Principal Investigators: Dmitry Beletsky (CILER) and David J. Schwab (NOAA/GLERL)

The Great Lakes respond very quickly to atmospheric forcing and other loadings. Consequently water quality managers and other planning and decision entities are increasingly calling for up-to-the-minute data on present water quality conditions or forecasts of these data that can be used to adjust or respond to quickly developing activities with environmental implications. Examples include the forecast of short term water quality conditions for the withdrawal of water for drinking water supply; short range predictions of potentially dangerous conditions at water supply intakes; the forecast of beach closings and openings from bacterial contamination from combined sewer overflow (CSO) discharges.

For these and other reasons, the Great Lakes Forecasting System (GLFS, Bedford and Schwab, 1994; Schwab and Bedford, 1994) has been developed to provide short-range operational (regularly scheduled) predictions of such conditions for the open waters of the Great Lakes. Predictions include every-six-hour nowcasts and twice-a-day short-range (48 hr) forecasts. Variables predicted include the three-dimensional velocity field, the three-dimensional temperature field, the water level distribution and the wind wave height, length, period, and direction.

When contrasting the information needs of water quality managers with the forecasting experience to date, three issues remain. First, the information requirements all occur with regard to activities in, near, and around the near-shore/inshore zone. It is well known that greatest demand for lake/coastal resources is in the near-shore zone and accurate information is required in this zone. Second, the information needs of the managers are for water quality data; data not yet predicted or available in forecast form. Third, the water quality forecasts require knowledge of both point and non-point sources. This research program will focus on point source loadings of E. coli (EC) into coastal environments from particular rivers and its impact on beach closures.

Both numerical modeling efforts and integrated field activities are proposed to characterize the study region and test model adequacy. A modeling hierarchy based upon the GLFS can accurately forecast the need for beach advisories and for the first time credible real-time short-range forecasts will be possible. Additional benefits will also include the potential to forecast other water quality variables of interest and the general applicability of this modeling system to other sites in the Great Lakes.
The objectives of this project are:

• Develop a modeling system based upon a fully three-dimensional hydrodynamic model (GLFS) for forecasting E. coli and Enterococci concentrations along Great Lakes coasts impacted by a specific plume (ultimately pathogens).
• Test model adequacy with extensive comparisons to data obtained from moored current meters, dye studies, and in situ water quality sampling.
• Determine the extent of ecological consequences from model simulations under various weather and loading conditions and if a well-constrained set of ecological outcomes exists.