Water Quality and Natural Functions of Floodplains

Why do we need floodplains and stream buffers?


Floodplains are the land needed by a river or stream to convey and store flood waters. When there are high amounts of rain and/or snowmelt, rivers and streams fill with water. If there is enough water, the river or stream will rise higher than the banks and spread out into the low lying areas along the river or stream, called the floodplain. Floods allow sediment to be deposited along streams and rivers, which makes the soil more fertile over time. Floods also transport large woody materials that provide fish habitat and bank stability and promote plant establishment.

The Louisville Metro Floodplain Management Ordinance requires a 25 foot stream buffer be maintained along all blue line streams as defined by the USGS Topographic Maps. The purpose of the stream buffer is to help stabilize stream banks, provide habitat for wildlife, control erosion and sedimentation, and to improve water quality by filtering pollutants. Vegetation in stream buffers is a major source of energy and nutrients for stream and overhanging vegetation keeps streams cool. Vegetation along streams also allows water to soak into the ground and recharge groundwater.

When stream buffers are removed, water quality in the stream is worsened and fish and wildlife populations are reduced. Water temperatures are increased and dissolved oxygen levels are decreased. Loss of stream vegetation also contributes to stream bank erosion and sedimentation of the stream.


Why is water quality important?

Drinking water for much of Jefferson County comes from the Ohio River upstream of Louisville. Our local streams carry pollution from Jefferson County, and discharge into the Ohio River downstream of our drinking water intake. Therefore, our activities impact the water supply for the people down river of Jefferson County. The water supply for these communities is dependent on how well we manage our streams, just as we are dependent on those communities upriver from us. Over three million people get their drinkin g water from the Ohio River.

We depend on our streams for recreation (fishing, wading, swimming, and canoeing) and aesthetics. Water from our streams is used to irrigate golf courses, to water farm animals, and is also utilized by fish and wildlife. Unfortunately, the poor water quality of many Jefferson County streams does not provide suitable conditions for recreational uses such as fishing and swimming, and is a degraded habitat for fish and other aquatic species. 

Keeping our streams clean and flowing are important to the overall health of our waterways. MSD policies encourage the preservation of natural vegetation and trees as helpful to water quality, erosion control, removal of pollutants from run-off, and preservation of natural wildlife habitats. 

How can you help?

Don’t Litter!: Street litter, such as plastic bags, paper, and cups often are swept away with rainwater, entering into storm drains and eventually ending up in the streams and later, rivers. A great deal of litter is plastic. Plastic takes hundreds of years to break down. Recycle as much of trash as possible and put all litter in garbage cans. Never throw trash in the street or down a storm drain. If you see trash on the ground, pick it up and toss it in the nearest trash can. 

To report drainage problems, illegal dumping, or construction activity in a floodplain call 587-0603.

Grass Clippings, Leaves, and Fill: Brush, grass clippings, and leaf debris can easily cause flooding. Dumping of material can restrict the stream and force water to back-up behind debris. This can cause the water to overflow stream banks and ditches and flood upstream areas or your neighborhood. Grass clippings and leaves also can "choke out" the plants and animals within the stream. Never dump grass and leaf litter into a ditch or a stream. When the grass and leaf material break down it can increase nutrients, decrease oxygen, and cause death of aquatic organisms. The result is a degraded stream with reduced biodiversity. 

Illegal Dumping: Illegal dumping of chemicals, household products, garbage, septic waste, commercial waste, industrial waste, and yard waste can create impacts in streams. Illegally dumped or discharged waste can frequently produce impacts to plants and animals. Organic waste and yard waste can also stimulate bacteria and algae, causing rapid growth in populations, and resulting in reduced oxygen levels in the water. Dumped materials also may draw undesirable animals; create foul odors, and present physical dangers to wildlife and people.


Oil/Antifreeze: Motor oil and antifreeze contaminates water and can damage or kill plants and animals. Never pour used motor oil or antifreeze down a storm drain, on to the soil, or into a waterway. Put used oil or antifreeze in a sturdy container and take it to a recycling center.

Hundreds of chemical spills occur annually in the Louisville metropolitan area. However, with 24-hour response and required spill control plans, environmental impacts are greatly reduced.

Animal Waste Collection: Animal wastes contribute significantly to the number of bacteria and organic matter in storm water runoff. This problem is particularly serious because the wastes are deposited directly into the streams. Animal wastes can be controlled by the collection and removal of the waste from curbsides, yards, parks, roadways, and other areas where the waste can be washed directly into streams. 

Install a rain barrel: Rain barrels collect and store rain water from your roof top to use later for watering your garden or lawn. Reusing the water keeps it out of the drainage system and saves you money in water costs. More information about installing a rain barrel.

Install a rain garden: Rain gardens infiltrate storm water runoff by catching runoff before it reaches the storm drains. Diverting storm water into rain gardens from our roofs and other hard surfaces such as driveways or patios helps improve the water quality of our local streams and at the same time creates functioning gardens which support biodiversity. More information on how to plant a rain garden.