THE VISION CAME FROM BILL BOICOURT: a Chesapeake Bay observing system called CBOS could use moored buoys stationed along the mainstem and major rivers of the estuary to capture the kind of data scientists needed to expand their understanding of the Chesapeake.

"We wanted to go back and look at the physics of the basic circulation," says Boicourt. That physics had first been outlined back in the 1950s by Don Pritchard, then head of the Chesapeake Bay Institute at Johns Hopkins University. Estuaries have a structure, Pritchard discovered, a structure composed of two distinct layers. Along the surface is river water sliding seaward. Along the bottom is ocean water pushing up the estuary. In the Chesapeake Bay, the salty ocean layer is shifted towards the east side of the estuary, pushed there by the rotation of the earth. Salinities in the Chesapeake Bay are highest at the mouth and decline steadily towards the head.

That was the fundamental insight, but it left a lot of questions for oceanographers like Boicourt, a scientist who studied under Pritchard and then focused much of his own work on examining the way winds can drive or disrupt that underlying circulation. "How do we convert wind mixing and tidal turbulence into this strange, two-layer flow," says Boicourt. "It's subtle. So we need long-term records that can resolve all kinds of variability."

The buoys of CBOS could capture data all day every day, creating a long-term record of wind events, river flows, storm surges, tidal surges, and tidal ebbs — the kind of record that would help scientists make connections and correlations, form hypotheses, and test them. That was the founding vision.

The first buoy went on station in the spring of 1991, the second in 1993, followed by five others stationed at different locations for different periods of time.

Winter ice was the recurring threat. Buoys in the northern Bay had to be pulled every winter before the ice arrived — if a big boat was available. Buoys in the mid-Bay could usually — but not always — survive a mild winter.

Funding was the final problem. Buoys are expensive to build and maintain, and the last CBOS buoy was hauled out of the Bay in 2012. The vision survives, however, in networks of observing systems now found in the Chesapeake and along much of our coastlines.