The Chesapeake Bay supports a variety of species of submersed aquatic vegetation, from Zostera marina in the lower bay to a collection of freshwater species in the upper bay and tributaries. In the late 1970s, analysis of aerial photography conducted at VIMS documented an unprecedented decline in submersed aquatic vegetation in Chesapeake Bay and suggested a direct link with declining water quality in the Bay (Orth & Moore, Chesapeake Bay: An unprecedented decline in submerged, 1983). Recognizing the importance of SAV as both a key indicator of water quality conditions and a provider of ecological services that are critical to the health of the Bay (Dennison, et al., 1993), VIMS initiated an annual SAV monitoring program in 1984 with funding from a variety of sources including the EPA Bay Program, state management agencies, and private funds. The goal of the program is to monitor the distribution and abundance of SAV in the Bay and its tributaries each year as part of the effort to monitor success of Bay cleanup. The most effective available technology is used to achieve this goal, while ensuring that the annual assessment is consistent with the long-term record of SAV trends in the region.