Before And After

Using water quality data extracted from USEPA's STORET database (as described in Chapter 3), before-and-after conditions for summer (July-September), tenth percentile DO levels in RF1 reaches selected from the case study watersheds (Figure 4-1) clearly demonstrate dramatic improvements during the period after the CWA from 1986-1995 for all the case study sites (Figure 4-2). Before the CWA, during the 10-year period from 1961 to 1970, "worst-case" DO levels were in the range of 1 to 4 mg/L for most of the case study sites. After the CWA, worst-case DO levels had improved substantially to levels of about 5 to 8 mg/L during 1986-1995, with the worst-case oxygen levels of less than 2 mg/L before the CWA improving to 5 mg/L or higher after the

TABLE 4-1 Case Study Assessments of Trends in Water Quality and Environmental Resources

Information Presented

TABLE 4-1 Case Study Assessments of Trends in Water Quality and Environmental Resources

Information Presented

0 0

Post a comment