You can see here that the dam has been breached to allow the laying of the pipe.
In this photo, Mark Blair (on the left) and Lewis Smith ('Lush' to one and all) are working on the laying and fixing of the pipe.
You can see the cage in the distance. The idea is that the beavers will want to find the leak in the dam and not suspect that the water may be going through a pipe set some metres upstream inside a cage.
This gateway just south of the dammed ditch has been waterlogged for some time now. Two years of very wet summers and a wet winter have made for a deeply muddy gate way.
This is the manual that guided Lush and Mark. It comes from Snohomish County, Washington, USA and is posted on the Martinez Beavers brilliant web site:
Beaver paw marks.
A stone is placed over the pipe where it passes through the dam.
With the pipe installed the dam can be repaired and the whole system left for the beavers to consider.