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Twin Creek Sunshine Sparkle,
Germantown MetroPark, Ohio
This photo of Twin Creek, Ohio's most biologically diverse stream, was taken on a sunny summer morning just upstream of the Germantown Dam.
The dam was one of five earthen retarding dams built in the Miami River Valley after the disastrous Great Dayton Flood of 1913. That flood resulted from several days of intense downpours in late March, when the ground was saturated and/or frozen, flooding large portions of Dayton, Middletown, and Hamilton, Ohio.
There are no floodgates on these dams; they cannot be closed. They are not for water impoundment, and so do not form permanent reservoirs. Instead, each one serves as an orifice through which normal water flows are allowed to run right through, unimpeded.
Only when storm runoff gets severe do the dams temporarily hold back the extra water, due to the limited diameter of their tunnels. The stormwater which is held back floods the park land above the dam, emptying gradually of its own accord.
The five dams were built by and continue to be administed by the Miami Conservancy District, a visionary stewardship organization of the Great Miami River watershed of southwest Ohio. The concept of "dry dams" for temporary floodwater retention to protect downstream communities struck a unique balance between flood control and river modification. It avoided much more severe straightening and channelization of the Great Miami River, allowing it to remain in relatively good shape, biologically. The park land around the dams became the core units of what is today known as Five Rivers MetroParks, another stellar Dayton area conservation organization.
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