You’ll find 70,000 workers in the Water Street corridor these days — along with many of the city’s largest companies and small signature firms. But you won’t find much water. Once upon a time, Water Street bordered the shipyards of the East River, but untold tons of landfill over the years ended all that. So in 1973, when I.M. Pei and & Partners designed Wall Street Plaza between 100 Wall and 88 Pine, they added a water feature of their own.