Flooding Impacts on Missouri's Water Quality - PUB2753

Health Risk

Floodwater is not safe to drink or directly contact. This includes wading and recreational activities, such as swimming, boating or fishing. Avoid contact with floodwater as much as possible.

Floodwater could contain harmful pathogens and toxic chemicals from sources in the flood plain and from upland stormwater and snowmelt runoff. Common contamination sources include public and private wastewater facilities, chemical storage areas, gasoline and diesel dispensers, solid waste disposal areas, farmland and hazardous waste facilities.

While the volume of stormwater dilutes the concentration of these hazards, it is not enough to prevent potential harm to people when they come into contact with floodwater. If you must be in contact with floodwater, wear protective, waterproof clothing, including long pants and sturdy, closed-toe shoes.

If you do come in contact with floodwater, take the following precautions:

• Wash the area with soap and clean water, or alcohol-based sanitizer, as soon as possible.
• Take care of wounds and seek medical attention if necessary.
• Wash contaminated clothing in hot water and detergent before reusing.

Department Actions

While nothing can prevent all harmful chemical releases into floodwaters, the Missouri Department of Natural Resources is working closely with the facilities we regulate to minimize detrimental effects on water quality. Ongoing department efforts include the following:

• Working with drinking water facilities that have intakes on the Missouri and Mississippi rivers to adjust treatment to ensure drinking water remains as safe as possible.
• Working with public water supply and wastewater treatment facilities to remove and secure hazardous chemicals, and to mitigate infrastructure damage so that treatment can resume as soon as possible.
• Monitoring electric power plants to ensure that environmental impacts from coal and waste ash piles are minimized.
• Working closely with solid waste and hazardous waste disposal areas and facilities, including Superfund sites, to limit the release of harmful wastes.

Municipal Drinking Water and Wastewater Treatment Facilities

Many municipal drinking water and wastewater facilities that serve Missouri communities maybe affected by recent flooding.

Waste Facilities

The department monitors hazardous waste and solid waste sites that could impact floodwaters. These include petroleum storage sites, manufacturing facilities that store hazardous waste, hazardous waste cleanup sites, coal ash disposal sites and solid waste landfills.

Private Water Wells

Flooded Wells

Owners of private water wells should take precautions to protect their wells against flooding. If a well has been impacted by floodwater, it is important to disinfect it carefully to ensure the water is safe to drink. Wells also should be disinfected whenever a water sample tests positive for bacteria or when work has been completed on the well, such as a pump replacement or liner installation. The following links provide helpful guidance:

• Reducing the Impact of Flooding – Private Water Wells - PUB2500
• Disinfecting Your Water Well - PUB2733
• Flooded Well Guidance – EPA
• Managing a Flooded Well – Water Systems Council

When Repairs are Needed

If repairs must be made to the water well, hire a permitted contractor to do the work. Well and pump installation contractors licensed to do business in Missouri is available by using the department’s online Well Installation Online Services search tool.

Bacteriological Testing

For more information about bacteriological testing for private drinking water, contact:

• Missouri Department of Health and Senior Services
• County Health Department

Orphaned Tanks and Containers

Floods often carry different types of storage tanks and containers downstream and deposit them as the floodwaters recede. These “orphaned” containers can include propane tanks, anhydrous ammonia tanks and barrels containing a wide variety of chemicals. The department is working with the Missouri Department of Transportation to identify orphaned containers, identify their contents and safely transport them to approved reuse or disposal locations.