Restoration of the Clark Fork and Blackfoot Rivers near Milltown Dam : [fact booklet]

8 Pages·2003·2.8 MB·English

by  Montana.Natural Resource Damage Program

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This fact booklet summarizes the Draft Conceptual Restoration
Plan for the Clark Fork River and Blackfoot River Near Milltown Dam.
The State of Montana,in cooperation with the U.S.Fish and
Wildlife Service and Confederated Salish and Kootenai Tribes,
released this plan in May 2003 for public review and input.
Objectives of the Draft Conceptual meandering channels with more floodplain.River flows remain
II
Restoration Plan in the channel up to normal high flow,and then expand onto
the floodplain at higher flows.Both types ofvalley landforms
The Draft Conceptual Restoration Plan for the Clark Fork River exist in the study area as summarized in Table 1.Natural chan-
and Blackfoot River Near Milltown Dam1(DCRP) provides a nels are designed to support natural processes such as sediment
vision ofhow these rivers might be restored ifMilltown Dam transport and deposition,channel adjustments including erosion
and a large portion ofcontaminated sediments behind it were ofbanks,and flooding.However,these processes are less severe
removed.The U.S.Environmental Protection Agency (EPA) and and more predictable in healthy,stable channels like those built
the Montana Department ofEnvironmental Quality (DEQ) have using natural river design.
proposed this removal as the preferred alternative in their April The opportunity exists to recreate a setting similar to historic
2003 proposed remediation or “clean-up”plan for the Milltown conditions at the site.To develop the DCRPand describe the
Reservoir.2The DCRP is a broad scale plan that provides restora- potential river attributes,the two rivers were partitioned into six
tion concepts,draft plan views,elevation information,and reaches based on several criteria,including:1) existing channel and
restoration cost estimates.The DCRPbuilds on the proposed valley type;2) the potential features ofrestored channels;3) the
remediation plan and was developed with the following objectives: availability ofinformation;4) the upstream influence ofMilltown
dam;and 5) the nearest stable point to end the restoration.Figure
■ Restore the confluence area ofthe Blackfoot and Clark Fork
1 and Table 1 identify these reaches and their potential attributes.
Rivers to be naturally functioning and self-maintaining;
Four reaches (CFR1,CFR2,and CFR3 and BFR1) are directly
■ Use natural,native materials,to the extent practicable,
affected by the dam.Restoration ofthe two additional reaches
for stabilizing channels,banks and floodplain;
(BFR2 and CFR4) was included in order to provide a comprehen-
■ Improve water quality by reducing the rate ofrelease sive restoration plan that will be successful in the long-term.
ofcontaminated sediments through bank erosion outside The DCRPproposes a diversity ofwetland habitats.Some
the area covered by the remediation plan; wetlands would remain and others would be created through
■ Provide high quality habitat for fish and wildlife; restoration.Restoring sections ofthe Clark Fork River requires
changing the channels from damaged,braided channels to a
■ Improve aesthetic values in the area by creating a diverse,
single channel.Abandoned stream channels would be partially
natural setting;and
filled,converting open sections to isolated wetlands.These
■ Provide recreational opportunities such as river boating,
wetlands would be fed by flood flows and groundwater.
fishing,and trail access for hiking and bicycling.
Some deviation from historic conditions would be necessary
to protect bridges,limit erosion ofremaining contaminated
A Vision for Restoring Two Rivers:
IIII sediments,and protect newly constructed sections ofriver.
The Conceptual Plan
Rock weirs (Figures 2 and 3) are proposed to maintain riverbed
stability and protect bridge pilings in the Blackfoot and Clark
Fork Rivers near the dam.Rock structures would provide grade
The State proposes restoring the Blackfoot and Clark Fork Rivers control,thereby protecting newly constructed channels above
in the area ofMilltown Dam using natural channel design. and below where Milltown Dam currently exists.These struc-
Natural channel designs restore injured rivers by emulating the tures will also provide high quality fish habitat and recreational
pattern and shape ofhealthy channels and floodplains in valleys boating,particularly in reach CFR1 and the lower halfofreaches
ofsimilar landform.Materials such as native vegetation,trees CFR2 and BFR1.
and rock are used to The natural channel design proposed by the DCRPrelies on
construct or repair existing vegetation and intensive revegetation.This strategy pro-
river channels and vides for bank stability,reduced energy ofwater flowing onto flood-
floodplains so that plains,high quality fish and wildlife habitat,and the aesthetics and
they look and function recreational opportunities found in a natural river setting.It re-
naturally.The pattern establishes native plant communities and inhibits noxious weeds.
and shape ofthe chan-
nel and extent ofthe
Relationship Between Remediation
floodplain depend on IIIIII
and Restoration
the river basin’s water
capacity and valley
landform.Narrow, The relationship between remediation and restoration activities
steep valleys have is both simple and complex.Simply stated,remediation,required
straighter channels by EPA and DEQ,is intended to protect human health and the
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Paul F. gradual valleys have proposed remediation plan at the Milltown Dam Operable Unit
Table 1 Potential Attributes and Estimated Costs of Restoration Actions by Reach
REACH
FEATURE CFR1 CFR2 CFR3 CFR4 BFR1 BFR2
Extent of direct
Duck Bridge Stimson
Downstream point I-90 Bridge Confluence influence of Confluence
Grade Dam
Milltown Dam
Extent of
Extent of direct
Duck Bridge Turah Stimson influence of
Upstream point Confluence influence of
Grade Bridge Dam Stimson Dam
Milltown Dam
and fill
Approximate valley length (ft.) 5,250 3,850 7,000 15,400 5,640 6,500
Moderate– Moderate–
Gradient Low Low Low Low
Low Low
Moderate-
Meandering Moderate High High Moderate Moderate
High
Step-pool;
Instream habitat Step-pool Riffle-pool Riffle-pool Step-pool Step-pool
Riffle-pool
Valley type Narrow Narrow–Wide Wide Wide Narrow Narrow
Moderate,
Moderate, Moderate, Moderate,
Floodplain width & shape sloping – Wide, flat Wide, flat
sloping sloping sloping
Wide, flat
Estimated Restoration Costs (millions) $10.5 $9.2 $4.9 $5.8 $2.9 $5.1
involves two primary objectives:1) protecting human health by restoration activities along Silver Bow Creek downstream ofButte.
cleanup ofthe groundwater aquifer beneath Milltown through The EPA and DEQ have indicated their support for integrating
the removal ofthe most contaminated sediments and the dam’s remediation and restoration actions at the Milltown Dam site.
spillway and radial gate sections;and 2) protecting downstream
fish and aquatic insects from releases ofcontaminated reservoir
Recreational Components of the Restoration Plan
sediments,which occur with ice scour,draw down or high flow IIVV
events.The remediation plan is also designed to comply with
applicable regulations such as water quality regulations. The DCRPenhances many recreational activities for the public.
Restoration actions,in contrast,go beyond remediation actions River boating,fishing,wildlife viewing,hunting and trail access
with the objective ofreturning a site to an uncontaminated, are some ofthe activities that would be improved.A diverse
more natural,“baseline”condition.In addition to the objectives landscape with native plants would also improve aesthetics and
in the remediation plan,the DCRPproposes several objectives further enhance recreational activities.Rock structures would
for restoring and preserving natural resources,as well as enhanc- enhance whitewater boating by producing drops and repeated
ing the enjoyment ofthe site by people. step-pools as well as create excellent trout habitat and fishing
Table 2 summarizes the major features ofremediation and opportunity by scouring pools (Figures 2 and 3).Diverse terres-
changes needed for restoration.The DCRPoffers a more trial and wetland habitats comprised ofnative plants would
detailed,“action-by-action”comparison ofproposed remedia- enhance wildlife use.
tion and restoration. The DCRPalso proposes a pedestrian bridge across the Clark
Many remediation plan elements,such as sediment removal, Fork River at the location ofthe current Duck Bridge grade in
would not be altered under restoration.Other remediation and reach CFR2.This bridge would tie access to the Missoula/Clark
restoration activities at the Milltown Dam site can be combined Fork trails along the southwest bank ofthe Clark Fork River
and coordinated in two ways.First,restoration designs can be between Missoula and East Missoula with the Milltown and
combined with remediation designs.For example,it would be Bonner area communities and the Blackfoot River corridor.
inefficient to have remediation actions build a river channel to
meet clean-up objectives and then have restoration contractors
later remove the remediation-designed channel and construct a
Example of
more natural channel to meet restoration objectives.Second,
a Cable Stay
restoration designs can “augment”remediation designs.An Pedestrian Bridge
example would be increasing the quantity and diversity ofplant- Note that the piers
ings in the floodplain beyond what is planned under remedia- are located outside
ofthe bankfull
tion.Combining the two plans would allow remediation and
channel and the
restoration to be implemented at the same time and reduce the
bridge spans part
costs.An example ofgood coordination is remediation and ofthe floodplain
The bridge would accommodate walkers,runners,and non- location,these structures would severely constrict the floodplain
motorized cyclists.The piers supporting the bridge would be and cause “backwater”conditions and sediment deposition
small and placed outside ofthe active channel to help maintain upstream during flood events.Extensive and costly maintenance
river health and safe boating. after each flood event would likely be needed.Addressing these
Although not detailed in the DCRP,access for launching problems would necessitate a complete change in the natural
boats,more trails,and picnicking are possible amenities that channel design concept,requiring substantial hardening ofthe
would enhance use ofthe area by the public.Further planning channel bed and banks similar to that proposed in the remediation
and public input would help develop these and other ideas. plan.Other probable effects ofleaving the powerhouse and asso-
ciated structures area are detailed in the DCRP.
The proposed remediation plan does not involve removing
Powerhouse Removal and Preservation Proposal the powerhouse.It calls for the removal ofthe spillway and radi-
VV
al gate sections,creating a channel width ofabout 250 feet.This
The DCRPobjectives cannot be achieved with the powerhouse in channel,constructed ofhard engineering structures such as
its current location.Under the DCRP,the powerhouse is within riprap,was designed to contain a 100-year flood event.The pow-
the 5-year floodway (Figure 2).So,the powerhouse,divider block, erhouse would be outside the 100-year floodway.This type of
and north abutment must also be removed.Ifkept in their current channel is contrary to the objectives ofthe DCRP.
Table 2 A Comparison of the Remediation and Restoration Proposals
EPA’s Proposed Remediation Plan Draft Conceptual Restoration Plan
Includes all of Reach CFR 2 and parts of Reaches CFR1 and Includes reaches CFR1, CFR2, CFR3, CFR4, BFR1
BFR 1 — 5,350 feet total valley length. and BFR2 — 43,460 feet total valley length.
1. Remove contaminated sediments from Area I (shown in Figure 1) 1. Same: no additional removal of sediments beyond remedy
to a repository west of the reservoir. is proposed for restoration.
2. Leave Area III channel sediments in place. Sheet pile isolating 2. Remove all sheet piling
Area I sediments will be removed or left in place and cut off
below ground surface.
3. Remove Milltown dam spillway and radial gate structures. 3. Remove all dam structures including powerhouse, divider block
Other dam structures (powerhouse, divider block, and north and north abutment wall and restore the entire area to a natural
abutment wall) would be left in place. channel and floodplain.
4. Establish grade control on the Clark Fork River in the area 4. Establish grade controls throughout all reaches with use of many
of Duck Bridge Grade and on the Blackfoot River near the different kinds of structures to benefit natural channelprocesses,
Interstate 90 overpass. fish habitat, fish passage, floodplain function, boating and other
resource goals. No single massive grade control structures are
planned as proposed under remediation.
5. Excavate a river channel into the alluvium. The channel will be 5. Excavate a new channel into the alluvium that is designed to carry
capable of carrying up to the 100-year flood within its banks. natural channel forming flows (bankfull discharge occurring about
The streambanks will be rip rapped throughout Area I. every 1.5 years). The excavation depth would be less than under
The confluence of the Clark Fork River and Blackfoot River the remediation plan. A floodplain is designed adjacent to the active
will be established upstream of the present dam location. channel to accommodate flood flows including a 100-year flood.
Streambanks would be stabilized using vegetation, rock and log
structures. No riprap or armored banks are proposed. The confluence
of the two rivers would be established upstream from the present
dam location, slightly downstream of the confluence proposed in
the remediation plan.
6. Backfill the floodplain of the Clark Fork River to re-establish a 6. Backfill the floodplain of the Clark Fork River as necessary to re-
floodplain and proper grade. The floodplain would be re-vegetat- establish a floodplain to the level appropriate for the valley setting.
ed with grasses. A more intensive revegetation plan will establish diverse, self-
sustaining native plant communities in the floodplain and riparian
areas. Plantings will include native grasses, forbs, trees and shrubs.
1 Draft Conceptual Restoration Plan for the Clark Fork River and Blackfoot River Near Milltown Dam,prepared for the State ofMontana,Natural Resource Damage Program and the
Department ofFish,Wildlife and Parks,in consultation with the U.S.Fish and Wildlife Service and the Confederated Salish and Kootenai Tribes by Water Consulting,Inc.and Mr.Dave
Rosgen,February 2003.
2 Superfund Clean-up Proposal,Milltown Reservoir Sediments Operable Unit ofthe Milltown Reservoir/Clark Fork River Superfund Site,U.S.EPA,April 2003.
3 Milltown Reservoir Sediments Site Final Combined Feasibility Study,prepared by Atlantic Richfield Company/EMC2,Dec.2002
River
ot
o
kf
c
a
Bl
Figure 1 Milltown Conceptual Restoration Plan
Possible Alignment and
Reach Break Map
Reach Break
Milltown Sediment
Accumulation Areas Proposed Channel
Alignment
0’ 0’ 0’ 0’
0 5 5 0
5 2 2 5
2 1 0 1 2
Cl
ar
k
F
or
k
Ri
ver
Sediment Accumulation
Area Boundary
Reach Alignment
Reach Break
The State understands the importance the powerhouse repre- Milltown powerhouse
sents to the history ofthe towns ofMilltown and Bonner,and during 1908 flood
Removing the power-
the Clark Fork River.Various preservation alternatives exist to
house is a necessary
retain the historic value ofthe powerhouse.One alternative is to
step to fulfill the goals
establish a museum or park with a replica ofthe powerhouse ofthe DCRP,however
lfolocoadtepdl aninea ur nthdee rc tuhrer eDnCt lRoPca.tTiohne ,rbeuptli coau tcsoiudeld t hinec 1lu0d0e-y peaarrts of Publishing ptou cbolincs iindperu tid ies aisn vtoited
the original structure such as generators.The State intends to Histories psirgensiefricvaen ictse .historical
itnivveo flover tthhee ppuowbleicrh ionu tshee adnedc ihsiiostno raisc tpor wesheravt aisti othne. best alterna- Pictorial
Figure 2 Milltown Conceptual Restoration Plan
Proposed channel and floodplain widths
with possible in-channel structures
Bankfull Channel
L
Active Floodplain E
G
5-Year floodplain E
N
In-channel
D
Structures
0’ 0’ 0’ 0’
0 5 5 0
9 4 0 4 9
Figure 3 In-channel structures
Rootwad and Log Vane W-Weir
Bank Stabilization Grade Control
Natural channel design
uses a variety ofstructures
for bank stabilization,
grade control,and fish
habitat.These structures
include the use ofnative
vegetation,trees,and
rocks and are designed to
mimic features that occur
naturally in stable rivers.
Converging
Double Wing Deflector J-Hook Vane Rock Clusters
m
& Liz Larco
Craig
Natural channel design will enhance water
recreation opportunities like kayaking and rafting.
VVII Restoration Costs and Timeline
The estimated costs to implement the DCRPwere prepared,in
part,using unit cost estimates developed by the U.S.Army Corp
ofEngineers for the proposed remediation plan and the costs
presented in EPA’s 2002 Focused Feasibility Study.3Costs for sta-
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&
The total cost for all six reaches is estimated at $38.4 million.The man
total cost ofrestoring the four reaches closest to the dam is esti- Nor
mated at $27.5 million.It is believed that significant cost savings The confluence of the Blackfoot River with the Clark Fork River.The
can be achieved by integrating the restoration and remediation Old Milwaukee Railroad bed and the Milltown Powerhouse are on the left.
plans.With these savings,the total cost for the entire restoration The towns ofBonner and Milltown lie below the mountains.
project and for restoring the four reaches closest to the dam
would be significantly reduced.
These estimates were prepared without detailed ground sur- Figure 4 Design Phases and Public Input
veys.In addition,about 55% ofthe restoration cost estimate is
earthwork,and is subject to modification.At this point,several
assumptions and contingencies have been applied to the esti-
Phase I Draft Conceptual
mates,resulting in a significant level ofuncertainty.Therefore,a
Restoration Plan
contingency of25% is included in the cost estimates.The DCRP
cost estimates
➡
do not include
costs for any
land acquisi- Public Review Process/
tions or ease- Public Meetings
ments that
might be needed ➡
to implement
restoration
Revised Conceptual
actions or for
Restoration Plan
the building ofa
powerhouse Bauer ➡
replica. Tom
The DCRP Numbers ofbull trout,like this one sampled by a
Phase II
provides for FWP biologist on the Blackfoot River,have declined
restoration since Milltown Dam was built.The DCRPobjective Data Collection Activities
design and to provide high quality habitat would help this
implementation species rebound in its native waters as well as ➡
enhance angling for other trout.
to occur in a
phased approach Draft Phase III
over an 11-year period in coordination with the proposed
Design Plan
remediation.Phase I involves finalizing the DCRPafter public
comment.Phase II design would refine and validate the DCRP ➡
with additional field data,analyses and surveys.Phase III would
be the final design phase,which will include peer review,
Public Review Process/
detailed drawings and information adequate to permit and
Public Meetings
implement the project.The design phase is anticipated to take
three years.Constructionwould then begin in the upstream
➡
reaches of the two rivers and move downstream over an eight-
year period.The remediation design and sediment removal
would go forward at about the same time.Dam removal and Final Phase III
work in CFR1 and BFR1 would occur in the last two years Design Plan
under both remediation and restoration projects.
The State will hold two public meetings on the DCRPfor the
VVIIII Public Participation
purpose offurther describing the draft plan to the public and
receiving public comment:
The State is seeking public input on the DCRP.Please send
your written comments by Friday,August 15,2003 to Doug
Wednesday, June 11, 2003 Wednesday, June 18, 2003
Martin,Natural Resource Damage Program,P.O.Box 201425,
Saint Ann’s Church City Council Chambers
Helena,MT 59620-1425,faxed to 444-0236 or emailed to 9015 Highway 200 Missoula City Hall
[email protected]. Bonner, Montana 435 Ryman Street
Copies ofthe DCRPare available for viewing at the public 7:00 PM Missoula,Montana
libraries in Missoula,Anaconda,Butte,and Deer Lodge,the 7:00 PM
Bonner School Library,the University ofMontana library,the
The State recognizes that landowner cooperation and approval
Missoula City County Health Department,and the Montana
will be necessary to assure the success ofthis restoration project.
FWP Missoula office.Copies can also be downloaded from the
In the next few months,State NRDP and Montana FWP represen-
NRDP website at under “Montana Lands”or from the FWP
tatives will meet with landowners in the restoration project area
website at under “Public Notices.”A CD version ofthe DCRPis
to provide information and obtain input on the DCRP.
also available upon request from FWP or NRDP at the contacts
State representatives are willing to meet with area groups
indicated below.
interested in knowing more about the DCRP.To request a meet-
Figure 4 provides a general flow chart for the restoration
ing or obtain more information,contact:
planning process that highlights public input opportunities.
Public input at this initial phase ofrestoration planning is Doug Martin Pat Saffel
important to help develop the best blueprint for restoring the NRDP Montana FWP
P.O.Box 201425 3201 Spurgin Road
Clark Fork and Blackfoot Rivers in coordination with the pro-
Helena,MT 59620-1425 Missoula,MT 59804
posed remediation.The State will also solicit public input as
[phone] [phone]
part ofdeveloping a final design plan for the restoration actions. [email protected] [email protected]
Copyright ©2003 by the State of Montana
Graphic design and map illustrations produced by Luke Duran, Helena,Montana • Cover photo by Craig & Liz Larcom
NRDP
Natural Resource Damage Program
P.O.Box 201425
Helena,MT 59620-1425