The Squamscott River has had extended episodes of low dissolved oxygen (DO) that have been recorded at a site near its mouth over the past few years. These episodes were recorded as a result of temporally intensive monitoring by a datasonde, whereas data for the rest of the river has been spotty. Thus, the spatial extent of low DO episodes is not known. This study was designed to better characterize the spatial extent of DO conditions along the full length of the river, as well as to determine nutrient and other water quality parameters along the transect to help understand possible causes of low DO levels. Sampling and measurements were taken on five dates in 2005 and one in 2006. Only one date, August 19, 2005, showed spatially extensive low DO levels. Results on the other sample dates were either acceptable levels or low DO levels were confined to small areas on two other dates. The areas where low DO levels occurred on the three dates were all distinctly different areas of the river, possibly reflecting different causes, tidal transport of low DO waters, or sample timing relative to conducive conditions.