Shades Creek needs our help. Stormwater from our urbanized landscape is causing erosion and property loss along the creek and endangering fishes and other stream critters.
During the past century, much of the Shades Creek watershed has been urbanized. This has caused two sets of problems for the creek – problems that affect stream wildlife and the people who live, work, or play along the creek.
The first problem involves dirt. In mountain streams like Shades Creek, the small critters at the base of the food chain live in the crevices between rocks in the stream bottom. When too much clay, sand, and small gravel is swept into a stream, this sediment pollution covers the rocky stream bottom. This destroys the important wildlife habitat that supports the stream ecosystem.
Where does the sediment pollution come from? During the construction of buildings and other structures, a lot of sediment is usually exposed to the sky. During a heavy rainfall (and we get a lot of these in Birmingham), these sediments are washed downhill. If proper sediment erosion controls are not in place, the sediments are washed into our stormwater systems, which then take the water to our creeks. Locally, construction-site erosion is a big challenge because much of the Birmingham metro area is on a steep slope. Another source of sediment pollution in the urban environment is the collapse of stream banks. We’ll get to that below.
The other set of threats to urban streams such as Shades Creek involves too much water. In a forest, rainfall soaks into the soil and becomes groundwater that seeps into the creek over a few days, weeks, or months. Urbanization changes that. Streets, parking lots, and buildings are impervious surfaces that do not absorb water. Rainwater from these structures is shunted to the creek by our stormwater system. The result is that an excessive amount of water is sent to the creek during rainstorms. This extra water causes the water level to rise and the current to quicken. Some areas along our urban streams cannot hold all this water and flood regularly. These floods endanger human lives and damage property.
Another problem caused by the excess water is that it saturates the stream bank, making it easy for the strong flood currents to cause the stream bank to collapse. This erosion can eventually threaten buildings and streets. The clays, sands, and gravels released by the bank failure add to the sediment-pollution problem. The strong currents also sweep away the logs and large rocks that provide cover for many wildlife species.
Over the years, the problems of excess stormwater have changed Shades Creek a lot. The stream is wider due to bank failure. And, the stream has also cut deeply into the floodplain. In many places along the Shades Creek Greenway, the bank drops six to eight feet straight down. A healthy stream would have banks that slope gradually toward the stream edge.
These problems plague all the streams and rivers flowing through the Birmingham metropolitan area. As a consequence, the portions of Shades Creek within the metro area have fewer freshwater fishes and other species than streams of similar size in adjacent areas. Fortunately, there are ways to help the creek and improve the lives of people affected by its degradation. These initiatives require a lot of community cooperation and public support. You can read about such efforts to save Shades Creek here.
R. Scot Duncan