The Power of Information

National Drinking Water Database


Mason City Utilities - Mason City, IL


Serves 2,558 people

Arsenic (total)

Arsenic contaminates drinking water due to mining runoff, erosion of natural deposits, emissions from glass and electronics processing and the use of arsenical compounds as wood preservatives and pesticides.
 
This Drinking Water System
Test Days Exceeding Health GuidelinesDefinition of what this is
25 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)
24 days
Test DaysNumber of days in which this chemical has reported results in the data we received from the State
25 days
Tests ConductedNumber of individual tests done for this contaminant
43 tests

Testing Summary

ContaminantAverage/
Maximum
Result
Health Limit
Exceeded
Legal Limit
Exceeded

Testing History

-Tested      -Detected      -Over Health Guidelines      -Over Legal Limit*
Arsenic (total)Arsenic contaminates drinking water due to mining runoff, erosion of natural deposits, emissions from glass and electronics processing and the use of arsenical compounds as wood preservatives and pesticides.19.49 ppb
26 ppb
Yes
MCLGA 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.: 0 ppb
Yes
10 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 Arsenic (total)

Health Based Limits for Arsenic (total)

StandardDescriptionLevel
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.0 ppb
California Public Health GoalsDefined by the State of California Office of Environmental Health Hazard Assessment (OEHHA) as the level of contaminant that is allowed in drinking water. For acutely toxic substances, levels are set at which scientific evidence indicates that no known or anticipated adverse effects on health will occur, plus an adequate margin-of safety. PHGs for carcinogens or other substances which can cause chronic disease shall be based solely on health effects without regard to cost impacts and shall be set at levels which OEHHA has determined do not pose any significant risk to health.<0.01 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.0.02 ppb
One in one million (10-6) Cancer RiskThe concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 1,000,000. Source: U.S. Environmental Protection Agency.0.02 ppb
One in ten thousand (10-4) Cancer RiskThe concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 10,000. Source: U.S. Environmental Protection Agency.2 ppb
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.10 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.10 ppb

Testing Results

Testing DateAverage
Result
Samples taken that dayNumber of Non-DetectsRange of Results
2009-02-0235 ppb+2018 to 52 ppb
2008-10-2018 ppb1018 ppb
2008-10-0920.7 ppb1020.7 ppb
2008-09-0916 ppb1016 ppb
2008-04-2120 ppb2017 to 23 ppb
2008-01-1420.5 ppb2015 to 26 ppb
2007-12-1426 ppb1026 ppb
2007-12-1016 ppb1016 ppb
2007-07-1322 ppb2018 to 26 ppb
2007-04-1619 ppb2016 to 22 ppb
2007-01-1620 ppb2017 to 23 ppb
2006-10-2323 ppb2018 to 28 ppb
2006-07-2421 ppb2018 to 24 ppb
2006-04-1923 ppb1023 ppb
2006-04-0617 ppb1017 ppb
2006-01-1922 ppb2019 to 25 ppb
2005-10-3121 ppb2019 to 23 ppb
2005-08-0120.5 ppb2018 to 23 ppb
2005-04-2517.5 ppb2014 to 21 ppb
2005-01-2620 ppb2016 to 24 ppb
2004-10-2619 ppb2017 to 21 ppb
2004-07-1420 ppb2017 to 23 ppb
2004-05-052 ppb202 ppb
2004-02-0920.5 ppb2018 to 23 ppb
2004-01-2623 ppb2020 to 26 ppb