Review of Trace Element Blank and Replicate Data Collected in Ground and Surface Water for the National Water-Quality Assessment Program, 1991–2002
By Lori E. Apodaca1, David K. Mueller2 and Michael T. Koterba3
Scientific Investigations Report 2006-5093, published 2006.
Table 1
Upper 95-percent confidence limit by percentiles for contamination in trace elements from ground-water field-blank data.
[Bold faced values indicate contamination greater than the common reporting level. Al, aluminum; Ag, silver; As, arsenic; B, boron; Ba, barium; Be, beryllium; Cd, cadmium; Co, cobalt; Cr, chromium; Cu, copper; Fe, iron; Pb, lead; Li, lithium; 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; na, not applicable; µg/L, microgram per liter; <, less than; —, too few data to compute]
 AlSbAsBaBeBCdCrCoCuFePbLiMnM oNiSeAgSrTlUVZn
USEPA Drinking-Water Standard¹²50–200³6³10³2,000³44600³5³100—51,300²300515—43004404100³50410044,000³2³30—42,000
Common Reporting Level (µg/L)1.01.01.01.01.04.01.01.01.01.03.01.00.31.01.01.01.010.10.11.01.01.0
Number of blanks3303473293443461643533433433454233433754634133930234318615136837341
Percentile95-percent Upper Confidence Limit (µg/L)
50th (median)3.0<1.0<1.0<1.0<1.05.9<1.0<1.0<1.0<1.0<3.0<1.0<0.3<1.0<1.0<1.0<1.0<1.0<0.1<0.1<1.0<1.01.0
75th 4.0<1.0<1.0<1.0<1.09.2<1.0<1.0<1.0<1.05.0<1.0<0.3<1.0<1.0<1.0<1.0<1.00.16<0.1<1.0<1.03.0
85th4.9<1.0<1.0<1.0<1.012<1.0<1.0<1.01.08.0<1.00.36<1.0<1.0<1.0<1.0<1.00.30<0.1<1.0<1.06.0
90th6.0<1.0<1.0<1.0<1.013<1.0<1.0<1.02.011<1.00.781.0<1.0<1.0<1.0<1.00.78<0.1<1.0<1.08.0
91st6.5<1.0<1.0<1.0<1.013<1.0<1.0<1.02.112<1.00.781.0<1.0<1.0<1.0<1.00.78<0.1<1.0<1.09.0
92nd7.0<1.0<1.0<1.0<1.013<1.0<1.0<1.03.015<1.00.781.0<1.0<1.0<1.0<1.01.6<0.1<1.0<1.011
93rd8.0<1.0<1.01.0<1.014<1.0<1.0<1.03.020<1.0—1.0<1.0<1.0<1.0<1.02.0<0.1<1.0—14
94th8.3<1.0<1.01.0<1.015<1.01.0<1.03.821<1.0—1.0<1.0<1.0<1.0<1.02.3<0.1<1.0—14
95th9.0<1.0<1.01.1<1.015<1.01.0<1.04.029<1.0—1.2<1.0<1.0<1.0<1.03.0<0.1<1.0—18
96th10<1.0<1.01.5<1.019<1.01.1<1.04.436<1.0—1.6<1.0<1.0<1.0<1.03.4<0.1<1.0—21
97th12<1.0<1.03.9<1.019<1.02.0<1.05.342<1.0—2.0<1.01.0<1.0<1.06.1<0.1<1.0—36
98th14<1.0<1.05.0<1.0221.02.01.01246<1.0—2.0<1.02.01.2<1.019<0.1<1.0—38
99th91<1.01.07.9<1.0—1.04.51.51011007.0—4.0<1.02.52.41.0——1.6—68
                        
Common Reporting Level (µg/L)0.30.20.180.20.220.30.20.20.2na0.3na0.10.20.50.70.2nana0.20.210.5
Number of blanks1471529147152142153144152154na152na19015214940148nana1534146
Percentile95-percent Upper Confidence Limit (µg/L)
50th (median)2.9<0.2na<0.2<0.25.1<0.3<0.2<0.20.24na<0.3na<0.1<0.2<0.5<0.7<0.2nana<0.2na0.92
75th 3.6<0.2na0.27<0.27.9<0.30.27<0.20.56na<0.3na0.15<0.2<0.5<0.7<0.2nana<0.2na2.1
85th4.1<0.2na0.47<0.210<0.30.33<0.20.79na<0.3na0.25<0.2<0.5<0.7<0.2nana<0.2na3.5
90th4.8<0.2na0.6<0.211<0.30.50.21.4na<0.3na0.35<0.2<0.5<0.7<0.2nana<0.2na6.8
91st4.8<0.2na0.77<0.212<0.30.540.221.8na<0.3na0.44<0.2<0.5<0.7<0.2nana<0.2na7.0
92nd5.0<0.2na1.0<0.212<0.30.680.361.9na<0.3na0.47<0.20.51<0.7<0.2nana<0.2na7.2
93rd5.2<0.2na1.3<0.212<0.30.720.372.2na<0.3na0.54<0.20.51—<0.2nana<0.2na12
94th5.6<0.2na1.9<0.212<0.30.760.422.7na0.42na0.61<0.20.62—<0.2nana<0.2na18
95th6.4<0.2na3.6<0.213<0.30.830.823.9na0.57na0.79<0.20.75—<0.2nana<0.2na25
96th6.5<0.2na3.9<0.213<0.30.890.894.3na0.7na0.86<0.20.85—<0.2nana<0.2na38
97th8.5<0.2na5.2<0.2140.421.11.413na7.0na1.10.251.0—<0.2nana<0.2na68
98th—<0.2na—<0.2—0.42—1.413na7.0na1.20.251.0—<0.2nana<0.2na—
99th——na———————na—na—————nana—na—
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 are 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.