Wastewater Treatment Facility Planning

The City of Watertown owns and operates a mechanical wastewater treatment facility (WWTF) for the benefit of its residents and citizens. This facility, which treats wastewater produced by homes and businesses is located at 700 Lewis Avenue N.


Every time you turn on a faucet or flush a toilet and run water down the drain, the waste water is transported through a series of pipes and lift stations throughout the community to this facility. Here the waste water is cleaned and treated via mechanical, biological, and chemical processes, and deposited into the Crow River. The City takes in and treats on average 350,000 gallons of waste water per day. The waste and solids removed from the water are then stored, allowed to dewater, and later transported to a landfill or used for agricultural purposes.

Minnesota Pollution Control Agency Runs the Facility

The type of treatment provided to water processed and eventually returned to the Crow River at the plant is dictated by the Minnesota Pollution Control Agency (MPCA). Through the permitting process, the type and level of chemicals and compounds that can be in discharged water is determined. This is called "effluent limits". 


The permit that the City is currently operating under expired in September of 2014 and the City is awaiting for a determination from the MPCA on the new effluent limit for the plant. These limits are broadly affected by water quality conditions, especially of those downstream within the Mississippi River and Lake Pepin. It is anticipated that the phosphorus limit allowed within the water that is discharged into the Crow River will be drastically reduced and will not be reasonably attainable via the current mechanical, biological, and chemical processes at the plant. Once a new permit limit is set, the City will have five years to be compliant.

Max Load Population

The plant was built in 1993 with a maximum flow design to support a population of 4,800 people. The actual demand on the plant can be greatly affected by heavy commercial, institutional, and industrial users, however currently those types of users are not anticipated in the near future. The City estimates that an additional 150 to 200 residential equivalent connections could be made within the community before the plant would be at its capacity to take on and treat waste water generated in the community.

Maintenance Needed

As the plant comes upon its 25th year of operation, many of the plant components are beginning to show their age. Many of the major mechanical components are of original installation and through proper maintenance continue to meet the demands of today’s users. In the near future, investment will be needed to refurbish and replace some of these components, much like you would have to replace tires on a vehicle or a refrigerator in your home.

Draft Facility Study

With the knowledge of the three pressure points facing the facility of the condition, permit limits, and capacity, the City Council commissioned a facility study to review current conditions and the plant’s ability to meet or not meet the expected demands placed upon the facility. The City’s engineer has recently completed a Draft Facility Plan (PDF) that attempts to identify components that address these three areas in a phased approach. A complete replacement of the plant that meets all of the anticipated demands could carry a price tag of $9.5 million dollars. Being sensitive to the impact that an investment of this size has upon the current and future residents of the community a final decision will be approached methodically and with the future of the community in mind. Prior to any decision being made by the Council, a public hearing will be held to gather input from citizens.