CCC-SC-28

Difference Between 16-year and 82-year Analyses of Water Quality Impacts

Figure 1: Increases in specific conductance (EC) on Old River at Bacon Island for water years 1922-2003 and 1976-1991 (82-years and 16-years, respectively). The water quality data are from the WaterFix Biological Assessment (BA) Proposed Action (PA) and No Action Alternative (NAA) at Early Long Term (ELT). (SWRCB-104). Using only a 16-year average underestimates the adverse impacts in February-June and overestimates the

simulated benefits in November-January.

CCC-SC-28 Difference Between 16-year and 82-year Analyses of Water Quality Impacts Page 2

Figure 2: 16-year and 82-year averages of Bacon EC data for March from the Biological Assessment modeling with the Proposed Action EC plotted as a function of the No Action Alternative EC (red square and blue diamond, respectively). Because this

location is close to a D-1641 Municipal and Industrial compliance location, equivalent chloride concentrations of 150 mg/L is also shown. The equivalent 100 mg/L chloride

concentration is plotted for comparative purposes.

CCC-SC-28 Difference Between 16-year and 82-year Analyses of Water Quality Impacts Page 3

Figure 3: 16-year subset of daily-averaged Bacon EC data for March from the Biological Assessment modeling with the Proposed Action EC plotted as a function of the No

Action Alternative EC (496 data points). Also shown are the corresponding 16-year and 82 year averages (red square and blue diamond). Because this location is close to a D-

1641 Municipal and Industrial compliance location, equivalent chloride concentrations of 150 mg/L is also shown. The equivalent 100 mg/L chloride concentration is plotted for

comparative purposes.

CCC-SC-28 Difference Between 16-year and 82-year Analyses of Water Quality Impacts Page 4

Figure 4: 82-years of daily-averaged Bacon EC data for March from the Biological Assessment modeling with the Project Action EC plotted as a function of the No Action Alternative EC (2,542 data points). Also shown are the corresponding 16-year and 82-

year averages for March (red square and blue diamond). Because this location is close to a D-1641 Municipal and Industrial compliance location, equivalent chloride concentrations of 150 mg/L is also shown. The equivalent 100 mg/L chloride

concentration is plotted for comparative purposes.

CCC-SC-28 Difference Between 16-year and 82-year Analyses of Water Quality Impacts Page 5

Figure 5: 82-years of daily-averaged Bacon EC data for November from the Biological Assessment modeling with the Project Action EC plotted as a function of the No Action

Alternative EC. Also shown are the corresponding 16-year and 82 year averages for March (red square and blue diamond). Because this location is close to a D-1641

Municipal and Industrial compliance location, equivalent chloride concentrations of 250 mg/L and 150 mg/L are also shown.