Frequently Asked Questions
Q: Is MMSD part of the City of Madison?

A: No, although the City of Madison is our biggest customer.  The District is actually a separate entity, created under state statute to protect watershed areas which might cover many municipalities.  Legally, we are a "municipal corporation."

Q: Do you send utility bills to homeowners?
A: No; our customers are the cities, villages, and town districts within our service area.  We bill them and they bill individual customers.

Q: How much wastewater does MMSD handle in an average day?
A: About 42 million gallons a day; think of this as filling a ten story building the size of a football field!

Q: Where does the wastewater come from?
A: It comes from toilets, household cleaning, bathing and cooking, as well as industrial cleaning and manufacturing.  There is also some from other sources such as rainwater. We especially see a large increase during heavy thunderstorms or when snow is melting.

Q: Where does the water go after the District has treated it?
A: Most of the water leaving the plant (effluent) is pumped through a five mile underground pipeline and discharged into Badfish Creek, which diverts it around the Madison Lakes.  Some is also sent to Badger Mill Creek in order to balance the amount the District takes from the watershed.

Q: How clean is the treated wastewater?
A: The Nine Springs treatment plant is an advanced secondary treatment facility.  As such, the water we discharge is comparable to the quality of natural surface waters, and is safe for fish and other aquatic life. Both the effluent and the receiving waters are monitored to make sure the standards are met.

Q: Could you drink the treated wastewater?
A: This is not recommended; while the water we discharge is a high quality effluent, our plant is an advanced secondary treatment facility.  Additional purification steps would be necessary to prepare our effluent for human consumption.  There is NO surface waters in the Madison area suitable for drinking without further treatment.

Q: How much does it cost to treat the wastewater at MMSD?
A: It only costs about 15 cents a day per capita.  Each of us produces (directly or indirectly) about 140 gallons of wastewater per day, or about 50,000 gallons a year.

Q: What are the shiny domes on the north side of the treatment plant?
A: After the water has been cleaned at the treatment plant it is pumped to two streams, Badfish Creek and Badger Mill Creek.  There are times of the day when the water is coming into the treatment plant faster than it is being pumped out and other times when the water is coming in at a slower rate than the pumps are pumping it to the streams.  To provide a buffer and serve as a well for the pumps, there are two concrete tanks on the north end of the plant.  These tanks are called the effluent storage tanks.  In the summer of 2006 aluminum domes were placed over these tanks.

The treatment plant uses ultraviolet light to disinfect the treated water.  It has been found that if the water is exposed to sunlight too soon, the sunlight can repair the damage that has been done to some microorganisms by the ultraviolet light.  Since some of the treatment water is stored in the effluent tanks, the water needs to be protected from sunlight until it can be pumped out of the tanks.  The aluminum domes provide that protection.

When the District first began using ultraviolet light in 1984 supported domes where installed over the effluent storage tanks.  Those covers were replaced with black floating cover in 1995.  Over the years, the life expectancy of those covers had deteriorated and needed to be replaced.  The aluminum domes are expected to have a useful life of at least 50 years.