The Power of Information

National Drinking Water Database

Alameda County Water District Utilities - Oakland, CA

Serves 271,000 people

Selenium (total)

Selenium is a naturally occurring element that contaminates water due to mining or petrolum refining, fly-ash from coal-burning power plants, and irrigation of arid farmland soils high in selenium.
This Drinking Water System
Test Days Exceeding Health GuidelinesDefinition of what this is
0 days
Test Days Exceeding Legal LimitsNumber of days in which the samples taken in that day exceed the Maximum Contaminant Level (Depending on the contaminant and its MCL, that may or may not trigger an MCL violation. Some MCLs are based on averages spanning several months to a year)
0 days
Test DaysNumber of days in which this chemical has reported results in the data we received from the State
30 days
Tests ConductedNumber of individual tests done for this contaminant
285 tests

Testing Summary

Health Limit
Legal Limit

Testing History

-Tested      -Detected      -Over Health Guidelines      -Over Legal Limit*
Selenium (total)Selenium is a naturally occurring element that contaminates water due to mining or petrolum refining, fly-ash from coal-burning power plants, and irrigation of arid farmland soils high in selenium.0 ppb
0 ppb
50 ppb
50 ppb
NOTE: Each dot in the above graph represents one month.
* Water utilities are noted as exceeding the legal limit if any test is above the maximum contaminant level (MCL). Most MCLs are based on annual averages so exceeding the MCL for one test does not necessarily indicate that the system is out of compliance.

Health Based and Legal Limits for Selenium (total)

Health Based Limits for Selenium (total)

Maximum Contaminant Limit (MCL)The enforceable standard which defines the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to health-based limits (Maximum Contaminant Level Goals, or MCLGs) as feasible using the best available analytical and treatment technologies and taking cost into consideration. Source: U.S. Environmental Protection Agency.50 ppb
Maximum Contaminant Limit Goal (MCLG)A non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.50 ppb
Lifetime health-based limit, non-cancer riskConcentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for a lifetime of exposure. The Lifetime health-based limit (or Health Advisory, HA) is based on exposure for a a 70-kg adult consuming 2 liters of water per day. Source: U.S. Environmental Protection Agency.50 ppb
EPA Human Health Water Quality CriteriaWater quality criteria set by the US EPA provide guidance for states and tribes authorized to establish water quality standards under the Clean Water Act (CWA) to protect human health. These are non-enforceable standards based upon exposure by both drinking water and the contribution of water contamination to other consumed foods. Source: U.S. Environmental Protection Agency.170 ppb
Drinking Water Equivalent LevelA lifetime exposure concentration protective of adverse, noncarcinogenic health effects, that assumes all of the exposure to a contaminant is from drinking water. Source: U.S. Environmental Protection Agency.200 ppb

Testing Results

Testing DateAverage
Samples taken that dayNumber of Non-DetectsRange of Results
2009-02-190 ppb110 ppb
2009-01-210 ppb550 ppb
2008-12-090 ppb110 ppb
2008-11-120 ppb110 ppb
2008-10-280 ppb550 ppb
2008-07-230 ppb19190 ppb
2008-07-160 ppb660 ppb
2008-05-220 ppb110 ppb
2008-04-080 ppb550 ppb
2007-08-070 ppb110 ppb
2007-07-110 ppb10100 ppb
2007-07-100 ppb11110 ppb
2007-06-210 ppb110 ppb
2007-04-260 ppb110 ppb
2007-04-110 ppb550 ppb
2007-03-280 ppb220 ppb
2007-03-200 ppb110 ppb
2007-02-130 ppb14140 ppb
2007-02-120 ppb440 ppb
2006-10-250 ppb23230 ppb
2006-06-210 ppb660 ppb
2006-06-200 ppb19190 ppb
2006-02-150 ppb18180 ppb
2005-11-140 ppb19190 ppb
2005-06-010 ppb21210 ppb
2005-02-230 ppb18180 ppb
2004-10-280 ppb21210 ppb
2004-06-150 ppb23230 ppb
2004-04-140 ppb110 ppb
2004-02-180 ppb22220 ppb