Strange Creatures Called The 'Livers Of Rivers' Are Reappearing In Southwestern Pennsylvania's Waterways

Through the 19^th and early 20^th centuries, Southwestern Pennsylvania was synonymous with industry. The region's largest city, Pittsburgh, became internationally known as the Steel City thanks to industrialist Andrew Carnegie, who capitalized on the region's abundant coal and iron ore to found Carnegie Steel. This was a boon for the local economy but bad news for the region's waterways, which became polluted by industrial waste and runoff. But western Pennsylvania's identity started to shift after the steel industry collapsed in the 1980s. The one-time steel capital of Pittsburgh has been revitalized into one of America's most livable cities, where former steel mills now function as creative hubs with tours.

The environment in southwestern Pennsylvania has experienced a similar renaissance. While the legacy of industry can still be seen in the presence of contaminants like manganese and cadmium in the water, the levels have gone down enough that local wildlife is starting to come back. This includes the animal group known as the "livers of the rivers" — freshwater mussels, which play a pivotal role in the ecosystem but are especially sensitive to pollution. Just like the liver in a human body, mussels function as filters. An adult mussel can filter up to 15 gallons of water every day, and in the process removes harmful algae, microorganisms, and chemicals. In short, they help to keep water healthy for the other lifeforms that call the river home, a big reason why their presence is seen as a good sign for overall river health.

Pittsburgh is situated at the confluence where the Allegheny and Monongahela Rivers form the Ohio River. All three rivers were heavily impacted by industrialization and other human activity, and have been the focus of clean-up efforts in recent decades. Historically, the Ohio River had the most mussel diversity in Pennsylvania, home to 53 of the 67 freshwater mussel species found in the state. While that full complement hasn't yet been restored, the Ohio River today has 22 living mussel species. In one recent survey of the Emsworth Pool, between the McKees Rocks Bridge and Brunot Island, researchers found a record 10 species, the highest number in that location since its first survey in 1904.

Of course, this doesn't mean the local watersheds are completely out of the woods. 12 of Pennsylvania's mussel species are endangered. This includes the Pistolgrip, Rabbitsfoot, and Clubshell mussels in the Allegheny, as well as the salamander mussel, whose population in the Ohio River is one of just 66 across its entire range. Unfortunately, 80% of these mussel populations are currently at high risk of extinction. Still, for those who enjoy fishing at spots like the amusement park turned nature escape at Cascade Park, the resurgence of local mussels is a good sign that you'll still be able to enjoy this outdoor entertainment for years to come.