GAM Run 08-64

The groundwater availability model for the northern portion of the Trinity Aquifer was used to simulate a 50-year predictive simulation of groundwater flow in the Woodbine Aquifer and northern portion of the Trinity Aquifer System. Average recharge conditions were used for the first forty-seven years of the simulation, followed by the three-year drought-of-record. Pumpage was assigned for each stress period, or year, in the simulation based on the specifications provided by the groundwater conservation districts within Groundwater Management Area 8. Specific differences between this run and the previous GAM Run 08-06 (Donnelly, 2008a) include: a decrease in pumpage underlying Coryell County from 3,777 acre-feet per year to 3,714 acre-feet per year; a change in the spatial distribution of pumpage underlying Coryell County per layer (254 acre-feet per year in layer 3; 783 acre-feet per year in layer 4; 836 acre-feet per year in layer 5; and 433 acre-feet per year in layer 7); the allocation of an additional, uniform distribution of pumpage underlying the western portion of Coryell County (shown in Figure 1) within layers 5 (928 acre-feet per year) and 7 (480 acre-feet per year); a decrease in pumpage underlying Comanche County from 27,000 acre-feet per year to 25,000 acre-feet per year; a decrease in pumpage underlying Erath County from 32,000 acre-feet per year to 30,000 acre-feet per year; a decrease in pumpage for the Trinity Aquifer System and the Glen Rose Formation underlying Montague County (layers 3, 4, 5 and 7) from 2,682 to 506 acre-feet per year; pumpage in the Woodbine Aquifer (layer 1) underlying Cooke, Denton, an