In 1945, a causeway was built to separate the lake from the flooded canyon portion of the old Prickly Pear Creek.

The concrete piers of the steel bridge, which was sold for scrap and dismantled in 1952, can still be seen just north of the causeway.

Lake Helena supported a commercial carp fishery for decades.

The marshy west end of the lake is now a popular birding location.

This Lewis and Clark County, Montana state location article is a stub.