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How often do you get the chance to protect an intact natural lake in Indiana? One of the state's last remaining undeveloped lakes and fringing wetlands will forever remain a wild, natural place for the future. Houghton Lake was an opportunity of a lifetime, and one that the Conservancy could not resist. Houghton Lake in Marshall County is a wonderful example of a highly alkaline natural lake. It lies at the bottom of a broad valley that likely once carried off massive quantities of glacial meltwater. The lake is primarily fed by groundwater discharges from the surrounding hills of rolling glacial till. As water seeps through the till, it picks up a heavy load of dissolved limestone, which then precipitates out as marl in the valley bottom. The bottom of Houghton Lake and its shoreline are cement-gray, the color of deep marl deposits. The surrounding wetlands reflect this as well. Extensive fens at Houghton Lake are a mixture of alkaline peat and, nearer the lake, pure marl.
But by no means is Houghton Lake a perfect system. As with most of Indiana, the tillable lands that surround the lake are in agricultural production. Many of those agricultural fields were once fens. Ditches and tiles move water out of the fields and away from our wetlands and the lake. And invasive species are as abundant here as they are elsewhere in the state. One of the worst is common buckthorn, which out-competes native plants for nutrients, light, and moisture and degrades wildlife habitat.
What remains so remarkable for Indiana, is the fact that an entire site, all 360.63 acres, was purchased as a single unit. Unlike most conservation areas where we and our partners work piecemeal, the lake and surrounding wetlands were located in the heart of a family-owned farm that was on the market. With a decisive stroke, we were able to purchase the half of the farm that included the 100+ acres of high-quality lands that included the lake and all the surrounding wetlands. We also acquired around 90 acres of lower-quality natural lands that include old marl pits, second growth forests and a very interesting small glacial outwash rise that supports about 5 acres of overgrown oak savanna. Once restored to more open savanna conditions and managed with fire, the sand and gravel soils on this small rise will provide important nesting and foraging habitat for turtles and snakes that currently have limited opportunities to lay their eggs near the wetlands.
But perhaps most importantly for the long-term, we control almost 180 acres of agricultural fields that surround the site. These include a mix of rolling hills that drain agricultural runoff towards the lake, as well as tiled muck fields that were once part of the wetlands themselves. These are the lands that have the most impact on the future of the site and the rich variety of species it supports. The agricultural drainage system is obviously designed to pull water from adjacent muck soils. This decreases the extent of the wetland complex, but also diverts the flow of groundwater away from the lake. Many of the ditches cut deeply into the perimeter of the natural area, creating fens that seem unnaturally dry. The lake itself is much lower than it once was because of this drainage. Much of the fen, including portions that grow on heavy marl soil, is on recently exposed lake bottom. Lowering the water table has helped problematic species as well, allowing both native and non-native aggressive species to become well-established on ditch spoils and field edges. The future of this preserve depends on our successful restoration of the adjacent fields over the next few years.
Nature picture credits (top to bottom, left to right): Photo © Rich Fields/IDNR (Houghton Lake); Photo © The Nature Conservancy. |
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