Floodplain Management

What is a Flood?

Anywhere it rains, it can flood. A flood is a general and temporary condition where two or more acres of normally dry land or two or more properties are inundated by water or mudflow. Many conditions can result in a flood: hurricanes, overtopped levees, outdated or clogged drainage systems, snowmelt and rapid accumulation of rainfall. When a watershed receives a lot of rain, the receiving stream or river will rise higher than its banks and spread out into the floodplain. Just because you haven’t experienced a flood in the past, doesn’t mean you won’t in the future.

What is a Floodplain?

A Floodplain is an area of low lying ground adjacent to a stream or river that is formed mainly of river sediments, and is subject to recurring flood events. Jeff Opperman, a senior freshwater scientist for the Nature Conservancy, explains that a river and its floodplain are actually one single highway for moving water downstream and not just water, but also sediment. It’s just that the floodplain part of this highway is dry much or most of the time.

“Building in a floodplain is like pitching your tent on a highway when there are no cars coming”.

Dr. Vicki Miller, University of Montana

What is the Flood and Floodplain Relationship?

What most people don’t realize said Jeff Opperman, a senior freshwater scientist for the Nature Conservancy, is that floods are not some departure from the way a river is “supposed” to behave – witness the common description in the press of a river “bursting from its banks” during a flood, like a convict breaking out of jail. Instead, Jeff asks people to think of the river-floodplain system as all the highway lanes at a bridge toll crossing. For much of the day and night only a few booths are open and only a few lanes needed. But for the occasional “rush” hours, the flood of cars can only be contained by using all the booths and filling all the lanes. The cars are not “bursting out of their street”– they are simply using all of the lanes only during the moments of intense traffic flow. For more of Jeff Opperman’s insight on floods, follow the link at the bottom of the page titled: Why Rivers Flood – and How to Reduce Risk.

What is a Regulatory Floodplain?

The Federal Emergency Management Agency (FEMA) regulates and manages a large portion of the floodplain which is known as the Regulatory Floodplain, or more commonly referred to as the 100 Year Floodplain. The 100 Year Floodplain is the total land area that FEMA predicts will flood during a 100-year flood event, which has a 1% chance of occurring in any given year. The 100-Year Floodplain is used to administer the National Flood Insurance Program (NFIP).


Following the Midwest floods of 1993, a Missouri farmer likened a 100 year flood event to a bag full of marbles: “If you have a bag with 100 marbles-of which 99 are white, and one is blue- every time you stick your hand in the bag and pull out the blue one you will find yourself with a 100-year flood. Of course, each time you grab the blue marble you then have to put it back and shake the bag up before picking again”.

The laws of probability say that there is always a chance of picking the blue marble one, two or even three times in a row. But flood probabilities are never known with perfect certainty.

-Friends of the River

Federal Floodplain Legislation:

U.S. Department of Homeland Security: Federal Emergency Management Agency (FEMA):

FEMA administers and overseas the National Flood Insurance Program (NFIP), which regulates floodplain development. Nearly 20,000 communities across the United States and its territories, including Summit Township, participate in the NFIP by adopting and enforcing floodplain management ordinances, in which minimum standards are set by FEMA, to reduce future flood damage. In exchange, the NFIP makes federally backed flood insurance available to homeowners, renters and business owners in these participating communities. Flood insurance is designed to provide an alternative to disaster assistance to reduce the escalating costs of repairing damage to buildings and their contents caused by floods. Flood damage is reduced by nearly $1 billion a year through communities implementing sound floodplain management requirements and property owners purchasing flood insurance. Buildings constructed in compliance with NFIP building standards suffer approximately 80 percent less damage annually than those not built in compliance. In addition to providing flood insurance and reducing flood damages through floodplain management regulations, the NFIP identifies and maps the nation’s floodplains. Mapping flood hazards creates broad-based awareness of the flood hazards and provides the data needed for floodplain management programs across the Country.

How is Summit Township Managing the Floodplain?

At a Public Meeting on February 3, 2014, Summit Township Supervisors adopted the Floodplain Management Ordinance. The Floodplain Management Ordinance was adopted to comply with the NFIP as required by FEMA in order to more effectively manage the floodplain. By passing the Floodplain Management Ordinance, Summit Township also adopted FEMA’s Flood Insurance Study (FIS) and the accompanying Flood Insurance Rate Maps (FIRMs) that became effective on February 19, 2014. Any areas of Summit Township, located in the 100 Year Floodplain are identified in the FIS and FIRMs issued by FEMA. Both the FIS and FIRMs are available to be viewed in the Summit Township Land Development and Zoning Office. Through Summit Township’s Floodplain Administrator, the Floodplain Management Ordinance is enforced to ensure that any proposed development within the 100 Year Floodplain completes the Floodplain Development Permit Application, and through that process adheres to all regulations and standards required by the Floodplain Management Ordinance.

Summit Township Floodplain Management Links:

Floodplain Management Ordinance
Floodplain Development Permit Application

Construction & Commercial Industry Floodplain Management Links:

Below-Grade Parking Requirements
Non-Residential Floodproofing – Requirements and Certification
Flood Damage – Resistant Materials Requirements
Protecting Building Utilities From Flood Damage
Ensuring That Structures Built on Fill In or Near Special Flood Hazard Areas Are Reasonably Safe From Flooding

Homeowner & Residential Floodplain Management Links:

National Flood Insurance Program

After a Flood: The First Steps
Above the Flood: Elevating Your Floodprone House
Protecting Building Utilities From Flood Damage
Homeowner’s Guide to Retrofitting: Six Ways to Protect Your House from Flooding