MASSIVE EROSION OF FLORAS CREEK AND NEW RIVER IN CURRY COUNTY, OREGON RESULTING FROM BREACHING OF NEARBY SAND DUNES

Floras Creek originally flowed from the mountains near Langlois, Oregon into the New River which then traveled approximately 10 km along a coastal dune system before flowing into the Pacific Ocean. The dunes have been purposely breached since 1970 near the confluence of Floras Creek and New River to drain the wetland next to the New River to convert it into a ranch. Since the initial breach, the Floras Creek has responded to the changes in base level and massive erosion has been noted. The initial breach caused a significant increase in slope for the creek. It nearly tripled from 0.64m/km prior to breaching to 1.72 m/km after. The increase in slope disturbed the natural equilibrium of sediment aggradation, erosion and incision of this meandering stream that was very close to base level. Analysis of aerial photos from 1954 to 1997 have indicated that parts of Floras Creek have widened up to 1130% of the 1954 creek width and downcut 1-2 meters. The creek has become less sinuous. Extensive fish habitat and wetland destruction has occurred.