I followed a bit of a rabbit hole on Wikipedia tonight, and came across this article concerning nuclear waste in Washington State. Some of you may find it interesting. http://en.wikipedia.org/wiki/Hanford_Site
A huge volume of water from the Columbia River was required to dissipate the heat produced by Hanford's nuclear reactors. From 1944 to 1971, pump systems drew cooling water from the river and, after treating this water for use by the reactors, returned it to the river. Before being released back into the river, the used water was held in large tanks known as retention basins for up to six hours. Longer-lived isotopes were not affected by this retention, and several terabecquerels entered the river every day. By 1957, the eight plutonium production reactors at Hanford dumped a daily average of 50,000 curies (1,900 TBq) of radioactive material into the Columbia. These releases were kept secret by the federal government. Radiation was later measured downstream as far west as the Washington and Oregon coasts.
The plutonium separation process also resulted in the release of radioactive isotopes into the air, which were carried by the wind throughout southeastern Washington and into parts of Idaho, Montana, Oregon, and British Columbia.