Prior to 1940, the Williamson River Delta was a large expanse of diverse wetland habitat, hosting a multitude of fish, including the endangered Lost River (Deltistes luxatus) and Shortnose (Chasmistes brevirostris) suckers, bird, and plant species. The last four miles of the Williamson River fed around 5,500 acres of deltaic wetland, dynamically weaving through productive marsh habitat before emptying into Upper Klamath Lake. By the 1950s, approximately 22 miles of levee were built around the area and the wetlands were drained for farming and ranching. The river was channelized and dredged, cutting it off from the historic floodplain, and connectivity between the river, wetlands and lake was lost.

 

The loss of the wetland ecosystem and the severed hydrologic connection had profound detrimental effects on both fish populations and Upper Klamath Lake water quality. Suckers, whose larval stage require the shallower, warmer, vegetated waters once provided by the delta, were federally listed as endangered species in 1988. 

Wetlands provide an essential ecosystem service as an effective nutrient sink. Anthropogenic activity has dramatically increased nutrient loads in the lake from fertilizer inputs, leaching from soils, and increased sediment erosion. Overall, the human impact has led to unsustainable ecosystems.

 

The Nature Conservancy began purchasing portions of the delta in 1996 to implement a pioneering wetlands restoration project. The goals of the project were to,

1) restore the river-delta wetland ecosystem,

2) restore habitat for larval and juvenile Lost River and Shortnose Suckers, and

3) improve water quality conditions in Upper Klamath Lake.

In 2007 restoration work began on Tulana, the northern portion of the delta. Internal levees were shaved down mechanically and in October, four areas comprising almost 2 miles, were breached using explosives: https://www.youtube.com/watch?v=GpD9mHLedJE.

 

Within a few days the northern half of the delta was inundated. In 2008 levees were removed from Goose Bay, the southern portion of the delta. A historic oxbow channel was excavated and restored, and the levees along the river were lowered to create a riparian bench. Today, approximately 5,500 acres have been flooded and restored. Also, check out our page at nature.org!