Detroit River phosphorus loads: Anatomy of a binational watershed

Lake Huron’s Phosphorus Contributions to the St. Clair–Detroit River Great Lakes Connecting Channel

“…Of the usable Ontario images, 72, 57, and 60% showed occurrences of moderate or large sediment resuspension in 2016, 2017, and 2018, respectively. These frequencies are similar to those reported for 2010 (64%) and 2012 (54%) for the same region . The percentages for large occurrences were 22, 38, and 41% for 2016, 2017, and 2018, respectively.…”

“…Using measured TP concentrations at the outlet of Lake Huron, Burniston et al estimated its load to be almost 3 times the previous estimates that were based on TP concentrations in the ultraoligotrophic Lake Huron. , They also showed that TP concentrations, especially particulate P, downstream in the St. Clair River were higher than upstream where Lake Huron enters, and that difference has increased over time. Because the concentration differences were not due to additional lateral loads to the river, , it has been suggested that the difference originates from episodic sediment resuspension in Lake Huron that is not captured at the upstream St. Clair River monitoring station. Accounting for this additional source, these recent estimates also showed that Lake Huron loads have increased over time , and currently are almost twice again as high as those of Burniston et al…”

“…Because the concentration differences were not due to additional lateral loads to the river, , it has been suggested that the difference originates from episodic sediment resuspension in Lake Huron that is not captured at the upstream St. Clair River monitoring station. Accounting for this additional source, these recent estimates also showed that Lake Huron loads have increased over time , and currently are almost twice again as high as those of Burniston et al…”

“…Over 30 years ago, Mortimer pointed further north to Lake Huron’s Ontario nearshore region as a potential significant source of sediment for Lake St. Clair and Lake Erie. Scavia et al , suggested that this wave-induced resuspended sediment carried additional P and that it was often missed by the Canadian monitoring program that samples semimonthly to monthly at a fixed point intake at the outlet of Lake Huron. They showed that increases since 1998 paralleled climate-driven decreases in ice cover and increases in wave heights.…”

One size does not fit all: Toward regional conservation practice guidance to reduce phosphorus loss risk in the Lake Erie watershed

“…The majority of the P loads to Lake Erie are supplied by the Western Lake Erie watershed and the Huron-Erie corridor (Dolan & Chapra, 2012;Maccoux et al, 2016;Wilson et al, 2019), particularly from Lake Erie's Maumee and Detroit tributaries (Maccoux et al, 2016). Although there have been reductions in P loads in some tributaries such as the Detroit River due to improvements by the Great Lakes Water Authority Water Resource Recovery Facility (see Scavia et al, 2019), Maccoux et al (2016) indicated that there had been no significant change in overall annual TP loads over the past ∼25 yr. However, a profound re-eutrophication of Lake Erie has occurred since the mid-1990s, including cyanobacterial blooms in the western basin, hypoxia in the central basin, and resurgence of benthic algae in the eastern basin (Depew et al, 2018;Scavia et al, 2014).…”