[5] The reservoir was built in 1797 to supply water to the Wendover Arm of the Grand Union Canal.

[1] The southwestern and southern parts have extensive reed beds and this is where water mudwort and orange foxtail are both found, both plants being rare in Buckinghamshire.

There is a more varied flora in the southeastern part, with grey clubrush and lesser bulrush.

The two chalk streams that flow into the reservoir pass through an area of tall fen and here, and by the side of a small pond, early marsh orchids grow.

The areas around the reservoir have tall fen, reed beds and willow carr, declining habitats in Britain.