20 Hydrology and Water Quality in the Southeast U.S. I

Thursday, 20 March 2025
1:30 PM - 3:30 PM
Alleghany B/C

THE EFFECTS OF INTENSIVE AGRICULTURE AND RIPARIAN BUFFERS ON ECOSYSTEM HEALTH IN THE SHENANDOAH VALLEY

Paper number: 20-8
Program: Theme Sessions
Time: 3:15 PM – 3:30 PM

Authors

Abstract

Intensive agricultural practices in the Shenandoah Valley have significantly impacted ecosystem health, with livestock runoff contributing to contamination by harmful bacteria such as total coliform and E. coli. A 2021 study by the Virginia Department of Environmental Quality (VA DEQ) reported elevated E. coli levels at 80% of monitored sites. To address this, the USDA's Conservation Reserve Enhancement Program (CREP) encourages the use of riparian buffer vegetative strips along waterways—to reduce runoff pollution and improve water quality. This study assessed the effectiveness of riparian buffers in controlling nutrient and bacterial contamination in farming systems adjacent to streams flowing into the North or South Fork of the Shenandoah River. Water samples were collected in summer 2023 from three locations (upstream, midstream, downstream) along riparian buffer zones at six streams/farms. Samples were analyzed for cations using Varian Atomic Absorption Spectroscopy and anions using Dionex High-Performance Ion Chromatography. Environmental and landscape factors, such as slope, elevation, and proximity of farms to streams, were quantified using Geographic Information Systems (GIS: ArcGIS Pro 2.0). Statistical modeling (R Studio 4.3.1) was performed to evaluate the influence of riparian buffer and farm characteristics on nutrient levels. Unfiltered water samples collected in spring 2024 were analyzed for total coliform and E. coli using the IDEXX Quanti-Tray method (EPA 9223B). Results showed elevated nutrient levels, with nitrite exceeding state standards due to fertilizer use and low summer rainfall. Bacterial analysis revealed reductions in total coliform and E. coli from upstream to downstream in farms with larger riparian buffers, compared to those with smaller buffers. These findings highlight the benefits of riparian buffers in reducing pollution and improving water quality. However, long-term studies are needed to examine spatial and temporal variability in nutrient and bacterial levels across these systems.

Geological Society of America Abstracts with Programs. Vol. 57, No. 2

doi: 10.1130/abs/2025SE-409037

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