Sites with parameter concentrations that have equaled or exceeded drinking water standard(s) (DWS), including location and parameter(s) are shown in Table 3.7-7A.  Impaired lakes and streams with site type, name, length of impaired stream reach, area of impaired lake, designated use standard and parameter(s) exceeded is shown in Table 3.7-7B.  Figure 3.7-9 shows the location of exceedences and impairment keyed to Table 3.7-7.  Not all parameters were measured at all sites; selective sampling for particular constituents is common.  A description of water quality data sources and methods is found in Volume 1, Appendix A. 

Well, Mine or Spring sites that have equaled or exceeded drinking water standards (DWS)

• Refer to Table 3.7-7A.

• Thirty-seven sites have parameter concentrations that have equaled or exceeded DWS. 

• The most frequently equaled or exceeded parameter was arsenic.

• Other parameters commonly equaled or exceeded in the sites measured in this basin were nitrate, total dissolved solids, mercury, cadmium and radionuclides. 

Lakes and Streams with impaired waters

• Refer to Table 3.7-7B.
• Water quality standards were exceeded in one 15 mile reach of the Gila River.
• The parameter exceeded in this reach was selenium.
• This reach is part of the ADEQ water quality improvement effort called the Total Maximum Daily Load  (TMDL) program.  The draft TMDL report is underway.

Click for Table 3.7-7 Water Quality in the

Duncan Valley Basin

Click for Figure 3.7-9 Duncan Valley Basin

Water Quality Conditions

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