Sierra Wildlife Coalition
Beaver Dams & Lodges
Beaver Dam and Pond near Truckee
Beaver Dam near Lake Tahoe
Rock and cobble dam on a creek near Tahoe
Beavers build dams and ponds for safety only if water is not deep enough. Water needs to be deep enought to escape predators, to provide underwater entrances to their lodges, and to provide access to food. If streams are more than 3' deep they may not need to build a dam.
Often they will build one large pond with their lodge, and several smaller ponds up and/or downstream for access to food. They use any available materials, including rocks, logs, sticks and other vegetation, then always pack mud against the structure for reinforcement.
Two types of Beaver Lodges:
- The 'classic' island/mound in the middle of a pond, or
- Bank lodges, which are dug into the bank of a stream,
more common on smaller streams in the Tahoe area.
Both types always have underwater entries for safety from predators,
and have dry chambers above the water for eating and sleeping.
Lodges are built up of logs, sticks and mud, or if they are excavated into the bank, sticks and mud are added on top, for insulation and protection.
Beavers never build lodges in their dams, as some think - that open/void would weaken the dam, and Beavers are Nature's (best) Engineers!
Beaver Channels for safe access
Beavers are very good at digging, and often dig channels to have safe access to food and building materials - sometimes the channels start as paths, as in the photo at left.
Above, the beavers made a 2nd channel parallel to the creek to access their lodge, upstream on the left.