WICHITA, Kan. (AP) — As more people canoe and kayak on Kansas waterways, concerns about low-head dams are growing.

The Wichita Eagle reports that Kansas has an estimated 100 such dams, but no state regulations for warning signs. So far this year, 22 deaths have been reported at low-head dams nationwide.

The victims include Brian Bergkamp, a seminarian from Garden Plain. He died this summer after trying to help a fellow kayaker who went over one such dam in the Arkansas River in Wichita.

The hydrology behind low-head dams is why experts call them “drowning machines.” As water flows over the top of the dam, it creates a circular current on the down-river side. That causes people and debris to be pulled down, up and back toward the dam in an unrelenting cycle.