Sometimes, the storm hits years after a development is complete. Indeed, stormwater runoff can give rise to liability against a developer long after stormwater management facilities are constructed according to an approved final plan. Accordingly, it is important for developers to understand (1) how trespass is applied in the stormwater context and (2) that they might never be fully insulated from such claims.

Pennsylvania follows the “common-enemy rule” with respect to stormwater runoff. Under the Rule, an “upper” landowner may discharge its stormwater on the land of a “lower” landowner. However, water artificially diverted from its natural channel across a “lower” landowner’s property can be considered a trespass. In that case, the “upper” landowner could be liable for damages resulting from the diversion.  There is a two-year statute of limitations for trespass that can insulate a developer from an aggrieved lower landowner’s direct claim for liability.  However, a condominium or homeowners association might still prevail with a claim for indemnification against its developer. In other words, if a lower landowner sues an association for damages caused by stormwater runoff, the developer might be required to pick up the bill years after it packed up and moved on to the next project. This precise issue is currently pending before the Beaver County Court of Common Pleas on remand.  Kowalski v. TOA PA V, L.P., 206 A. 3d 1148 (2019).

In Kowalski, a landowner situated downhill from a recently constructed condominium complex sued the condominium association for causing increased stormwater runoff on his property. The association, in turn, sued the developer for indemnification. As to the landowner’s claim against the association, the Court held that the increase in runoff was tantamount to a “continuing trespass”. Put simply, the landowner can sue the association each and every time his property incurs additional runoff as a result of the development, so long as he files his lawsuit within the two-year statute of limitations period for trespass claims.

Although developers should keep an eye on the pending indemnification lawsuit in Kowalski, a ruling in favor of the association is not by itself problematic. A landowner must still prove damages for increased runoff, which are often speculative and difficult to ascertain. However, it is clear that an aggrieved landowner is entitled to compensatory damages for any increase in runoff above and beyond the normal amounts prior to development, “however slight”.

The Kowalski decision is important because it ties together several well-established areas of stormwater jurisprudence. Depending on the Court’s disposition of the indemnification lawsuit, developers could be exposed to liability for runoff well after completing construction of a development. Accordingly, developers should always be mindful of constructing appropriate stormwater facilities and not merely rely on the requirements of municipal ordinances as a defense.