The change in concentration is often attributed to natural processes related to depleting ground water supplies.
Although one cannot discount the role of "natural processes" in causing elevated uranium levels in drinking water, few accounts address polluting human activities.
I don't believe this is an innocent omission. There is a clear pattern of denial of human-caused radioactive contamination, even in the most glaring of illustrations. For example:
A recent example from South Carolina illustrates the role of human pollution:
Fretwell, Sammy (24, July 2018). Radioactive pollution leaked through floor of SC nuclear fuel plant. The State. Available https://www.thestate.com/news/business/article215355955.html
Radioactive uranium has leaked through the floor at the Westinghouse fuel factory on Bluff Road, contaminating the soil in an area of Richland County with a nearly 35-year history of groundwater pollution from the plant.
The U.S. Nuclear Regulatory Commission says the uranium, a toxic substance used to make nuclear fuel rods, seeped through a 3-inch hole in a concrete floor in part of the factory where an acid is used. The hole extends 6 feet into the ground, according to the NRC. The NRC learned of the leak July 12.How long do you think that hole in the floor (extending 6 feet into the ground) was known?
The article reports that government officials "have no reason to believe" the uranium contaminated public water supplies and/or the adjacent Congaree River Floodplain.
People need to remember that holes at industrial sites, particularly nuclear sites, NEVER contaminate drinking water.
Those holes are containment sites. They are kind of like black holes that never let go of any matter or energy sucked into their vortex.
Most all contaminants in drinking water are naturally occurring. Because they are naturally occurring, they pose little risks to biological health.
Fukushima Daiichi taught me these lessons well:
July 18 2018
Fukushima Diagram leaked by the Swiss Embassy in Japan: