We shut off the flow of water in the pipe, drained it and thereby removed the source of tritium leaking into Indian Creek. However, low levels of tritium remained in the soil of the watershed and we detected low levels of tritium in Indian Creek for several months. Fermilab will continue to monitor Indian Creek frequently and the results will be displayed on this page. A second page provides more information, and we have posted an aerial view of Indian Creek as well.

The Illinois Emergency Management Agency confirmed the accuracy of Fermilab's measurements by taking samples in Indian Creek on December 12, 2005 and May 4, 2006 and analyzing them independently.

About the graph: A solid dot appears on every day in which a sample has been taken and analyzed. For samples in which a level of tritium above the limit of detection has been measured, the uncertainty of the measurement is indicated by an error bar attached to the solid dot. Samples with no detectable level of tritium are represented by a solid dot without error bar.

Footnote: A picocurie is the unit used to specify how many tritium particles in a water sample decay into helium particles each second. Standard tests can detect levels of tritium in water that are larger than about 1 picocurie per milliliter.