Evaluating water-quality trends in agricultural watersheds prioritized for management-practice implementation

Journal of the American Water Resources Assocation
By: , and 

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Abstract

Many agricultural watersheds rely on the voluntary use of management practices (MPs) to reduce nonpoint source nutrient and sediment loads; however, the water-quality effects of MPs are uncertain. We interpreted water-quality responses from as early as 1985 through 2020 in three agricultural Chesapeake Bay watersheds that were prioritized for MP implementation, namely, the Smith Creek (Virginia), Upper Chester River (Maryland), and Conewago Creek (Pennsylvania) watersheds. We synthesized patterns in MPs, climate, land use, and nutrient inputs to better understand factors affecting nutrient and sediment loads. Relations between MPs and expected water-quality improvements were not consistently identifiable. The number of MPs increased in all watersheds since the early 2010s, but most monitored nutrient and sediment loads did not decrease. Nutrient and sediment loads increased or remained stable in Smith Creek and the Upper Chester River. Sediment loads and some nutrient loads decreased in Conewago Creek. In Smith Creek, a 36-year time-series model suggests that changes in manure affected flow-normalized total nitrogen loads. We hypothesize that increases in nutrient applications may overshadow some expected MP effects. MPs might have stemmed further water-quality degradation, but improvements in nutrient loads may rely on reducing manure and fertilizer applications. Our results highlight the importance of assessing MP performance with long-term monitoring-based studies.

Publication type Article
Publication Subtype Journal Article
Title Evaluating water-quality trends in agricultural watersheds prioritized for management-practice implementation
Series title Journal of the American Water Resources Assocation
DOI 10.1111/1752-1688.13197
Volume 60
Issue 2
Year Published 2024
Language English
Publisher Wiley
Contributing office(s) Pennsylvania Water Science Center, VA/WV Water Science Center
Description 16 p.
First page 305
Last page 330
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