A middle-class family with several children find their dream home in a new metropolitan subdivision, fall in love with it and buy it. It's really more than they can afford, but the couple decide to stretch their budget to provide more space for the children they dote on. The pretty house has a large yard and the kids will love that, too.
It's midwinter when they move in and everything is fine. But when spring comes, the little creek at the back of the yard turns into a roaring torrent. It takes a while, but the couple begins to realize the creek is actually devouring their yard. Two months later half of the backyard is gone, and the creek is still eating its way toward the house. They call in an engineer, who suggests building a dike or retaining wall at the back of the yard. Cost: up to $100,000.
The couple doesn't have the money; developers of the subdivision claim innocence in the whole affair. City managers sympathize with the couple, but take no responsibility and offer no solutions. The whole thing will probably end up in court, and there will be no winners, whatever the outcome.
In many of Missouri's rapidly-developing areas, once-docile local streams are overloaded with all of the water running off of new roads, parking lots and all the other hard surfaces that make subdivisions and shopping malls possible. Homes, buildings and other structures built too close to these streams may be threatened or destroyed.
Often a quaint, seemingly-harmless creek that you could "step over" only 10 years ago turns downright mean. Although most people who live near these streams are aware of visible problems, few understand the causes or realize the consequences that these problems have on the ecology of local streams.
What happens to streams in developing areas? Simply put, their watersheds change. Natural streams in undeveloped watersheds are covered by natural vegetation, mostly forests or prairies. This land retains a great deal of rainfall much like a sponge, slowly releasing it into nearby streams and creeks. Streams adapt to this naturally controlled runoff over thousands of years and form meandering channels with minimal erosion.
When parts of a watershed are cleared for urban development, its water holding capacity is greatly reduced. Urban areas, in particular, are covered with vast expanses of "impervious surfaces," including roads, parking lots and rooftops. These surfaces absorb little or no water.
When it rains, water quickly runs off these surfaces and into small streams, either directly or via a stormwater system. They flood, and the stream channel is eroded by torrents of water; the creek deepens and widens to hold all the excess water. That's why a once-tiny creek may now be 50 feet wide with steep, eroding banks that threaten homes, backyards and roads. The problem worsens as continued development directs more and more runoff into the ailing stream.
Homeowners may have to deal with a stream gobbling up their yard, or even worse, the foundation of their home. Municipalities aren't safe either. They have to pay for expensive roads and bridges threatened by these streams.
The ecology of these streams also is damaged. A lack of trees along these creeks means less woody cover (branches, even entire trees) that provides important habitat for aquatic insects and the fish that eat them. Tree roots are important, too, because they hold soil in place, making the streambank more resistant to erosion, and they provide additional fish habitat when hanging in the water.
Water temperatures, to which many species of fish are sensitive, may increase as a result of a lack of shade normally provided by the dense canopy of a wooded corridor. The fact that water often drains into urban streams from nearby parking lots and streets warmed by the summer sun doesn't help, either.
Water quality, essential to aquatic life, may also be harmed. Oil and other chemicals spilled on parking lots, streets and driveways find their way into streams via stormwater systems. Soil from eroding streambanks and construction sites pollutes the stream, as well. Sediment, the number one pollutant by volume in Missouri streams, may result in a loss of fish habitat as it fills once deep pools.
In an effort to control stormwater in developed areas, urban streams are sometimes lined with concrete. Unfortunately, these so-called "improved" channels provide little in the way of habitat for the fish and aquatic insects that once thrived. Stream channels that are straightened or moved to accommodate a bridge or other type of development have a similar lack of habitat diversity; the channel has a uniform depth and velocity not found in an undisturbed stream.
Urban development can ruin the diversity of stream life. Urban streams are dominated by "tolerant" species of fish and insects, such as green sunfish and midge fly larvae. These organisms can survive in an environment with reduced water quality, warmer water temperatures and lack of habitat diversity. Sensitive species, like darters and mayfly larvae, cannot thrive under these conditions.
Urban development requires common sense and good planning. Leaving wooded greenways or buffer zones along streams will help protect them from erosion. At the same time, these greenways can help filter out many chemicals, such as fertilizers, that can harm the stream.
Greenways also provide travel lanes, food, escape cover and nesting sites for wildlife, and trees shade the water, keeping it cool in the summer. As a bonus, greenways are excellent places for nature trails-they are aesthetically pleasing and often increase the property value of adjacent lands.
Ponds and lakes that are included in developments, residential or commercial, can serve to detain water, slowing its journey into nearby streams. Routing runoff from pavement and rooftops into retention or detention ponds (instead of directly into a creek) is an excellent means to hold back water so it can be released at a more natural rate.
At the same time, common wetland plants found in ponds can act as a natural filter to remove many chemicals contained in water draining from surrounding streets, lawns and parking lots. Ponds also can make a development more attractive.
You can help by contacting your local planning and zoning board to request that stream-friendly methods be included in your community. In addition, you may want to get involved with a Stream Team to help clean up and monitor the health of your favorite local stream.
The next time you drive through your neighborhood on a rainy day, take some time to think about all the rainwater and where it is going when it empties into the storm sewer. Watch as the water level in the creek nearest to your home rises dramatically. It will soon become apparent just how much urbanization is affecting your favorite stream.
To find out more about stream teams in your area, write Stream Team Coordinator, Conservation Federation of Missouri, 728 W. Main, Jefferson City 65101-1534.
Editor - Tom Cwynar
Assistant Editor - Charlotte Overby
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Artist - Mark Raithel
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