When you drive around the community, you may notice several stream beds and ditches that have overgrown areas. You may have thought to yourself that maintenance wasn’t keeping up with the work out here. Actually, these are areas designed to help keep our lake water clean.
These “riparian zones” provide several benefits. The first one is that these plants stabilize banks. The plants that grow along the edge of the stream actually hold the soil in place very well and help slow down the erosion of the streams and surrounding area. The roots grow deep into the soil and act as a set of fibers holding everything together as seen in this photo.
The second major effect of riparian zones have is that their grasses and plants reduce erosion, which also slows and reduces total sediment flow. These zones can also remove sediment from the water column. During a large water flow, water will rise high enough along the banks that it will move up into the plants and into the riparian zone. Runoff is slowed down greatly and a large amount of the sediment is dropped out into these plants.
The riparian zone has other benefits. The plants that live within the area are heavy users of nitrogen and phosphorus. These plants use and hold nitrogen and phosphorus that flow through these streams and ditches after they leave the farm fields yards. If allowed to grow, these plants can clean a stream of its nitrogen and phosphorus and reduce the load deposited in the lake. These plants also provide areas for microorganisms to thrive and help hold nitrogen and phosphorus in place. These microorganisms also have even been shown to hold some metals from nearby water.
A unique benefit that these riparian zones provide is habitat for a large number of animals including frogs, toads, and other amphibians. They also provide habitat for birds and mammals. These mammals can be smaller rodents, rabbits, and even larger foxes, weasels, beavers, otters and raccoons. Some of these mammals could create problems for road traffic, but they are a great benefit for geese reduction. Raccoons, foxes, and other predators will hunt for and kill the eggs of the geese and duck populations.
The last benefit is that a riparian zone is self-sufficient. Once in place a riparian zone will need almost no real maintenance. The only way in which a riparian zone will change is if humans interfere with it or if an invasive species is introduced to the region. Once in place and left alone, a riparian zone will provide these benefits in perpetuity.
So, if you see workers planting in and along the ditches, know that they are developing riparian zones, which provide cleaner water for our lake along with great habitats for wildlife here at the lake.
(Article contributed by Eric Thomas who is a student intern from Colorado State University and is helping the Water Quality Committee this summer.)