Near to the island was a " tumbling bay ", an overfall weir with its crest just below normal low water level.
12.
At the end of the overfall area nearest Route 9 stands the gatehouse, a granite structure with a rectangular main block and a smaller wing.
13.
The Glenmaggie Dam wall, which creates the Glenmaggie Lake, is a mass concrete overfall dam with irrigation outlets on both sides of the river serving irrigation channels.
14.
The of lower banks, required to satisfy the Holderness Drainage and known as the overfall, were built near Grovehill, at the southern end of the level.
15.
The name was changed to Hudson Strait in honor of the first European to sail beyond the Furious Overfall in 1610 : English explorer Henry Hudson in the English ship " Discovery ".
16.
This was not successful, as the low banks of the Hull meant that there was little spare capacity, and the pumped water would often return to the drain because of the overfall near Grovehill.
17.
In October 1832 the main stream of the Warta was moved westwards, the former stream being closed off with an overfall weir ( " Gro�e �berfall " ), connected to a seven-span defensive bridge.
18.
They had to alter the lock at Hempholme, to allow for the lower water levels, but the restrictions on the height of the banks and the necessity of the overfall, imposed by the 1798 Act, were removed.
19.
Near the southern bank, there was a sluice ( marked " E " on the sketch ), which was wide, and was fitted with flood gates and overfall boards, to accommodate a drop of in the river level.
20.
The self-acting doors were replaced by a sluice in the 1860s, which effectively brought navigation to an end, and the sluice was replaced by a pumping station in 1966, which removed the need for the overfall weir.
