Welcome to the Lake Montowese Association!

Property Owner Login: click on the blue "Owner Login" button at the top right.

Board Member Login: click on the orange "Board Login" button at the top right.

Lake Montowese is a private, mid-sized recreational lake community located in Byrnes Mill, Jefferson County, Missouri, that was originally established in 1941 by the Lake Montowese Development Company, Inc. Originally designed as a secluded weekend retreat for St. Louis residents, it has evolved over the decades into a permanent, close-knit residential neighborhood. Today, the residents of Lake Montowese continue to govern themselves and their property through the Lake Montowese Association, along with various other committees, using many of the original Rules & Regulations. The Lake Montowese Social committee, also known as the Lake Montowese Community Services Organization or LMCSO, organizes and hosts numerous gatherings throughout each year. The lake has truly become a beautiful place to live—full of connection, activity, and charm.