Aquatic%20Restoration%20Rivers

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Aquatic RestorationRivers

• Unit 6, Module 25 July 2003

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Objectives

• Students will be able to
• describe current statistics regarding the
  physical degradation, water quantity, and water
  quality of streams.
• identify goals and considerations of stream
  restoration.
• evaluate the factors that influence the dynamic
  equilibrium of streams.
• provide examples of potential causes of bank
  erosion.
• describe restoration techniques used to alter
  accelerated bank erosion.
• identify potential causes and restoration
  measures for altered width/depth ratios in
  streams.
• identify potential causes and restoration
  measures for altered sinuosity in streams.
• identify potential causes and restoration
  measures for altered flow in streams.
• identify potential causes and restoration
  measures for altered temperatures and dissolved
  oxygen levels in streams.

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Overview

• Introduction
• Lake Restoration
• Stream Restoration
• Wetland Restoration

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Restoration philosophy

• Process of returning a river or watershed to a
  condition that relaxes human constraints on the
  development of natural patterns of diversity.

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Restoration philosophy

• Restoration does not create a single, stable
  state, but enables the system to express a range
  of conditions dictated by the biological and
  physical characteristics of the watershed and its
  natural disturbance regime
• (Frissell and Ralph 1998)

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State of the Streams

• Approximately 3.2 million miles (5.15 km) of
  streams in the U.S.
• Only about 2 of streams remain in relatively
  undisturbed, natural conditions
• Less than 1/3 of 1 preserved as national and
  scenic rivers
• (Echeverria 1989)

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Physical Degradation

• 40 U.S. perennial streams affected by siltation

Miles Percent Siltation 265,000
39.8 Bank erosion 152,000 22.8 Channel
modifications 143,500 21.5 Migratory blockages
9,700 6.0 Bank encroachment 9,000 1.4
(Modified from Judy et al. 1984)
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Water Quantity Issues

• 40 U.S. perennial streams affected by low flows

Miles Percent Diversions Agricultural 105
,000 15.8 Municipal 10,700
1.6 Industrial 3,290 0.5 Dams Water
supply 30,800 4.6 Flood control 26,900
4.0 Power 24,800 3.7 (Modified from Judy
et al. 1984)
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Water quantity issues

• Over 2.5 million dams in the U.S. (Johnston
  Associates 1989)
• Only about 75,000 dams more than 6 feet tall
  (USACE 2002)
• 600,000 stream miles are under reservoirs
  (Echeverria 1989)

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Water Quality Issues

• Over 41 of nations streams impacted by
  turbidity

Miles Percent Turbidity 277,000 41.6 Elev
ated temperature 215,000 32.3 Excess
nutrients 144,000 21.6 Toxic substances
90,900 13.6 Dissolved oxygen
75,400 11.3 pH 26,000 3.9 Salinity
14,600 2.2 Gas supersaturation 5,500
0.8 (Modified from Judy et al. 1984)
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Stream restoration goal

• To alter biophysical processes and structures to
  promote a dynamic equilibrium with diverse
  abundant aquatic species and channel stability

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Other stream restoration considerations

• In addition to in-stream habitat, current
  restoration projects should consider
• Geomorphology at a watershed scale
• Inclusion of physical scientists
  (interdisciplinary)
• Fluvial geomorphology, sediment transport,
  channel hydraulics, hydrology
• Historical information to document the evolution
  of the channel
• How processes have been altered by human
  activities in the watershed

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Stream channel stability

• Morphologically defined as the ability of the
  stream to maintain, over time, its dimension,
  pattern, and profile in such a manner that it is
  neither aggrading nor degrading and is able to
  transport without adverse consequences the flows
  and detritus of its watershed (Rosgen 1996)

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Dimension (cross section)

• Width/depth ratio at bankfull stage
• Entrenchment ratio
• Width of flood prone area/bankfull width
• Dominant channel materials
• sizes or types

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Pattern (plan view)

• Sinuosity
• stream length/valley length
• Meander width ratio (secondary measurement)
• meander belt width/bankfull width

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Profile (longitudinal)

• Slope
• difference in elevation/stream length
• Bed features (secondary measurement)
• Description of characteristics such as
  riffle/pools

• Image Stream Corridor Restoration Principles,
  Processes, and Practices, 10/98, by FISRWG.

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Dynamic equilibrium

• Qs . D50 in balance with Qw . S
• Qs sediment load Qw stream discharge
• D50 sediment size S stream slope
• (Lane 1955)

• Image Stream Corridor Restoration Principles,
  Processes, and Practices, 10/98, by FISRWG.

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Dynamic equilibrium

• Qualitativelyvariables are in balance at channel
  equilibrium. If one factor changes, the other
  variables change to reach a new equilibrium.

Sediment load Sediment size
Stream discharge Stream slope
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How would the stream respond. . .

• if stream discharge (Qw) increased?
• Width, Depth (Dimension)
• Meander wavelength (Pattern)
• Slope (Profile)
• if sediment load (Qs) increased?
• Width, Depth (Dimension)
• Meander wavelength? (Pattern)
• Slope (Profile)

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How would the stream respond. . .

• if stream discharge (Qw) increased and sediment
  load (Qs) decreased?
• Width, Depth (Dimension)
• Sinuosity, Meander wavelength (Pattern)
• Slope (Profile)

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Potential causes of bank erosion

• Vegetative clearing
• Channelization
• Streambed disturbance
• Dams
• Levees
• Soil exposure or compaction
• Overgrazing
• Dredging for mineral extraction
• Woody debris removal
• Piped discharge
• Water withdrawal

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Measuring bank erosion potential

• Measure the following variables then rate from
  very low to extreme
• Bank height/bankfull height
• Root depth/bank height
• root density
• Bank angle (degrees)
• Surface protection
• Soil stratification
• Particle size

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Restoration Techniques for Accelerated Bank
Erosion

• Bank shaping
• Fascines
• Live Staking
• Root wads

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Bank shaping

• Purpose
• Alter the bank angle so that bank angle (degrees)
  that it is stable
• Efficacy
• Usually necessary before vegetation can be added
  to the bank

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Fascines

• Live shrubs (willow) bundled together with rope
• Purpose Vegetate eroded banks providing
  stabilization and habitat (root density and soil
  surface protection)

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Fascines

• Efficacy
• Simple and works immediately because shrubs grow
  rapidly to hold soil in place
• Higher success if allowed to grow for one year
  before water rerouted
• Works well by itself for small streams

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Live staking

• Purpose Vegetate eroded banks providing
  stabilization and habitat (root density and soil
  surface protection)

• Efficacy
• Effective with small erosion problems or in
  combination with brush mattresses, fascines, or
  erosion control blankets
• Best if allowed to grow for one year before water
  rerouted

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Live staking
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Root wads

• Purpose
• Deflects current away from unstable banks
• Provides complex instream cover for fish and
  substrate for aquatic macroinvertebrates
• Efficacy
• Effective with larger erosion problems

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Stream restoration case study 1

• Vermilion River, Minnesota
• Impact - bank erosion
• Over 220 feet in length, 8 feet above water level
  in one spot
• Receded over 6 feet in 1 year

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Vermilion River restoration

• Goals of 1997-2000 Restorations
• Reduce the sediment load to improve downstream
  water quality
• Create more productive fish habitat
• Protect the adjacent property
• Provide a demonstration project for other erosion
  problems on the Vermillion River

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Vermilion River Methods

• Fascines
• Rootwads

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Vermilion River Methods

• Bank shaping
• Boulder vanes

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Live Staking
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Vermilion River restoration

• Evaluation
• Property is protected
• Valuable as demonstration projects
• Clear objectives
• But, were objectives based on stream morphology
  or just chosen because the techniques are new?
• Unknown if fish habitat and sediment loads have
  been measured

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Altered width/depth ratio

• Potential causes
• Vegetative clearing
• Water withdrawal
• Channelization
• Streambank armoring
• Streambed disturbance
• Dams
• Levees
• Hard surfacing

• Roads and railroads
• Overgrazing
• Reduction of floodplain
• Dredging for mineral extraction
• Bridges
• Woody debris removal
• Piped discharge

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Altered width/depth ratio restoration

• Wing deflectors
• Purpose
• Reduces the width to depth ratio
• Forms scour pools and increases velocity and
  depth providing habitat
• Single wing deflectors can direct current away
  from eroding banks

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Wing Deflectors

• Efficacy
• Effective, but require monitoring and
  maintenance

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Potential causes of altered sinuosity

• Channelization
• Streambank armoring
• Streambed disturbance
• Dams
• Levees
• Hard surfacing
• Reduction of floodplain
• Land grading
• Woody debris removal
• Piped discharge

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Sinuosity restoration

• Carbon Copy Technique
• Restore stream to the pattern before disturbance
• Use historical aerial photographs
• May not be stable with current conditions
• Empirical relationships
• Measure bankfull width and discharge then
  calculate meander length and sinuosity
• Use if soil conditions have remained the same

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Sinuosity restoration

• Systems approach
• Analyze meanders on a watershed scale
• Evaluate geomorphology
• Compare to find dominant meander wavelength
• (Fourier analysis)

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Potential causes of altered flow

• Vegetative Clearing
• Channelization
• Streambank armoring
• Water withdrawal
• Dams
• Levees
• Soil exposure or compaction

• Irrigation or drainage
• Hard surfacing
• Overgrazing
• Roads and railroads
• Reduction of floodplain
• Land grading
• Piped discharge

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Altered Flow Restoration

• Dam Removal
• Sediment
• Needs treatment if contaminated
• Concentrations of nutrients in sediment probably
  high
• Hard to predict what will happen when dam removed
• Stream type will evolve after dam removal

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Dam removal

• 2. Temporary coffer-dams built to work behind

• 1. Breaching of dam

• 3. Sediment removal

• 4. Disposal of timbers off-site

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Increased Water Temperatures and Reduced Instream
Oxygen Concentrations

• Potential Causes
• Vegetative Clearing
• Channelization
• Streambank armoring
• Water withdrawal
• Dams
• Levees

• Hard surfacing
• Overgrazing
• Reduction of floodplain
• Dredging for mineral extraction
• Woody debris removal
• Piped discharge

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Altered Temp and DO Restoration

• Revegetation of riparian areas
• Site preparation
• Possibly re-grade bank
• Control existing exotic species
• Check the soil conditions (lack of nutrients)
• Tillage and mulching may increase planting
  success and decrease weediness
• Best management practices such as fencing
  livestock

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Revegetation

• Method
• Use a reference site
• Determine species diversity, horizontal and
  vertical structure of canopy, sub-canopy,
  understory, and ground-layer
• Determine which plants will recolonize site
  naturally
• Small existing plant populations, seed bank,
  nearby populations of wind and animal dispersed
  species a reference site

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Revegetation

• Planting techniques
• Final density, multi-stage, dense initial, or
  accelerated succession
• Works well as a community stewardship project

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Revegetation

• Other considerations
• Landscape connectivity to existing habitats
• Increase in woody debris could be positive
• How will nutrient cycles be impacted?

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Revegetation

• Management
• Vital to water plants
• Continue to control exotic species
• Consider impacts of herbivores

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Stream restoration case study 2

• Weminuche River, CO
• Drains 30 mi2 in southwestern Colorado
• Shows how observation and understanding of stream
  classification and historical information helped
  set specific goals to create channel stability
  based on the stream type

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Weminuche River, Colarado

• Impacts of 1978 riparian vegetation removal
  (government cost-share program increasing grazing
  areas) caused channel instability
• Width/depth ratio increased form 14 to 35
• Meander width ratio decreased from 10 to 2
• Down valley meander migration rate increased
  approximately 8 feet/year
• Increased sediment supply (erosion) and decreased
  transport capacity led to excessive bar
  deposition (aggradation)
• Meander length and radius of curvature increased
  (sinuosity decreased)
• Fish habitat and aesthetic values decreased
• Poised to cut through banks to create new main
  channel

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Weminuche River, Colorado

• Funded as a mitigation
• Goal of 1987 restoration
• Return stream function and channel stability to
  benefit brook trout
• Techniques
• Recreated dimension, pattern, profile of a
  stable stream type
• Studied pre-disturbance features, developed
  empirical relationships

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Weminuche River, Colorado

• Evaluation
• Channel stability returned
• Width/depth returned to 14
• Slope from 0.01 to 0.005
• Sinuosity returned to 2.0
• Meander wavelength established at 10 bankfull
  widths
• Meander radius of curvature at 2.8 bankfull
  widths
• Willow transplanted along streambanks
• Great example of considering stream morphology
  instead of just addressing bank erosion in small
  sections

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Stream restoration case study 3

• Merrimack River,New Hampshire Massachusetts
• Drains 5010 mi2 in NH and MA flowing to the
  Atlantic Ocean
• Demonstrates a watershed approach to stream
  restoration of point and non-point pollution

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Merrimack River, MA and NH

• Impact from human use
• 1930s contamination from pollutants such as raw
  sewage, paper mill waste, tannery sludge
• Too polluted for domestic water supply uses
• One of the 10 most polluted streams in nation

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Merrimack River, MA and NH

• Passing of the Clean Water Act of 1977 (water
  quality standards) and formation of the Merrimack
  Watershed Council brought about restoration
  actions
• 84 wastewater treatment plants constructed
• Majority (85) of industries complying with
  federal standards
• Suspended solids decreased (by 1/3 in one reach),
  coliform bacteria and organic loading
  concentrations reduced, dissolved oxygen levels
  increased

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Merrimack River, MA and NH

• Future goals of the Merrimack Watershed Council
• Improve the protection of present and future
  water supply
• Improve water quality throughinteragency
  cooperation on water quality issues
• Continue work on flow issues
• Promote growth management within the Watershed
• Continue to improve access to the River and the
  acquisition of open space

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Merrimack River, MA and NH

• Evaluation
• Good example of a watershed scale restoration
  with cooperation between multi-state agencies and
  organizations
• Reminder that some industries still not in
  compliance with water quality standards set in
  1977
• Shift from a point pollution focus to non-point
  and water quantity issues

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