Lampricide Hindcast Modeling in Missisquoi Bay

In an effort to restore fisheries within Lake Champlain from the harmful behavior of the parasitic sea lamprey both federal (U.S. Fish and Wildlife) and state (New York State Department of Environmental Conservation and Vermont Fish & Wildlife) agencies have been working together to develop a sea lamprey control program. Sea lampreys are eel-like fish that feed on other fish, most often salmon or trout, however their prey include a variety of other fish species. Their presence has had a significant effect on the survival of the fish community within the lake as well as the fishing industry that has been built around the lake. As young sea lamprey spend the first four years of their lives within the bottom surface of the rivers and reaches that discharge into Lake Champlain, one component of the control program is the use of a chemical lampricide in these areas to control the young lamprey population. Lampricide applications are effective at targeting lamprey while having negligible effects on populations of other species. Applied Science Associates, Inc. (ASA) was contracted by the Vermont Fish and Wildlife Department to perform a hindcast study of the application of lampricide 3-trifluouromethyl-4-nitrophenol (TFM), which took place in November 2008 at the Swanton Dam in the Missisquoi River. The Missisquoi River discharges into Missisquoi Bay which is a small embayment located in the northeastern corner of Lake Champlain. Prior to the TFM application ASA had completed a modeling study to estimate the extent and duration of TFM in the study area under a variety of application and environmental conditions; however the studied conditions varied significantly from those observed during the actual application. All modeling efforts were performed using BFHYDRO and BFMASS, part of ASA's WQMAP modeling system (Mendelsohn et al., 1996), to simulate the circulation and mass transport respectively. WQMAP is a boundary-fitted model which can be used in three dimensions to predict flow, velocities and mass transport. The model system calculates the circulation and mass transport in the far-field region, where the initial plume momentum has dissipated and the plume is affected only by the ambient currents. This paper includes an overview of the WQMAP modeling system, relevant environmental conditions used for model forcing, model predictions and a comparison of model predicted concentrations to those observed during the field program executed by Vermont Fish & Wildlife; due to publication length requirements the reader is often referred back to the original comprehensive hindcast study report (Crowley et al., 2009). In the hindcast study observational data was used to validate the WQMAP numerical model application for use in simulating the fate and transport of the conservative constituent TFM. While numerical modeling limitations resulted in under predictions of peak concentrations at increasing distance from the application point, the model performed well at recreating the extent of the plume both spatially and temporally.