Flood Plain & LPDA Information

Individuals interested in floodplain elevation, floodway, wetland, LPDA or past history of a property may contact;

 

Table 1: Contact information.
Contact Telephone
Karen Daulton Lange, Stormwater Administrator (630) 434-5489

What is a Flood Plain?

A flood plain is the land area that will flood under conditions of a storm event that has a 1% chance of occurring in any given year.  This translates to a 26% chance of flooding within the life of a 30-year mortgage and a 67% chance of flooding within a span of 100 years.  You may have also heard of it called the "100-year flood plain," which is also sometimes referred to as the Special Flood Hazard Area (SFHA).  The National Flood Insurance Program's flood plain management regulations must be enforced within the SFHA's by a community as a condition of participation in the flood insurance program.  

Do I Need Flood Insurance?

If you don't already have flood insurance, consider purchasing it for the structure and its contents.  Most homeowner's insurance policies do not cover damage from floods, so check your policy!  The Village of Downers Grove participates in the National Flood Insurance Program (NFIP) allowing any property owner or renter to purchase flood insurance.  Additionally, because the Village of Downers Grove participates in FEMA's CRS program, owners of property within the Special Flood Hazard Area (SFHA) are eligible for a 15% reduction in premiums.  The SFHA is more commonly known as the 1% annual chance flood or "100-year flood."

If you are building inside the flood plain, the purchase of flood insurance is mandatory if using a federally regulated/insured bank for a loan.  Even if your home or business is not in a flood plain, purchasing flood insurance may be a good idea.  Approximately 25% of all claims paid out by NFIP are for properties not in the SFHA.

What is an LPDA?

LPDA stands for "Localized Poor Drainage Area." The Village identified these areas as locations prone to flooding due to topography. In other words, LPDAs are areas of land that are bowl-shaped. Stormwater runoff that cannot infiltrate the ground tends to accumulate in LPDAs, creating flooding. Although LPDAs are not officially recognized by FEMA as regulatory flood plains, Village building codes regulate both LPDAs and flood plains similarly.

Is My Property Located in a LPDA?

Check the Village Drainage Control Map to see if your property is near a LPDA. To be certain whether or not a LPDA is located on your property, a topographic survey is required utilizing two approved DuPage County or FEMA benchmarks.

Are There Any Restricted Property Uses in an LPDA?

General and recreational use of the property is permitted. Landscaping and gardening that does not include fill is generally permissible, provided that stormwater drainage is not impacted and erosion does not become a problem. Storage of materials is generally prohibited.  Any permanent structure, including swing sets and other playground equipment, requires a permit when placed in an LPDA.   Please refer to Section 26.1303 of the Village Code for more information.

Buildings constructed near, but just outside, an LPDA must have lowest adjacent grades a minimum of one foot above the 100-year flood elevation. For more detailed information, refer to Section 26.505 of the Village Code.

What is the Risk of Flooding?

Risk of flooding within an LPDA or flood plain is generally higher than areas not in an LPDA or flood plain. The actual level of risk depends upon the specific location within the LPDA. Theoretically, there is a 1% chance of flooding in a single year at the outer limits of a LPDA.  Areas closer to the center of the LPDA could have a considerably higher risk if the ground elevation is lower there. It is important to keep in mind that flood elevation calculations and historical flood records are not perfect in their ability to predict the future. Floods do occur outside of flood plains and LPDAs.  A 100-year storm can occur more than once every 100 years. Flood elevations can surpass the 100-year mark in an extreme storm event. 

Why does the Village regulate LPDAs while FEMA does not?

The purpose of regulating LPDAs is to help ensure that new construction will be reasonably safe from flooding and that new construction will not adversely affect other properties. Filling in a portion of an LPDA could cause an increase in flood elevation, potentially leading to flooding of adjacent properties. LPDAs are often located in older neighborhoods that do not have stormwater detention basins. LPDAs serve as natural detention basins to limit flooding in other areas of the Village.

Why Protect Flood Plains?

Flood plains play a valuable role in providing natural and beneficial functions to Downers Grove.  Relatively undisturbed flood plains provide natural erosion & sediment control, open space so flooding damage does not occur, and provides improved habitat for a variety of plants and animals.  Flood waters can spread over a large area providing benefits such as:

  • Reduces the speed at which the flood waters move (higher speeds cause more damage)
  • Provides storage of flood waters, which reduces the water that reaches downstream areas, thus protecting downstream properties
  • Allows water to soak into the ground and recharge the groundwater aquifer
  • Moderates flood water temperatures, reducing the possibility of harmful effects on aquatic plants, fish, and animals

Within Downers Grove, good examples that serve these purposes are the Lyman Woods and Hidden Lake County Forest Preserves, Wallingford Park, Fifty-ninth Street & Main Park, and  O'Brien Park to name a few.

How Can I Stay Safe in a Flood?

The following common sense guidelines can help you avoid the dangers of flooding.  When a flood occurs, stay safe!  Keep these points in mind:

  • Do not walk through flowing water.  Currents can be deceptive.  Six inches of water can knock you off your feet.
  • Do not drive through a flooded area.  More people drown in cars than any where else.  A mere 2' of water can float a car.  Don't drive around road barriers; the road or bridge may be washed out.
  • Stay away from power lines and electrical wires.  The number two flood killer after drowning is electrocution.  Turn off the power at the service box to your home if it is about to be flooded. 
  • Keep children & pets away from flood waters, ditches, culverts and storm drains and detention basins.  Flood waters can carry fecal bacteria and dislodged items from buildings or yards.  Culverts & storm sewers can suck smaller people and pets into them.
  • Be alert for gas leaks.  Turn off the gas to your home before it floods.  If you smell gas, alert the gas company.  Do not use candles, lanterns, or open flames unless you know the gas has been turned off and the area has been ventilated. 
  • Do not use gas generators or charcoal fires indoors.  Carbon monoxide exhaust can be deadly.
  • Look out for animals.  Small animals that have been flooded out of their home may seek shelter in yours.
  • Clean everything that has been wet.  Flood water will be contaminated with sewage and other chemicals which pose severe health hazards.

How Can I Protect My Home?

If your property is susceptible to flooding, there are many flood damage reduction measures you may wish to consider.  Some of these need permits, so check first with our Community Development Department.

  • Watertight seals applied to brick and block walls to help protect against low-level flooding.
  • Elevate water heaters, furnaces, air conditioners and other major appliances to higher floors or on raised platforms.
  • Raise the entire home above flood levels.  Most wood frame houses can be elevated, allowing flood waters to flow under the house without damaging it.
  • If the sanitary sewer backs up into the basement during heavy rains, a plug or standpipe can stop this if water does not get more than one or two feet deep and if there are no toilets on the lowest level.  The most effective solution for sewer backup flooding is installation of an overhead sewer connection.
  • Temporary measures such as moving furniture and other valuables to higher floors or sandbagging exterior openings may also help.

Drainage System Maintenance - How You Can Help

As simple as it may sound, simply keeping smaller ditches and creeks free of debris (including landscape debris) can dramatically improve the run-off capacity, as well as greatly reduce blockages that significantly contribute to flooding. 

The Public Works Department maintains Village rights-of-ways and ponds where the Village has ownership or easements.  Every part of the Village includes drainage systems - ditches, storm sewers, creeks, ponds, etc., many of which are on private property.  It takes a concerted effort from all of us - public entities, private property owners, and the general public - to protect these drainage systems.  Some things you can do:

  • Do not dump or throw anything into the ditches or creeks.  It is illegal to do so and in violation of Village of Downers Grove Code Section 13.7.(d).  Even grass clippings and branches can block drainage. When it rains, the water has to go somewhere!  If you see someone in the act of dumping or see debris in one of our drainage systems, please contact the Community Response Center at 630-434-2255.
  • Report construction or filling without a Village permit posted.  Call the Community Response Center at 630-434-2255.

The Village does not pump water from basements.  However, the Village may perform pumping from a private property (exterior only) to help protect a primary residential structure in imminent danger from rising floodwaters per Village Council Resolution 2009-91.  In situations where the homeowner is responsible to address flooding problems, the Village is still interested in receiving information about the extent and cause of flooding.  Such reports can help us determine potential need for future drainage improvements

Flood Hazard Areas

The back-bone of the Village's stormwater drainage system is provided by three creeks:

  • Lacey Creek, which is north of Ogden Avenue;
  • St. Joseph Creek. which flowsthrough the central portion of the Village; and
  • Prentiss Creek, which is south of 63rd Street.

All three creeks drain westward and empty into the East Branch of the DuPage River. The Village Drainage Control Map highlights the three creeks. Storm drainage pipes, inlets, culverts, and ditches drain water from streets and properties to the three creeks.

 

Additional Information

Flood maps and flood protection references are available at the Downers Grove Library as well as the Community Development Department at Village Hall and with the Stormwater Administrator at the Public Works Facility (kdlange@downers.us).

Local Flood Plain Information

www.co.dupage.il.us/swm  (DuPage County, Stormwater Management - includes flood plain maps, rain & stream gauge information)

 

Property Protection, Flood Insurance, Flood Safety

www.fema.gov  (Federal Emergency Management Agency - FEMA- general disaster information)

www.ready.gov/floods (FEMA - be informed, make a plan, be prepared)

www.floodsmart.gov  (National Flood Insurance Program - NFIP - estimates of premiums, finding an agent)

 

Environmental and Planning Information

www.drscw.org  (DuPage River Salt Creek Workgroup - water quality issues)

www.theconservationfoundation.org  (The Conservation Foundation - land and watershed protection)

Village of Downers Grove - Comprehensive Plan

www.cmap.illinois.gov  Chicago Metropolitan Agency for Planning