Floods: Minimizing pollution and health risks
On This Page
- Hazardous household materials
- Preparing heating oil tanks for flooding
- Drinking water well contamination
- Cleaning up after a flood
- Septic systems: What to do after the flood
For farms and businesses:
- Manure-storage facilities
- Underground and aboveground storage tanks
- Industrial hazardous wastes
- Wastewater treatment plants
- Construction stormwater requirements
Floods can create environmental problems if precautions are not taken to minimize pollution and health risks. Use the links to the right to get information on what Minnesota residents can do to protect their businesses, homes and families from environmental problems caused by floods.
If your home or business is flooded this year, be sure to read the recommendations for cleaning up after a flood.
Homeowners and businesses with other questions about preparing for floods or cleaning up afterward should contact the nearest MPCA office at the numbers listed below.
- Detroit Lakes Office….218-847-1519
- Duluth Office…………218-723-4660
- Brainerd Office……….218-828-2492
- Mankato Office………507-389-5977
- Marshall Office……….507-537-7146
- Rochester Office……...507-285-7343
- Saint Paul Office………651-296-6300
- Willmar Office………...320-214-3786
Homeowners in areas that are likely to flood should move hazardous household materials to a safe area that is likely to remain dry throughout the flooding.
Hazardous household materials include such items as:
- drain cleaner
- furniture stripper
- motor-vehicle oil
- toilet-bowl cleaner
Items such as vehicle batteries and propane tanks should also be moved to higher ground because they pose a danger if their contents are released to the environment.
Use the Healthy Home Checklist to identify products in your home that could become household hazardous wastes.
Any household products that come in contact with floodwater will need to be disposed of properly. Directions on how those products will be collected for disposal will be given out by the city or county after the flood.
For more information on hazardous household products and wastes, call your county solid waste office and ask for the Household Hazardous Waste Program staff.
Visit the MPCA household hazardous waste page for more information about chemicals in the home.
Residents with heating fuel tanks may want to take extra precautions if flooding is likely.
Because fuel is lighter than water, floodwaters that enter a basement and are deep enough to come into contact with a fuel tank may cause the tank to become unstable, tip over and/or float to the surface if the tank is not secured. Also, if the tank's vent and fill pipes or other openings are not water tight, the floodwaters may enter the tank and force the fuel out, into the home or office.
Secure the tank as best as you can so it will not turn or tip over if waters in your flooded basement cause it to float.
If possible, contact an area bulk fuel distributor to remove the fuel from your tank before floodwaters reach your home. Although this will make your tank more buoyant in the floodwaters, it will also prevent leakage of fuel into your home or office in the event water tips over and/or enters your tank through an opening.
If water is (or will be) present in your home or office but does not directly come into contact with your tank, monitor the situation to make sure the tank's supports are secure and/or that the tanks stability is not undermined by the water. Tank owners are reminded to call the Minnesota Duty Officer at 651-649-5451 or 800-422-0798 if their tank has leaked.
Read the "Cleaning up after a flood" section below for information on cleaning up oil or other debris after floodwaters have receded.
For more information on preparing home heating tanks for possible flooding, please contact your local fire marshal.
Officials from the Minnesota Department of Health (MDH) also urge awareness of potential public health risks associated with a flood situation. The major public health concern during a flood is contamination of private drinking water wells.
Wells that may have been contaminated should be disinfected and tested before being placed back in service. A well should be considered contaminated — and should be disinfected and tested — any time the floodwater comes in contact with the well casing.
Detailed instructions for disinfecting and testing wells are available from your local health department or the nearest district office of the MDH. The MDH maintains offices in the Twin Cities, Bemidji, Duluth, Fergus Falls, Mankato, Marshall, Rochester and St. Cloud.
Asbestos-containing materials are found in many homes and public buildings. Floodwaters can damage asbestos-containing materials, resulting in risks to human health.
To minimize the health risks, special precautions must be taken during and after cleaning up flood-damaged buildings that may have contained asbestos materials.
Asbestos may be found in over 3,000 building materials, including but not limited to:
- pipe insulation
- floor coverings
- textured surface materials
- furnace insulation
If it you must repair or remove any damaged asbestos-containing material, consult a specially trained asbestos-removal contractor.
The most frequently asked questions regarding asbestos in homes are answered on the Minnesota Departmernt of Health's Asbestos: Homeowner Information webpage. The MPCA has asbestos information for contractors and consultants on its Asbestos Program page.
For additional guidance on identifying and handling asbestos in buildings or to receive a list of licensed asbestos-removal contractors, call the MPCA at 651-757-2304 or 651-757-2647.
If your home falls victim to flooding this year, here are some recommendations to consider once waters recede and you begin cleanup. Because there may be large volumes of solid waste generated during flooding, the MPCA sometimes arranges for temporary, alternative disposal options. These disposal options differ from those normally available to you. Please read the fact sheet below for more details. Additional information about flood cleanup activities may be available from the MPCA office nearest you.
Ventilate your basement before and during cleaning with chemical solutions, and if oil is present. When basements flood, there is usually some sewer backup as well. Therefore, after the water and/or sewage has been removed, it is important to disinfect the surfaces to eliminate odors and bacteria.
If your basement had oil spilled in it, use a detergent to clean oil off the surfaces. Sheetrock and paneling should be removed and properly disposed at a transfer facility, incinerator or sanitary landfill. Concrete walls, wood supports, ceiling structures, and beams will soak up oil like a sponge. Therefore, those surfaces will need to be sealed with an epoxy paint sealer once they have dried out.
If you discover oil floating in your basement, please notify the Minnesota Duty Officer at 651-649-5451 or 800-422-0798. You will then be connected to or contacted by the MPCA for information and assistance on flood cleanup efforts in your area. Sorbent pads will be available to assist you in cleanup of fuel in your home.
When conditions allow you to pump floodwater out of your basement, pump down to a level that allows you to lay sorbent pads on the surface to soak up the oil, but does not allow the oil to come into contact with the basement floor. As the pads turn pink, flip them over. A broom handle, rake or pitchfork will work well for flipping pads.
Please wear rubber gloves during cleanup and avoid direct contact with floodwaters. Change the pads as they get saturated. All soaked pads should be placed in garbage bags, and the bags tied or sealed closed. Contact your local emergency operating center for information on disposal of used sorbent pads.
Oil or sewage-soaked debris
Any personal belongings, carpeting and/or construction materials that have been soaked with oil or sewage, and are not salvageable, will have to be hauled to a transfer facility, incinerator or a sanitary landfill. Check with your local facility before hauling your debris. If you have questions, contact your local solid waste coordinator.
Fuel oil tanks
Check with your supplier to determine if you have water present in your fuel oil tank and for pumping fuel oil/water mixtures out of your tank.
The following fact sheet provides information on what to do with your septic system after the flood waters have receded:
More information about septic systems is available at:
- Local county — contact your county for additional advice and assistance.
- University of Minnesota — information for septic system owners.
- MPCA Septic Systems — information for homeowners.
To reduce the likelihood of an overflow, feedlot operators are encouraged to divert water from manure-storage facilities if possible. Manure stockpiles located in areas that could flood should be removed immediately.
Farmers must contact the Minnesota Duty Officer immediately at 651-649-5451 or 800-422-0789 if their manure-storage facilities overflow, if manure enters surface waters, or if their manure storage structure is inundated by floodwaters.
Farmers can also contact the feedlot inspector in the nearest MPCA regional office if their manure-storage facilities are in danger of overflowing.
Farmers should contact their local Soil and Water Conservation District office or Minnesota Extension Service for more information on allowable application rates and suggestions for the best fields to apply manure to reduce the risk of pollution from floods.
If flooding appears likely, tanks owners should make sure their tanks are properly installed and anchored to minimize the risk of underground tanks "popping" out of the ground. Keeping tanks full of product adds weight, making it less likely that the tank will become dislodged and float away.
MPCA officials also recommend that tank owners secure all openings in the tank. Shear valves on underground tanks should be closed or "tripped" and power should be shut off to the system in the event of flooding. Shutting off the power prevents product from leaving the system if floating debris knocks over a dispenser.
Tank owners are also reminded to call the Minnesota Duty Officer at 651-649-5451 or 800-422-0789 if their tanks become damaged or product is released. Tank owners can also call the tank inspector at the nearest MPCA regional office if their tanks become damaged or product is released, or for additional information on flood preparedness.
More information is available on the following fact sheet:
If you handle and/or work with hazardous materials and hazardous wastes, these tips may help businesses prepare for potential flooding.
- Make sure that drums and other containers of hazardous wastes/products or used oil are closed, sturdy and leakproof.
- Label all containers of hazardous wastes with the words "hazardous waste," a description of the container's contents and the date when first adding waste to the container.
- Secure containers to protect from inadvertent damage.
- Place containers in an appropriate storage location - remove from lower areas such as basements.
- If possible, contract for the proper disposal of hazardous waste before flooding begins.
- Ship hazardous waste offsite to a permitted hazardous waste transporter or facility, a very small quantity generator collection point, or other recycler as appropriate (e.g., used oil recycler).
- Keep copies of shipping manifests and receipts upon disposal of any hazardous waste.
If you do not have an EPA identification number, which is needed to ship wastes, contact the MPCA Customer Assistance Center at 651-297-2274 or toll free at 800-646-6247. Additional information is available in the document below:
To report spills of hazardous materials, wastes or other potential pollutants, contact the Minnesota State Duty Officer at 651-649-5451 or toll-free at 800-422-0798.
Flooding can cause serious problems for municipalities and industries that operate wastewater-treatment facilities (WWTFs). Below are some items to help WWTF operators prepare for potential floods and recover operations afterward.
Avoid Bypassing if Possible
Every WWTF operator wants to avoid bypassing untreated wastewater at all times, if possible. However, sometimes it becomes necessary for a number of reasons, including:
In the event of a power outage, bypassing can be avoided or minimized if generators are available to provide emergency electricity to power lift pumps. For those facilities that have emergency generators available, it is important to start the generators ahead of the need to make sure they will operate properly in emergency situations. It is also wise to plan ahead for fuel for the generators.
Lift pump failures
The most common problem during floods is failure of overworked lift pumps. If possible, lift pumps should be inspected and serviced ahead of a potential flood so they will operate at peak efficiency as flows begin to rise.
If your lift pumps have had recurring problems with specific parts or components in the past, it might be wise to have spare replacement parts on hand to repair pumps in emergency situations.
As floodwaters rise, sump pumps begin running full time and water may find its way into the sanitary sewer collection system through leaky manholes, open connections or cracked and leaky collection pipes. Lift pumps can be overwhelmed and unable to transport all of the flow to the treatment system.
Sump pumps should be disconnected from the sanitary system. If possible, some manhole cover sealing can be done. Open connections should be located and sealed.
Treatment system problems
Pond systems are normally very full in the spring. Extra water from flooding can raise water in ponds to critical levels.
In this situation, it is preferable to open the discharge structure to allow water to leave the pond system at the same rate it is entering. Be cautious of allowing water to continue to accumulate in the ponds to the top of the dikes. The clay dike core or vinyl liner does not extend all the way to the dike top. Maintaining water above the core or liner can lead to catastrophic dike failure.
If You Must Bypass
If bypassing is the only alternative, your first obligation is to contact the Minnesota Duty Officer at 800-422-0798 or 651-649-5451. If you need assistance or advice from the MPCA, you can inform the Duty Officer or contact the MPCA directly.
Your second obligation is to discontinue the bypass as soon as possible. If a bypass is expected to last more than a day or two, contact your MPCA representative and keep them informed of problems and progress.
Fuels in sewers
During floods, spills of fuel can sometimes which enter WWTF collection systems. Significant amounts of fuel can cause many problems for treatment systems.
If a fuel spill enters the collection system, call the Duty Officer immediately. Determine the origin of the spill and approximate volume.
Fuels are lighter than water and will float, so it is sometimes possible to contain the spill in the wet well by adjusting float levels or running the pumps manually, so the water level does not pump all the way down.
If the spill does reach the treatment system, the type of system and amount of fuel will determine how serious the problem becomes. Fuels can completely kill beneficial bacteria in a mechanical system and it may need to be "reseeded" after the fuel has passed.
Pond systems can handle some fuel without major problems. The fuel should be contained in a single pond, where it may be recoverable with proper equipment.
Flooding around a pond system
During times of heavy flooding, dikes become saturated from inside and out. This can weaken dikes and, as floodwaters recede, may lead to dike failure from the pressure of the water in the ponds pushing against saturated dikes.
In some instances pond operators may be advised to open gates and valves and allow water in the ponds to go down with the receding floodwaters. This should only be done when absolutely necessary and after consultation with MPCA staff.
Additional information is available in the following fact sheet:
If they are members of the MnWARN mutual aid program, wastewater-, water supply-, and stormwater-treatment facilities can get help getting the personnel, equipment, materials and associated services they need to protect the health and welfare of their customers during flooding. Not a member? Go to the MnWARN website for details.
A provision in the state's construction-stormwater rules (Minn. R. 7090.2020) allows certain emergency construction activities to begin before a permit application is submitted, so long as the construction activity is needed to minimize the impacts of the emergency situation that present an "imminent threat to human health, public drinking water or the environment." In such cases, the landowner needs to notify the MPCA when construction begins.
This rule allows flexibility in meeting construction stormwater permit application requirements in emergency situations, and should not be interpreted as an exemption from permit requirements in the flooded areas. This provision is applicable only in rare cases where there is an "imminent threat."
See the following fact sheet for more information:
Finally, if you believe you may face flooding problems, contact MPCA staff to discuss potential problems. Make sure you have emergency numbers handy and that other staff who may assist you are aware of these numbers and of the need to contact the Minnesota Duty Officer or others for assistance.
If you have other questions about, or need assistance with, environmental problems caused by flooding in Minnesota, call the MPCA regional office nearest you:
Detroit Lakes Office — 218-847-1519
Duluth Office — 218-723-4660
Brainerd Office — 218-828-2492
Mankato Office — 507-389-5977
Marshall Office — 507-537-7146
Rochester Office — 507-285-7343
St. Paul Office — 651-296-6300
Willmar Office — 320-214-3786
Links to Minnesota flood information
Minnesota Stream Levels -— Minnesota Department of Natural Resources and MPCA Cooperative Stream Gaging
National Weather Service (NWS) — Minnesota forecasts and flood information and forecasts.
USGS Stream Flow Conditions — Provides daily updates on stream and river flooding conditions in Minnesota.
Minnesota Department of Health — Cleanup and health tips for homeowners and businesses.