Illinois Environmental Protection Agency Lake Oakland TMDL Implementation Plan
26 Final Report
Even more important than the filtering capacity of the buffers is the protection they provide to
streambanks. The rooting systems of the vegetation serve as reinforcements in streambank soils, which
helps to hold streambank material in place and minimize erosion. Due to the increase in stormwater
runoff volume and peak rates of runoff associated with agriculture and development, stream channels are
subject to greater erosional forces during stormflow events. Thus, preserving natural vegetation along
stream channels minimizes the potential for water quality and habitat degradation due to streambank
erosion and enhances the pollutant removal of sheet flow runoff from developed areas that passes through
the buffer.
Converting land adjacent to streams for the creation of riparian buffers will provide stream bank
stabilization, stream shading, and nutrient uptake and trapping from adjacent treated areas. A GIS
analysis of land use within 25 feet of the streams in the Lake Oakland watershed indicates that 82 percent
of the land is currently farmed; 6.5% percent is developed and the remaining areas are either forest or
wetland.
Riparian buffers should consist of native species and may include grasses, grass-like plants, forbs, shrubs,
and trees. Minimum buffer widths of 25 feet are required for water quality benefits. Higher removal
rates are provided with greater buffer widths. NCSU (2002) reports phosphorus removal rates of
approximately 25 to 30 percent for 30 ft wide buffers and 70 to 80 percent for 60 to 90 ft wide buffers.
Riparian corridors typically treat a maximum of 300 ft of adjacent land before runoff forms small
channels that short circuit treatment. In addition to the treated area, the land converted from agricultural
land to buffer will generate 90 percent less phosphorus based on data presented in Haith et al. (1992).
Buffer widths based on slope measurements and recommended plant species should conform to NRCS
Field Office Technical Guidelines. A riparian buffer protecting the stream corridor from adjacent
agricultural areas is shown in Figure 4-8. Figure 4-2 highlights areas in the watershed that have potential
to house riparian buffers.
