Monitoring Bacterial Water Quality for Application to Watershed and Nearshore Fate and Transport Model Development

Abstract:

There is increasing interest in linking watershed processes with nearshore processes in order to predict the fate and transport of pollutants, including bacteria, for application to management of recreational waters. However, traditional nearshore bacterial water quality monitoring programs are not sufficiently informative for understanding the spatio-temporal variability of water quality at scales that are relevant to process modeling. During the summer and fall of 2012, 2013, and 2014, we conducted increasingly intensive monitoring specifically designed to aid in the development of a linked watershed-hydrodynamics modeling framework for simulating the impacts of Michigan’s Clinton River on the nearshore bacterial water quality of Lake St. Clair. Monitoring incorporated multiple sampling “events,” including routine weekly sampling at 19 points along 19 km of shoreline, periodic transects perpendicular to the shoreline, periodic offshore sampling corresponding to the shoreline sampling points, repeated shoreline sampling over several 3-day periods, weekly river grab samples, hourly sampling of the river at baseline conditions, and hourly sampling of the river during high flow events. These sampling events allow exploration of the spatiotemporal variability of nearshore water quality resulting from local physiographic factors as well as the temporal variability of water quality in the river outlets. We present results describing the spatiotemporal variability as it relates to the watershed and hydrodynamics processes represented in a linked modeling framework which is under development.