THE EFFECT OF A CONSTRUCTED WETLAND ON A NEARBY NATURAL WETLAND

Mitigated wetlands are used to replace destroyed wetlands and the location of such mitigated wetlands is important to its sustainability. What is the impact of placing a mitigated wetland within proximity of a natural wetland? We attempt to examine the relationship between a mitigated wetland and a natural wetland based on the initial observation of increases in biomass within the constructed wetland and reduced surface water in the natural wetland.

The constructed wetland situated near a natural wetland is located in Fox Island County Park, Allen County, Indiana. The park is made up of a nature preserve with swamp and marsh type wetlands. This research project attempts to answer the question ‘does the constructed wetland drain the natural wetland?'

Four ground water monitoring wells lined with 3 centimeters ID PVC pipes were screened 5 cm from the bottom of the wells. Three of the wells were within 30 centimeters of the constructed wetland. A well nest was installed at the northern edge of the constructed wetland. The depths to ground water were measured in the monitoring wells for six weeks and the waters in the wells were tested for temperature, conductivity, iron, phosphate and nitrates. Also, precipitation data were collected for the duration of this project.

The depths to groundwater measurements within the well nest suggest upward movement of groundwater into the constructed wetland and the surrounding monitoring wells would suggest water movement away from the constructed wetland into the natural wetland, about ten meters away. All water level measurements in the monitoring wells within the constructed wetland have same trends, suggesting that these wells are all in the same aquifer. The monitoring well depths vary from 91 centimeters to 183 centimeters. Analysis of the results does not appear to support the hypothesis that the constructed wetland may be draining the natural wetland. The chemical data at this point is suspect due to equipment failure at several stages of this project.