FLOODING IMPACTS ON MISSOURI'S WATER QUALITY

Department of Natural Resources fact sheet
06/2019
Department of Natural Resources Director: Carol S. Comer
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:

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:

Municipal Drinking Water and Wastewater Treatment Facilities

Many municipal drinking water and wastewater facilities that serve Missouri communities along the Missouri and Mississippi rivers and their tributaries have been affected by recent flooding. A total of 18 communities have sustained flood damage to their drinking water systems:  

A total of 52 Missouri communities have reported flood impacts to their wastewater treatment facilities:

Waste Facilities

The department is monitoring more than 100 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. Of those sites:

The department is working closely with EPA to monitor flooding effects at three EPA Superfund sites in Missouri: Conservation Chemical Company in Kansas City, Hayford Bridge Road Site in St. Charles and HCI Chemtech in St. Louis.

Flooding is also possible, but unconfirmed, at the Herculaneum Lead Smelter Site in Herculaneum. While the current status of these sites is unknown, the department will evaluate their condition as soon as floodwaters recede and the sites can be safely accessed.

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:

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 may be found by using the department’s online search tool at dnr.mo.gov/mowells/.

Bacteriological Testing

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

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.