Coal Mining: SkyTruth Work Helps Link Mountaintop Removal and Water Pollution

It’s official: strip-mining for coal using the massively disruptive process known as “mountaintop removal” definitively pollutes streams and rivers.

Duke University researchers just announced the results of a new study (published July 2012 in the Environmental Science and Technology Journal) that quantitatively links the amount of mining activity within West Virginia watersheds to levels of key pollutants downstream, including sulfates, selenium and other metals with known environmental and human health effects. This is significant (groundbreaking, actually) because, as one researcher puts it, the results

directly link changes in the stream water chemistry to the area of the watersheds that has been disturbed by mining activities.

How did the team determine the area of the watersheds that was impacted by mining? Glad you asked: SkyTruth’s work provided a key component of this study. Our satellite image analysis of surface mining impacts throughout Appalachia from the 1970s through the 2000s gave researchers the spatial and temporal information they needed to correlate mining activity with water-quality measurements.

Now we have a predictive tool, a way to forecast the water-quality impacts of proposed new mining activity. This may mean mining companies need to figure out ways to better protect water quality if they hope to get new mining permits approved. That’s good news for aquatic creatures, and great news for those of us humans living downstream who drink this water every day.

Mountaintop Removal Mining, Part 1: Measuring the Extent of Mountaintop Removal in Appalachia

Aerial shot of mountaintop removal mining, Kayford Mountain, WV – Photo courtesy of Ohio Valley Environmental Council and Southwings

SkyTruth, in partnership with Appalachian Voices, documented the impact of mountaintop removal mining for coal over a 59-county area in Kentucky, West Virginia, Tennessee and Virginia. The goal of the project was to map the direct landscape impact — the “footprint” — of mountaintop removal mining (MTR) over a 30-year period, from 1976 to 2005.  The analysis was designed and conducted by our Chief Scientist, geologist and remote-sensing expert Dr. David Campagna.

Map showing total extent of surface mining from 1976 – 2005, color-coded by decade

With this analysis, and some great database and Google Earth work by Appalachian Voices, we can tell you exactly which mountains in Appalachia have been – or are are being -destroyed to power your home or business (thought you might like to know…). The methodology involved several steps. The first step included a land cover classification for each decade that identified all the mining occurrences at that point in time. This digital spectral classification process was accomplished using a Landsat satellite image database totaling eight gigabytes of data. Classification required a two-step process where the spectral signatures of land cover types were identified (vegetation, soil, barren or rock, water, etc) and then, through a decision tree analysis, mined areas are classed.

The next step was to classify these mine areas as “MTR” and “Other Surface Mining.” The definition of MTR, as put forth by the U.S. Office of Surface Mining, Reclamation and Enforcement, guided the development of a reproducible, rules-based method to classify the mines. Using digital elevation data from the U.S. Geological Survey 1:100,000 series, the terrain parameters of ridge top, slope, and valleys were calculated.  MTR mines were identified by calculating the amount of ridge top that comprised the mine’s total area.  Any continuous mined landscape that spanned over 320 acres and removed at least 40 acres of ridge top, or spanned between 40 – 320 acres and contained at least 10 – 40 acres of ridge top, was classified as MTR.  Mined areas that were smaller than 40 acres, or did not meet these conditions, were classified as “Other Surface Mines.” 

This analysis shows a 250% increase in the MTR footprint occurring in the last two decades, from 77,000 acres in 1985 to over 272,000 acres in 2005. The size of mining operations also increased, with some contiguous mined areas reaching over 15 square miles. Over 2,700 ridges were impacted by mining. Summary statistics are shown below:

Mountaintop Removal Mines
Total MTR Area Since 1976 = 445,792 Acres
Largest Contiguous Mined Area = 10,410 Acres
Median Mined Area = 128 Acres
Average Mined Area = 406 Acres
Number of Mines > 1 mile2 = 73 
Number of Ridges Mined = 2,789
Total Acres of Impacted Ridges = 130,655 Acres
Average Ridge Length Mined = 1/2 Mile
Largest Ridge Removed = 504 Acres


Historical Analysis (Acres Directly Impacted by Mining)