Agenda - Environmental Policy Board - 04/07/2014

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Floodplains and Floodplain Management Definitions floodplain: Any normally dry land area susceptible to surface -water flooding. 100-year flood: A flood that has a 1- percent chance of being equaled or ex- ceeded in any year. floodway: The river channel and that portion of the floodplain required to pass 100-year floodwaters without increasing the water surface elevation more than a designated height (6 inches in Minnesota). flood fringe: The portions of the 100-year floodplain outside the floodway but still subject to flooding. Federal Emergency Management Agency (FEMA): Agency whose mission is to reduce loss of life and property and protect critical infrastructure from hazards. Flood Insurance Rate Map (FIRM): The official map on which FEMA has delineated the areas of special flood hazards. It is used to determine flood insurance premiums. Special Flood Hazard Areas (SFHA): Areas in a community that have been identified on FEMA maps as susceptible to a 100-year flood. National Flood Insurance Program (NFIP): Program under which communi- ties are eligible for federal flood insurance if they enroll in the NFIP and administer floodplain management regulations. Information Links Series of information sheets related to floodplain management: www. dnr. state.mn.us/publications/waters Flood insurance information: www.floodsmart.gov FEMA website: www.fema.gov What are floodplains? Floodplains are areas susceptible to flooding that are adjacent to rivers, streams, and lakes. In flat areas, the floodplain can extend more than a mile from the flooding source. Floodplains can also be the normally dry areas adjacent to wetlands, small ponds, or other low areas that cannot drain as quickly as the rain falls. A smaller area might be covered by floods every other year, on average (50-percent chance or 2-year floodplain), but a larger area will be covered by the flood that has a 0.2-percent chance of happening in a given year (the 500-year flood). The 1-percent chance (or 100-year) flood is the standard for Minnesota and federal minimum regulations. There is a 1-percent chance of this flood level being equaled or exceeded in any given year. The 100-year floodplain is the land adjoining lakes and rivers that would be covered by the 1-percent chance (or 100- year) flood. Along large rivers, like the Mississippi River or Red River of the North, floodplains usually are flooded during spring after heavy snow seasons. On these and other floodplains, flooding can also result from intense rains. In fact, climatologists have seen a trend toward a greater percentage of the total annual precipitation coming during the intense rains that can cause flooding. In areas with small streams or ponds, flooding can occur within hours of the intense rain. On the larger rivers and lakes, there may be days of warning. How are floodplains managed? Local units of government identify permitted land uses through zoning regulations. Floodplain management regulations are also administered by local zoning authorities. If you want information about permitted land uses on a floodplain within the municipal boundary, check with your city zoning authority. If you are in a rural area, check with your county zoning office. DNR Waters and Federal Emergency Management Agency (FEMA) staffs may assist local officials, especially on complicated issues, but the permitting decisions are made locally. If your community has a FEMA Flood Insurance Rate Map (FIRM) that shows flood -prone areas, your community should have enrolled in the National Flood Insurance Program (NFIP) and adopted zoning regulations to September 2006 Page 1 of 2