Fish-filled waters, game-rich forests, and a flat fertile valley drew trappers and early visitors into the Upper Cohos wilderness as English settlement pushed up the Connecticut and Merrimack valleys. John and Israel Glines came here prior to 1750, several years before any expedition of discovery was sent into the area, and were attracted by fishing where two tributaries of the Connecticut River later became known as Israel's River and John's River. There were actually two or three Israel Glineses who used the shores of Israel's River as a base camp for numerous expeditions into the valley. For many years the earliest settlers forded Israel's River in summer and crossed it on ice in winter, until the first bridge at the fording place was built by Emmons Stockwell, who was said to have paid five gallons of brandy for the privilege of being the first to cross it. Annual flooding shaped life on the land, with ice floes raking open spaces, striking trees, scouring away soil, and depositing mostly sand, about 0.5 inches deep on most of the island, while also bringing nutrients, seeds, uprooted plants, and cuttings that helped trees and plants grow. The Israel's River flood of 1886 destroyed and carried away Wilson's Shop, and the first iron bridge over Israel's River was carried away in 1895 when a log boom broke. The island's upside-down teardrop shape resulted from water currents, with sediments accumulating upriver and washing away downriver, causing the island to migrate upriver. Recent water quality monitoring showed the waters were in excellent condition for recreation but not for drinking.