Iowa’s native prairie and savanna had deep, rich, healthy soil with abundant microbiology and good infiltration rates. Most rain soaked into the soil, recharging groundwater, that eventually fed our lakes and streams with clean water. Now many roads, buildings and compacted lawns shed rainfall instead. In
Water Water Everywhere #1 (too long ago to be a series...?) we went into changing land use in detail. For this next part we will talk about how this effects water quality and pollution.
|Increased runoff through a suburban development in Ankeny|
With this increased runoff and flooding, this water now has the energy to pick up lots of trash and other pollutants.
|Trash in Yeader Creek (and yes it looks like this every time it rains)|
Photo courtesy of Julie Perreault – Polk Soil & Water Conservation District
Along with garbage, water coming off parking lots, driveways and roads can be contaminated with gasoline, motor oil and heavy metals. (Grass clippings and leaves in the street are also easily carried away, more about those later.) These compounds, and toxic elements, breakdown slowly in the environment and directly threaten the health of people, fish and other aquatic organisms.
|Oil in parking lot at Easter Lake Park|
|Oil slick in Yeader Creek|
Photos: Julie Perreault – Polk Soil & Water Conservation District
Increasing water speed also creates erosion, damaging property and picking up sediment. Sedimentation is a major contributor to water pollution by reducing water clarity and smothering habitat in streams and lakes. Recreational lakes downstream may fill in with sediment and need to be dredged out, at considerable expense. Sediments also carry with nutrients, especially phosphorus.
|Eroded streambank near West Des Moines|
Nutrients like nitrogen and phosphorus can stimulate harmful algae blooms and bacteria growth, reducing water oxygen levels and sometimes toxic on its own. Grass clippings, leaves, pet waste and lawn fertilizers are other stormwater pollutants that contain high nutrient levels, as well as additional bacteria, that contribute to poor water quality. All of thes factors can lead to fish kills and beach closures.
These swarms often cause even more contamination, as the cure is worse than the disease...
What's the buzz on mosquito sprays?
Watch for the next post in the Water Water Everywhere series (it hopefully won't be as long between) as we look at solutions for homeowners, farmers and anyone concerned about clean water.
|Badger Creek at Sunset|