A Fiasco On Carmans River

The Beaver succession pond analogy as it relates to Lower Yaphank Lake an impoundment of Carmans River

Most people will be generally familiar with the work beavers but understanding the nature of the successive stages from dam construction to beaver meadow to forest may help create a better understanding of low head dams such as the dam of the Carmens river at Lower Yaphank Lake.

Stage 1 – Forest to beaver pond – The beaver builds a dam at a point along a creek of river causing the upstream section to flood. All things being equal, which they never are, the same flow passes over the beaver dam that originally flowed through the stream. As the water rises it may escape to flow away from the main flow of the dammed stream. The flooded forest dies off. For the beaver the flooding allows access to food which includes leaves plant and inner bark of specific trees.

Stage 2 – The beaver pond habitat – The beaver pond is established and maintained by the beavers. The stream now flows over a much large area and travels at a greatly reduced velocity this allow fine solids that would normally remain suspended in the current to settle in the areas where the current is the slowest. On the shallow water fringes of the pond aquatic plants establish themselves encouraging sediment from runoff to settle and build. Over a long period, the buildup of sediment and establishment of aquatic vegetation progresses across the pond from the fringe toward the center depending on topography.

Stage 3 – The beaver meadow – Sediment builds to the point where plant growth on the fringes is no longer purely aquatic. The stream now follows a more central channel as the vegetated fringe builds on itself and eventually aquatic plants give way to grasses that thrive on the nutrient rich soil of the what is now a beaver meadow. It is worth noting that colonial farmers sought river-bottom land with mature beaver meadows because of the rich and easily tillable soil and proximity to the nearby stream.   

Stage 4 – Back to the forest – Eventually meadows give way to conifers which are finally over shadowed and displaced by hardwoods.

The Dam and Mill at Lower Yaphank Lake – Apparently built in 1762 the dam for the mill created a lake that is now late in stage-2. The proposed removal of a massive volume of sediment to improve recreation and eradicate invasive aquatic plants is ill-advised. Allowing succession and even planning succession it support of protecting the wild, rare and unique stretch of river to the south would in my view provided the much greater public benefit. species, largemouth bass, yellow perch and sunfish that Lower Yaphank Lake supports are not threatened in the way                     

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