous 10 years preceding the filing of the complaint.

(3) The type of water right or rights claimed by the party for the extraction of groundwater.

(4) A general description of the purpose for which the groundwater has been used, and if for an agricultural use, the type of crops grown during each of the 10 calendar years immediately preceding the filing of the complaint.

(5) The location of each well or other source through which groundwater has been extracted.

(6) The area in which the groundwater has been used, and if for an agricultural use, the number of acres the party irrigated during each of the 10 calendar years immediately preceding the filing of the complaint.

(7) Any claims for increased or future use of groundwater.

(8) The quantity of any beneficial use of any alternative water use that the party claims as its use of groundwater under any applicable law, including, but not limited to, Section 1005.1, 1005.2, or 1005.4 of the Water Code.

(9) Identification of all surface water rights and contracts that the party claims provides the basis for its water right claims in the comprehensive adjudication.

(10) The quantity of any replenishment of water to the basin that augmented the basin's native water supply, resulting from the intentional storage of imported or non-native water in the basin, managed recharge of surface water, or return flows resulting from the use of imported water or non-native water on lands overlying the basin by the party, or the party's representative or agent, during each of the 10 calendar years immediately preceding the filing of the complaint.

(11) The names, addresses, telephone numbers, and email addresses of all persons possessing information that supports the party's disclosures.

(12) Any other facts that tend to prove the party's claimed water right.

(b) The Judicial Council may develop a form for initial disclosures made pursuant to subdivision (a) to facilitate the consistent, independent, impartial, and accessible administration of comprehensive adjudications. The Judicial Council may coordinate with the department in developing the form.

(c) A party shall make its initial disclosures based on the information then reasonably available to it. A party is not excused from making its initial disclosures because it has not fully investigated the case, because it challenges the sufficiency of another party's disclosures, or because another party has not made its disclosures.

(d)

(1) If a party claims in an initial disclosure to extract not more than 100 acre-feet of water per year, as required by paragraph (2) of subdivision (a), the court shall presume the accuracy of the facts asserted in the initial disclosure.

(2) A party who challenges the facts asserted in an initial disclosure described in paragraph (1) has the burden of proving the inaccuracy of those facts.

(e) A party that has made its initial disclosures, as described in subdivision (a), or that has responded to another party's discovery request, shall supplement or correct a disclosure or response in all of the following situations:

(1) In a timely manner if the party learns that in some material respect the disclosure or response is incomplete or incorrect and the additional or corrective information has not otherwise been made known to the other parties during the disclosure or discovery process.

(2) If the party extracts groundwater from the basin after the complaint is filed. A supplement filed pursuant to this paragraph shall report the quantity of water extracted and be filed within 90 days after the end of the calendar year.

(3) As ordered by the court.

(f) To the greatest extent possible, a party shall serve their initial disclosures electronically. If it is not possible for the party to serve their disclosures electronically, the party shall serve the disclosures in an electronic format saved on a portable storage media device such as a compact disc or flash drive.

(g) A party's obligations under this section may be enforced by a court on its own motion or the motion of a party to compel disclosure.

(h) A party's disclosures under this section shall be verified under penalty of perjury as being true and correct to the best of the party's knowledge.

End

Plain-English Summary

Instead of leaving each party's factual claims to emerge gradually through discovery, § 842 requires an early, comprehensive disclosure from every appearing party. Within six months of appearing (absent a stipulation or court order changing that timeline), a party must serve an initial disclosure covering twelve categories of information: contact information, historical extraction quantities and measurement methods for the prior ten years, the type of water right claimed, the purpose of use (including crop history for agricultural users), well locations, irrigated acreage history, claims for increased or future use, any alternative-water-use credit claimed, surface water rights or contracts underlying the claim, historical replenishment activity, contact information for supporting witnesses, and any other facts tending to prove the claimed right.

Subdivision (b) lets the Judicial Council develop a standard form for these disclosures, potentially in coordination with the Department of Water Resources. Subdivision (c) makes clear a party must disclose based on information reasonably available, without waiting for full investigation or using another party's incomplete disclosure as an excuse.

Subdivision (d) gives small extractors a practical break: if a party discloses extraction of no more than 100 acre-feet per year, the court presumes the accuracy of those facts, and a challenger bears the burden of proving otherwise. Subdivision (e) requires supplementing or correcting a disclosure that turns out to be materially incomplete or inaccurate, or when a party extracts groundwater after the complaint is filed (with that supplement due within ninety days after the calendar year ends), or as the court orders. The remaining subdivisions require electronic service where possible, allow court enforcement of disclosure obligations, and require the disclosures to be verified under penalty of perjury.

Frequently Asked Questions

How soon after appearing must a party make its initial disclosure?

Within six months, unless the parties stipulate otherwise or the court orders a different timeline.

What information must the initial disclosure include?

Twelve categories, including historical extraction quantities, the type of water right claimed, use purpose and crop history, well locations, future use claims, replenishment activity, and supporting witness information.

Does claiming a small amount of extraction give any procedural advantage?

Yes. Under § 842(d), a party claiming no more than 100 acre-feet per year gets a rebuttable presumption that the disclosed facts are accurate, and a challenger bears the burden of disproving them.

What if a party's circumstances change after the initial disclosure?

The party must supplement or correct the disclosure, including reporting new extractions within ninety days after the calendar year ends.

Must the initial disclosure be sworn?

Yes, § 842(h) requires it to be verified under penalty of perjury as true and correct to the best of the party's knowledge.

Amendment History

Amended by Stats 2025 ch 643 (AB 1466),s 3, eff. 1/1/2026. Added by Stats 2015 ch 672 (AB 1390),s 1, eff. 1/1/2016.

Source & verification. Section text is reproduced verbatim from the California Legislative Information. Enacted by the California Legislature. Last verified July 28, 2026. · Official source

Also known as: initial disclosure groundwater adjudication californiawater use disclosure requirements california