Small land cover changes in the transboundary Kootenai River basin greatly alter water quality

Increased nutrient loading in aquatic environments can have a long-lasting influence on ecosystem processes and functions. The Kootenai River was historically oligotrophic, but nitrate levels been steadily increasing since the mid-2000s, while phosphorus remained low. Our study objective to evaluate current distribution throughout watershed context of land use cover change. Each three types we assessed, agriculture, developed areas, surface mines, encompass less than 1% area watershed. We measured nitrate, ammonium, soluble reactive (SRP) monthly at sites spanning 400 river km River, co-located tributary British Columbia, Canada, Montana Idaho, USA. During July 2017, same nutrients along each selected tributaries with sub-catchment tributaries. Sites were include range contributing drainage areas identified as agricultural, developed, or mining. Nutrient concentrations ranged from 0.012 4.299 mg/L for 0.0005–0.02 0.003–0.076 SRP. Nitrate elevated downstream mining cover, decreased distance areas; however, compared not affected by activity. If imbalance N:P continues increase due loading, resources available biota may become skewed, resulting alterations functions critical support biodiversity River.