Floodplains

Local Flood Management


Ever notice that as Spring thaws come, puddles from melting snow show up in low spots? The puddles may be large or small. If you live near a drainage ditch or creek, water may creep onto your yard. This inundation usually is a natural result of snowmelt, or rainfall on snow; those wet areas may be in a floodplain or be seasonal wetlands. (If the inundation is a result of an obstruction in the creek or ditch, please call the District office immediately).

Coon Creek Watershed District (CCWD) has been tracking precipitation amounts to not only record what is happening locally, but to also manage flood possibilities, among other things. In fact, flooding is the reason citizens petitioned to establish the Coon Creek Watershed District in 1959. As the city of Coon Rapids developed after World War II, balancing the need for flood control downstream with agricultural drainage upstream became a significant issue, enough for citizens to establish a watershed district.

Defining Floodplains


Floodplains are divided into floodways bordered by flood fringe. The floodway is the channel plus the area "required to pass 100-year floodwaters without increasing the water surface elevation more than 6 inches" (MN Statute 103). The flood fringe is the portion of the floodplain outside the floodway, yet still gets flooded. (source: MN DNR Waters "Floodplains..." September 2006)

100 Year Flood Event


Please note, the term "100-year flood event" is misleading. It is not an event that happens once in 100 years. It is the amount of precipitation needed to achieve a flood elevation, and this event has a 1% chance of being equaled or exceeded in any given year.

In the CCWD, it is the elevation based on a 24-hour rainfall of 6.2 inches. So, the 100-year event can happen in any year. It is also the standard used by the National Flood Insurance Program (NFIP) to determine the need for flood insurance.

Fill in Floodplains


Remember, the floodplain is not just the surface of the land, but an actual elevation. Placing fill in floodplains can increase flood stages and raise flood elevations upstream. Generally, within a floodplain no fill is allowed. If fill is allowed, the volume must be compensated within the same area. Therefore, fill activities require permits; then CCWD and the City can prevent or minimize flood damage potential.


Determine Your Floodplain Areas


If your property has floodplain, work done outside the floodplain area shown on your plat yet below the flood elevation still affects the floodplain. If you are not sure about floodplain on your property, find your plat and call or visit CCWD or the city office. For more information, contact CCWD at 763-755-0975 or email the District.