## Facts

- Plaintiffs owned land within an artesian belt and relied on flowing artesian wells for domestic use and irrigation of valuable crops and plantings.
- Defendant owned nearby land over the same artesian belt and sank wells and made excavations that extracted large quantities of subsurface water.
- Defendant conveyed the extracted water to distant lands for sale and use off the overlying land.
- Plaintiffs alleged defendant’s pumping reduced or destroyed the flow from their artesian wells, causing serious and irreparable injury.
- Plaintiffs sought an injunction to stop the diversion.
- The trial court granted a nonsuit for defendant on the theory that the water was percolating and, under an absolute-ownership rule, could be taken without liability.
- Plaintiffs appealed.

## Issues

1. Whether the subsurface supply in the artesian belt was a defined underground watercourse subject to riparian rules or percolating groundwater subject to different doctrines.
2. Whether an overlying landowner has an absolute right to extract and export percolating groundwater regardless of harm to neighboring overlying owners, or instead is limited to reasonable use under correlative rights.
3. Whether plaintiffs’ allegation of diversion from an “underground stream” barred relief when proof showed percolating groundwater.

## Decision

- The court reversed the judgment of nonsuit.
- It held the artesian-belt supply was not a watercourse and was not governed by riparian law.
- It rejected an absolute-ownership rule for percolating groundwater in this context and held overlying owners have correlative rights limited by reasonable use.
- It held plaintiffs’ pleadings stated a claim to enjoin wrongful diversion of percolating groundwater; any “underground stream” characterization could be treated as surplusage.
- It concluded plaintiffs could seek injunctive relief against unreasonable diversion that exported groundwater off-tract for distant use and caused irreparable injury to neighboring overlying owners.

## Legal Principles

- An underground body of water in saturated soil that does not flow in a defined channel is percolating groundwater, not a watercourse, and is not governed by riparian-rights doctrine.
- Overlying owners in a common groundwater area are entitled to a reasonable, beneficial use of percolating groundwater on their own land, even if such use incidentally affects neighbors.
- An overlying owner may not unreasonably divert percolating groundwater—especially by exporting it for sale or use on distant lands—when doing so materially impairs neighbors’ reasonable overlying uses.
- Correlative rights among overlying owners limit each owner’s withdrawals; property use is constrained by the principle that one may not use land so as to injure another.
- A complaint seeking to restrain harmful diversion can support relief based on percolating-water proof despite surplus allegations describing the supply as an underground stream.

## Conclusion

The court established that, for percolating groundwater in an artesian belt, overlying owners possess correlative, reasonable-use rights rather than absolute dominion, and that unreasonable off-tract export causing irreparable harm to neighboring overlying owners may be enjoined.


Katz v. Walkinshaw, 141 Cal. 116, 74 P. 766 (Cal. 1903)