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Willard-Owens Statement on <br /> Protection of Hydrologic Balance <br /> Our statements suggesting that the transmissivity and <br /> specific yields of the Mesaverde Formation are so low that <br /> the regional hydrology would not be significantly altered <br /> by mining activities are supported by the general conclusions <br /> of the "West Central Colorado Coal Environmental Statement . " <br /> In pursuing additional data on the transmissivity and specific <br /> yield of the Mesaverde Formation, we contacted personnel with <br /> the USGS office in Grand Junction . The USGS is currently <br /> undertaking a 3 to 5 year program to evaluate all groundwater <br /> aquifers in the area . However , the Mesaverde Formation is not <br /> a particularly significant aquifer in this study . As yet , <br /> the USGS personnel have collected no permeability data on <br /> the Mesaverde Formation and do not intend to initiate work <br /> on this unit for at least 2 years . The lack of data on the <br /> Mesaverde Formation (with the exception of the work done by <br /> Brogden .and Giles USGS Water Resources Investigation 76-70) <br /> was further confirmed by USGS Pe sonnel . The estimates of <br /> transmissivity (ranging from 10 to 1 foot per day) and <br /> estimates of specific yields (ranging from 5% to 7%) were <br /> based upon an evaluation of the grain size distribution of <br /> the major sands in the formations , upon notations made on <br /> exploratory drilling records concerning water production from <br /> this unit , and upon records of water production from the mine . <br /> These values were not arrived at analytically ; however , we <br /> feel they are reasonable figures for the Mesaverde Formation . <br /> For reasons previously discussed , we do not feel the construction <br /> of 1 , 000 to 3 , 000 foot-deep wells west of Huntsman Ridge to <br /> gather transmissivity data is justified . It is expected that <br /> environmental damage caused by the construction of access roads , <br /> and by the drilling operations would far exceed any potential <br /> damage to the Mesaverde aquifer caused by mining . <br /> Although this discussion does not provide all the data <br /> requested by the state , all the available data were presented <br /> in our report . We hope this discussion clarifies some of the <br /> points brought up in the adequacy review and presents a justifi- <br /> cation for not pursuing additional drilling and test well <br /> development in the Mesaverde Formation . <br /> 75 . 1 <br />