Las Posas Valley Water etc. v. Ventura County Waterworks etc.

CourtCalifornia Court of Appeal
DecidedMarch 5, 2026
DocketB330837
StatusPublished

This text of Las Posas Valley Water etc. v. Ventura County Waterworks etc. (Las Posas Valley Water etc. v. Ventura County Waterworks etc.) is published on Counsel Stack Legal Research, covering California Court of Appeal primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Las Posas Valley Water etc. v. Ventura County Waterworks etc., (Cal. Ct. App. 2026).

Opinion

Filed 3/5/26 CERTIFIED FOR PUBLICATION

IN THE COURT OF APPEAL OF THE STATE OF CALIFORNIA

SECOND APPELLATE DISTRICT

DIVISION SIX

LAS POSAS VALLEY WATER 2d Civ. No. B330837 RIGHTS COALITION, (Super. Ct. No. VENCI00509700) Plaintiff, Cross-defendant (Santa Barbara County) and Respondent;

v.

VENTURA COUNTY WATERWORKS DISTRICT NO. 1 et al.,

Defendants, Cross- complainants and Respondents;

CALLEGUAS MUNICIPAL WATER DISTRICT,

Defendant and Cross- complainant;

MAHAN DEVELOPMENT CORPORATION et al.,

Defendants, Cross- defendants and Appellants; FOX CANYON GROUNDWATER MANAGEMENT AGENCY et al.,

Defendants, Cross- defendants and Respondents.

The Las Posas Valley Water Rights Coalition, an unincorporated association comprised of landowners with claimed groundwater rights to the Las Posas Valley Groundwater Basin (Basin), initiated a comprehensive adjudication to determine all groundwater rights in the Basin. The adjudication proceeded in three phases. In phase 1, the trial court set the Basin’s initial “Total Safe Yield” and quantified the water rights for two public water suppliers. In phase 2, the court determined and allocated the remainder of individual groundwater rights based on a settlement agreement supported by a majority of the parties. In allocating water rights, the court gave priority to the overlying landowners with correlative rights and found there was no surplus for appropriators, who have second priority rights. In phase 3, the court adopted a “physical solution” and appointed Fox Canyon Groundwater Management Agency (Fox Canyon) as the Basin’s watermaster to implement it. The final judgment includes the physical solution and is supported by nearly all the parties and the Basin’s major public water agencies.

2 But not all parties are satisfied. A group of landowners— Mahan Ranch, LLC and associated parties 1 (collectively Mahan Ranch)—and two mutual water companies—Del Norte Water Company (Del Norte) and Solano Verde Water Company (Solano Verde)—objected to aspects of phases 2 and 3 and the final judgment. These appellants raise numerous contentions, including that the trial court allocated the water rights contrary to law and deprived the mutual water companies of their water rights. We affirm the judgment. FACTUAL AND PROCEDURAL HISTORY The Basin underlies an area of approximately 42,200 acres located entirely within Ventura County. It roughly extends from the eastern end of Saticoy through the city of Moorpark. The Basin is bordered in the north by South Mountain and Oak Ridge, on the east by Big Mountain, on the south by the Springville Fault and Las Posas Hills, and on the west by the Oxnard subbasin. The groundwater pumped from the Basin supports agricultural, commercial, and domestic uses. Agriculture use accounts for the majority of groundwater use. Some landowners use private wells. Others are shareholders of mutual water companies. A mutual water company is a corporation organized for or engaged in the business of selling, distributing, supplying,

1 Ralph D. Mahan, Trustee of the Ralph D. Mahan Separate Property Trust of June 12, 2003; Ralph D. Mahan and Georgia A. Mahan, as Trustees of the Mahan Family Trust of June 12, 2003; Mahan Development Corporation; Oro Del Norte, LLC; RBV 2+5 LLC; RBV-Vanoni, LLC; US Horticulture Farmland, LLC; Debra A. Whitson, Thomas E. Olson, and Thomas K. Strain, Trustees of the McGonigle Ranch Trust dated April 1, 2021.

3 or delivering water to mutual shareholders. (Corp. Code, § 14300.) A landowner can exclusively receive water from mutual water companies (exclusive shareholders) or can receive water from both private wells and from mutual water companies (hybrid shareholders). Some water users also receive water from three public agencies: Calleguas Municipal Water District (which imports water), and two county waterworks districts, Ventura County Waterworks District Nos. 1 and 19 (which supply groundwater and imported water). In 1982, the Legislature created Fox Canyon. Fox Canyon was tasked as the groundwater management agency (GMA) to plan, manage, control, preserve, and regulate the extraction and use of groundwater within the Basin. Fox Canyon had previously set groundwater pumping allocations based on each user’s historical allocations. Over the years, Fox Canyon made efforts to reduce pumping in the Basin, including the adoption of Emergency Ordinance E in 2014. This ordinance prohibited the issuance of permits for new groundwater wells and limited extractions from existing wells. After this adjudication began, Fox Canyon adopted another allocation ordinance based on a proposed allocation schedule created by the Las Posas Users Group (LPUG) called the LPUG White Paper. LPUG includes landowners, public agencies, and mutual water companies that came together to discuss and develop groundwater sustainability in the Basin. The Department of Water Resources (the Department) recognizes the Basin as a single basin in a publication known as Bulletin 118, which defines groundwater basin boundaries. Fox Canyon has recognized and created management areas based on the location of geologic structures. Currently, Fox Canyon

4 manages the Basin by east and west management areas, divided by the location of the Somis Fault. The exact location of the fault has only been approximated in this litigation. In 2014, the Legislature enacted the Sustainable Groundwater Management Act (SGMA) (Wat. Code, § 10720 et seq.) to provide for the sustainable management of groundwater basins. SGMA designated Fox Canyon as the Basin’s groundwater sustainability agency (GSA). (Wat. Code, § 10723, subd. (c)(1)(D).) GSA’s are responsible for regulating groundwater extractions, imposing fees, and enforcing SGMA requirements. (Wat. Code, §§ 10725.2, 10726.4, 10730, 10732.) The Department designated the Basin as a “high-priority groundwater basin,” meaning it was “subject to critical conditions of overdraft.” (Wat. Code, § 10720.7, subd. (a)(1).) Overdraft occurs where the average annual amount of groundwater extraction exceeds the long-term average annual supply of water to the Basin. (Wat. Code, § 10735.) As required under SGMA, Fox Canyon submitted a groundwater sustainability plan (GSP), a planning document with the objective of achieving sustainable groundwater management in the Basin within 20 years. (Wat. Code, §§ 10727, 10727.2.) The Department approved the GSP in January 2022 with recommended corrective actions. Commencement of the litigation In March 2018, the plaintiffs filed a complaint alleging, among other things, that Fox Canyon’s pumping restrictions were contrary to law and disregarded water rights priorities. The plaintiffs sought a comprehensive determination of the groundwater rights and priorities in the Basin. The trial court

5 ordered the adjudication to proceed in three phases. (Code Civ. Proc., 2 § 840, subd. (b)(5).) Phase 1 In phase 1, the trial court determined the initial estimated “Total Safe Yield” of the Basin and quantified the water rights for Ventura County Waterworks Districts Nos. 1 and 19 (collectively Waterworks Districts). The parties entered into a phase 1 stipulation which set the initial “Total Safe Yield” to be approximately 36,000 acre-feet 3 of groundwater per year (AFY). The stipulated definition of “Total Safe Yield” is the “amount of inflow of water from” “native and non-native sources of water within the Basin. . . presently and in the future.” The phase 1 stipulation allocated a total of 12.31 percent of the Total Safe Yield to the Waterworks Districts. 4 It provides that the “remainder of the Total Safe Yield (87.69%) will be allocated in future phases of the litigation among the Water Rights Holders other than the Districts.” It also states that “[n]othing in this Stipulation will be deemed to resolve any issues

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