Water quality in the Delaware River, USA, has improved significantly since the Federal Water Pollution Control Act (1948), Clean Water Act of 1972, and authorization of the Delaware River Basin Commission Compact in 1961. Initial economic analysis by the Federal Water Pollution Administration in 1966 concluded the multimillion dollar pollution abatement programme would generate $350 million in annual benefits by improving dissolved oxygen levels to fishable standards in the Delaware River. Although water quality in the Delaware has improved substantially, scientists have called for raising the 1960s dissolved oxygen criteria from 3.5 mg/L to 5.0 mg/L to ensure year‐round propagation of anadromous American shad and Atlantic sturgeon. This higher level would also mitigate atmospheric warming resulting in increased water temperatures and sea water incursion, both of which would lead to reductions in dissolved oxygen saturation in the river. Additional economic valuation of this water quality improvement shows direct use benefits in the Delaware River to range from $371 million to $1.1 billion per year. Other economic sectors benefiting from improved water quality include recreational boating ($46–$334 million), recreational fishing ($129–$202 million), agriculture ($8–$188 million), nonuse value ($76–$115 million), viewing/boating/fishing ($55–$68 million), bird watching ($15–$33 million), property value ($13–27 million), water supply ($12–$24 million), commercial fishing (up to $17 million), and navigation ($7–$16 million). Future economic research is needed in the Delaware River watershed to more precisely measure nonuse benefits by public willingness to pay for improved water quality.
