NOAA is providing forecasts in Chesapeake Bay for harmful algal blooms (HABs) of the dinoflagellate Margalefidinium polykrikoides, often known as rust tide, which typically blooms from late July to October. Blooms have been observed annually in the York River since 2007, and in more recent years in the lower Bay’s mainstem and in the James, Elizabeth and Lafayette Rivers. These blooms are a concern due to their impact on water quality and toxicity to finfish and shellfish. A demonstration forecast is currently being run for the York River, VA and will be expanded to other regions of the Bay pending validation efforts. A combination of satellite imagery (showing bloom location and extent) and a coupled bio-physical model provides information on the current status of the bloom and forecasted position at both surface and at depth over the next 6 days. See individual products and our FAQs for more information.