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Oregon Lake Profile Analysis Tools

March 14, 2022

Harmful algal blooms (HABs) have occurred in many of the large water storage reservoirs in the Willamette River Basin, resulting in health advisories for water contact recreation and drinking water due to the presence of cyanobacteria toxins (cyanotoxins). In 2018 for the first time in Oregon, cyanotoxins from a HAB in Detroit Lake affected the State capital of Salem's drinking water for about a month. Similar types of cyanobacterial blooms occur in Blue River and Cougar Reservoirs, in the McKenzie River Basin, with similar threats to drinking water for the City of Eugene.

To address this issue, and to complement on-going limnological surveys, the USGS partnered with the City of Salem, the Eugene Water and Electric Board, and the U.S. Army Corp of Engineers to monitor algal blooms in Detroit Lake, Blue River Lake, and Cougar Lake - and the downstream rivers - using continuous water-quality monitors that transmit data to water treatment plant operators, dam operations, researchers and the public in near real-time. Water quality parameters, including water temperature, conductance, turbidity, and HAB parameters are collected vertically in the reservoirs every meter for the top 10 meters, then every 5 meters down to 30 meters depth. HAB parameters include surrogates for algal biomass (fluorescence of total chlorophyll [fCHL] and blue-green pigment phycocyanin [fPC]), and indicators of photosynthetic activity (dissolved oxygen and pH). Fluorescing dissolved organic matter [fDOM] -- a reliable surrogate for dissolved organic carbon, an important parameter for water treatment -- is also collected at each depth.