Boundary of I ° ° o o 8,00 0^X2> study area-l North Q ^ ^ TOT 0 eft* Chloride (Cl) 250 Fluoride (F) ' 1.5 Nitrate (NOs) 45 Water levels in wells that typify the seasonal fluctuations and longterm trends in some places in the sandstone aquifers are available in table 6 and several published reports. For Hodgeman and northern Ford Counties, water levels in wells in the Dakota Formation are given by Lobmeyer and Weakly (1979). Water-level records during 1966-70 are available from Broeker