The biologists at Cason & Associates have published scientific literature based on our years of collective experience managing lakes, ponds and habitat.
SPECIES SELECTIVITY OF GRANULAR 2,4-D HERBICIDE WHEN USED TO CONTROL EURASIAN WATERMILFOIL (MYRIOPHYLLUM SPICATUM) IN WISCONSIN LAKES
A total of 24 pre-and posttreatment plant frequency data sets were analyzed from 15 Wisconsin lakes treated with granular 2,4-D BEE herbicide for the control of Eurasian watermilfoil (Myriophyllum spicatum). Six data sets from four untreated control lakes were analyzed for comparison. The data sets included the results of line-transect aquatic plant surveys and point-intercept aquatic plant surveys. The results from these two survey methods were analyzed separately. Analysis of pre-and posttreatment changes in frequency of occurrence for 46 species of aquatic plants indicated Eurasian watermilfoil was the only species to show significant declines in all the surveys. At application rates of 112 kg ha 21, Eurasian watermilfoil declined an average 65.9% among the line-transect surveys; and 58.0% among the point-intercept surveys. At application rates of 168 kg ha 21, Eurasian watermilfoil declined by 94.4% and 76.5% among line-transect and point-intercept surveys, respectively. Among the control lakes, Eurasian watermilfoil increased an average of 77% in year 1 and 24% in year 2. Northern watermilfoil (Myriophyllum sibiricum), a closely related native plant, underwent declines in frequency at the higher 2,4-D application rate (20.0%) but showed an increase (88.9%) at the lower rate among the line-transect surveys. Northern watermilfoil exhibited declines at both rates among the point-intercept surveys (48 and 50%, respectively); however, the plant also exhibited declines in the control lakes in year 2. Most other native aquatic plant species were unaffected or showed increases following treatment with 2,4-D BEE. The high degree of selectivity to Eurasian watermilfoil found in this survey of operational treatments with 2,4-D BEE suggests that this herbicide is an important tool for restoring plant communities that have been degraded by Eurasian watermilfoil.
IMPACTS OF AERATION ON EFFLUENT TSS IN STORMWATER PONDS: A LITERATURE REVIEW
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World wide, aeration is perhaps the most widely used tool for managing aquatic systems. Aeration is most commonly used for treatment of wastewater (EPA, 1989), improvement of fisheries, mosquito control, ice management, reduction of nutrient loading, sediment management, improvement of water clarity and control of algae. Stormwater detention ponds are created primarily to act as settling basins for urban stormwater runoff. These detention ponds have been shown to reduce effluent, nutrients, chemical oxygen demand and heavy metals. Their primary function though, is to reduce effluent total suspended solids (TSS) (Prey, 1994). Wet detention basins tend to be shallow (3-7 feet) and fertile due to high nutrient loading. Therefore they are prone to noxious algae blooms. They also tend to be stagnant and anoxic due to a small surface to volume ratio. These conditions discourage fish life and encourage production of insects, such as mosquitoes. Many stormwater ponds are located in residential areas where these factors produce health concerns, reduce aesthetics and depress real estate values. As a result, many municipalities, homeowners, neighborhood associations and real estate developers have employed aeration technology in order to mitigate the negative aspects of stormwater ponds. This report attempts to explore the potential impacts of aeration on the primary function of stormwater ponds: reduction of effluent TSS.