HADLEY — Reservoir waters have been rising steadily higher and higher at the Conklingville Dam. Levels are less than a foot and a half from brimming the spillway, a slide-like structure designed to provide prescribed discharges of excess water from the Great Sacandaga Lake to the Sacandaga River. “We may see water just conveyed just over the spillway or it could just crest short of that,” said John Callaghan, executive director of Hudson River-Black River Regulating District. Water levels, as of Tuesday, are at 769.74 feet (NAVD 1988 datum) at the Hadley site, whereas at the same time last year,…