Water-level, canal stage and discharge, and rainfall data collected in a wetland in Dade County, Florida, were analyzed to determine the effects of pumping at the Northwest Well Field on water levels in the wetland. The Northwest Well Field is the first major well field in south Florida to be operated in a wetland, away from saltwater intrusion and the potential for contamination caused by urbanization.
Duration curves were used to analyze trends in water levels for seven observation wells near the Northwest Well Field. One observation well is 5.5 miles north of the well field, three wells are outside the cone of depression of the well field, and three are within the cone of depression. The water level data were analyzed for four time periods that were determined by a double-mass analysis of cumulative rainfall and cumulative canal discharge. Before 1984, water levels in all seven wells were above land surface 25 to 50 percent of the time. Since the well field began operating in 1984, water levels in the three wells within the cone of depression have been above land surface less than 1 percent of the time. Water levels at the four wells outside the cone of depression showed no effect from pumping at the well field.
Water levels have declined in 30 percent of the 65- square mile study area since the well field began operating. In 15 percent of the area, water levels have been lowered below land surface.
