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MS4, EDU, CWA, EPA. It might sound like the makings of alphabet soup, but those letters are acronyms representing key components of stormwater management.

If you haven’t yet heard of stormwater management, you likely will soon. And, when you do, terms like municipal separate storm sewer system, equivalent dwelling unit, Clean Water Act and the U.S. Environmental Protection Agency will quickly become part of your vocabulary.

Andy Yencha, a Penn State Extension water resources educator in Cumberland County, discussed stormwater fees and how they affect rural property owners.

His goal during the March 6 webinar was to help farmers and other rural residents better understand what has become a controversial topic in Pennsylvania.


Rooftops, parking areas and roadways are common on rural properties and can result in surprisingly high stormwater fees. Some municipalities offer ag-focused credits to reduce these costs.

Prefacing his presentation with a “Don’t shoot the messenger” disclaimer, Yencha explored the interrelation of rain and regulations.

Pennsylvania’s average rainfall is about 42 inches per year, and Yencha attributes increased intensity in rain events to climate change. Additionally, the state’s infrastructure for handling stormwater is generally old and in need of replacement. About 20% of Pennsylvania’s annual rainwater becomes run-off, which, Yencha said, “is what stormwater management is all about.”

While regulations flow from the state and federal level, stormwater is a local government burden. Municipalities are responsible for managing flood risks, as well as designing, building and maintaining stormwater infrastructure in compliance with state and federal rules.

Stormwater management is expensive and involves things like developing plans, doing drainage studies and providing flood management. Implementation isn’t cheap either — think about capital improvements that require excavating roadways to replace old drainage pipes, not to mention constructing basins, ditches, inlets and outlets to convey stormwater into local waterways.

Infrastructure inspection and maintenance plus administrative functions must also be paid for.

Yencha said these stormwater management costs are continually rising, especially in Pennsylvania, where the American Society of Civil Engineers gives the state’s aging stormwater infrastructure a grade of “D.”

With increased development, more impervious surfaces — roofs, concrete, asphalt — are created, causing more run-off and flash flood risks.

Yencha listed grants, loans, bonds, special assessment districts and plan review fees among possible funding resources for local governments. However, he said, expenses typically require taxes or user fees to adequately support stormwater improvements.

Increasing taxes is unpopular and not necessarily a good funding fit for what is basically a utility cost, Yencha said. Tax-exempt properties are excluded and there is considerable competition for tax dollars to fund other community needs.

User fees, he said, are better targeted to those utilizing the services. Tax-exempt properties aren’t excluded from paying fees, and fees can only be used for their designated purpose. Thus, user fees tend to be the most equitable way for financing stormwater management programs.

While stormwater management might seem relatively new to some, it dates to the 1972 Clean Water Act, which was amended in 1987 to address water pollution from Municipal Separate Storm Sewer Systems.

Initially affecting only large cities, in 1999 smaller cities came under MS4 regulations and more rural areas followed. By 2013, Pennsylvania’s amended laws allowed municipalities to form stormwater authorities, and in 2016, second class townships were permitted to assess stormwater fees without forming an authority.

By 2022, Pennsylvania had more than 60 MS4s charging stormwater fees, with rates typically based on the impervious surface of a property. The billing unit is the Equivalent Residential Unit (ERU). Using methods like aerial photos, light detection and ranging, or field measurements, the municipality determines its average amount of impervious surface on a single-family lot.

That average impervious surface area becomes the municipality’s ERU, also used in calculating the fees for larger, non-residential properties, based on their square footage of impervious surfaces divided by the ERU square footage. Determining the amount of each property’s stormwater fee requires knowing the municipality’s stormwater budget for the year so that amount can be divided by the total number of its ERUs to arrive at the cost per ERU.

A property’s ERU(s) would then be multiplied by the budget cost per ERU to arrive at its annual stormwater fee. These fees are typically billed quarterly.

Rural properties with considerably more pervious space may wonder why they are billed for stormwater management. Since all properties contribute to stormwater and also benefit from their municipality’s stormwater services, it is considered only fair that all properties pay their fair share to fund this community service.

That said, since rural properties tend to be larger, they are also likely to have more roofs, driveways and compacted parking areas. This impervious square footage can translate into multiple EDUs per property and, when multiplied by the municipality’s cost per EDU, can amount to a sizable financial impact.

But property owners can potentially reduce their stormwater fees.

Yencha pointed out mechanisms in MS4 plans through which a property owner can ask for a reassessment based on a suspected miscalculation of impervious area or if the amount of impervious surface has been reduced. Some municipalities might also have multiple fee categories and, if a property has been misclassified, that can be appealed.

Another way for property owners to reduce stormwater fees is through earning stormwater credits by installing or adopting new management practices or other activities that minimize stormwater impacts. Consulting with municipal staff, elected officials and the local conservation district are recommended ways to learn about possible credits and the necessary application procedures.

Agricultural properties often have the most credit options, Yencha said. He recommends downloading the applicable municipality’s stormwater credit manual to learn the specifics. Typical credit categories include conventional, state-recognized Best Management Practices (BMPs) to reduce stormwater flows off the property, assisting educational institutions with public stormwater education, submitting innovative ideas which a municipality finds credit-worthy, or possible special fee reduction opportunities for low-impact parcels in communities with large-lot suburban properties and/or agricultural land which have less than 10% of its property covered in impervious surfaces.

Yencha also spoke about special stormwater partnerships between a municipality and owners of non-residential properties who implement pre-approved innovative strategies or practices in return for credits. For example, a municipality might give owners certain percentage reductions in their stormwater fee in return for having a manure or nutrient management plan and/or an ag erosion and sedimentation or soil conservation plan for the property. Turf management credits are also available in some municipalities.

Yencha’s webinar was recorded and can be accessed here.