FERGUSON TOWNSHIP — A small but growing subset of Pennsylvania municipalities are turning to stormwater fees as they face the burden of maintaining aging infrastructure that is being tested by climate change.

The model is facing pushback from farmers who employ separate mitigation practices and large property owners confronted by pricey bills. The latter group includes West Chester University, which won a judgment in state court last year that found the fee was actually a tax that nonprofits like the school don’t have to pay.

Municipal entities say the case, currently on appeal to the state Supreme Court, threatens a multimillion-dollar revenue source and their ability to keep pollution out of local waterways. The pipes, drains, and gutters that make up stormwater systems are largely invisible to most people until something goes wrong, but they are critical to prevent flooding, property damage, and pollution.

As Pennsylvania’s stormwater infrastructure — graded a “D” by the American Society of Civil Engineers in 2022 — gets older and heavy rain becomes more frequent, maintaining deteriorating pipes and drains is getting harder and more expensive.