This report is one in an annual series of reports that depicts water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers, and compaction in the Chicot and Evangeline aquifers in the Houston-Galveston region. The Houston-Galveston region comprises Harris, Galveston, Fort Bend, Waller, and Montgomery Counties and adjacent parts of Brazoria, Grimes, Walker, San Jacinto, Liberty, and Chambers Counties. The report was prepared in cooperation with the Harris-Galveston Coastal Subsidence District, the City of Houston, the Fort Bend Subsidence District, and the Lone Star Groundwater Conservation District. For the Chicot and Evangeline aquifers, maps show approximate water-level altitudes in 2006, water-level changes from 2005 to 2006, and approximate water-level changes from 2001 to 2006, from 1990 to 2006, and from 1977 to 2006 (figs. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10). For the Jasper aquifer, maps show approximate water-level altitudes in 2006 and water-level changes from 2005 to 2006 and 2000 to 2006 (figs. 11, 12, 13). The report also contains a map showing borehole extensometer (well equipped with compaction monitor) site locations (fig. 14) and graphs showing measured compaction of subsurface material at these sites from 1973 or later to 2005 (fig. 15).

The U.S. Geological Survey (USGS) has published annual reports of water-level altitudes and water-level changes for the Chicot and Evangeline aquifers in the Houston-Galveston region since 1979; and annual reports of same for the Fort Bend subregion (Fort Bend County and adjacent areas) since 1990. The USGS published its first water-level-altitude map for the Jasper aquifer in the greater Houston area (primarily Montgomery County) in 2001. The 2006 water-level-altitude and water-level-change maps for the three aquifers are included in this report.