## Facts

- Two adjoining riparian owners operated steam mills on a small, nonnavigable stream (“branch”), each using both a well and stream water to run a steam engine.
- The downstream mill property was purchased by Henry W. Merriweather; the upstream mill was owned by John Evans.
- In ordinary conditions, the branch supplied sufficient water for both mills.
- During a 1837 drought, the branch’s flow became insufficient to run Evans’s upper mill continuously.
- A dam was constructed just below Evans’s mill that diverted all stream water into Evans’s well, drying the branch below the dam.
- As a result, Merriweather’s mill could operate only about one day per week and otherwise relied on his well.
- Merriweather sued Evans in an action on the case for obstructing and diverting a watercourse and obtained a $150 verdict.
- Evans appealed, challenging the trial court’s jury instructions and arguing he had directed workers not to stop or divert the stream.

## Issues

1. Whether an upper riparian owner may divert or consume the entire flow of a small, nonnavigable stream for manufacturing use when doing so deprives a downstream riparian owner of the flow.
2. Whether, during scarcity, the law distinguishes between water used for natural wants and water used for manufacturing, and how that affects the legality of diversion.
3. Whether the upstream owner may be held liable when an employee constructed the diversionary dam and the owner benefited from its operation.

## Decision

- The Supreme Court of Illinois affirmed the judgment for Merriweather.
- The court held that Evans could not lawfully divert the whole stream into his well for mill operation so as to dry the watercourse on Merriweather’s land.
- The court approved a reasonable-use approach: riparian rights are correlative, and one owner’s use must not unreasonably injure another’s use.
- The court treated the evidence as permitting a finding that Evans acquiesced in, and took advantage of, the diversion despite claimed contrary instructions to workers.

## Legal Principles

- Riparian rights in a running stream are usufructuary and correlative; the right is to reasonable use of the flow, not ownership of the water itself.
- A riparian proprietor may use stream water, including for hydraulic or manufacturing purposes, only to the extent the use does not injure other riparian proprietors.
- Uses for “natural wants” (domestic needs and watering livestock) are superior; if necessary, a proprietor may consume the whole flow to satisfy those needs.
- “Artificial” or extraordinary uses (including manufacturing and irrigation) are limited; where a small stream is insufficient even for natural wants, none may divert it for manufacturing or irrigation.
- Where water is not needed for natural wants but is insufficient for all proprietors’ manufacturing uses, no proprietor may take all the water; each has a right to participate, and an action lies against one who diverts or consumes the whole stream.
- No fixed quantitative measure governs apportionment in scarcity; whether a defendant used more than a just proportion is generally a jury question under all the circumstances.
- An owner who knowingly permits or benefits from an unlawful diversion may be held responsible even if an employee performed the physical act of damming.

## Conclusion

The court affirmed damages for the downstream riparian owner, holding that an upstream proprietor’s diversion of an entire small stream for manufacturing, which dries the stream below and materially impairs the downstream owner’s use, violates the correlative, reasonable-use limits of riparian rights, subject to the priority of natural wants and jury assessment of reasonableness in context.


Evans v. Merriweather, 4 Ill. 492 (Ill. 1842)