Readings from test wells at the Vermont Yankee nuclear plant show a decline in the amount of radioactive tritium in one well, and increases in others.
The Vermont Health Department said yesterday that the most recent sample taken from a well that has shown the highest readings was 2.2 million picocuries per liter of water of radioactive tritium, down from a high of 2.6 million.
But the well that showed the second highest readings was said to be trending upward, with the most recent reading showing 937,000 picocuries per liter.
Vermont Yankee first reported tritium showing up in a test well more than a month ago; the source has not been found.
Tritium has been linked to cancer if ingested in large amounts.