With all the potential that comes with a cleaner environment in and around the Susquehanna River, challenges remain going forward.
In few places is that clearer than the section that flows through the midstate, where there are high-level discussions about listing it as impaired because of the decline of the well-known smallmouth bass fishery.
But at the same time, that's a delicate needle to thread, because "impaired" can be interpreted as downright dangerous and could chase people away permanently.
Brian Mangan, director of the Susquehanna River Institute at King's College in northeastern Pennsylvania, said he founded the institute because people along the river's banks had either given it up to pollution or had associated it with deadly and devastating flooding.
A voice was needed for the river's positive attributes.
In a way, the fact that commercial shipping — which developed on many of the nation's major rivers — did not grow on the river helped it, Mangan said. The river also retains much of the woodlands directly adjacent to its banks as a resource.
Mangan is among trumpeters of the fact that the river is vastly improved compared with when he first monitored the waterway as a consultant three decades ago.
But with fewer overtly deadly contaminants in the water, scientists can observe what is stressing organisms and the environment — sometimes with severe consequences.
Among the problems they are seeing today is that male smallmouth bass are becoming "feminized," meaning eggs are developing inside male fish.
An example of how so-called endocrine disrupters can reach waterways is the hormones that get into the water from sources such as residential homes, he said.
The human body excretes hormones and people take medications that contain them, and these are not filtered out by wastewater treatment, Mangan said. And there are a lot of people living in the river's watershed, he said.
It's a problem without a foreseeable solution, because no usable technology exists to effectively take hormones out of the water.
Then there is the issue of bedsore-like lesions forming on adult smallmouth bass, said Harry Campbell, Pennsylvania senior scientist for the Maryland-based Chesapeake Bay Foundation.
Moreover, young bass are dying at "unprecedented rates," he said. Acidity, or low pH, is an identified issue, particularly in shallower sections of the river that are important for sheltering young bass.
The root cause of these problems is unknown.
The Pennsylvania Fish and Boat Commission has asked that the state Department of Environmental Protection include the lower Susquehanna River in an impaired waterway listing, Campbell said.
Under the federal Clean Water Act, such an impairment listing mandates that stakeholders find out what is causing symptoms of poor water quality and devise a plan to fix it, he said.
"Without that listing, we don't have that promise," Campbell said.
DEP originally did not list it in a draft, Campbell said. Putting the large section of river on the list submitted to the federal Environmental Protection Agency would be unprecedented, because the list normally includes smaller lengths of waterways, Campbell said.
The foundation supports the listing in order to turn resources toward an investigation and remedy, though Campbell said he shares Mangan's sentiments that it's a delicate balance between getting the needed attention and scaring people — who are, in essence, potential clients — away from the river.
But at the end of the day, the cause needs to be found, he said.
"If the river is fouled, then we spend more on treatment," Campbell said. "At the end of the day, it ultimately affects all of us in one way, shape or form."
On a scale of 1 to 10 — with 1 being the climax of 20th-century pollution and 10 being the water purity level and huge populations of fish when European settlers arrived — the river is about a 2.5, said Michael Helfrich, the Lower Susquehanna Riverkeeper.
Water problems over the years have included high levels of sediment from large-scale logging, coal in the water from upstate operations, metals from iron and steel foundries and chemicals that became prevalent in later manufacturing operations, Helfrich said.
"Waterways have been the source of pollution disposal for at least 5,000 years, possibly more," he said.
The "brown trout" — a reference to fecal matter prevalent in waterways — and suspected carcinogens that would cause direct human health impairment have receded since passage of the Clean Water Act in 1972, he said.
But between residual damage and the continued but less visible pollution from sources such as fertilizers, restoration of the river has a long way to go, Helfrich said.