## Facts

- Two married couples owned and lived on properties near a municipal sewage treatment plant operated by the Town of Stonington through its Water Pollution Control Authority (WPCA).
- The plaintiffs alleged persistent offensive odors and increased insects from the plant that substantially interfered with the use and enjoyment of their homes and reduced property values.
- The plant operated under state environmental permits; in related administrative activity the agency found “unreasonable pollution” yet renewed the plant’s permit.
- The plaintiffs sued the town and WPCA in Superior Court for common-law private nuisance seeking money damages.
- A jury found for the plaintiffs and awarded damages; the trial court denied post-trial motions and entered judgment on the verdict.
- Defendants appealed; the appeal was heard by the Connecticut Supreme Court.

## Issues

1. Whether the jury instructions incorrectly allowed the jury to find “unreasonable use” in private nuisance based only on harm to the plaintiffs, without weighing the utility and public necessity of the sewage plant and regulatory compliance.
2. Whether prior environmental agency proceedings and permit renewal collaterally estopped the plaintiffs from litigating private nuisance.
3. Whether the defendants were immune from private nuisance liability because operation of the plant was mandated by law and authorized by permit.
4. Whether the trial court improperly allocated peremptory challenges by granting each individual plaintiff a separate set rather than treating each married couple as a single party with a unity of interest.

## Decision

- The Supreme Court affirmed the judgment for the plaintiffs.
- The jury instructions, read as a whole, properly required consideration of multiple factors and did not make harm to the plaintiffs dispositive of unreasonableness.
- Collateral estoppel did not apply because the administrative permitting process did not decide the identical issue presented by a private nuisance damages claim between these parties.
- A permit and governmental function did not immunize defendants from nuisance liability; legality of the facility did not excuse an unreasonable manner of operation that substantially interfered with neighboring land use.
- The trial court did not abuse its discretion in granting separate peremptory challenges to each plaintiff given their individual damages claims.

## Legal Principles

- Private nuisance is a nontrespassory invasion of another’s interest in use and enjoyment of land that is intentional and unreasonable (or otherwise actionable under negligence or strict liability).
- “Unreasonable” in private nuisance requires a contextual balancing, including the gravity of harm against the utility and social value of the defendant’s conduct, along with factors such as locality and feasibility of mitigation.
- Regulatory permitting and compliance are relevant evidence but do not categorically bar or defeat a common-law private nuisance claim.
- Collateral estoppel requires that an identical issue was actually litigated and necessarily determined in a prior proceeding after a full and fair opportunity to litigate; environmental permitting decisions generally do not adjudicate private nuisance damages claims.
- Trial courts have discretion in allocating peremptory challenges when multiple parties’ interests are not strictly identical, even when parties are related or jointly own property.

## Conclusion

The Connecticut Supreme Court upheld a jury’s nuisance damages award against a town and its WPCA for odors and insects from a permitted sewage treatment plant, holding that proper nuisance balancing applies despite the plant’s public utility, agency permitting did not preclude the suit, and permit-based governmental defenses did not provide categorical immunity.


Walsh v. Town of Stonington Water Pollution Control Authority, 250 Conn. 443, 736 A.2d 811 (Conn. 1999)