Swift, hard-running waters, primed by high-country snowmelt, have resulted in a tubing ban on the St. Vrain River and its creeks in Boulder County.

The sheriff’s office, after consultation with the town of Lyons and the Lyons Fire Protection District, imposed the ban in the interest of public safety, according to a news release. The ban also includes single-chamber flotation devices.

The closure took effect Friday on the North and South St. Vrain creeks and the St. Vrain River from the western county line through Boulder County. Sheriff’s deputies will be posting notices along the waterways.

The closure covers single-chamber rafts, single-chamber belly boats and inner tubes. Kayaks and whitewater canoes are permitted, but kayakers are strongly encouraged to exercise caution and wear personal protection equipment, including a life jacket.

Violators face a $50 fine.