Every year, the village of Frei-Weinheim and its inhabitants were exposed to the danger of floods and icefalls. The first reports about this date back to the 15th century. At that time, dams and sluices already existed, but a closed dam system was missing. The most serious natural disaster occurred on February 28, 1784, when flood waters carried heavy ice floes that damaged three quarters of the houses, knocked down trees and destroyed half of the livestock. As a result, a new dam was built by 1795, which had to be renewed as early as 1803. The land ownership situation was always problematic. Under the Grand Ducal Hessian government, all land in the dam area was declared state property. Thus, in 1825, a high and closed dam system could be created along the river front. In the residential house of the then mayor Nikolaus Thorn (Dammstraße No. 3) there was a room for the dam watch at the end of the 19th century. At that time, beyond the dam flowed the diverted Selz River, the mouth of which formed part of the harbor.
