Understanding the issue

How our stormwater system works in Columbia, Missouri

Stormwater is water that originates during precipitation events. It may also be used to apply to water that originates with snowmelt that enters the stormwater system. Stormwater that does not soak into the ground becomes surface runoff, which either flows directly into surface waterways or is channeled into storm sewers, which eventually discharge to surface waters.

flow diagram

Stormwater is of concern for two main issues: one related to the volume and timing of runoff water (flood control and water supplies) and the other related to potential contaminants that the water is carrying, i.e. water pollution.

Stormwater is also a resource and ever growing in importance as the world’s human population demand exceeds the availability of readily available water. Techniques of stormwater harvesting with point source water management and purification can potentially make urban environments self-sustaining in terms of water.

Separate vs. Combined

On a recent site visit to a storm drainage system, I was met by a property owner. While we were talking, I looked down into the curb inlet and noticed multiple piles of dog waste. About that time, I noticed the property owner had a large dog. I asked the property owner if they knew that stormwater going into that curb inlet went directly to the water way across the street and into Bear Creek about ½ mile away. “Really? I had no idea.”

Columbia has SEPARATE stormwater and sanitary sewer systems.

two separate underground pipes

All storm water runoff that flows into curb inlets travels through a few pipes, long or short, and discharges to the closest water way. All water ways in Columbia end up in the Missouri River by way of one of our creeks such as Hinkson, Flat Branch, Bear Creek, Grindstone, Bonne Femme. Therefore, the pet waste was going directly to the creek without treatment!

All waste water from the sanitary sewer system goes to the waste water treatment plant (WWTP). Therefore all toilets, sinks and baths from your home and any drains inside a building travel through miles of pipe to go to the WWTP. Processes at the WWTP remove all solid waste and pollutants from the sewage. The WWTP further filters the treated wastewater through an extensive wetland system and then discharges to Perche Creek right by the Missouri River. The removed waste products and pollutants are recycled and disposed properly.

Some towns and cities like Kansas City and a part of downtown St. Louis have a COMBINED storm water and sanitary sewer system. These systems are typically under a consent decree by the EPA to separate their system or eliminate raw sewage from discharging to creeks and rivers during storm water runoff events.


 Columbia officials in the early half of the 1900’s saw the benefits of having SEPARATE stormwater and sanitary sewer systems. Outhouses used to dump directly to the Flat Branch (photo above), now Columbia has an extensive sanitary sewer system throughout the City that takes our raw sewage to the Columbia Regional Wastewater Treatment Plant.Wastewater Treatment Plant

Since we do have a SEPARATE system, everything that goes into the storm drain goes right to our creeks and waterways.




– Anatomy of a Stream Learn more from local experts

The anatomy of a stream is a complex subject which affects the entire community now and in the future.


– Stormwater Management – Learn about how Columbia residents can help

Learn about how Columbia residents can help with stormwater management and what the city is currently doing.


– Stormwater Infrastructure – Understanding the issues

The stormwater infrastructure of Columbia, Missouri is gradually getting older. The Public Works department is trying to devise a plan for the future to assure that the infrastructure can be properly funded.


– Stormwater Questions, Issues and Answers – Around the house

Public Works Engineering Aide answers questions and explains stormwater issues with private residences.



Boone County, City of Columbia and the University of Missouri coordinate stormwater activities. The three institutions are joint holders of a Phase II Stormwater Permit issued by the Missouri Department of Natural Resources under the National Pollutant Discharge Elimination System (NPDES).

Learn more about our partnership to improve stormwater City and County wide



Back to Stormwater Education page