PORTLAND, Ore. (KOIN) — The National Weather Service has issued a low water alert for boaters navigating the Willamette River in Portland this week.

Meteorologist Tyler Kranz with Portland’s National Weather Service office told KOIN 6 News that shallower areas of the river may present new hazards as river levels drop.

“Boaters need to exercise caution in shallow areas because objects underwater like large rocks, tree trunks, maybe even a sandbar could be exposed or just beneath the surface,” Kranz said. “With water level this low, that boulder could be very close to the surface and cause a boater to hit it.”

Flood stage conditions forecast for the Willamette River show especially low water levels in Portland this week. (NWS)

Low water advisories are issued for Portland when the Willamette River flood stage level sinks to 1 foot. NWS data shows that the Willamette River is expected to drop below this mark multiple times between Sept. 5 and Sept. 11. During this period, the river’s waterline will be 18 feet lower than heights typically seen during a minor flood.