The Power of Information

National Drinking Water Database


South Tahoe Pud - Main Utilities - South Lake Tahoe, CA


Serves 60,000 people

Radon

Radon is a radioactive breakdown product of radium and uranium in soil, rock and water; it is often present in groundwater.
 
This Drinking Water System
Test Days Exceeding Health GuidelinesDefinition of what this is
20 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
20 days
Tests ConductedNumber of individual tests done for this contaminant
80 tests

Testing Summary

ContaminantAverage/
Maximum
Result
Health Limit
Exceeded
Legal Limit
Exceeded

Testing History

-Tested      -Detected      -Over Health Guidelines      -Over Legal Limit*
RadonRadon is a radioactive breakdown product of radium and uranium in soil, rock and water; it is often present in groundwater.1976.58 pCi/L
4916 pCi/L
Yes
1.5 pCi/L
Legal at any levelThis is the Federal Limit. State Limits may be lower.
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 Radon

Health Based Limits for Radon

StandardDescriptionLevel
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.1.5 pCi/L
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.150 pCi/L

Testing Results

Testing DateAverage
Result
Samples taken that dayNumber of Non-DetectsRange of Results
2009-01-15309 pCi/L2071 to 547 pCi/L
2008-10-16348.5 pCi/L2071 to 626 pCi/L
2008-08-204740.5 pCi/L203611 to 5870 pCi/L
2008-07-233516.67 pCi/L60595 to 15536 pCi/L
2008-06-173063.71 pCi/L140223 to 8209 pCi/L
2007-08-224916 pCi/L201170 to 8662 pCi/L
2007-07-251331.57 pCi/L70664 to 2716 pCi/L
2007-06-26935.57 pCi/L70243 to 2457 pCi/L
2006-08-302625.5 pCi/L20973 to 4278 pCi/L
2006-07-26766 pCi/L50202 to 1501 pCi/L
2005-09-293207 pCi/L103207 pCi/L
2005-08-244127 pCi/L104127 pCi/L
2005-07-20764.17 pCi/L60200 to 1497 pCi/L
2005-06-21959.5 pCi/L60453 to 2148 pCi/L
2004-09-30629 pCi/L10629 pCi/L
2004-09-03333 pCi/L10333 pCi/L
2004-08-314294.5 pCi/L202693 to 5896 pCi/L
2004-07-28629 pCi/L10629 pCi/L
2004-07-27807.83 pCi/L60234 to 1598 pCi/L
2004-06-161227.67 pCi/L60578 to 2598 pCi/L