Section 1 - Introduction Restoration Plan for the Clark Fork River and Blackfoot River near Milltown Dam – October 2005 SECTION 1 INTRODUCTION The State of Montana in consultation with the Confederated Salish and Kootenai Tribes, and the U.S. Department of the Interior - U.S. Fish and Wildlife Service, contracted with WestWater Consultants, Inc., River Design Group, Inc., Wildland Hydrology and Geum Environmental Consulting, Inc. to prepare the Restoration Plan (RP) for restoration activities associated with the Milltown Reservoir Sediments Operable Unit (MRSOU). The RP follows earlier efforts including the Phase I Draft Conceptual Restoration Plan (DCRP) (Water Consulting, Inc. and Wildland Hydrology, 2003; amended 2004). The Final Restoration Plan will be completed following final data collection, and receipt and acknowledgement of comments from the Trustees, a peer review panel, and the public. The RP documents the Phase 2 data collection, analysis, and conceptual restoration design for the Clark Fork River (CFR) and Blackfoot River (BFR) following the removal of Milltown Dam and a large portion of the contaminated sediments stored in Milltown reservoir. The RP incorporates recommendations and information included in the Environmental Protection Agency’s (EPA) Record of Decision for removing Milltown Dam and the excavation of sediments. The RP culminates the second phase in the restoration planning process. Previous and future phase tasks are outlined as follows. Phase 1: The Phase I DCRP as amended in June, 2004. The DCRP was a broad scale planning document that provided restoration concepts, draft plan views, and elevation information. Although the level of detail in the document was adequate to provide the best possible cost estimate based on existing information at the time, the document was based on limited field data collection and contained only conceptual restoration design plans. Phase 2: Phase 2 RP includes field data collection activities completed in late 2004. Data were collected to characterize existing channel conditions and reference (or most probable state) river corridor attributes on the CFR and BFR in both the MRSOU and on other reaches of the CFR and BFR. Data were used to establish design alternatives and evaluate the feasibility of proposed design alternatives. Field data included existing topography, aerial photography, channel and floodplain morphology surveys, sediment investigations, and a riparian vegetation assessment. Aerial photograph interpretation and review of historical documents complemented field activities. Recent and time series aerial photos were reviewed to evaluate channel alignments, valley-channel interactions, and the influence of human infrastructure on the landscape. Phase 3: The Phase 3 Design Plans will refine the restoration plans based on additional data and analyses as discussed in the RP and public comment. Thereafter, final design plans will be developed and will be used for acquiring permits and for directing restoration plan implementation. 1-1 Section 1 - Introduction Restoration Plan for the Clark Fork River and Blackfoot River near Milltown Dam- 1-2 Section 1 - Introduction Restoration Plan for the Clark Fork River and Blackfoot River near Milltown Dam- 1.1 PURPOSE AND SCOPE The RP serves as the second stage planning document for orienting restoration planning for the CFR and BFR following the removal of Milltown Dam and the most contaminated sediments contained within Milltown reservoir. Information included in the RP culminates data collection, analysis, and modeling efforts completed in 2004 and 2005. Field data collection, aerial photograph interpretation, and review of historical documents served five primary purposes. To predict or at best, characterize, the likely historical conditions of the CFR and BFR in • the vicinity of the confluence. To characterize the existing conditions of the CFR and BFR in the MRSOU and in • upstream reaches. To propose the desired future morphological characteristics for restoring the CFR and • BFR channels in the vicinity of Milltown reservoir based on data collected in reference reaches in other portions of the CFR and BFR watersheds. Restoration designs will also account for restoration project area constraints and limitations. To provide data necessary for modeling and evaluating flood frequency, channel stability • and sediment transport capacity. Hydrologic and hydraulic modeling results are incorporated with empirical data to develop and evaluate channel restoration designs. To provide a complete topography of the restoration project area including bathymetry of • existing deep water features that may be used for future design phases and analysis. The intent of the RP is to present a summary of these efforts in addition to presenting restoration designs for the Clark Fork and Blackfoot rivers near the MRSOU. The RP has been submitted for peer review and peer review comments has been incorporated in the RP. This RP will be available to the public. Review and comment by others outside of the restoration design team to should maximize the potential for restoration project success and is a key component of the planning effort. The extent of the proposed work will extend on the BFR from the confluence with the CFR, upstream to just below the Stimson Dam; and on the CFR from the Burlington Northern-Santa Fe (BNSF) railroad bridge below Milltown Dam, upstream to the extent of the reservoir and Duck Bridge hydrologic influence (Figure 1-1). The following products are intended to be completed during Phase 2. Develop a thorough understanding of historical and existing river processes responsible • for forming the channel dimensions, planform, and profile. Example information that was collected and reviewed includes information pertaining to riparian conditions, hydrology, sediment transport, and anthropogenic land uses. Develop appropriate restoration recommendations based on historical, existing, and • potential channel conditions while acknowledging the constraints that will be placed on the final restoration design. Example constraints include the location of contaminated sediments to be left in-place within the restoration project area, existing infrastructure, and budgetary limitations. 1-3 Section 1 - Introduction Restoration Plan for the Clark Fork River and Blackfoot River near Milltown Dam- Acknowledge and apply as appropriate a range of analysis techniques to thoroughly • evaluate existing and potential river conditions. Appointed analytical techniques are based on the experience of a wide range of practitioners in the fields of fluvial geomorphology, hydrology, hydraulic engineering, and restoration ecology among others. Provide the collected information and proposed restoration designs for peer review and • public critique to ultimately strengthen the restoration plan and provide the State with the best possible restoration project. The State envisions the restoration of the CFR and BFR near Milltown Dam as a portion of a larger watershed scale effort being conducted in the CFR watershed. Restoration efforts on the CFR are largely in response to the waste from mining, milling and smelting operations in Butte and Anaconda. Existing river corridor have been injured by hazardous substances, including arsenic, cadmium, copper, lead and zinc. Addressing contaminated waste though various clean- up efforts has been underway since the 1980s. Removal of Milltown Dam and a portion of the contaminated sediment in the reservoir will result in the elimination of a large depository of contaminated materials from the CFR corridor. 1.2 PROJECT GOALS AND OBJECTIVES The Trustees revised the goals and objectives presented in the Draft Conceptual Restoration Plan (DCRP) for the DRP per the peer reviewers recommendations. The review panel agreed with the conceptual goals and objectives but suggested more explicit wording that corresponded with our more detailed data and understanding of the site. The following goals and objectives were defined for the Draft Restoration Plan, April 2005. These goals and objectives will need to be refined further during the Phase 3 Design to reflect the monitoring that will be identified to measure the success of this project. Overall Project Goal: Restore the confluence of the Blackfoot and Clark Fork Rivers to a naturally functioning, stable system. This goal can be achieved with the understanding that: • Infrastructure, contaminated sediment repositories, private land and the geomorphic setting must be maintained; • Erosion and migration of the river channels is part of a naturally functioning and stable river system. In the long-term, vegetation such as cottonwoods and willows is integral this restoration; • For the short-term (15-25 years) after reconstruction, structures will be relied upon to provide stability until the vegetation is mature. To the extent possible, structures will be similar to those naturally occurring in less altered sections of the rivers. 1. Goal: Improve water quality by reducing the erosion of contaminated sediments. • Rock, wood, and vegetation will be used to construct instream, streambank, and floodplain structures mimicking natural structures found in other, similar Montana rivers; 1-4 Section 1 - Introduction Restoration Plan for the Clark Fork River and Blackfoot River near Milltown Dam- non-native biodegradable material may be used. (Measurement1: Material used is native or it is not, structure consistent with setting); • Bank and in-stream structures installed to maintain channel and floodplain stability until vegetation has matured on the floodplain and streambank; o After the streambank and floodplain vegetation has matured (15 to 25 years) the channel and bank structures will have degraded allowing the river to migrate and develop channel(s) naturally across the floodplain (Measurement: Channel migration starts after vegetation has met ROD requirements and is structurally effective, monitor erosion rates, bed stability (aggradations/degradation) compared to reference reaches). 2. Goal: Provide channel and floodplains that will accommodate sediment transport and channel dynamics appropriate for the geomorphic setting. • Design parameters for the channel to allow the 1.5 to 2.0 year flood frequency to access the floodplain. Design of the floodplain, terrace, and wetland features will accommodate all levels of flooding consistent with setting. Channel and meander geometry will remain consistent over time. (Measurement: sediment is transported through restored reaches without excess aggradations or scour, channel hydraulic geometry remains within design criteria.. Bank pins, cross-sections, and profiles will be monitored); • Revegetation of the streambank and floodplain using a diverse community structure will be an integral part of the floodplain design (Measurement: ROD requirements met or exceeded) 3. Goal: Provide high quality habitat for all native fishes and other trouts, including continuous upstream and downstream migration while minimizing habitats that will promote undesirable fish species. • Channel design will provide habitat features similar to reference conditions and consistent with stream type or geomorphic setting. Instream and bank structures will maintain habitat features until bank and floodplain vegetation matures allowing the geomorphic forces to create this habitat naturally. (Measurement: Goal 3 met thru achievement of Goals 1 and 2); • To the extent practicable while restoring these large river systems, habitats favorable to northern pike or other potential undesirable species, e.g. shallow, slow, and warm water will be eliminated. (Measurement: northern pike spawning areas eliminated and not created) 4. Goal: Provide functional wetlands and riparian communities, where feasible. These communities will also provide improved riparian and wildlife habitat within the restored area. • Wetland design will reference upstream and downstream wetland areas (Measurement: created wetlands with equal or higher ranking than exists in upstream or downstream wetland areas); 1 Measurements are listed as potential guidelines for which goals and objectives will be measured. Examples of indices are listed as indices that could be used. Further refinement in the restoration planning and development of the monitoring and maintenance plan will discuss the indices that will be used. 1-5 Section 1 - Introduction Restoration Plan for the Clark Fork River and Blackfoot River near Milltown Dam- • Use of a diverse vegetation plan will improve wetland quality (Measurement: created wetlands with equal or higher ranking than exists in upstream or downstream wetland areas); • A majority of the floodplain should develop into wetlands, but is dependent on groundwater elevations after dam removal. (Measurement: measure wetland areas). • Revegetation activities proposed increase floodplain vegetation diversity and provide for long-term floodplain and channel stability. (Measurement: ROD, Appendix G) 5. Goal: Improve visual and aesthetic values through natural channel design, revegetation and the use of native plants and materials. • The design will create a riparian zone that has a diverse vegetative cover (Measurement: vegetation ROD requirements met); • The river channel design will function similar to reference sections (Measurement: channel maintains designed stream type and dimensions, see goal #1); • Revegetation, floodplain, and channel design will consider other proposed land uses (Measurement: integration of other restoration projects considered to the extent practicable without compromising these Goals and Objectives). 6. Goal: Provide safe recreational opportunities compatible with other restoration goals, such as channel and floodplain stability, sediment transport, and fish habitat. • Establishing a naturally functioning system within the boundaries and limits present at the site are a priority; however, safety considerations will be evaluated with every aspect of the project. A totally safe river system cannot be built, rivers are inherently dangerous, and a system that is similar to other rivers in similar environments within Montana will be used to guide decision makers. (Measurement: Met goals 1 thru 5.) 1.3 PROJECT CONSTRAINTS AND LIMITATIONS Restoring the CFR and BFR in the vicinity of Milltown Dam entails many inter-related parts that must come together to make a complete project for ecological restoration to be a success. The RP presents a restoration design that for it to be effective must be successfully transferred from a report to an on-the-ground project. With this under consideration, there are several constraints and limitations that were acknowledged during the design of the RP and that will have to be accounted for moving forward. Project constraints include the location and toxicity level of contaminated soils to be left in-place; existing infrastructure that restoration designs must accommodate; and budgetary limitations. More so than limiting the potential success of the project, the project constraints are issues that will be acknowledged and planned for during the project design. The following terms and definitions are provided to clarify the concepts presented in the following sections. A restoration project area map is included in Figure 1-1. Sediment Accumulation Areas (SAA): Designated areas where contaminated sediments are located. Five SAA’s were identified by the EPA within the MRSOU, three are within the Remediation Project Area and two are located upstream of the remedial area. 1-6 Section 1 - Introduction Restoration Plan for the Clark Fork River and Blackfoot River near Milltown Dam- Remediation Project Area: The area where remedial actions will occur. This area extends from Milltown Dam upstream to the bridges on the BFR and upstream on the CFR to Duck Bridge. Restoration actions will be implemented inside the Remediation Project Area, but many of these actions are limited by the Consent Decree outlining project responsibilities of the State and the Settling Defendants. Restoration Project Area: The area where restoration actions will take place. The restoration proposed at this time is limited to the current upstream and downstream distances identified in the 2004 Amendment to the Draft Conceptual Restoration Plan (Water Consulting, Inc. and Wildland Hydrology, 2003). Work outside the current restoration project area may be completed in the future. The restoration project area is delineated in Section 1.5.2. The DCRP proposed starting the CFR channel restoration just upstream from Turah Bridge and extending downstream to approximately Station 28+00 on the valley profile. Turah Bridge was selected because the bridge location was considered a stable point in the respect that it probably will not change location in the foreseeable future. The bridge and reach may change, but due to land ownership and access issues, the bridge location will likely remain constant. It is important for the upstream end of the restoration project to begin at a stable point to minimize the risk of channel change concerning channel location and gradient. Channel stability is necessary to minimize restoration project risk. 1.3.1 Sediments to be Left In-Place High level toxicity sediments will be left in-place in SAA I along the Interstate 90 embankment and SAA IIIB in the existing CFR channel. The EPA allowed these sediments, approximately 350,000 cubic yards of contaminated material, to be left in-place. These areas will require stabilization in order to protect these sites from fluvial entrainment. The SAA IIIB sediments shall be located out of the 100-year floodplain. Removal of the SAA IIIB sediments is not required since they are not a source of contamination to the alluvial aquifer beneath Milltown and Bonner (USEPA, 2004). Removal of the SAA I sediments near the Interstate 90 embankment will not be required to facilitate construction of the bypass channel. Envirocon estimated a cost of $5 million to $8 million for the removal of these sediments. Considering the cost of material removal relative to the benefit that removal would provide, EPA deemed it acceptable to leave these sediments in place. The proposed channel and floodplain extent will be limited to a narrower belt width through the reach bracketed by the SAAIII-B sediments to the south, and the Interstate 90 embankment to the north. The USEPA also determined that 4 million cubic yards of contaminated sediment in SAA II, IV, and V (see Figure 1-1) are not a threat to human health or the environment. The Trustees’ goal is to minimize erosion in these areas through the use of intensive revegetation and bank stabilization structures. 1-7 Section 1 - Introduction Restoration Plan for the Clark Fork River and Blackfoot River near Milltown Dam- 1.3.2 Existing Infrastructure There are seven existing bridges within the restoration project area. Five of the bridges are located on the BFR, including the two Interstate 90 bridges, the BNSF railroad bridge, the Highway 200 Bridge, and the decommissioned county bridge that is now limited to pedestrian traffic. On the CFR, two bridges are located downstream from Milltown Dam. The BNSF railroad bridge is immediately downstream from Milltown Dam, and the Interstate 90 bridge is located where the CFR enters a northerly heading downstream from the dam. Preliminary scour analyses have been completed on the BFR bridges by the Settling Defendants. Scour analyses will be refined during Remediation Design and completed for the BNSF railroad in the Phase 3 design. Other important infrastructure in the area includes the Interstate 90 highway embankment, secondary roads in the transportation corridor, and land development paralleling the river will need further consideration during final design phase. Individual land holdings will be evaluated relative to predicted flood elevations. 1.3.3 Recorded Archaeological Sites There are five recorded archaeological sites in the vicinity of Milltown Reservoir. None of these sites are expected to be affected by Milltown restoration based on the RP. The State will continue to consult concerning these archaeological sites with the other Trustees and EPA during development of the RP and the implementation of the Restoration Plan 1.3.4 Land Ownership Much of the restoration project area will occur on private land. Landowners have been contacted, but permission to implement many of the specific restoration actions has not been granted at this time. 1.3.5 Integration of Remediation and Restoration The Consent Decree outlines specific responsibilities that the Trustees’ restoration plan must complete within the Remediation Project Area. To address these responsibilities, the State will design the final channel and floodplain configuration, including dam removal depths, and the Settling Defendants will construct the design. The State will be responsible for the placement of channel structures, except on the BFR where grade control is the Settling Defendants’ responsibility. The State will also revegetate the site and will be responsible for floodplain maintenance and channel stability until vegetation is established. 1.3.6 Restoration Activities Schedule The timing of restoration actions within the Remedial Project Area will be important. The contractors completing the remediation work have a schedule that is dependent on their production rates and progress. If certain restoration actions are to be integrated with aspects of the remedial process, the restoration schedule must coincide with the RA schedule. An example of effective integration would be incorporating the excess excavation material from Reach CFR 1-8 Section 1 - Introduction Restoration Plan for the Clark Fork River and Blackfoot River near Milltown Dam- 3 into the backfill in CFR 2. The excess material generated in Reach CFR 3 will need to be available for use as backfill in when the SD’s are ready to use it as backfill in Reach CFR 2.. 1.4 HOW TO USE THE DOCUMENT The RP is structured to 1) provide the reviewer with a thorough understanding of the concepts we followed in characterizing the CFR and BFR; 2) define the historical, existing, and potential river corridor conditions; and 3) develop restoration designs for reconstructing both rivers in the restoration project area. This section includes descriptions of the systems that were employed in assessing the CFR and BFR; it defines time frames for ecological and hydrological restoration, explains the most probable state or reference condition concept and its application to river restoration, and provides an overview of the primary sections that comprise the remainder of the RP. 1.4.1 Technical Systems Used The different technical systems used in our analysis were chosen because they are standard within each of their particular disciplines. Some were developed regionally, while others have been universally applied independent of geography. Systems may be delineated according to field and analytical techniques. Field techniques include methods for characterizing existing channel, aquatic habitat, and riparian conditions. Analytical techniques include remote sensing tools, and hydrologic, hydraulic, and sediment transport models. Key field-based technical systems include the following methods. River morphology and channel classification concepts developed by Rosgen (1994; 1996) • and other practitioners (Montgomery and Buffington, 1997; Montgomery and MacDonald, 2002). Presented methods are widely referred to in the literature and are applicable to the river systems evaluated. The classification concepts are used for describing assessed river reaches at a course level, and are primarily presented as a communication tool for conveying the general characteristics of specified stream reaches. The applied valley classification system focuses on the relationship of a stream system to • its valley. Similar to the stream classification system, valley morphology classification is useful for conveying general information about stream valley characteristics including formative processes, dimensions, and how the valley morphology influences stream dynamics. Valley morphologies are classified according to guidelines presented in Rosgen (1996). Classification and Management of Montana’s Riparian and Wetland Types (Hansen et • al., 1995) is a vegetation-based ecological classification system centered on the dual concepts of ecological potential (habitat types) and disturbance-process-driven potential (community types). As a result, this approach provides a useful language for discussing desired future condition and understanding how restoring natural processes may influence vegetation communities on the landscape. 1-9 Section 1 - Introduction Restoration Plan for the Clark Fork River and Blackfoot River near Milltown Dam- Key analytical technical systems used in this document include the following methods. Flood frequency analyses produced by the U.S. Geological Survey (USGS) (Parrett and • Johnson, 2004) and updated by EMC2 (2005) were evaluated for predicting the bankfull discharge and flood series for streamflow gaging stations on the CFR and BFR. Aerial photograph analyses were completed for the CFR and BFR in the restoration • project area as well as in upstream reaches. Recent color aerial photographs were ® georeferenced using DIME photogrammetric software and served as the base imagery for field maps, river planform analysis, and valley morphology assessment. Time series aerial photos of the CFR from Turah downstream to Milltown Dam were also ® georeferenced in DIME . Historical channel alignments were digitized to assess past channel locations and patterns. River corridor topographic surveys were completed using a combination of ground • survey, bathymetric survey, and photogrammetry. Data were merged to create a digital terrain model (DTM) of the restoration project area. Existing condition modeling was executed using both the DTM and the individual data components (e.g. cross-sections and channel profiles). Hydraulic models were developed to evaluate channel stability, incipient motion of • sediment particles, and sediment transport properties. WinXSPro (West Consultants, 1998), HEC-RAS (U.S. Army Corps of Engineers, 2004), and Microsoft Excel (Microsoft, 2003) were the primary software programs used to develop the models. Bed resistance equations (Bathurst, 1997) and sediment transport equations (presented in Barry et al., 2004) were used to evaluate channel stability and sediment mobility in existing reaches and for the design channel dimensions. Reference reach data and regime equations describing potential channel conditions were • evaluated to develop design channel dimensions. These regime equations based on large datasets included a range of variables including sediment, channel morphology, discharge, and vegetation condition characteristics (Wolman and Leopold, 1957; Millar, 2000; 2005). All hydrology and morphology data were stored and processed using RIVERMorph (RIVERMorph, 2005). 1.4.2 The Reference Reach Concept Proposed restoration designs included in the RP have their basis in several methods including, analog (reference reach), empirical (regime and regional equations), and analytical (physical processes modeling) techniques. The reference reach concept is referred to throughout this document. Reference reaches were surveyed on both the CFR and BFR, and were located in reaches that exhibited conditions believed to represent the “best possible” river corridor conditions. Conditions exemplified by the channel’s dimensions, pattern, and profile; the distribution and characteristics of sediment and sediment loading to the channel; and the riparian 1-10