|Map shows mined areas in red and a star on study area.|
It has long been known that excavation of rock around coal seams, which is then placed into engineered fills at stream headwaters, releases salty substances into streams. But the study also confirmed something that has long been surmised, that "the porosity of the crushed rocks increases the water storage capacity of the valley fills. This decreases natural storm runoff during high-flow winter months while contributing proportionately more water to stream flows during the drier months that make up about 80 percent of the region's calendar year, says a UW press release published in Science Daily.
|3-D map and chart in study compare streamflow in mined and non-mined areas.|