DISTURBED TAMARACK "BOG" IN NORTHERN OHIO REVEALED AS A FEN

In Ohio, as in other US states, many wetlands have been eliminated or severely modified post-European settlement. Restoration of these ecosystems requires an understanding of their original hydrologic function. We studied a wetland (the "Tamarack Bog") in Bath Township, Summit County, Ohio in order to guide a 10-year restoration project. Ditching between 1963 and 1969 reduced the wetland from an original 13.8 acres to its present 4.36. Examination of surrounding geology, surface hydrology, groundwater hydrology, and geochemistry, allows an understanding of the current and original hydrologic function. Ten wells (including 3 paired installations) and 6 borings were accomplished by hand and direct-push both in the wetland and on its perimeter. These permitted construction of hydrostratigraphic cross-sections, as well as groundwater level/geochemical monitoring. Over the course of a year 14 surface and groundwater geochemical samples were collected. The wetland is mostly surrounded by thick clayey till, though some thin sandy aquifers are found. The bulk of water level data indicate a gradient towards the wetland, with seasonal variation as typical in humid regions. Downward gradients in paired wells within the wetland indicate potential losses, though probably minor due to low permeability. On the western margin, occasional lateral leakage to a lower wetland is indicated. One perennial and 4 ephemeral streams feed the wetland. The perennial stream has its source in a seep a few hundred meters away, with flow about equal to the outflow from the Tamarack Bog. Continuous monitoring of wetland stage shows rapid rising and falling limbs in response to rainfall/snowmelt. Water from both perimeter and Bog wells was of calcium-magnesium bicarbonate type. pH of the water was circumneutral ranging between 6.13 to 7.64. Field-measured conductivity exhibits moderately high values, especially for water from perimeter wells 1A (2105 μS/cm) and 2A (1000 μS/cm). Although this wetland receives limited or no direct groundwater input, the perennial stream that feeds it is groundwater sourced, providing a relatively stable baseflow. Therefore, based upon hydrologic and chemical consideration, this "Bog" is more appropriately categorized as a fen, and efforts to restore the ecosystem should be so targeted.