Table of Content
Purpose and Introduction
Dam Removal and Fish Populations
Monitoring the River
Testing the Health of a Waterway
Runoff and Non-Point Source Pollution
Best Management Practices and Buffers
Stormwater and Erosion
Conclusions and Opportunities
Best Management Practices vary from state to state according to each state’s individual standards. Virginia outlines some of the most problematic aspects of construction, forestry and agriculture and subsequently makes suggestions to control these problems. Sedimentation and nutrient loading, as noted before, pose significant problems during land disturbing events, like construction projects. Sedimentation can be controlled using systems designed to catch the eroded soil. A silt fence is a temporary structure used on sloping land to catch any soil that is running down the slope toward the bottomland and/ or waterway. Many agricultural practices lay fallow during the winter months. To avoid leaving bare soil exposed to mass amounts of rainfall and subsequent erosion, farms can implement cover crops and crop rotation to stabilize the soil. A cover crop of grasses and other low growing vegetation would also be sufficient in controlling nutrient runoff. Another control effort for nutrient runoff is to use only the necessary amounts of fertilizer and likewise crops that will absorb the majority of the applied nutrients leaving only trace amounts on the ground surface (Haslam). Animal wastes contain pathogens that can leach into the groundwater or run into the adjacent waterway. The opportunity for movement of the pathogen should be limited. The pathogen has less chance of survival if the water containing it remains stagnant. A buffer would also be a very sufficient solution to, in the very least, minimize the impact that sedimentation, nutrient loading and animal waste pathogens have on the watershed (Haslam). A buffer is a strip of land lining the river that is comprised of trees, grasses and low growing shrubs. Like many regulations and guidelines the standards of a particular riparian buffer varies from state to state. Virginia suggests at least a 50 foot deep buffer in the riparian zone. However, the more depth of vegetation only adds to the benefits. A buffer should consist of native vegetation. This will discourage unnecessary spreading of the vegetation onto the farmland. Unfortunately, some alien species, like Lespedeza, are heavy seeders. These plants, once established, will spread broadly across the landscape, possibly encroaching on the agriculture land. A well-established native vegetative buffer along the river will provide a habitat for native wildlife and will coincide well with the surrounding farm or even urban landscape (Haslam). Many sites on the Tye River were noted as having no buffer. This leads to streambed erosion. These sites were often hayfields, cattle grazing fields, residential properties and both private and public recreational sites. There is a lot of opportunity for riverbank restoration on the Tye. Restoration programs are available from federal government funding and often from local conservation district aid. Private residences can contact their local extension agent to find the most appropriate restoration program for them. Large agricultural practices have many options available and can sometimes receive a monetary return from the efforts put into conservation of their land. Any type of construction or land alteration that takes place in the riparian zone is required by law to receive a permit before commencement of the project. One site documented on the Tye River has already implemented its own restoration project. These projects take time, but even the initial stages can prove to be beneficial. At waypoint 88 and 89 (Lat. N37 43.355 Lon. W78 58.134) a restoration project is taking place. Currently there are trees planted along the edge of the river. The species chosen for this restoration project were maple and sycamore which are a naturally occurring species along riverbanks. There is an abundance of grass covering the heavily eroded bank. This appears to be for temporary bank stabilization, but the planted trees will soon root down to provide more stabilization.
A riparian buffer can offer a multitude of benefits for the riparian ecosystem. Buffers can act as filters for contaminants carried in surface water and groundwater. Buffer strips can contain up to 90 percent of the Nitrogen and sediment and up to 75 percent of phosphorus that is leached from the surrounding land. Buffers also create obstacles for water before it reaches the waterway, which slows the velocity of the surface water. They also work well as bank stabilization so that when water rises, the bank is not washed directly back into the river (PEC).
An ideal buffer consists of 3 zones. Zone one is closest to the channel and should be comprised of tree species that provide ample shade for the waterway which helps control the temperature of the water, creating ideal habitat conditions for aquatic life. The root system of the vegetation in zone one should be strong enough to provide bank stabilization and reduce erosion. Ultimately, zone one will be the last visit for pollutants en route to the water. In that case, vegetation in zone one must have good filtering capabilities and possibly be a high nutrient demanding species to assure the absorption of excess nutrients being carried into the water from the adjacent land. Requiring an even more rigorous filtration system is Zone Two. This section of riparian buffer will do most the harnessing of pollutants. Native species that specialize in nutrient uptake are especially efficient in this zone. The third zone has a more herbaceous inhabitance. Grasses, wildflowers and low growing native plants create an easy transition of landscape by absorbing nutrients, chemical pollutants and slowing the flow of surface runoff. Also this will be the first zone of riparian buffer where groundwater infiltration will occur. Any groundwater or surface water filtration that takes place in zone 3 will assist the larger zones one and two with the removal of excess nutrients and possible contaminants before they have the chance to reach the water. (PEC)
A buffer creates windbreaks for both the waterway and the adjacent land (Edmonds). Also, with regard to agriculture, a forested strip along the river bank can help contain the potential for wildlife and insect pest damage to crop land. Farms taking advantage of the surrounding water supply to hydrate livestock and water their crops will benefit by having cleaner water, as it has ideally been filtered by the buffer zone. Government incentives give plenty of opportunity for economic benefits in riparian buffers. The Farm Service Agency provides opportunities such as the Conservation Reserve Program (CRP) and the Conservation Reservation Enhancement Program (CREP). Both programs encourage farmers to increase the environmental quality of their land by planting buffers near waterways, creating habitat for wildlife and preventing soil erosion by using cover crops (Cestti). A long term agreement with either program can offer annual rental payments to the farm and cost-share assistance from the government (Agriculture, Conservation Programs). Harvesting of grasses or tree within the buffer zone can have significant economic return. However, harvesting of the resources that make up the buffer zone should primarily be done in zone two or three and have a devised plan for restoring the buffer post-harvest. A large enough buffer could be considered hunting land and could benefit a landowner either directly or in leasing opportunities. With respect to community-wide economic benefits, a buffer along the river can lead to an increase in recreation (Iowa DNR).
SUGGESTED VEGETATION FOR BUFFER ZONE
Hardwoods are a better choice than conifers for streamside buffers. Flood tolerant species are necessary in the riparian zone, as water levels will vary and during high water levels is when bank stabilization is most important. Maples (Acer spp.), Oak( Quercus spp.), American Basswood (Tilia americana). Siberian elm (Ulmus pumila), Persimmon (Diospyros virginiana), and Sycamore (Platanus occidentalis) are flood tolerant. These trees can survive flooding for one growing season. The most practical choice of tree species as riparian buffers are those that can withstand flooding for two or more growing seasons. These species are cottonwood (Populus deltoids), green ash (Fraxinus pensylvannica), poplars and willows (Salix spp.) (Barkley).
Also to be considered is the herbaceous vegetation and grasses that should make up zone 3 of the riparian buffer. The species in zone 3 should have a fairly strong root system to help improve soil quality. Zone 3 of the riparian buffer should be considered separate from any grazing land that it is adjacent to. Hay and grasses used for cattle grazing do not provide ideal conditions for surface water filtration nor groundwater infiltration. Also, certain riparian buffers, if properly planned, can help prevent cattle from entering the river and ideally, the entire riparian zone. Plants in zone 3 should provide ideal conditions for wildlife habitat (Society, Conservation Practice Standard).
Along with the many shade benefits that trees provide on the banks of a river, they also provide habitat to many birds and other small animals. The animals can thrive in a buffer zone on fruits, nuts and seeds. The trees also provide a safe canopy for moving along the forest floor. The leaves from the trees also contribute to the health of the aquatic life. As they decompose, they are consumed by aquatic macroinvertabrates. Wildlife diversity is necessary in the riparian zone and a buffer lush with vegetation can provide good habitat for many different kinds of animals. The width of the riparian buffer does play a role in the birds’ inhabitance. Some migratory species have been found to prefer a particular width of forested area. In Virginia, some species will not make their home in a buffer less than 50 meters deep (US Army Engineer, Riparian Zones). Migratory species are found along the Tye River. Compared to other migratory bird sanctuaries in the region, the James River is known to have the highest density of bald eagle population during the eagles’ migration to the Chesapeake Bay Region. During the visual survey juvenile and adult eagles were seen foraging along the Tye River. The eagles favor the James and Tye because of the vast amount of roosting trees near the water making it ideal for foraging (Service, James River). Hawks and Osprey are also found in abundance near the James and Tye Rivers. Other birds sighted along the Tye were the green heron and the great blue heron. The hooded merganser, a fairly common species along the eastern United States was spotted along the Tye as were mallards