The South Fork Boise River Watershed Collaborative Overview
Anderson Ranch Dam to Arrowrock Reservoir
The South Fork Boise Watershed Collaborative is a group aimed at identification, prioritization and implementation of improvements to the South Fork Boise Watershed between Anderson Ranch Dam and Arrowrock Reservoir. The group had its Kickoff Meeting on October 19, 2023 and has created sub-committees to investigate topics in the six improvement categories identified by the group. The current plan is to host meeting announcements, meeting notes, presentation files, meeting recordings/transcripts and other files on www.southforkboise.org. This StoryMap will host a general overview of the spatial GIS information and imagery for the collaborative. A second StoryMap ( https://arcg.is/0mb8jy) provides more detailed information, access to spatial models and will provide detailed spatial information on potential projects as they are developed. If you would like to provide input or be involved in the process please reach out to Anthony Prisciandaro at Anthony.Prisciandaro@tu.org.
Mainstem Reaches
The mainstem South Fork Boise River below Anderson Ranch Reservoir can be separated into four reaches. The Upper Roadside Reach between the dam and Danskin Bridge/boat launch is 12.4 miles long. The Middle Reach is 4.4 miles between Danskin and where the canyon walls close in on both sides. The Canyon Reach is 12.9 miles with whitewater. The Reservoir Transition Reach varies from not existing when Arrowrock is at full pool to 7.8 miles at low pool.
Tributaries
Tributaries are represented by their drainage areas with the areas of perennial streams displayed here. The tributary maps that follow only have the polygons of the drainage areas for easier viewing.
Waterfalls
The steep canyon nature of the river results in many natural waterfalls that are barriers to fish connectivity. Select any of the camera symbols to see the gradient profile of the stream and/or a photo of the waterfall on the stream.
Tributary Connectivity
The current understanding of connectivity of tributaries for fish wanting to leave the mainstem to spawn or take refuge.
Tributaries - Fish-bearing
The current understanding of which tributaries have fish. Some tributaries may only have young of year fish or certain sections of the creek that can support a population. Stocking in the Smith Creek Drainage has been limited to triploid rainbow trout being released into Smith Creek Lake (a high mountain lake at 8000ft) since 2000. Fertile rainbow trout were last stocked in Smith Creek in 1989 and Smith Creek Lake in 1994. Stocking in the South Fork Boise River between Anderson Ranch Dam and Arrowrock Reservoir was ended in 1976. Anderson Ranch and Arrowrock reservoirs are still periodically stocked with rainbow and kokanee that could move into the South Fork Boise.
Tributaries - Bull Trout
This map depicts the current understanding of bull trout in the watershed. The polygons depicts modeled suitable habitat for bull trout that is used by many agencies. The green lines represent a more recent 2022 model that refines this information based on waterfalls, temperatures and stream size. The blue line depicts areas within the watershed that are listed as critical habitat by the U.S. Fish and Wildlife Service.
Mainstem Spawning locations 2007
Click on the image to open in a new window where you can zoom in/out. Informal rainbow trout spawning surveys were performed in 2007 from Anderson Ranch Dam down to Danskin Bridge. Most redds were concentrates in complex habitat with islands and/or side channels. 2007 was a low flow year with flows at 300 cfs until April 3rd then 600 cfs until May 30.
Recreation Facilities
Recreation Facilities- Click on any boat ramp, bathroom or campsite to see more information and photos.
2013 Elk-Pony Complex Wildfire
The 2013 Elk-Pony Complex Fire burned a large portion of the watershed. Heavy rains after the fire caused major debris flow events that created new rapids and modified many sections of river.
Elk-Pony Fire Aftermath
Move the slider back and forth to view before (2011) and after (2015) aerial imagery showing changes caused by the 2013 Elk/Pony Complex Fire. Note the Tailwaters boat ramp on the right side of the image. The rapid that formed after fire related debris flows limits the usability of this ramp.
Navigate on the map below to see fire impacts anywhere in the watershed
Before (2011) and after (2015) the Elk/Pony Complex Fire aerial imagery. Zoom in to any area of interest and use the swiper to visualize fire impacts.
Examples below show how the fire and related blowouts changes the river and riparian habitat.
Granite Creek
Mouth of Granite Creek pre-fire, 2011
Granite Creek
Mouth of Granite Creek post-fire, 2015.
Upper Granite Creek
Upper Granite Creek pre-fire, 2011.
Upper Granite Creek
Upper Granite Creek post-fire, 2015.
Pierce Creek
Mouth of Pierce Creek pre-fire, 2011
Pierce Creek
Mouth of Pierce Creek post-fire, 2015.
Tailwater Boat Ramp
Tailwater boat ramp and campsite pre-fire, 2011.
Tailwater Boat Ramp
Tailwater boat ramp and campsite post-fire, 2015.
Pierce Creek Before and After Fire
Post fire recovery
Granite Creek After Fire 2015 and 2023
