Location: Water Quality and Ecology Research
Title: Influence of integrated watershed-scale agricultural conservation practices on lake water quality Authors
Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 2013
Publication Date: N/A
Interpretive Summary: As we continue to try to improve water quality through the use of agricultural best management practices (BMPs), we need to better understand how effective these BMPs are within an entire watershed. To address this, we collected water quality measurements of water clarity, total suspended sediment and total dissolved solids in Beasley Lake, a Conservation Evaluation Assessment Program watershed in the Mississippi Delta from 1996 to 2009. We observed how a variety of BMPs in the watershed changed lake water quality. BMPs put in place from 1997-2006 included within-field, edge-of-field, and Conservation Reserve Program (CRP) practices. Over the 14 years we studied lake water quality, the lake had clearer water, less suspended sediments, and lower dissolved solids coinciding with the amount of BMPs put in place and these changes were seen most strongly during spring. Our study showed that BMPs put in place improved lake water quality and will help make a healthy, sustainable lake. These results are of interest to regulatory and other agencies and farming stakeholders by providing additional information to improve and sustain lake and flood plain water quality and overall environmental quality using conservation practices.
Technical Abstract: Watershed-scale management efforts to improve conservation of water resources in agricultural watersheds depend upon the effectiveness of integrated multiple agricultural best management practices at this scale. This requires large-scale, long-term (>10 y) studies measuring key water quality parameters. One such suite of critical water quality parameters includes water clarity, total suspended solids (TSS), and total dissolved solids (TDS). To address this, Beasley Lake, a 25-ha (62-ac) oxbow lake located in a 915 ha (2,261-ac) watershed of intensive row crop agricultural activity, was studied. The lake was sediment impaired when monitoring was initiated in 1995 and was a candidate to assess the effectiveness of watershed-wide agricultural conservation practices (BMPs) on lake water clarity (as Secchi depth), TSS concentrations, and TDS. A variety of BMPs within row crop fields, at field edges throughout the watershed, and enrollment of 112 ha (277-ac) into the Conservation Reserve Program (CRP) between were implemented from 1997-2006 focusing on reducing soil erosion and concomitant sediment runoff. Selected parameters were measured approximately bi-weekly from 1996-2009. During this 14-year period, changes in row-crop management and BMP implementations and alterations were observed and recorded in conjunction with targeted water quality parameters. While annual improvement in water quality occurred, distinct seasonal effects were noticeable. Observed changes in water clarity and TSS concentrations were greatest during spring and least in winter in association with increased BMPs, vegetated buffer strips west of the lake and CRP north of the lake, as well as changes in addition to increases in milo (Sorghum bicolor L. Moench) and increases in soybean (Glycine max [L.] Merrill) production. Observed decreases in TDS concentrations were greatest during summer and fall in association with implemented CRP north of the lake. Reductions in spring TSS by >60% often directly increased spring water clarity by >100%. Results of this study indicate clear improvement in lake water quality with watershed-wide implementation of integrated multiple agricultural BMPs and these improvements, manifested most strongly during spring, will assist to promote a healthy, sustainable lake ecosystem.