Pittsburgh's three rivers provide a diverse habitat for many fish species, though during the Industrial Era they became severely polluted by waste from riverfront factories and large amounts of city sewage, creating serious ecological problems that continue to be corrected today. As industry declined during the 1970s and 1980s, environmentally aware organizations and government officials turned their attention to protecting and restoring the rivers and riverfront. With improving water quality, more than thirty native fish species are returning, and the rivers are again becoming places where people can relax, stroll, and enjoy boating, swimming, and fishing.