Upper Oregon Creek Restoration

Project Description

Oregon Creek is a headwater tributary to the Big Hole River on the Continental Divide (Big Hole River< Deep Creek<French Creek<California Creek<Oregon Creek) and is within the state-owned Mount Haggin Wildlife Management Area (WMA). The area has an extensive history of mining-related disturbance, logging, and livestock grazing.  Aerial emissions from smelting activities in Anaconda deposited heavy metals (e.g. Copper, Arsenic, Cadmium, Lead, and Zinc) on nearby mountains which killed upland vegetation and, together with intensive logging to fuel the smelters, removed a vast majority of the vegetation community from the upper extents of the WMA. Devoid of vegetation, large areas developed extensive networks of rills and large gullies during heavy rain events, most severely in areas with geologic parent material of highly erodible volcanic welded tuff.  These erosive processes persist on 25 acres of uplands in the upper reaches of Oregon Creek (above our 2019 Oregon Creek restoration project), contributing annual plumes of fine sediment into the creek and eventually into the Big Hole River.  These acres were purchased by FWP in 2020 and added to the WMA.

Additionally, 100 years of sedimentation along with anthropogenic alterations to the stream channel have left 1,126 feet of stream channel straightened, downcut, lacking in riparian vegetation, and the surrounding floodplain perched and disconnected from the channel.  An FWP fish survey in 2020 showed no fish above these plumes.  In comparison to nearby reference conditions throughout the WMA, this reach of Oregon Creek lacks grade controls or the functional qualities of overbank flood events that attenuate sediment.

This project will eliminate most TMDL estimated sediment loading from upland erosion and improve riparian habitat in the headwater reaches of Oregon Creek.  This will be accomplished by following the same three-pronged strategy we’ve employed under Superfund in the Mount Haggin Injured Area:

1. Establish vegetation on 25 acres of upland slopes to prevent sheet erosion
2. Detain sediment in 15 gully networks
3. Capture sediment on the floodplain by restoring stream function and dynamics with in-stream and floodplain structures.

This project will also reconnect 11 acres of historic floodplain to the channel by implementing a  modified “stage 0” cut and fill restoration approach to approximately 600 feet of straightened and incised section of stream.

Results

Major 2022 Upper Oregon Creek project accomplishments include:

• Installation of 99 in-stream structures (beaver dam analogs (BDAs)/post-assisted log structures (PALS)) to capture sediment in the channel and on the floodplain.
• Installation of 74 gully check dams and 18 gully slash filters in the gully networks to capture eroding upland sediment.
• Approximately 600 ft of straightened and incised channel filled in and re-established to reconnect 11 aces of floodplain (“Stage 0” component).
• 25 bare and eroding acres revegetated (seeded) and fertilized by hand and by helicopter.
• Removal of a failed culvert, reconnecting approximately .5 miles of Oregon Creek headwaters.
• 30 acres of aspen enhancement and 8,300 linear feet of gullies filled with slash and wood.

Additional work/maintenance of all gully check dams, gully slash filters, in-stream structures, and revegetation treatments are scheduled for the fall and summer of 2023.

People and Organizations Involved

Big Hole Watershed Committee

Natural Resource Damage Program
Montana Fish, Wildlife and Parks (landowner)

Funders

Montana Department of Environmental Quality

Trout and Salmon Foundation

Contractors

Watershed Consulting

Montana Conservation Corps

Worman Forest Management

Project Documents

Upper Oregon Creek Implementation Plan

Upper Oregon Creek Monitoring Plan

Project Photos

Incised and straightened channel conditions in the lower reach of project area.

Sediment plume entering upper Oregon Creek.

Sediment plume entering upper Oregon Creek. BHWC has identified 15 sediment inputs from upland/gully sources.

Active sediment loading into upper Oregon Creek.

One of many sediment plumes finding its way into upper Oregon Creek.

Bare and eroding hillside above project area. Highly erodible volcanic tuff exacerbates rill and gully formation.

Conditions in the uplands above upper Oregon Creek. Smelter emissions from the Anaconda Smelter killed all upland vegetation, leading to terrible erosion.

Fine sediments choking Oregon Creek. Sediment source is from eroding uplands above.

Sediment choked upper Oregon Creek.

Excessive sediment in upper Oregon Creek. Perched culvert blocks upstream fish passage.

Perched culvert in the upper reaches of Oregon Creek. This project will remove this culvert to connect upstream habitat for native fish.

Large gully outwash plume. This sediment eventually finds its way into Oregon Creek, devastating fish habitat and water quality.

Investigating depth of in stream sediment.

Excessive sediments in Oregon Creek. These conditions are common throughout the project area.