## Facts

- Los Angeles sued multiple municipalities, a water district, and private pumpers to quiet title and declare priority rights to surface and groundwater in the Upper Los Angeles River Area (ULARA), seeking to subordinate defendants’ pumping.
- ULARA includes the Los Angeles River watershed above a gauging station and contains several connected but distinct groundwater basins, including the San Fernando Basin and related subbasins.
- Los Angeles historically used native surface and groundwater for municipal supply and claimed a paramount “pueblo right” as successor to the Mexican pueblo, along with asserted appropriative rights.
- Los Angeles also imported large quantities of water from outside ULARA, intentionally spreading some for percolation (storage) and delivering some to users expecting measurable return flow back into the basin.
- By the mid-20th century, pumping exceeded safe yield, producing overdraft and conflict among competing municipal and other pumpers.
- After a lengthy nonjury trial, the superior court denied Los Angeles an overall priority, awarded broad mutual prescriptive rights to both Los Angeles and defendants, and imposed continuing pumping restrictions under a court-supervised “physical solution.”
- Los Angeles appealed, challenging the priority determinations, the prescriptive-rights framework, and treatment of imported-water storage and return flow.

## Issues

1. Whether Los Angeles held a superior pueblo right to native waters of the Los Angeles River system and associated groundwater, and the scope of that right.
2. Whether Los Angeles’s pueblo and related groundwater rights were reduced or lost through prescription, including under a theory of “mutual prescription” in an overdrafted basin.
3. Whether Los Angeles retained a protectable priority to imported water it introduced into the basin and to quantifiable return flows, including rights to store and recapture that supply.
4. Whether a comprehensive physical solution with continuing judicial supervision could be used, and how it must reflect the correct hierarchy of water rights across separate basins.

## Decision

- The California Supreme Court reversed in substantial part and remanded with directions to reformulate the judgment and physical solution consistent with proper priorities.
- The Court reaffirmed Los Angeles’s pueblo right to native waters of the Los Angeles River system and the San Fernando Basin, while clarifying limits on its exercise.
- The Court rejected key aspects of the trial court’s broad mutual-prescription approach as a basis to cut down Los Angeles’s senior rights absent adequate proof of adverse prescriptive use.
- The Court held Los Angeles had prior, protectable rights to imported water it intentionally recharged or that returned by percolation from its imported-water deliveries, including rights of recapture against later pumpers.
- The Court approved the use of a basin-wide physical solution and continuing jurisdiction, but required that allocations and restrictions be recalculated by basin and aligned with the corrected priority structure.

## Legal Principles

- A municipality succeeding to a Mexican pueblo may hold a preferential “pueblo right” to take sufficient native water for municipal needs, subject to reasonable, nonwasteful exercise consistent with California water law.
- Prescriptive rights require adverse use against a superior right that is open and notorious, actual, continuous, and hostile under claim of right for the prescriptive period; generalized overdraft and long-term pumping do not automatically establish “mutual prescription” that defeats senior rights.
- Imported water intentionally introduced into a basin for storage or delivered with foreseeable, quantifiable return flow remains subject to the importer’s superior right of recapture to the extent it can be identified and quantified, protecting the importer from uncompensated taking by later pumpers.
- Groundwater adjudications may employ a court-supervised physical solution (including a watermaster and continuing jurisdiction), but the solution must respect basin separateness where relevant and allocate pumping in accordance with the established hierarchy of rights (including pueblo, overlying, appropriative, and imported-water recapture rights).

## Conclusion

The court required ULARA’s adjudication to be restructured to recognize Los Angeles’s superior pueblo right to native water in the San Fernando Basin and its priority to recapture imported water and measurable return flows, while limiting mutual prescription and directing that any ongoing physical solution allocate and restrict pumping by basin under correct priority rules.


City of Los Angeles v. City of San Fernando, 14 Cal. 3d 199, 537 P.2d 1250 (Cal. 1975)