Chesapeake Bay hypoxic zone predicted to be 3rd lowest on record

The 2009 Forecast: Nitrogen load of 151,503 kg/day, this summer’s hypoxia volume forecast is 5.1 km and also the 3rd lowest in the post-1985 period. Given average Jan-May 2009 total3, the lowest since 2001 (4.8 km3).

NOTE: There have been some reactions to the Chesapeake Bay forecasts for this year suggesting surprise that the forecast is for a relatively small hypoxic volume given all of the rain in the past month. The model has been calibrated with average January-through-May loads and the forecast is therefore based on those loads this year. The Jan-May loads were considerably below the last several years and that led to the forecast of a relatively modest hypoxia year (1.2 cubic miles; 5.1 km3). However, the model does attempt to incorporate the considerable variability in the relationship between those loads and hypoxia (see below) and that is represented by the range provided in the forecast (0.7-1.8 cubic miles; 2.7 and 7.4 km3). The forecast press release indicates that, because of “continued high flows in June …the actual size may be near the higher end of the forecast range”.

For the full forecast see http://sitemaker.umich.edu/scavia/files/2009_chesapeake_bay_hypoxic_volume_forecast.pdf