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<DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>This feature class contains the current extent of alluvial valley floors (AVFs) at and near coal mines in Wyoming. The dataset represents AVF determinations given by WDEQ-LQD to all permitted coal mining operations in the state, as well as operations that were never permitted and operations that were permitted but never mined. The feature class was created by the Land Quality Division (LQD) of the Wyoming Department of Environmental Quality. The feature class was created by editing previous AVF maps produced by WDEQ-LQD and incorporating new AVF determinations. In 1986/1987, WDEQ-LQD compiled existing AVF determinations from the permit State Decision Document (SDD), WDEQ-LQD correspondence, or other permit materials. The AVF determinations for each mine were drawn by hand onto 1:24,000-scale USGS topographic maps. In 1995/1996, these maps were digitized to produce a GIS coverage file. In 2009, accuracy of this coverage file was checked against findings in the SDD, LQD correspondence, and permit documents. The data was updated again in July 2022. Edits and new AVF determinations were added by scanning, georeferencing, and digitizing maps from the permit files. This feature class represents the current extent of AVF units. The WDEQ-LQD approved extent on some AVFs has changed over time at the Buckskin Mine, Dry Fork Mine, Coal Creek Mine, North Antelope Rochelle Mine, and Antelope Mine. This feature class represents the most current WDEQ-LQD approved extent of AVFs at these mines. The AVF extents in this feature class are considered current as of July 2022. Please refer to the supplemental documentation for further details on the AVF determinations for each mine and the mapping methods and assumptions used to create this dataset. These data are for display purposes only and do not represent survey grade information. The Land Quality Division of the Wyoming Department of Environmental Quality makes no warranties as to the validity, and assumes no liability associated with the use or misuse of this information.</SPAN></P><P><SPAN>Each AVF in the feature class has a list of attributes that provides an identification or a description of the AVF.</SPAN></P><P STYLE="margin:1 1 1 20;"><SPAN>"AVF_NAME" gives the name of the river or stream the AVF is located on, followed by the mine property name to identify the specific AVF.</SPAN></P><P STYLE="margin:1 1 1 20;"><SPAN>"MINE_PROP" gives the name of mine property that the AVF falls under.</SPAN></P><P STYLE="margin:1 1 1 20;"><SPAN>"DECL_DESC" specifies which mine determination the AVF is part of.</SPAN></P><P STYLE="margin:1 1 1 20;"><SPAN>"LQD_DECLAR" specifies the type of AVF declaration made by the WDEQ-LQD for the AVF.</SPAN></P><P STYLE="margin:1 1 1 20;"><SPAN>"DATE_DECL" shows when the AVF declaration was made.</SPAN></P><P STYLE="margin:1 1 1 20;"><SPAN>"FILE_REF" references the document or file from the permit that includes original information on the determination for the AVF.</SPAN></P><P STYLE="margin:1 1 1 20;"><SPAN>"NOTES" includes additional information on what was referenced to digitize the AVF extent.</SPAN></P><P STYLE="margin:1 1 1 20;"><SPAN>"24K QUAD" serves as a geographic identifier for the AVF and names which quadrant from the Wyoming State 24K grid the AVF is in.</SPAN></P><P STYLE="margin:1 1 1 20;"><SPAN>"ACRES" gives the real world area of the AVF in acres.</SPAN></P><P STYLE="margin:1 1 1 20;"><SPAN>"REGION", "SUBREGION", "BASIN", "SUBBASIN", "WATERSHED", "SUBWSHED", and "HUC_12_ID" all serve to identify the specific watershed location of the AVF.</SPAN></P><P STYLE="margin:1 1 1 20;"><SPAN>"SHAPE_Length" and "SHAPE_Area" describe the dementions of the AVF polygon in ArcMap or ArcPro.</SPAN></P><P STYLE="margin:1 1 1 20;"><SPAN>"AVF_ID" is a specific identifier assigned to individual AVFs which includes a prefix that stands for the river basin in which the AVF is located.</SPAN></P></DIV></DIV></DIV> |