What is Stormwater?
Stormwater is the rain and melted snow that flows across the ground during and after a precipitation event. When water lands on natural surfaces like soil or grass, much of it can soak in. But on hard surfaces such as roofs, roads, sidewalks, and driveways, the water cannot absorb and instead runs off. As it travels, stormwater can pick up leaves, sediment, chemicals, and other pollutants, carrying them into storm drains, ditches, and eventually local waterways like the Fox River. Understanding how stormwater behaves is important because it influences flooding, erosion, water quality, and the overall health of our environment.
What is a Stormwater Utility?
A Stormwater Utility is a municipal utility district that operates in the same fashion as a sanitary sewer or water utility. Charges collected by a Stormwater Utility are used for the administration, planning, construction and maintenance of the City’s existing and future stormwater system. Stormwater systems include all natural and manmade stormwater conveyance facilities operated and maintained by the City, including retention/detention ponds, ditches, storm sewers, culverts, bridges, curb & gutter, seawalls, drainage ways and waterways. A Stormwater Utility also funds City maintenance operations such as street sweeping, catch basin cleaning, and leaf/brush collection.
The Stormwater Utility was created by Ordinance on by the City Council. A complete copy of the Ordinance can be obtained at City Hall. All properties within the City are subject to the fees charged by the Utility.
Why Implement a Stormwater Utility?
The City of Omro currently pays for Stormwater services out of the General Fund using property tax revenues. Property taxes are not always a good metric for relating stormwater system use to landowner payments, since property taxes are based on tax status, land value and building value. For example, landowners with a tax-exempt status do not pay any property taxes and don’t contribute toward the City’s stormwater system costs. Also, landowners that generate a larger quantity of runoff do not necessarily pay a proportionately larger amount of stormwater system costs. For example, a parcel with a ½ acre parking lot and a parcel with a ½ acre office building generate similar amounts of stormwater runoff; however, the landowner of the office building pays a substantially larger property tax as compared to the landowner of the parking lot.
A more equitable method of charging stormwater system costs to landowners is to establish payments based on the landowner’s use of the stormwater system. Similar to electric, gas, drinking water and wastewater systems, a stormwater user-based fee system requires the landowner to pay for the services consumed on a per unit basis. In the case of a stormwater utility, the amount of stormwater runoff generated by the landowner provides the unit basis.
In Wisconsin, the metric typically used to estimate the amount of stormwater runoff is the amount of impervious surface on the parcel. This approach provides a financial incentive for the landowner to reduce the amount of impervious surface on their property. In developed urban areas, less imperviousness typically results in smaller runoff volumes, smaller peak discharge rates, and improved stormwater quality. In addition, this approach provides the municipality with a method to encourage landowners to install onsite stormwater best management practices (BMPs) that further reduce runoff volumes, peak flow rates, and/or stormwater pollutants. Typically, a credit policy allows a landowner to reduce its stormwater utility fee if the landowner reduces runoff volumes, peak flow rates, and/or pollutants discharging into the stormwater system or local water bodies.
How is the Charge Calculated?
Stormwater Utility charges are calculated based on the total number of 'Equivalent Runoff Units' or 'ERU's' assigned to each parcel. An ERU is defined as the average amount of impervious area that a typical single-family residential property located within the City of Omro. For reference, an ‘Impervious Area or Impervious Surface’ is defined as areas that have been paved, covered or compacted to inhibit the natural infiltration of water into the soil or cause water to runoff the area in greater quantities or at an increased rate of flow from the present under natural conditions as undeveloped property. Such areas may include, but are not limited to, roof, roof extension patios, porches, driveways, sidewalks, pavement, gravel, athletic courts and compacted surfaces. Excluded from this definition are undisturbed land, lawn and fields.
Using recent aerial imagery, 2% of the single-family residential properties within the City were reviewed to digitize impervious surfaces. A single ERU for a single-family residential property in the City was determined to be 3,172 square feet of impervious area. The Stormwater Utility charge for each parcel is calculated depending on the customer classification and the total number of ERU’s assigned to each parcel. See below for additional customer classification and billing information.
What are the Different Customer Classifications?
The City has classified each parcel within City limits with one of the following customer classifications:
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RESIDENTIAL – SINGLE-FAMILY
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1 ERU per parcel
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RESIDENTIAL – DUPLEX, CONDOMINIUM & TOWNHOUSE
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0.6 ERU per dwelling unit
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Common areas of the developments or parcels are not charged
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RESIDENTIAL – MULTI-FAMILY
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Total ERU’s calculated based on total impervious area on parcel
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Total # of ERU’s = Total Impervious Area / 3,172 sq ft (rounded to nearest tenth)
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NON-RESIDENTIAL
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Total ERU’s calculated based on total impervious area on parcel
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Total # of ERU’s = Total Impervious Area / 3,172 sq ft (rounded to nearest tenth)
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UNDEVELOPED
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0.2 ERU per parcel
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What if my House is Located on Two Parcels or I Own Multiple Contiguous Parcels?
Residential customers who own more than one contiguous parcel have been charged based on the following:
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Where a single-family home is physically located on two parcels, the property owner shall be assessed a charge of 1 ERU on the larger of the two parcels.
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Where a single-family home is located on one parcel with one or more contiguous parcel(s) under the same ownership, the property owner shall be charged 1 ERU for all the parcels combined.
What's the Implementation Schedule?
The City recognizes this a new charge and in an effort to minimize the burden in 2026, has decided to reduce all Stormwater utility charges by 50% in 2026. Each year after, the charge will be increased by 10% until it reaches it's fully 100% rate. That way, it is gradually implemented and provides time for anyone to apply for Stormwater credits
What are Stormwater Credits?
The purpose of the Stormwater Utility Credit Policy is to provide a credit structure to reduce stormwater utility charges for properties within the City of Omro. This credit policy is intended to encourage actions by property owners to reduce peak discharge rates and flooding potential within the City.
Credits approved by the City will be applied to the stormwater utility bill for as long as the property owner maintains their credit eligibility. Several types of credits are available to Residential and Non-Residential properties. The total maximum allowable stormwater utility credit is 75% of the annual Equivalent Runoff Unit (ERU) charge for a parcel or property.
The Stormwater Credit Policy and Application are included below.