LORAIN, Ohio -- The Black River powered Lorain's industrial economy for generations. But by the 1980s, it had earned a grim distinction: one of the worst "toxic hotspots" in the Great Lakes region.

Since then, major effort has been underway to revitalize the river once known as the "river of fish tumors" - and it's now just one step away from being removed from the EPA's toxic hotspot list.

Here's a look back at what led to the Black River becoming so polluted - and what's being done to bring it back.

The Early Years: Sewage, disease and industrial expansion

The Black River's decline began in the late 19th century as Lorain rapidly industrialized. In 1892, the city installed its first sanitary sewer system, which pumped untreated human waste directly into the Black River. Contaminated water caused typhoid cases to surge.

Soon, steel began to shape Lorain's economy and its river. In 1894, Johnstown Steel relocated to Lorain. The company, which would later become Lorain Steel, constructed its first blast furnaces in 1899.

By 1901, Lorain Steel had become part of U.S. Steel, and in 1905, the National Tube Company, a U.S. Steel division, produced its first pipe in Lorain.

Discharge poured into the Black River largely unchecked and unregulated for the next 65 years.

The turning point: environmental awakening

The environmental movement of the 1970s brought significant change. The Ohio EPA was formed in 1970. Two years later, the federal Clean Water Act passed, establishing a structure for regulating pollutant discharge into U.S. waterways.

In 1980, scientists began studying the Black River and its brown bullhead catfish populations. They found elevated levels of carcinogenic pollutants and high rates of cancerous growth, prompting significant public health warnings.

The Ohio Department of Health issued both a contact advisory -- warning people to avoid touching the water in the lower Black River -- and a "Do Not Eat Fish" advisory for any fish caught in polluted waters in 1983. That same year, the steel mill's coking plant, a source of carcinogenic pollution, closed its doors.

The Black River was officially identified as a Great Lakes Area of Concern - or AOC -- by the International Joint Commission in 1984. A total of 26 such locations have been identified in the U.S. This designation is reserved for the most severely degraded locations in the waters shared by the United States and Canada, according to the EPA.

Legacy and ongoing restoration

Since 2010, however, the Black River has received roughly $26 million through the Great Lakes Restoration Initiative. According to the EPA, the funding supported a variety of projects including control of invasive plant species, floodplain excavation, wetland restoration, fish shelf creation and the removal of steel mill contaminants that impacted a nearby 300-nest colony of Great Blue Herons.

To help address environmental problems and eventually become delisted, 14 potential Beneficial Use Impairments - or technical markers for environmental damage - were created to measure progress.

Nine of these markers were originally identified for the Black River, eight of which have since been removed by the Ohio EPA. They include: fish tumors and other deformities, undesirable algae, beach closings, loss of fish and wildlife habitat, degradation of aesthetics, fish and wildlife populations and restrictions on dredging activities and fish and wildlife consumption.

Don Romancak, chair of the Black River Area of Concern Advisory Committee, spoke about the progress at a recent Lorain County Commissioners meeting. He told commissioners that the committee is working closely with the Ohio EPA and the Ohio Lake Erie Commission to address the final hurdle. Once the last environmental restoration item is complete -- Degradation of Benthos-- the Black River can be formally delisted as an Area of Concern, ending its decades-long designation as one of the Great Lakes' most polluted rivers.

Steel, sewage and neglect: How Lorain County cleaned up its 'river of fish tumors'