AMD from the Duryea outfall enters the River from its east bank, just upstream from the Coxton Rd. bridge in the municipality of Duryea. This outfall originates about 500 m north of its confluence with the River at a point where it flows from a hole in the ground. A beaver dam lies about 100 m downstream of this opening creating a wetland around the outflow. Downstream of the beaver dam, the mine water comes together in a small channel that leads to the River. Though some metals are filtered out of the mine water by the beaver dam, high concentrations of iron from the outfall still reach the River and cover the River's substrate with iron oxides for the remainder of its reach to its confluence with the Susquehanna River (about 1 mile downstream). Iron oxides from the Duryea outfall add to the iron load already in the River carried downstream from the Old Forge Borehole. Combined, the two outfalls have severely restricted aquatic life within the final three mile reach of the Lackawanna River to its confluence with the Susquehanna River. The Duryea outfall originated in 1960 when the underground mine pool broke through the surface and initially shot out of the ground as a geyser before settling into a steady flow out of the hole it had created. Prior to this, mine water had begun to push its way out of the flooded underground mines through old boreholes and mine openings causing damage to private property. In 1961, the Old Forge Borehole was constructed to help relieve the hydrologic pressure that was forcing mine water up to the surface at the Duryea site.