Stormwater/Catch Basins

The stormwater system collects rain that falls on impermeable surfaces—that is, buildings, roads and parking lots that prevent water from being absorbed directly into the ground—in storm drains and catch basins on roadways and parking lots. While this water is not as dirty as wastewater, it can contain significant pollutants such as motor oil, road salt, pet wastes, winter sand and other chemicals.

Many of the pipes in Augusta carry both sewer and stormwater.  These pipes are commonly known as "combined sewers".

Heavy rains can cause combined sewers to overflow into the environment. These events are called Combined Sewer Overflows (CSO) by the Environmental Protection Agency.  Click here to learn more about combined sewer overflows in Maine.

CSO overflow diagram

Our long-term goal is to reduce the frequency of combined sewer overflows.  Methods to reduce overflow frequency include storing large amounts of combined sewer during wet weather events or separating combined sewers into both sewer and stormwater pipes to reduce the amount of runoff water going into the combined sewer.

We recently completed a one million gallon storage tank under Mill Park to capture CSO during storm events.  Combining this storage facility with new pipes and pumps has allowed the elimination of combined sewer overflows into Bond Brook.

Customers pay for stormwater based on the size of their property that is impermeable and, for businesses, the number of catch basins they use. Click here for more information about stormwater and catch basin rates.



GAUD charges most residential customers with a single-family home a flat rate for stormwater handling of $7.55 per month. This is one Equivalent Rate Unit (ERU). Other residential rates are all based on this:

  • Each multi-family unit or mobile home pays for .5 ERU ($3.78) monthly.
  • Each condo unit pays for .75 ERU ($5.66) monthly.


We charge commercial accounts in two ways: based on the number of ERUs for their impermeable property size, plus a monthly fee of $46.27 for each Catch Basin. Catch basins are underground holding tanks where stormwater is collected when it rains. You rarely see them but you do see the storm drains through which water enters them.

Notice of rate review

In response to issues raised by customers over the years, GAUD is reviewing our rate structure for catch basins. While this issue mostly relates to our commercial accounts, it may also have some effect on how we charge homeowners for stormwater.

GAUD is one of very few water districts in the U.S. that still charge for individual catch basins. Most other utility districts charge a single stormwater fee based on ERUs (sometimes called Equivalent Service Units or ESUs). Ratepayers are billed based on how much impervious area is on their parcel regardless of the total area of the parcel. One ERU is equivalent to the runoff impact of a typical single-family residential home’s footprint.  In Augusta, one ERU is 2,700 square feet.

GAUD is researching options to determine a simpler and more equitable way to calculate stormwater costs based strictly on ERUs, eliminating all charges per catch basin. This will involve a recalculation of ERU rates and the number of ERUs charged per parcel in order to keep the total revenue-neutral.

We will keep our customers informed through communications such as statement stuffers, newsletters and emails (click here to sign up for email alerts and updates). In addition, we will hold input and workshop sessions in the fall. In the meantime, please call Brian Tarbuck at (207) 622-3701 to discuss any questions or thoughts you may have.