201 4th Street SE, Room 108
Rochester, MN 55904
The Urban Water Cycle
Evaporation. Condensation. Precipitation. Infiltration. Runoff.
The water cycle describes how water changes forms and moves above and below the surface of the Earth. The impacts of development and urbanization have had great impacts on water. The Urban Water Cycle takes into consideration stormwater moving across hard landscapes where it can't soak into the ground, groundwater being pumped to the surface for use in homes and businesses, and wastewater traveling to water treatment plants.
Parts of the Urban Water Cycle
Rochester receives an average of 31 inches of rain and 44 inches of snow each year.
Rain and snow-melt that falls on buildings, streets, parking lots, and other impervious surfaces cannot soak into the ground. Instead, this stormwater will run off the landscape into area waterways. Compared to natural settings, the amount of stormwater that will runoff in an urban area is greater and the speed the water travels is faster. The increased amount of fast-moving water flowing across the land surface causes erosion and collects pollutants, which are then transported to receiving waters, such as, streams, rivers, ponds, and lakes.
The Federal Clean Water Act requires the City of Rochester to manage stormwater runoff within the city limits by law.
Wastewater is used water from residences, commercial buildings, and industrial facilities. It is also sometimes called sanitary sewage.
According to the U.S. Environmental Protection Agency (EPA), the average American produces 100 gallons of wastewater each day. The goal of the City of Rochester is to return wastewater to the water cycle at the Zumbro River with as little environmental impact as possible.
After water goes down the drain or the toilet is flushed, where does the water go? Wastewater is carried from homes, and commercial and industrial businesses, through a network of buried pipes, called a sanitary sewer collection system, to the Water Reclamation Plant located in NW Rochester. Once there, the water undergoes an advanced and complex process that reduces contaminants to levels required by the Water Reclamation Plant’s operating permit before being returned to the environment via the Zumbro River.
Did you know.... storm sewers and sanitary sewers are kept separate! Storm sewers carry stormwater directly to surface waters. Sanitary sewers carry wastewater to the water reclamation plant for treatment before being discharged into the river.
In Rochester, the City gets its water from deep under the ground. The entire process of taking the water from below ground and bringing it into the homes and businesses in Rochester is managed by Rochester Public Utilities (RPU).
Rochester’s water supply is extracted from bedrock aquifers which are large rock formations that hold water in small fractures within the rock layers or in the pore spaces between the particles that form the rock. Fractured limestone and porous sandstone are the aquifer-forming rocks in the Rochester area. To be a dependable source of water, aquifers must be both porous, (meaning there are spaces for the water to be in) and permeable, (the water can move easily through the rock). Most of Rochester’s water comes from the Jordan Aquifer which is composed of sandstone. Rochester sometimes also uses other aquifers such as the St Peter, Prairie du Chien limestone, the Ironton-Galesville sandstone, and the Mt. Simon sandstone.
Even though the quality of the water supply is good today, the local geology presents risks for contamination. Where the underlying soils and bedrock are both permeable, the wells are vulnerable to pollution. The thicker and the less permeable the soil layer, the more the filtering capacity, reducing the risk for groundwater pollution. Thus, our actions on the land can have a direct impact on the quality of our groundwater supply.