The South Fork Boise River below Anderson Ranch Reservoir is a regulated river. That means river flows are controlled as if with a spigot. Popular float boating flows in the summer are coupled with the steady, generous 300 cfs winter flows that benefit the wild trout fishery.
But a regulated river also affects the health of a river corridor and the riparian community. We have enjoyed fishing the river and it’s been pretty terrific that we may have been neglecting to notice the riparian conditions along the river.
Yes there have been some fencing and planting projects such as along Cow Creek and along the SFB on the north (river right) side downstream of the Cow Creek bridge.
But the long term issue with the river corridor and its current health is tied to the flow operations from 1955 to date that limit the high flows and thus the ability for a river channel to migrate laterally, carve out a new channel now and then, route sediment and gravel, form islands, and set the table for riparian species like willow and cottonwood to establish. There are lots of old trees, and few if any young trees. There is little wood in the river. River ecosystems need wood, both for abiotic structural functions and processes in a stream, and for the nutrient source wood provides to the food web.
Not much of a riparian area along this reach of the South Fork Boise River
This is a topic where we are exploring with the agencies some ideas about taking on an investigation of the current situation and then coming up with some ideas to address the needs of the river. In the future we will explore the history of some of the past projects and also the prospects for some field work in 2012.
