Henry Hagg Lake, Reservoir in Scoggins Valley, Oregon, US.

Henry Hagg Lake is a reservoir located in Scoggins Valley within the Oregon Coast Range foothills, created by a dam on Scoggins Creek. The water body provides multiple areas for fishing, boating, and trail access throughout its length.

Scoggins Dam was built in 1975 by the United States Bureau of Reclamation, which still owns and operates it. The dam impounds Scoggins Creek to form the reservoir, which holds 53,640 acre-feet of usable water. Some of that water is released by Clean Water Services in summer to cool the Tualatin River and improve its water quality; four cities and the Tualatin Valley Water District also draw on it.

The lake is named for Henry Hagg, a dairy farmer active in local agricultural committees in the first half of the twentieth century. Today Clean Water Services releases lake water into the Tualatin River in summer to lower its temperature and improve water quality; four cities and the Tualatin Valley Water District also draw on it.

The area offers hiking trails, two boat launching areas, and fishing opportunities for trout and bass throughout the warmer months. Plan to arrive early, especially on weekends, as the shoreline can draw crowds.

In 1967, fossilized shark remains were found near the lake, not marine creatures in general. The reservoir itself was built later, in 1975, when the Bureau of Reclamation finished Scoggins Dam. The find predates the lake by eight years.