WHAT'S HAPPENING NOW WITH THE CLEANUP?

CONSTRUCTION COMPLETED:  December 2025

PRELIM TOTAL COST:  $5.6 million (incl. monitoring, maint, reveg, etc.)

NEXT STEPS:  Design/build new wetlands; Public tour, summer 2026

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LOCATION & DESCRIPTION:  (See cleanup design & related docs HERE.)

A 40-acre site ~10 miles south of Deer Lodge to the east of Racetrack Pond, running 2.2 river miles SW to NE beginning just north of Gemback Road. 

CHARACTERISTICS:

Relative to other phases, the Strategic Plan characterized Ph. 7 as "Moderate Priority" for erosion of contaminated sediments into the river; and "High Priority" for contaminated soil levels, as the area includes a public fishing access (pp.11-12). DEQ estimated removal of 135,800 cubic yards of mine waste-contaminated material from the site.

STATUS (as of March 2026)

Construction was completed in Dec. 2025, and the parking lot, stated-owned portions of the floodplain, and the river are all currently open to the public. (If you access the site, please do not trespass on private property and be aware of tripping hazards.) The project cost ~$5.6 million, including construction, engineering, revegetation, streambank material, and surveying. This total is over original estimates, as more contaminated material needed to be removed (173,250 cubic yards), which also required more material for backfill. Costs and lessons learned from Phase 7 will inform the State's upcoming updates to its 2023 CFROU Strategic Plan.  NEXT STEPS:  Design and construction of a new wetlands feature on the east side of the site, which will reclaim some borrow areas and provide diverse waterfowl habitat in the area. 

CFRTAC is currently reviewing and providing input on the wetland design, and will participate in a public tour of the site, expected in June 2026. (See our earlier comments on Ph.7 design here, the State's response to comments here, and more info on Ph.7 in our February and May 2025 newsletters.) 

ESTIMATED START DATE:   No start date currently estimated

ESTIMATED TOTAL COST:   $20.62M (may change) 

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LOCATION & DESCRIPTION: 

Includes Arrowstone Park. Extends through Deer Lodge from the I-90 bridge at Exit 187 (eastbound) north to the city's boundary with Grant Kohrs Ranch (near the Cottonwood Creek confluence).  

CHARACTERISTICS:

This phase is of high concern because temporary soil caps installed ~30 years ago at Arrowstone Park are failing in some areas, exposing arsenic and other contaminants that have created public health risks. As noted in DEQ's 2024 Clark Fork River News, community concern led DEQ to prioritize cleanup here. In the interim, DEQ installed safety signage and added temporary soil caps on bare spots to cover exposed toxic contaminants. 

STATUS  (as of March 2026):

DEQ is conducting additional sampling at the site to fill data gaps, which entails examining soils at greater depth in some areas, and to doing additional surface-level sampling in other areas. These findings will help determine contamination removal boundaries and depths, which is necessary before a cleanup design can be drafted. DEQ hopes to finish its sampling plan in spring 2026. 

DEQ continues to coordinate with EPA to determine cleanup levels for arsenic. (See our May 2025 newsletter for details.) Cleanup here has been delayed as the State and EPA reexamine the arsenic cleanup standard to be used at the site. A stricter standard will be more protective of human health, but will likely also increase costs and cause delays. While the site is being monitored to determine if additional soil caps are needed to cover exposed soil, the public is advised to obey caution signs, avoid areas with exposed soil, and wash hands, boots, pets, boats, etc. after any potential exposure to contaminated soils, especially on the river banks. 

COMPLETED PHASES (maintenance & monitoring underway):

• Phases 1 & 2: Completed in 2014 and 2016
• Phases 3 & 4A: Completed in 2023
• Phases 5 & 6: Completed in 2016 (Ph 5 pictured above)
• Phases 15 & 16: Completed in 2021
• Deer Lodge Residential Yards; Trestle Area; Eastside Rd. Residential Area; and Eastside Rd Pastures: Completed in 2011, 2012, & 2016
• See Phase Status Map below for locations of these & other phases
• For a detailed technical update, read the 2023 Status Report (Qualitative Rapid Assessment) for Phases 1, 2, 5, & 6 - released by DEQ and NRDP in April 2024

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NEXT UP AFTER PHASE 7 & PHASE 13/14 (described above):

• Phases 10-12: These phases are combined as they share haul roads, which are all accessed from Sager Lane. Sampling plans for these phases is underway (as of September 2025), with spring 2026 sampling plans pending, as they require State and EPA approval. Cleanup work is estimated to begin in 2027.

Phases 7 and 10-14 (described above) were prioritized for cleanup based on the ranking criteria described on p. 12 of the 2023 Strategic Plan. Other phases will be addressed in an upstream-to-downstream sequence after these higher-priority phases are completed. These include:

• Phase 4B:  Estimated to start in 2029. Phase 4A was completed in 2023. 

• Phases 8 and 9:  Estimated to start in 2030 and 2031. This area of the river is considered to be suitable to provide refuge for fish and wildlife displaced by work in earlier phases. 

• Phases 17 - 22: To be completed in order after Phases 8 & 9, with some possibly being combined. At roughly one phase per year, (with Phase 17 A & B taking a year apiece), annual start dates will be from 2032 to 2038.

• Maintenance and monitoring for completed phases is ongoing. The Strategic Plan estimates this work will continue beyond construction of the final phase from 2040 through 2044.