Infrastructure
The Rain Bill Has a Lot Number: How a Stormwater Fee Gets Measured on Your Property
Many Midwest cities calculate stormwater charges from the hard surfaces on your lot, so the fee is easiest to check by measuring the property rather than arguing about the total.
Most Midwest households know their water bill because the utility sends it. A stormwater charge can arrive differently, sometimes as a line on the same statement and sometimes as a separate city bill. Its job is to pay for the system that carries rain away from streets, roofs, and parking lots. In many places the charge is set by how much of a property is covered by surfaces that rain cannot soak into. That makes the number easier to understand than it first looks, because the fee often tracks a measurement you can check yourself.
What "impervious" means on a lot
Engineers call a surface impervious when water runs off it instead of soaking in. Roofs, driveways, patios, and compacted gravel are common examples. Grass, mulch beds, and most natural soil absorb a good share of rain. When a lot has more hard surface, more rain reaches storm drains quickly and in larger volumes, and the city has more to manage. A stormwater fee based on area is an attempt to charge properties in rough proportion to that runoff.
Where the number comes from
Cities that bill by area usually build their figures from aerial imagery, parcel maps, or geographic information system data, and some check the results with staff visits. Ordinances differ on details. Some use a flat rate for typical single-family homes, others bill by measured square footage, and some combine tiers. The ordinance is the document that defines what counts as impervious area, which surfaces are excluded, and how often the figure is updated. Read that definition before you compare your bill to a neighbor's.
A stormwater fee also does not track your water use. A household that runs little water can still have a large roof and a long driveway, and a fee based on that footprint will reflect the footprint.
Credits and what they require
Some cities offer credits for changes that reduce runoff, such as rain gardens, rain barrels or cisterns, permeable pavement, or on-site detention. A credit usually requires more than a description. Expect to submit documentation, a site sketch, photographs, or an approved design, and some programs require an inspection before the credit applies. Find out whether the credit renews every year, has an expiration, or needs a new application after a sale. Keep receipts and dated photos in the same folder as the property records, so the paperwork is ready when the city asks.
Checking the measurement
Start with the parcel map your county or city publishes online. Compare the mapped hard surfaces with what is actually on the lot. Pay attention to recent changes, such as a new shed, a widened driveway, or a patio poured after the last aerial image was taken. Imagery can lag construction by months or more, so a map may be right about the past and wrong about the present. If the number looks off, contact the stormwater office and ask how to request a review. Ask whether there is a deadline for appeals and whether the review needs a survey or photographs. The answers will be in the ordinance or on the city's billing page.
Where federal money fits
Stormwater systems are mostly paid for locally, but federal and state loan and grant programs help some water infrastructure projects, and cities often watch those programs when they plan a budget. Water Finance and Management reported that the American Water Works Association sent a letter on Oct. 29 to Congressional leadership in support of "reauthorizing funding for federal water infrastructure programs." A letter from an advocacy group states a position. It does not establish a funding level or guarantee that money will arrive. Before a town counts on a federal program in its budget, the enacted law and the actual appropriation are the documents to read.
A short checklist before you call
Find the ordinance section that defines impervious area and the billing method. Pull the parcel map and mark any surface the map may have missed. Gather receipts and photographs for any runoff-reducing work you have done. Note the appeal or credit deadlines. With those four items in hand, a call to the stormwater office becomes a specific question about a specific number, which is usually the fastest route to a useful answer.