Through the 19th and early 20th centuries, Southwestern Pennsylvania was synonymous with industry. 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 environment in southwestern Pennsylvania has experienced a similar renaissance. An adult mussel can filter up to 15 gallons of water every day, and in the process removes harmful algae, microorganisms, and chemicals.