## Facts

- The dispute arose in California’s mineral region on public lands where neither party held private title to the land.
- Matthew W. Irwin built a dam and canal diverting water from a natural stream to supply miners for gold digging.
- After the diversion was established, Robert Phillips and others located mining claims along the banks of the same stream.
- Phillips asserted that Irwin’s diversion unlawfully deprived him of the stream’s natural flow under common-law riparian principles.
- Irwin asserted a superior right based on prior diversion and use of the water for mining necessities.

## Issues

1. Whether, on public mineral lands, a miner who first diverts water from a stream for mining purposes has a superior right to continue that diversion against later claimants along the stream invoking common-law riparian rights.

## Decision

- The California Supreme Court affirmed the judgment for Irwin.
- The court held that, in the mineral regions on public lands, a prior appropriator who diverted water for mining purposes has a superior right as against later streamside mining claimants.
- The court rejected treating Irwin’s works as a nuisance justifying self-help; any abatement would require statutory process, and the evidence did not show a nuisance.

## Legal Principles

- Common-law riparian doctrine, grounded in rights of private landed proprietors, is not controlling where the land is public domain and there are no private riparian owners.
- In California’s mineral regions, established local custom and government acquiescence recognize rights based on priority of appropriation and use for mining.
- Priority governs conflicts over water used for mining on public lands: first in time is stronger in right.
- Later entrants who interfere with a prior appropriator’s diversion may be treated as trespassers and are subject to liability; self-help abatement of alleged private nuisances is not permitted absent statutory authorization.

## Conclusion

The court upheld a mining-region rule of prior appropriation on public lands, giving the first diverter of stream water for mining a superior, enforceable right over subsequent claimants along the stream who sought to invoke riparian-style protections of natural flow.


Irwin v. Phillips, 5 Cal. 140 (Cal. 1855)