The USGS gauge on the Oswegatchie in Harrisville provides an "approximation". The benchmarks below have many variables, so make sure you assess each drop yours
After the old bridge pool, This will be the next horizon line and is one of the largest sections on this section. It changes greatly which varing water levels from a flaky slide with large curling waves to large waves and holes. To scout, take on on river left of the island. Portage is a neccessary for most paddlers with the easiest along river left, along the game trail in the woods.