NOAA Beach Water Quality Experimental Forecasts

Timely accurate forecasts of beach water quality are critical to protect human health against adverse exposure situations. The Great Lakes Environmental Research Laboratory (GLERL), National Weather Service Chicago, USGS, Lake Michigan Ecological Research Station, Univ of Michigan, developed and tested beach management forecast decision support systems (FDSS) at five beaches in the Chicago Park District adjacent to Lake Michigan. The NOAA Beach Water Quality Experimental Forecasts are possible because the Chicago Park District provided E. coli monitoring data. Ocean Observing Systems in the Great Lakes allow the National Weather Service to use model generated parameters as independent explanatory variables of E. coli.

These variables include wind velocity, lake currents, air and surface water temperatures, cloud cover, and sampling time. E. coli has been modeled at Foster, Oak, Calumet, Montrose, and 63rd Street Beaches. NWS Chicago operationally tested FDSS during the 2013/2014 swimming seasons between Memorial and Labor Day. The strength of the beach water quality experimental forecasts was the ability to indicate the likelihood of safe swimming conditions when bacterial counts were low (ave =98.3 +/- 3.9%). The accuracy for the five Chicago beaches ranged from 69 to 97 percent (ave = 84.7 +/- 10.6%) when compared with the Chicago Parks E. coli monitoring data. The FDSS was 86% accurate for Calumet Beach in keeping swimming available when bacterial concentrations were <235 counts/100ml.

For many that choose to swim within the shallow waters of the lakes, they are exposed to small concentrations of bacteria. While most do not react to these concentrations, there are times when bacteria growth is accelerated due to various meteorological conditions. This results in an increased risk to swimmers from being exposed to poor water quality, which could result in illness.

This talk will present the National Weather Service Forecast Office operational issues on making available 48 hour forecasts, and how we move forward on integrating our services into the health sector.