Diamond Lake's island, and the barge that serves it

There is a private island in the middle of Diamond Lake, just southeast of Cassopolis, and people really do live there. The Diamond Lake Association’s neighborhood page describes about 40 acres with 99 cottages and houses. There is no public bridge. A private six-car barge carries vehicles for homeowners, their guests, and contractors.

The Diamond Island Association was formed in 1951 to manage the crossing. The association says the present six-car barge entered service in 2019, replacing a four-car version that had run for almost 70 years. Its season and hours are set around island needs, so this is not a public sightseeing ferry or a ride visitors can simply join.

Cass County’s current master plan uses 1,020 acres for Diamond Lake. A Michigan DNR report uses the same area and a maximum depth of 64 feet. You may also see 1,078 acres on the lake association’s site. The sources do not explain the difference, so this page follows the government records instead of pretending the measurements agree.

The county lists a public access site for the lake. That does not make Diamond Island public. From shore or a boat, the barge is an unusual piece of local life to notice; access to the island itself belongs to its homeowners and invited guests.