Stormwater Utility Fee Information

City of San Marcos

Stormwater Utility Fee Fact Sheet

The City of San Marcos Stormwater Utility fee is structured to ensure better equity among customers and to conform to established drainage utility fee standards in Texas. The City of San Marcos Stormwater Utility was originally implemented in 1999 and is the primary funding source for drainage capital improvement projects and for the operation and maintenance of the City’s drainage infrastructure with the purpose of reducing flooding, improving water quality, and maintaining regulatory compliance of the municipal separate stormwater system (MS4).

How is the fee determined?

The stormwater utility fee is based on the amount of impervious surface on the customer’s property.  Impervious surfaces such as rooftops, parking areas, driveways, compacted surfaces and private walkways increase stormwater runoff volume and flow rate. The stormwater utility fee was originally determined in 1999 using a hybrid model. Residential properties were assigned a fee based on parcel land area, commercial use properties were assigned a fee based on total amount of impervious area, and multi-family developments were assigned a fee based on the total number of units.


On October 1, 2020, a revised stormwater utility rate structure was implemented. The current fee structure considered a wholly impervious-based system that utilizes a standardized unit of measurement, the equivalent residential unit (ERU), to apportion Stormwater Utility fees equitably among and between the different customer classes (residential and or non-residential). The following table summarizes customer class codes, customer descriptions, impervious cover ranges and the monthly stormwater utility fees.

Rate Table

What fee can customers expect?

Stormwater Utility Fees will be determined considering customer class types (residential or non-residential), impervious cover on the property, and an equivalent residential unit (ERU). Aerial imagining is used to measure the imperious cover on each property. The ERU, or equivalent residential unit, was determined to be 2,575 square feet, which reflects the average impervious cover for a detached residence within the City of San Marcos and establishes an equitable unit of measurement between these customer classes. For multifamily properties that have five (5) or more units, these properties will be billed to the owner or owner’s representative and placed in the non-residential (NR) customer class


As shown on the Stormwater Utility Rates (Monthly) table, there are three rate tiers (R1, R2, and R3) for residential properties based on the impervious cover on the property. Each property is assigned a flat fee based off imperious cover range their property falls within.


Non-residential (NR) properties consists of commercial, industrial, retail, government land use types, and multifamily properties (that have five (5) or more units). The method for determining the fee consists of taking the impervious area divided by the ERU and then multiplied by the Stormwater Utility rate, as shown below. 


How is the Stormwater Utility Fee collected?

The stormwater utility fee will be collected for properties located in the City of San Marcos and identified to have impervious areas. The stormwater utility fee is typically collected as part of the City’s utility billing of electric, garbage, water and sanitary sewer. It can also be billed as a single service to the property owner or the owner’s representative if the property does not currently have other active utility services. One such situation is when a property is vacant after a tenant has moved out and all other utilities have been disconnected or inactivated.

Have there been any other changes to the Stormwater Utility?

The rates have been increased by 6.5% since last year.

Rate Table Comparison

How can I find my Stormwater Utility fee?

Property owners can use the City’s Stormwater Utility Fee Lookup tool to identify the fee assigned to your property. To find an account, enter your address or Parcel ID and information such as parcel impervious cover totals and the Stormwater Utility fee associated with the parcel will be displayed.

Click here to access the Stormwater Utility Fee Lookup Tool

What if I believe my information is not correct or I have additional questions?

If a property owner believes there are errors in the information used to determine the Stormwater Utility fee, the City will work with you to answer any questions or resolve. Contact the City’s Public Works Department at (512) 393-8036, send an email to