Document Type

Technical Report

Publication Date

1-2021

Keywords

Upper Poteau River Watershed, UPRW, pollution management plan, water quality, land use, nutrient concentration

Abstract

The Upper Poteau River Watershed (UPRW) has been listed as a priority watershed in Arkansas since 1998 due to nutrient and sediment enrichment from point and nonpoint sources (NPS). According to the Arkansas NPS pollution management plan, the goals for the UPRW are to reduce pollutant levels that will restore all designates uses and target subwatersheds where implementation of management practices can have the greatest impact. Over the last several years, many 319(h) projects have been implemented and point sources have been reduced in order to improve water quality in the UPRW. The purpose of this study was to monitor 15 sites in the UPRW, three on existing U.S. Geological Survey (USGS) monitoring sites and 12 additional sites on the HUC-12 scale, for streamflow, nutrients, and sediments to add to the water quality database used by policy and decision makers of Arkansas.

This project successfully collected water samples across a range of flows at 15 sites over three years, collected stage and discharge measurements at 8 of the 12 HUC-12 sites, developed rating curves for sites with stage and discharge measurements, estimated monthly and annual constituent loads for sites with discharge measurements, conducted water quality trend analyses at the three USGS sites, and analyzed the relationship between nutrient concentrations and land use. At the three USGS sites, constituent loads were generally greatest in the 2019 project year, and long term trend analyses suggested flow-adjusted sediments were decreasing over time. However, flow adjusted N was increasing at both the Poteau River and James Fork, and flow-adjusted SRP was increasing only at the James Fork. At the HUC12 sites, constituent loads were generally greatest in 2020, and the largest magnitude of loads occurred from the Lower Poteau river site which is just downstream of the waste water treatment plant in Waldron, Arkansas. Finally, average and flow-weighted concentrations increased with increasing human development (which mostly consists of agricultural land use in the UPRW) across sites (with the exclusion of sites 3 and 9). Ultimately, the data collected in this project is important for understanding small-watershed pollutant sources and long term trends in water quality at the UPRW.

Comments

Funded by the Arkansas Natural Resource Division | Project 17-300

Report Number

MSC390

Page

62

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