City of Rochester’s Flood Control System

Rochester's flood control system is essential to the vitality of the City and surrounding areas. The system is actively managed to mitigate flood risk to reduce the social, infrastructural, and environmental impacts of a flood event. Much like the City’s other major infrastructure, such as the sanitary sewer system or City streets, the flood control system requires continuous investment to meet the expected level of protection, as well as augment and expand the system to build a resilient, sustainable City. The system is key to maintaining and improving water quality for the Zumbro River and its tributaries. It also provides a network of trails connected by pedestrian bridges and underpasses, decorative artistic features at key locations, and numerous recreational opportunities.

The original project cost $114 million dollars, with the majority being covered by federal funding. The City was responsible for $40.704 million of the project funding, which was raised through a voter-approved local option sales tax. The City is requesting approval of the local option sales tax in 2023 to allow for reinvestment in the system and to ensure adequate funding for years to come.

Please visit  RenewRochester.org  to learn more about the November referendum to renew the local sales tax, including details about the plan, the cost and tax impact.

Rochester was built in the floodplain created by the South Fork of the Zumbro River and its tributaries. The first recorded flood in Rochester was around 1855 and destroyed bridges with a crest 15 feet above normal water levels. Flooding continued through the years and the U.S. Army Corps of Engineers, in cooperation with the City of Rochester and Olmsted County, began taking a serious look at trying to prevent flooding in Rochester in 1962.

July 5-6, 1978 Rochester experienced the worst flooding on record. At the time more than one-third of the City, including 2,000 homes and businesses, were situated in the floodplain. Evacuation of 5,000 residents, some by boat, took place during the rainy night of July 5 and continued the next day, July 6. Five people lost their lives and damages were over $58 million ($250 million in 2023 currency).

Use the following interactive map to navigate through the impacts of the devastating 1978 flood.

In 1983, following the devastating 1978 flood, the City and its project partners; the USDA – Soil Conservation Service, U.S. Army Corps of Engineers, Olmsted County, and the Olmsted County Soil and Water Conservation District, received congressional approval to construct an extensive flood control system. The system was comprised of:

• Seven floodwater retention reservoirs
• A series of levees
• Floodwalls
• Conveyance channels
• The purchase of lands within flood prone areas

The flood control system was designed to protect the City from a 200 year flood event. Construction of the system was completed in 1996.

A 200 year flood event means a flood having a 0.5% chance of occurring any given year.

In addition to flood mitigation functions, the project established a citizen task force to recommend aesthetic and recreational improvements to the design. A network of trails along the Zumbro River, Cascade Creek, and Bear Creek, connected by pedestrian bridges and underpasses, was created and provides seamless passage. Distinctive railings and lighting were added throughout the flood control project corridor. Decorative floodwalls and water features were also added at key locations.

The project cost $114 million dollars, with the majority being covered by federal funding. The City was responsible for $40.704 million of the project funding, which was raised through the voter-approved local option sales tax.

Navigate through the following interactive map application to learn more about the City of Rochester's existing flood control system.

In the years since the 1978 flood there have been a number of changes within Rochester. Current conditions emphasize the importance of local flood control.

The City's population has more than doubled since 1980, going from 57,890 to 121,395 in 2020.

Changes in weather, as well as recent flood events, have shown that the system needs to be upgraded to address localized flooding within areas of the City. The system can only operate at full capacity when properly funded and maintained.  In addition, parts of Rochester are not protected by the existing system.

• More recent events have impacted both protected and non-protected areas
  • Events of note include 2007, 2010, 2016, and 2019

Use the following interactive map to navigate through impacts of these significant flood events.

The level of protection that the existing flood control system provides has given confidence over the years and allowed for billions of dollars of investment in the downtown Rochester area. Notable developments within the protected areas include, but are not limited to the Mayo Civic Center, Art Center, Government Center, Riverside Elementary, Rivers Edge Apartments, University of Minnesota Rochester future campus, the Lofts at Mayo Park, and the Flats on 4th. Significant regulatory relief was also provided to property owners by reducing flood insurance requirements.

Based on 1978 flood levels, approximately $1.49 billion of properties are protected by the flood control system (source: July 2023 land parcel data from Olmsted County, MN). Previous investments have resulted in a return on investment of approximately $1 billion. This approximation is based on the estimated savings of the system successfully managing the four major flood events over the last 15 years: 2007, 2010, 2016, and 2019.

In November 2023, Rochester voters will decide whether or not to renew the local sales tax. If approved, the $40,000,000 in funds generated by the sales tax would be used to expand and augment the existing flood control system through three different types of projects:

• Flood Storage/Detention Pond Projects
• Conveyance Improvement Projects, including dredging and channel stabilization
• Property Acquisitions