A Momentous Anniversary for USGS Continuous Water-Quality Monitoring in Oregon Release Date: April 16, 2021 May 7th, 2021 will mark 30 years of continuous water-quality monitoring in the Tualatin River for the USGS Oregon Water Science Center. The water-quality monitor in the Tualatin River at Oswego Dam (station 14207200) was installed in May, 1991 as part of a cooperative study between the U.S. Geological Survey (USGS) and Clean Water Services — the primary wastewater and stormwater management utility in the Tualatin River basin. A large water-quality monitoring network in the basin has grown from that initial study to support a wide range of USGS studies that have provided foundational science for improved basin-wide management of water resources. Although the USGS has monitored streamflow and water temperature at many sites for much longer than 30 years, it is extremely rare to have a continuous dissolved-oxygen record for such a long period of time