1.2 Effluent or Surface Water Gaining Conditions

Under hydrologic conditions where the water table is higher than the surface-water stage (river, lake, and wetland) and groundwater is discharging into the surface water, effluent conditions occur (Figure 4). The surface-water feature gains from groundwater discharge when effluent conditions are present. Representative monitoring wells open only at the bottom illustrate that wells open at different depths have water levels higher than the surface-water stage. In this setting, groundwater exits to the sides and bottom of the surface-water feature. Flux rates of groundwater are dependent on the magnitude of the hydraulic gradient at the boundary, as well as the hydraulic conductivities of the geologic sediments and the banks and bottom of the surface feature. The surface-water stage reflects the local water table.