A study was conducted, May 2008-August 2012, to determine the impact of BMPs on streams located in the upper subwatersheds of the Strawberry River, Arkansas (AR). Multiple BMPs, including fencing, alternative drinking sources, planting of native grasses and brush, nutrient and pest management, were implemented in a whole watershed approach in attempts to alleviate the impacts of cattle grazing on surrounding waterways. Six locations were monitored for chemical, bacteriological, biological and physical responses to BMPs.
Water quality variables used to assess the effectiveness of implemented BMPs included pH, turbidity, total suspended solids (TSS), NO2 -, NO3-, PO43-, Escherichia coli and Chlorophyll-a. The majority of detected values for all variables were within AR standards and reference stream values for the Ozark Highlands Ecoregion for the entirety of the study. Significant increases in turbidity, TSS, PO43- and Escherichia coli were indicated post-BMP implementation, July-December 2011 compared to pre-BMP implementation, May-December 2008. Turbidity and TSS concentrations exceeded AR standards in rainfall events throughout the study. Some sampling sites indicated bacterial impairment based on E. coli samples collected during-BMP implementation, January 2009-June 2011 and post-BMP implementation, July 2011-June 2012.
Spring and fall benthic macroinvertebrate (BMI) collections, in situ water and habitat parameters and aqueous and sediment toxicity testing were performed each May and October during BMP implementation, May 2009-May 2011 and post-BMP implementation, October 2011-May 2012. Results of BMI communities indicate the sampling locations were in an impaired state throughout the three-year study based on comparisons to least-disturbed reference streams in the Ozark Highland Ecoregion collected by the Arkansas Department of Pollution Control and Ecology (ADPCE) in 1987 and historical collections collected by the ADPCE in 1995 and Arkansas Department of Environmental Quality in 2002 and 2003. Historical collections took place in the upper subwatersheds of the Strawberry River, though not in the exact sampling locations of the current study. Some current BMI community results were indicated to be related to physical habitat parameters. Toxicity testing results varied and did not correlate to BMI results.
Physical habitat was monitored at the six sampling locations, May 2009-May 2012 and bank stability was monitored between the upper and lower locations August 2010-2012. Erosion pins were used to calculate stream bank loss May 2010-May 2012. Results of physical habitat, based on qualitative measurements, indicated a temporal decrease in overall habitat at six sampling locations. Total area of active erosion decreased for two subwatersheds, while increasing in the third. Estimated stream bank loss increased in two of the three assessed reaches.
This study concludes that BMPs were an effective preemptive effort at limiting concentrations of potential contaminants at base flow conditions, but that additional BMPs are needed to limit contaminants in rainfall events. With few exceptions, assessment of bacteriological, biological and physical parameters indicated that BMP implementation was not effective at limiting the influence of unrestricted cattle grazing in the upper subwatersheds of the Strawberry River. Severe climatic events (e.g. floods, ice storms) impacting measured results over the course of the study may have also played a significant role in the conclusions.
|Advisor:||Bouldin, Jennifer L.|
|Commitee:||Choi, Seo-eun, Green, Steven, Grippo, Richard, McKay, Tanja|
|School:||Arkansas State University|
|School Location:||United States -- Arkansas|
|Source:||DAI-B 74/04(E), Dissertation Abstracts International|
|Subjects:||Water Resource Management, Environmental science, Limnology|
|Keywords:||Benthic macroinvertebrates, Best managemement practices (bmps), Sediment, Stream bank erosion, Toxicity testing, Water quality|
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