Scientific Investigations Report 2006-5093 Table 6

[Ag, silver; As, arsenic; B, boron; Ba, barium; Be, beryllium; Cd, cadmium; Co, cobalt; Cr, chromium; Cu, copper; Fe, iron; Pb, lead; Li, lithium; mg/L, milligram per liter; Mn, manganese; Mo, molybdenum; Ni, nickel; Sb, antimony; Se, selenium; Sr, strontium; Tl, thallium; U, uranium; USEPA, U.S. Environmental Protection Agency; V, vanadium; Zn, zinc; µg/L, microgram per liter; <, less than; —, no data]

USEPA Drinking-Water Standard¹

²50–200

³6

³10

³2,000

³4

⁴600

³5

³1,00

—

⁵1,300

²300

⁵15

—

⁴300

⁴40

⁴100

³50

⁴100

⁴4,000

³2

³30

—

⁴2,000

Common Reporting Level (mg/L)

1.0

4.0

1.0

3.0

1.0

0.3

1.0

0.1

1.0

Ground Water

Number of samples

2,927

3,016

3,308

3,129

3,032

1,120

3,132

3,144

3,033

3,182

4,066

3,128

895

5,036

3,070

3,083

3,063

2,995

1,310

542

3,548

835

3,092

Median

3.0

<1.0

54.3

<1.0

37.5

<1.0

1.1

<1.0

1.05

<1.0

6.74

<1.0

1.1

<1.0

270

<0.1

<1.0

1.4

4.89

Maximum

1,450

6.3

550

5,050

3,380

148

684

2,040

81,000

479

1,230

28,200

4,730

666

93.5

44,000

0.72

553

190

3,290

Number equal to or greater than the USEPA drinking-water standard

250

—

1,000

—

595

142

—

Percent exceeding the USEPA drinking-water standard

3.14

0.03

7.56

0.1

0.16

3.39

0.25

0.03

—

0.03

24.7

0.19

—

11.8

1.53

0.23

0.2

4.27

4.0

—

0.03

Surface Water

Number of samples

3,171

2,471

2,441

3,445

3,030

1,853

3,612

3,158

2,468

3,473

4,929

3,388

665

2,170

2,773

3,250

3,094

3,329

1881

103

2,565

387

3,101

Median

13.0

<1.0

54.3

<1.0

1.4

23.3

<1.0

13.9

7.77

<1.0

140

<0.1

<1.0

1.74

4.0

Maximum

20,600

16.9

284

410

4,200

18.2

53.2

871

54,100

230

1,460

157

216

150

3,490

2.22

54.8

4,450

Number equal to or greater than the USEPA drinking-water standard

492

126

—

227

—

Percent exceeding the USEPA drinking-water standard

15.5

0.61

5.16

0.03

3.29

2.44

—

4.61

0.2

—

1.06

0.29

0.09

0.42

0.97

1.05

—

1.68

¹U.S. Environmental Protection Agency, 2004. ²Secondary Drinking Water Regulation (SDWR): is a non-enforceable Federal guideline to address cosmetic or aesthetic effects of drinking water. ³Maximum Contaminant Level (MCL): the highest level of contaminant that is allowed in drinking water. ⁴Health Advisory (HA): is an acceptable drinking-water level for a chemical substance that is based on health effects information. HAs are not legally enforceable, but is a standard that serves as a guidance to assist Federal, state, and local officials. ⁵Action Level (AL): concentration of a contaminant that triggers treatment or other requirements that a water system must follow. For lead and copper, the action level is the level where 10 percent of the homes tested exceed the standard.