The War Eagle Creek Watershed (WEC), a major tributary to Beaver Lake, the primary drinking water source for Northwest Arkansas, was identified as a hotspot for nutrient and sediment transport and a priority for conservation in the EPA approved watershed management plan. To evaluate nutrient patterns within WEC, water samples were collected from May 2025 through 2026 and analyzed for total nitrogen (TN), total phosphorus (TP), nitrite, soluble reactive phosphorus (SRP), and conductivity. Recent findings were compared to historical data from 2003–04 to assess nutrient changes over time. Additionally, land cover at the watershed and site catchment scales was calculated to identify potential sources of nutrient inputs.
Spatial variability in nutrient concentrations was observed across WEC, with higher concentrations generally occurring at downstream sites. Geometric mean TN and TP ranged from 0.09 to 4.66 mg/L and from <0.01 to 0.38 mg/L, respectively. These patterns are likely due to increased pasture land use and inputs from a wastewater treatment plant.
Comparison with historical data revealed temporal variability as well. Most sites showed increased conductivity and P concentrations over time, while N trends were more varied. TN increased at 54% of sites between 2003–04 and 2025–26, but the median TN geomean across sites decreased by 34%. In contrast, TP and conductivity increased at 63% and 72% of sites, respectively, with median site-level concentrations increasing by 2% for TP and 19% for conductivity. This indicates that temporal changes in nutrient concentrations are not uniform across WEC and vary in magnitude across sites.
Catchment land cover changed slightly between 2003 to 2024, including increases in urban (4.5% to 5.5%) and pasture cover (37% to 39%), and decreases in forest cover (58% to 55%). Site catchments experiencing increases in pasture and urban cover, along with declining forest cover, corresponded with higher observed nutrient concentrations in 2025–26 relative to 2003–04, highlighting land use change as a likely driver of nutrient inputs. Additionally, results will be compared with priority areas identified in the 2025 Beaver Lake Watershed Protection Strategy to assess patterns between observed nutrients and modeled management priorities.