Breakdown of the index of groundwater dependence rankings per hydrologic region.

The index was developed by summing the rankings of springs, groundwater dependent wetlands and baseflow index of HUC12 units in each hydrologic region. The index ranges from 0 (no groundwater dependence) to 12 (highest score of 4 for the three variables). Rankings were defined for each HUC as follows: None = 0; Very Low = 1–3; Low = 4–5; Medium = 6–7; High = 8–12.