Based on review of 19 water quality parameters grouped into four categories—nutrients, heavy metals, salts and pathogens, and physical — UMRBA's 2023 How Clean is the River? Report finds that water quality between 1989 and 2018 has generally improved, while there are pollutants of concern that have varying trends. Decreases in legacy heavy metals, sediment, and phosphorus, for example, show that public and private investments in managing water quality are beneficial and that the approaches taken have been effective. Chloride, and contemporary or emerging pollutants of concern, however, are rising and require a five-state approach to develop effective solutions. The results support UMRBA’s current focus on nutrients, chloride, and emerging contaminants as well as unified, Clean Water Act-focused monitoring on the river.
