Flash Flood Watch issued for greater Arlington area

ARLINGTON, Wash. -- Snohomish County authorities are urging people who live near the North Fork of the Stillaguamish River near Oso to evacuate the area before nightfall.

Concern for potential flooding is growing in the wake of a massive mudslide that has killed three people and injured at least six others.

A Flash Flood Watch has been issued for the greater Arlington area and all other areas along the Stillaguamish River north and east through Oso.

The mudslide has blocked the river and created an earthen dam. A river gauge downstream from the slide measured a drop in river depth from just over 3 feet to just a few inches deep in the aftermath.

River forecasters with the National Weather Service have concerns that are two-fold: The immediate flooding occurring in the area as the river backs up behind the slide, and the potential for flash flooding should that earthen dam give way and release all that water downstream at once toward Arlington.

Waters could rise quickly and cover roads and field and potentially flood homes in the area.

Meanwhile, officials are strongly urging people to stay away from the river banks. They have had reports of people walking in the nearly dry riverbeds and gazing at the low river levels from bridges and trestles above the river. Those people could be in great danger should the dam give way.

Snohomish County is also advising all those downriver from the slide to prepare in case they need to leave the area immediately.

A Red Cross shelter has been set up at Post Middle School in Arlington, and the Darrington Horse Owners Association says horses, cattle, and steerage that needs to be evacuated can go to the rodeo grounds at 42109 Hwy 530, Darrington, Washington.