Milltown Phase II Draft Restoration Plan How about a figure of picture here. I had a picture of the 1908 flood, but I think we should have a design picture or figure would be appropriate now. Doug Martin, State of Montana Gary Decker, WestWater Consultants, Inc. River Design Group, Inc. April 1, 2005 University of Washington Libraries

Presentation Outline Draft Conceptual Restoration Plan review Restoration plan overview Phase II data collection and analysis Summary results Draft design plan concepts Schedule moving forward You could put a figure here if you have one. Clark Fork Symposium 2005

Milltown Reservoir Sediment Operable Unit Please keep this picture, I want to highlight where remediation is taking place. Clark Fork Symposium 2005

Restoration Plan Objectives Restore the Clark Fork and Blackfoot rivers in the Milltown Reservoir Sediment Operable Unit (MRSOU) to be naturally functioning and self-maintaining Use native materials to the extent practical, for stabilizing channels and floodplain Improve water quality by stabilizing contaminated sediments to be left in place Provide high quality habitat for fish and wildlife Clark Fork Symposium 2005

Restoration Plan Objectives Maintain existing infrastructure stability Improve aesthetic values in the area by creating a diverse, natural setting Provide recreational opportunities such as river boating, fishing, and trail access for hiking and bicycling Clark Fork Symposium 2005

Draft Conceptual Restoration Plan Intent of DCRP Primary purpose was to develop a cost estimate for settlement and planning purposes Incorporated preliminary data to offer potential restoration options for the Remediation Plan – natural channel vs. armored channel Plan developed to gauge public support for dam removal and restoration of Clark Fork and Blackfoot rivers You could put a figure here if you have one. Clark Fork Symposium 2005

Draft Conceptual Restoration Plan DCRP Accomplishments Determined scope of restoration efforts Better understanding of Milltown Dam effects Developed information for integration with Remediation Actions Provided basis for removing the Milltown Dam powerhouse and Stimson Dam Favorable public comments for plan You could put a figure here if you have one. Clark Fork Symposium 2005

Public Process and Design Phases Phase I Draft Conceptual Restoration Plan (February 2003) Public Review /Public Meetings /Responsiveness Summary Amended Conceptual Plan (June 2004) Phase II Data Collection Activities (ongoing) Draft Phase II Design Plan and Peer Review (April 2005) Public Review Process/Public Meetings Final Phase III Design Plan Clark Fork Symposium 2005

Project Constraints Sediments left in place Infrastructure Cultural sites Integration with remediation Continuity with upstream and downstream reaches Landownership Clark Fork Symposium 2005

Phase II Data Collection and Analysis Clark Fork Symposium 2005 University of Washington Libraries

Phase II Purpose and Goals Validate DCRP assumptions and complete detailed data collection and analysis Determine appropriate channel morphology Determine design criteria for Final Design phase Update project cost estimates, phasing, and construction sequencing Assess potential restoration risk for restoration activities Address changes in wetland conditions from existing to proposed design – revegetation plan Clark Fork Symposium 2005

Questions to be Answered What were the most probable historical channel and floodplain morphologies? What are the current channel and floodplain conditions and how have they been influenced by historical and contemporary land uses? Can we restore the system to historical conditions given the project constraints and upstream conditions? Clark Fork Symposium 2005

Field Data Collection Overview Data collection to characterize conditions and to develop design plan 6 reaches on CFR, 4 on BFR Field techniques Geomorphic surveys Reference and existing conditions Bed material characterization Gage station calibration Riparian condition assessment Bank stability and erosion potential Valley morphology and transitions Clark Fork Symposium 2005

Remote Data Collection Overview Historical conditions research Current and time series aerial photograph interpretation University of Washington Libraries Clark Fork Symposium 2005

Data Analysis Techniques Existing and reference conditions – departure analysis Hydraulic modeling Incipient particle motion and sediment transport Valley morphology Channel planform Ice floe considerations Clark Fork Symposium 2005

Questions 1: Historical Channel and Floodplain Morphologies University of Washington Libraries Map from the Lewis and Clark Journals. Highlight of the Clark Fork and Blackfoot confluence. … the Cokahlahishkit R which falls in on the N.E. side [of the Clark Fork River], is 60 yds. wide deep and rapid. the banks bold not very high but never overflow. the East fork [Clark Fork River] below its junction with this stream is 100 yds. wide and above it about 90. the water of boath are terbid but the East branch much the most so; their beds are composed of sand and gravel. M. Lewis, July 3, 1806 Reviewed historical maps, journals, photos, and earliest aerial photographs Surveyed and evaluated project area and reaches with similar valley morphologies Regime equations addressing channel morphology (Millar, Knighton) Regime Equation Results for CFR3 Predicted Observed 0.0197 0.0028 0.0167 0.0028 0.0048 0.003 Regime equation predicts a meandering channel type Millar, 2000 CONCLUSION: Reviewed information and data suggest the Clark Fork River was historically a meandering river system. The historical channel is believed to have transitioned from an unconfined to confined system without braiding.

Questions 2: Current Conditions & Land Use Effects Reviewed historical maps, and journals Time series aerial photograph analysis Departure analysis comparing existing and reference conditions CONCLUSION: Human disturbance in the Upper Clark Fork River watershed and more immediate floodplain corridor perturbed the system. Periodic large magnitude flood events unravel the stream network. Inter-flood periods characterized by channel recovery. Clark Fork Symposium 2005

Questions 2: Current Conditions & Land Use Effects Reach Bankfull Width (ft) Average Depth (ft) Max Riffle XS Area (ft2) Width/Depth Ratio Braided (n = 3) 708 (633-779) 1.7 (1.6-1.8) 6.4 (5.4-7.4) 1,208 (1,128-1,361) 427 (385-451) Reference (n = 2) 183 (138-206) 3.2 (2.7-3.8) 4.9 (3.9-6.2) 572 (519-646) 60 (37-77) Land use effects date to 1860s Milltown Dam Mining Transportation corridor Channel straightening Grazing Agriculture Land development Braided Reach XS Reference Reach Riffle XS Clark Fork Symposium 2005

Questions 3: Restoration Potential within Existing Constraints Reference reach data from similar systems Hydraulic and sediment transport modeling results Riparian vegetation assessment CONCLUSION: It will be possible to reconstruct the channel and floodplain to emulate historical conditions. An upstream reference reach has maintained a functioning meandering pattern for 60+ years. Limiting project risk will be a priority. Clark Fork Symposium 2005

Phase II Draft Design Plan Clark Fork Symposium 2005 University of Washington Libraries

Draft Design Plan Applied reference reach data, modeling results, and regime equations to develop draft design plan Channel grading plan through reservoir to be integrated with remedial action Maintain channel stability through contaminated sediment reaches Incorporate off-channel habitats and floodplain wetlands in draft channel design plan Comprehensive revegetation plan Clark Fork Symposium 2005

Draft Design Plan Clark Fork Symposium 2005

Summary – Project Schedule Preparing Draft Design Plan: Due April 15 Peer Review Process: April 15 – May 27 Incorporate Trustee and Peer Review Comments Collect Final Data Complete Final Design Clark Fork Symposium 2005