Floodplain Management


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​​​ Fourth floor, 301 E Huron St., P.O. Box 8647, Ann Arbor, MI 48107​

Melissa Menerey
Stormwater and Floodplain Program Coordinator

734.794.6430 x43709

​​​​​​​​​​​Know your flo​od hazard

By entering an address into the search bar of the flood​​plain map, residents can quickly learn where their property exists in relation to the floodplain. All Elevation Certificates and Letters of Map Change that have been receiv​ed by the ci​ty are also available on the same floodplain map.

Hazard Mitigation Planning

Hazard mitigation means reducing the impact of hazards on people and property. A Hazard Mitigation Plan (HMP) identifies hazards, such as floodplains, and enables us to increase our resiliency to the risks by developing strategies to reduce impacts. The completed City of Ann Arbor 2022 HMP plan, enables the city to not only increase its resilience to hazards, but maintain its eligibility for state and federal hazard mitigation funding. The plan is required to be updated every five years. Within the 2022 HMP,  the Mitigation Action Plan (Table 6-5 in Section 6) sets the agenda for flood mitigation efforts by the City for the life of the five year plan.

Floodplain Management Overlay Zoning​​ District

On January 4, 2021 the City Council approved a new Floodplain Management Overlay Zoning District​ to add to Chapter 55​ (PDF), the Unified Development Code. The regulations including:​

  • Improved protection of public safety and welfare
  • Reduced loss of life and property, especially for vulnerable populations and neighborhoods
  • More consistency with State floodplain regulations
  • Clarifying the permit approval process
  • Better Community Rating System score
  • Saving money and resources by lowering flood insurance rates and less flood damages to repair
  • Furthering the City's sustainability and climate action goals

Regulation Highli​​ghts:

An overlay zoning district includes all lots in and within 50 feet of a floodplain. These lots are subject to the Floodplain Management regulations and restrictions as well as the typical zoning and development regulations, similarly to how historic district regulations work.

The Floodplain Management Overlay District regulates both lots in floodplains currently under EGLE (the Michigan Department of Environment, Great Lakes & Energy) jurisdiction and those non-EGLE jurisdiction floodplains the same. 

In the Flood Frin​​ge:

  • ​New residential buildings must have the lowest floor elevated 1 foot above the 0.2% annual chance flood elevation – the old “500-Year Flood".
  • New nonresidential buildings must be elevated or flood proofed to 1 foot above the 0.2% annual chance flood elevation – the old “500-Year Flood".
  • Substantial improvements to existing structures in the floodplain must meet the new construction requirements, but historic structures exempt.

​In the Floodway: 

  • New buildings of any kind are prohibited in the floodway, but redevelopment of an existing site may be allowed with certain additional requirements, such as no residential uses​

Floodplain Management through the Community Rating System​​

In May of 2017 the City joined a program within the National Flood Insurance Program (NFIP) called the Community Rating System (CRS) which rewards communities for going above and beyond the minimum NFIP floodplain standards with lower flood insurance rates. The City entered the CRS program at Class 7, which resulted in a 15% discount on all flood insurance policies for the citizens of Ann Arbor. On October 1, 2018 the City improved to a Class 6, resulting in a 20% discount. The City currently has 2,343 points in the following categories:

Activity 310 – Elevation Certificates: Having written construction certificate management procedures for all new and substantially improved/substantially damaged buildings. (38 points)

Activity 320 – Map Information Service: Furnishing inquirers with basic flood zone information from the community's latest Flood Insurance Rate Map (FIRM), and offering additional FIRM information, information about problems not shown on the FIRM, historical flood information, and natural floodplain functions. The service is publicized annually, and records are maintained. (90 points)

Activity 330 – Outreach Projects: Targeted floodplain outreach projects. These projects are disseminated annually. (60 points)

Activity 340 – Hazard Disclosure: State regulations requiring disclosure of flood hazards. (10 points)

Activity 350 – Flood Protection Information: Documents relating to floodplain management are available in the reference section of the Ann Arbor Public Library. Credit is also provided for floodplain information displayed on the community's website. (52 points)

Activity 410 – Floodplain Mapping: Conducting and adopting flood studies for areas not included on the FIRMs and that exceed minimum mapping standards. (173 points)

Activity 420 – Open Space Preservation: Preserving approximately 50 percent of the Special Flood Hazard Area (SFHA) as open space, protecting open space land with deed restrictions, and preserving open space land in a natural state. (827 points)

Activity 430 – Higher Regulatory Standards: Enforcing regulations that require development limitations, freeboard for new construction and substantial improvement, cumulative substantial improvement, protection of critical facilities and local drainage protection. Credit is also provided for the enforcement of building codes, a Building Code Effectiveness Grading Schedule (BCEGS) Classification of 4/3, other higher standards, and regulations administration. (435 points) 

Activity 440 – Flood Data Maintenance: Maintaining and using additional map data in the day-to-day management of the floodplain. Credit is also provided for establishing and maintaining a system of benchmarks and maintaining copies of all previous FIRMs and Flood Insurance Study reports. (165 points)

Activity 450 – Stormwater Management: Enforcing regulations for stormwater management, soil and erosion control, and water quality. (173 points) 

Activity 510 – Floodplain Management Planning: The 2017 City of Ann Arbor Hazard Mitigation Plan, adopted on November 20, 2017. (244 points) NOTE: The newly approved 2022 HMP has not been reviewed and scored for CRS points yet.

Activity 520 – Acquisition and Relocation: Acquiring and relocating 3 buildings from the community's regulatory floodplain. (19 points) 

Activity 530 – Flood Protection: 6 buildings that have been flood proofed, elevated, or otherwise modified to protect them from flood damage. (12 points)  

Activity 630 – Dams: State Dam Safety Program. (45 points)

Emergency al​erts

Floods can strike with little or no warning. If you rely on a cell phone or have recently disconnected your landline​, then it’s more important than ever to sign up for the city’s Alert Systems. This could be the city’s only way to reach you in an emergency.​