Comparison of the long-term water levels of created and natural reference wetlands in northern New York, USA

Long-term evaluation of hydrology on created wetlands in the United States is rare, as most such assessments are short-term and driven by regulatory and permit requirements. Long-term studies are critical to the understanding of the development of function in created wetlands. We measured water levels at 12-h intervals at five created wetlands at Fort Drum, northern New York, from 1994 to 2003 and compared that data with information from three reference wetlands, collected at the beginning and the end of that 10-year period. During that time span, the created wetlands were wetter than the reference wetlands as measured by median depth to water and the percentage of time water was within 30 cm of the surface. The two groups also differed in the duration of dry, saturated, and inundated periods. The mitigation wetlands were wetter than the reference wetlands likely as a result of the practice of excavating down to water table depths to generate site hydrology.