Does Ambient Water Quality Affect the Stringency of Regulations? Plant-Level Evidence of the Clean Water Act
研究了美国《清洁水法》的排污许可是否随当地水质变化而调整，发现水质下降1 mg/L会使许可限值降低5 mg/L，表明监管具有灵活性。
This paper provides evidence that the Clean Water Act implemented through effluent limits responded to local water quality. We choose biological oxygen demand as the pollutant and dissolved oxygen as a water quality indicator. We use a panel of permits for 100 plants in Maryland, Virginia, and Pennsylvania for 1990 to 2004. We estimate that decline in water quality by 1 mg/L lowers permits by 5 mg/L. This finding demonstrates greater flexibility than might be expected in an effluent standards–based approach. It suggests efficient resource use, with permits relaxed with water quality improvements and tightened with water quality declines. <i></i>