Changes in Groundwater Conditions in the Edwards and Trinity Aquifers, 1987-1997, for Portions of Bastrop, Bell, Burnet, Lee, Milam, Travis, and Williamson Counties, Texas

The purpose of this report is to update the Texas Water Development Board’s (TWDB) Report 326, Evaluation of Water Resources in Bell, Burnet, Travis, Williamson and Parts of Adjacent Counties, Texas, written by Gail Duffin and Steven P. Musick in 1991. The groundwater problems identified in the initial investigation included a lack of reliable supplies for both short-term drought demand and long-term economic development (Duffin and Musick, 1991). According to TWDB Report 326, during late summer dry conditions and drought, water levels quickly drop in the Edwards aquifer due to low area-wide storage and low permeability in the Trinity Group aquifer. In the study area, utilization of both aquifers prior to 1987 exceeded the projected amount for long-term safe yield (drought reliable) supply. According to TWDB Report 326, an underground water conservation district was not recommended as an appropriate management approach due to the varied interests in the area, which precluded the consolidation of political support needed to recommend formation of an underground water conservation district. The previous report recommended a continuation of existing efforts and additional voluntary efforts to restrict further groundwater development and limit groundwater pumpage where surface supplies have been developed or will become available. Continued conversion to surface water was strongly encouraged, as well as development of long-term conservation and contingency planning for drought and other emergencies. After review of the original study, the area was not designated as a critical area. Nonetheless, the TWDB and the Texas Water Commission (now the Texas Natural Resources Conservation Commission - TNRCC) continued to monitor groundwater levels over the ensuing five years to determine whether groundwater problems were being mitigated (TNRCC, 1997). The findings of this report support the previous conclusions stated in TWDB Report 326. If the rate of conversion to surface water is maintained and expanded, as suggested in th