appendix aa123.g.akamai.net/.../11558/www/nepa/80624_fsplt2_149045.pdfcomanche creek native trout...

Comanche Creek Native Trout Habitat Restoration Project Appendix A 1

Appendix A

Toolbox for watershed restoration

Listed below are methods that have been developed for stabilization of watershed areas impacted by past

land uses. These methods have application in wetlands, dry uplands and in stream channels. One or more

of each of these methods may be used in treatment areas in the Comanche Creek watershed. Treatment

descriptions and diagrams are provided.

Grade Control Structures

Grade Control structures are used to prevent down-cutting of a channel or to raise the grade of a channel

or swale. These structures are grouped together as “grade controls”, and include the Rock Check Dam,

One Rock Dam, Filter Weir, Media Luna, Rock Plug, Sheet Piling dam, and Straw Bale Filter Dam. The

different names of the structures reflect the details of construction and the unique positioning and purpose

of each structure. In general, raising the grade of a channel raises the water table, wets a larger area and

encourages the growth of wetland vegetation. More vigorous vegetation, in turn, stabilizes the grade

control structure, and over time, the structure disappears beneath the expanding wetland.

With the exception of the Sheet Piling Dam, Check Dam and Straw Bales, each of the above structures

are constructed from various sizes of rocks placed one rock high, with the height of the structure limited

by the size of the largest rock. Placing the rocks only one rock high greatly reduces the chance of the

rocks rolling off the structure, and makes for a more stable grade control. Each structure is built so that

the lowest row of rocks acts as a splash pad and prevents scour erosion at the base of the structure. These

structures are built using hand tools such as shovels, picks, digging bars and utilize either wheel barrows

or pickup trucks to transport rock to work sites

Rock Check Dams may be either small to moderate in size (constructed with hand tools and/or with a

backhoe or small bulldozer) or may be built with a D6 bulldozer to include the full channel width (in

ephemeral drainages only) and include the first terrace floodplain bench. Typically only the smaller sized

check dam will be used for most restoration sites and could be constructed with native rock or soils. The

smaller dams are usually less than 2-ft in height and designed to be porous to allow for slow water

percolation through the structure. The larger dams would be designed to significantly slow water

movement, thereby increasing sediment capture and wetland vegetation recovery. The larger dams are not

designed for long-term water storage but are expected to fill in with sediment over time and be overtaken

by wetland vegetation recovery.

A Filter Weir (One Rock Check Dam/Boulder Weir) is designed to raise the bed of a gully by trapping

sediment. It is used when the channel bed is primarily gravel or cobble. These are built in three sections

from several parallel rows of boulders placed in a channel bed at right angles to the direction of water

flow.

A Media Luna is used to disperse water flow from sheet erosion. “Sheet flow spreaders” have the tips up

to disperse channelized flow while the “Sheet flow collectors” are constructed tips down to create a

transition between sheets flow and channelized flow at the heads of rills and gullies.

Straw Bale Filter Dams are used to re-establish wetlands by promoting wetland vegetation establishment

in areas that had been impacted by wetland soil loss. The straw dams are installed in the wetland channel

to help slow water flow, capture sediment, increase organic content and create a stable growth medium

for wetland grasses. When available, wetland coir logs and Carex sp. sod mats will be used in conjunction

with straw bales. Straw bales will often be used in conjunction with soil amendments to increase the

capacity of the treatment site to encourage wetland vegetation re-establishment. Fencing of this structure


may be necessary to prevent damage by trampling or consumption by large ungulate grazers (elk and

livestock).

Sheet Piling Dams are metal structures that are pounded into the drainage channel and adjacent floodplain

to establish a grade control height. These structures are installed by using heavy machinery and can be

adjusted in height over time either by cutting or adding to it. This treatment method would be used to

anchor the gradient change of a perennial stream channel where associated expansive wetlands are in

danger of permanent loss due to incision of the perennial water channel. Large rock rip rap and graded

aggregate would be used downstream of the sheet piling to dissipate water energy and to protect the sheet

piling structure. Construction would require an excavator to prep the site and install the large rock rip rap

and graded aggregate. Small dump trucks (10 yard capacity) would be used to deliver rock material.

Maintenance of these structures may be needed over time to repair the effectiveness of a given treatment.

Maintenance would include adding new material to the treatment site, rearranging existing materials,

and/or the addition of mulch or fencing to protect the site until it is stabilized.

Headcut treatments

Many of the gullies and eroded channels found in tributaries of Comanche Creek are started by a headcut

(headward, or upstream cut). A headcut is a steep, eroding cut through the wetland soil that concentrates

water flow and causes a plunge pool to develop at the base of the cut. Through a combination of splash

erosion of the falling water, freeze and thaw erosion, and soil piping, the soil at the face of the headcut is

constantly eroding and being carried downstream. As the headcut moves up-valley, the channel that has

eroded becomes a gully and the water table drops to the bottom elevation of the headcut. The headcut

causes the soil area upstream and adjacent to the headcut to become drier; the vegetation weakens due to

water stress, roots become exposed, desiccate, and dieback. The erosive face of the headcut expands

laterally and advances upslope because the root masses have died back and are no longer able to bind soil

particles.

A number of headcut treatments have been proposed to address the concentration of water at the headcut

and re-vegetate the bare soil at the slope of the headcut. These treatments include; Worm Ditch, Zuni

Bowl, Rock Mulch Rundown, Log and Rock Stepdown, Straw Bale Filter Dams, and Earthen/Aggregate

Fill and Mulch Cover. Each of these techniques repairs the headcut by a combination of effects that

redirect surface flow away from the headcut, by reducing the concentration of water at the headcut, and

removing the erosive force of the water drop from the top of the headcut to the bottom of it. The final goal

of all of these treatments is a wider, gently sloping channel that can grow wetland vegetation that resists

headcut erosion. In the case of Straw Bale Filter Dams, only weed free certified straw will be used.


Maintenance would include re-digging or cleaning out a worm ditch, adding new material to the treatment

site, rearranging existing materials, and/or the addition of mulch or fencing to protect the site until it is

stabilized.

Channel reinstatement techniques

In addition to the progression of headcuts, many of the swales, wetlands and channels in the Comanche

Creek drainage and tributaries are impaired by gullying and channel erosion due to old roads, cattle trails

or road crossings. Formerly healthy slope wetlands have downcut to a narrow gully channel with a trickle

of water, effectively dissecting the wetland and causing a net groundwater loss. The most effective and

productive restoration techniques involve restoring the water to its former channel and elevation by a

number of channel reinstatement techniques. These techniques include Channel Plug, Plug and Pond,

Worm Ditch, and Historic Meander Channel.


Each situation is unique, but all involve blocking or restoring the headcut of the gully with a grade control

or headcut treatment, and a channel reinstatement technique to restore the water to its former channel

elevation. The channel reinstatement raises the water table to its pre-impact (historic) level and restores

groundwater storage capacity in the adjacent stream banks and wetlands. These techniques have the

capacity to create many acres of wetlands downstream of the treatment. The wetlands upstream of the

headcuts are also protected by these techniques, as the headcut is starved of the erosive forces.


Maintenance would include re-digging or cleaning out a worm ditch, relocating the treatment site as the

treated area responds to the treatment, adding new material to the treatment site, rearranging existing

materials, and/or the addition of mulch or fencing to protect the site until it is stabilized.

Deflector Treatments

The Induced Meandering stream restoration techniques use the power of flowing water and sediment to

re-meander a channel that has been straightened. Deflector treatments induce the channel to meander in a

Sine wave pattern. A meandering channel initiates the evolution of a healthy stream channel, creates and

expands floodplains, and increases alluvial storage. Sediment builds point bars, increasing the amount of

healthy riparian vegetation, leading to a reduction in water temperature due to shade. The force of

floodwaters is dispersed by the meandering form of the channel and by erosion against the outside

meander bends, and the downward force of the channel is reduced, preventing gullying and downcutting.

Meandering channels are found only when the slope is less than 4% and usually less than 2%. These

techniques will be used only in the flattest tributaries and the main channel of Comanche Creek. The

deflector treatments used include Post Vanes and Picket and Boulder Baffles.


Maintenance would include extending the treatment site as the treated area responds adding new material

to the treatment site, rearranging existing materials, and/or the addition of fencing to protect the site until

it is stabilized.

Live Vegetation

Many of the erosion features in the Comanche Creek watershed can be repaired in part or wholly by

planting live vegetation to anchor soil and arrest headcutting. This includes the use of wetland sod mats,

wetland sedge plugs, live willow fascines, live pole plantings. Most techniques used in the watershed will

include some live vegetation as “finishing material”. The vegetation will mostly be obtained on-site from

an area that will quickly re-grow by clonally propagated wetland vegetation. Source material could also

come from a USDA Plant Material Center and/or use of commercial sources of materials that fit within

the species composition that naturally occur in the area. Willows and cottonwoods will be obtained

nearby within the watershed from an area that has sufficient quantities.

Maintenance of these live vegetation plantings may be needed over time to replace material that died due

to planting shock and to effect the repair of a given treatment. Maintenance would include re-digging and

replanting live material on the treatment site, adding new material to the treatment site, rearrangement of

existing materials, and/or addition of mulch or fencing to protect the site until it is stabilized.

Seeding and Mulching

All the restoration techniques used in the Comanche Creek watershed may benefit from re-seeding and

mulching techniques. Seeding treatments include native seed mixes, and seed mats. Mulch will typically

be some form of certified weed free native straw or hay from a wetland grass hay source but may also

include woodchips, shredded wood fiber, jute netting, coarse woody material (crushed branches to small


logs) and even soil or aggregate cover. The seed mixture will include a number of species native to the

area.

Application of seed will use broadcast methods such as backpack or hand spreaders if the area is small in

size. All treatment sites are typically small (less than 0.5 acres) in size. The cumulative acreage of sites

treated in a given year could potentially justify use of a hydro seeder/mulcher. Use of a hydro

seeder/mulcher would likely be rare in occurrence and would be restricted in use due to road access

limitations.

The mulching techniques will provide shade, conserve soil moisture and protection from the elements so

that the seeds will germinate and survive easily. Mulching will also ultimately increase the organic

content of the soil at the treatment site and aid in restoration of the vegetation at the site. Mulch materials

will be weed free and may include a variety of either natural or manmade materials such as straw, hay

(from wetland or riparian pastures), jute netting, gravel, soil high in organic matter, coarse shredded wood

fiber/chips.

Maintenance of seeding and mulching areas may be needed over time to repair the effectiveness of a

given treatment. Maintenance would include re-seeding and/or re-mulching a site until it is stabilized.

Maintenance would also include monitoring of seeded sites for the presence of noxious weed species.

Wetland species that may be used include: Aquatic sedge (Carex aquatilis), Nebraska sedge (Carex

nebraskensis), Ovalhead sedge (Carex microptera) and Millet woodrush (Luzula parviflora). Riparian

species that may be used include: Alpine timothy (Phleum alpinum), Tufted hairgrass (Deschampsia

caespitosa), and Ovalhead sedge (C. microptera). Upland species that may be used include: Thurber

fescue (Festuca thurberi), Idaho fescue (Festuca idahoensis), Mountian muhly (Muhlenbergia montana),

Timothy (Phleum pratense), Muttongrass (Poa fendleriana), and Threadleaf sedge (Carex filifolia).

Fencing Treatments

Many of the erosion control and channel restoration treatments that will be implemented at Comanche

Creek will need to be surrounded by fencing to prevent elk and cattle from harming the treatment site or

eating the mulch or new vegetation that is responding to the restoration technique. In some cases fencing

alone would be the restoration treatment for the site to allow impacted soils and vegetation to recover

from historic impacts regardless of source of impact. Construction of fence sites may require either use of

hand tools and hand labor or may include use of a pickup truck, to deliver materials, and tractor or

backhoe to dig or fill post holes.

Some of the treatments may only require temporary fencing for a short duration (5 to 10 years) until the

restoration treatment is complete. Other fencing treatments may become a permanent feature since it

protects a key location of springs, seeps, or unique wetlands such as fens that are fragile to ungulate

impacts.

Drift Fencing will also be used as a restoration technique to protect stream meander bends from livestock

while they move between pastures. This technique forces grazing animals, elk and cattle, to meander their

trails and minimize the impact on landform and surface flow patterns. Short segments of fence placed

parallel to eroding banks deter trampling and encourage revegetation. The fencing techniques that will be

used at Comanche Creek include Post and Pole Fencing, Post and Wire Fencing, Drift Fencing, Hemi

Fencing and Exclosure Fencing.

Maintenance of these fence structures may be needed over time to keep them protecting a treatment area.

Maintenance would be needed to repair damage caused by normal weathering and by damage caused by

animals, humans, and flood events. Maintenance would include replacement of fence materials and posts


and may include changing the size and shape of a fencing area to adjust to: vegetation growth due to

treatment, change in trailing patterns by ungulates due to structure placement. Maintenance may also

include use of a tractor or backhoe to deliver materials and dig/fill posthole locations.

Road Treatments

The erosion found in the tributaries of Comanche Creek was caused by historic land uses that

concentrated water and created the conditions for headcutting and gully erosion. Many of the historic

trails and roads remain and continue to concentrate water and cause erosion downstream and upstream of

the trail or road. The solution to this water concentration is to control the grade of the erosion and re-

spread the water across the landform.

The road treatment techniques that will be used include Earthen/Aggregate Fill and Mulching (of road

cutbanks), Rolling Dip, Sediment Traps, and Road Crossing/Hardening Repair (Armored Cross Drains)

and Water Bars. These techniques have been used in many places in the Valle Vidal and have survived

seasons of erosion and runoff. The Earthen/Aggregate Fill and Mulch and Rolling Dip techniques are

typically built out of native soil, while the Road Crossing Repair technique generally requires an amount

of rock aggregate fill for stabilizing the roadbed within the drainage channel. Sediment traps are small

catch basins constructed to collect road drainage in areas where there is insufficient vegetative buffer to

filter road born sediments before it reaches perennial waters.

All of these techniques typically require the use of heavy equipment such as a light duty bulldozer and/or

a backhoe to transport material and shape it to meet the design of the site. On occasion, a heavy duty

trackhoe might be needed depending upon the size of the material needed and treatment site conditions. A

small 10-yard dump truck will be used to haul needed aggregate/soil material to the treatment sites.


Maintenance would include re-shaping rolling grade dips on roads, and repairing road drainage crossings

that may degrade over time due to water flowing in the drainage channel. Maintenance would typically

require using heavy equipment such as a light duty dozer, backhoe and/or a trackhoe for sites that need

major repair. Maintenance would also include adding new material aggregate material to the treatment

site, rearranging of existing materials, and/or the addition of mulch or fencing to protect the site until it is

stabilized.


Treatment Diagrams

Grade Control Structures

Rock Check Dam

Rock Check Dams are used when it is necessary to slow the flow of water across a swale or channel. In

addition to slowing the velocity of concentrated flows, they also capture sediment from the drainage area.

These Rock Check Dams are most effective when used with other erosion control measures.

One Rock Dam

A One Rock Dam is a grade control structure that works to reduce water velocity, shear stress, and scour

depth. The structure is one rock deep, several rows wide, wide as bankfull width, and no taller than 1/3

the channel’s bankfull depth. Rocks are uniform in size, with gaps between rocks filled to the vertical

level of the structure with small rocks and gravel. This chinking helps stabilize the structure until the

interstice spaces fill with fine bedload particles. This final filling will provide a substrate for subsequent

vegetation which will further anchor the structure to the channel.


A Filter Weir (Rock Check Dam/Boulder Weir) is designed to raise the bed of a gully by trapping

sediment. It is used when the channel bed is primarily gravel or cobble. These are built in three sections

from several parallel rows of boulders placed in a channel bed at right angles to the direction of water

flow.


Media Luna

A Media Luna is used to disperse water flow from sheet erosion. “Sheet flow spreaders” have the tips up

to disperse channelized flow while the “Sheet flow collectors” are constructed tips down to create a

transition between sheet flow and channelized flow at the head of rills and gullies.

Straw Bale Filter Dams (Straw Bale Falls) are suitable for the remediation of small headcuts. These act

to reduce the impact of water by forcing it to move more slowly through the porous structure. The straw

bale is a suitable media for growth of wetland vegetation. Consider that wildlife and livestock will graze

the bales of the structure and plan to fence the site accordingly.


Headcut Treatments

A Worm Ditch (also called a Bypass Channel) is constructed to starve a headcut of the water that is

causing excessive erosion. A Worm Ditch is started above the headcut in a valley broad enough to allow

for space for the Worm Ditch between the down-cutting channel and the hillslope. The length of the

worm ditch should be two times the length of the valley channel. The re-entry point to the down-cut

channel should be well armored with rock or a Zuni Bowl.

A Zuni Bowl is made of rock-lined step falls and plunge pools that prevent a headcut from

continuing to migrate upstream. They dissipate the energy of the falling water by forcing the

water to go over a series of smaller step falls.


A Rock Mulch Rundown is a treatment that armors the channel and associated banks of a head cut with

rock. This treatment can be used when the vertical face of a headcut can be sloped back resulting in a

more gradual gradient that reconnects the flow of the stream in the channel.

The channel is armored with rock to dissipate energy, mitigate erosion of stream banks, and to prevent

further down cutting of the channel. This structure can also be used to prevent head cutting in a channel

segment that is over-steepened compared to the valley slope. Channel banks should be armored to at least

a point that is above bankfull and preferably to the break in slope onto the channel’s flood plain. The

mulching, moisture retention effect of the rock also promotes re-vegetation of exposed channel banks.

These are uses only in low-energy headcuts.


The Log and Fabric Step Fall structure is designed to control headcuts that are advancing through

wetland or wet meadow soil. Establishment of vegetation will stabilize the edge of the headcut. Geotextile

fabric is optional and dependent upon soil type and headcut severity.

Straw Bale Filter Dam (see diagram and description above in Grade Control Structures section)


Sheet Piling Dam

The Sheet Piling Dam is used to control stream or channel gradient by establishing a fixed height to a

point in the channel. This type of treatment requires heavy equipment to install (to pound interlocking

sheets of metal) into the ground across the stream channel and tied back into the elevation of the 1st or 2

nd

terrace floodplain bench. These structures are adjustable and can accommodate changes in height. The

purpose of these dams are not to retain or dam up water but to stop in channel incisement and capture

sediments to re-establish upstream wetlands and increase groundwater accumulation.

Earthen Aggregate and Soil Mulch

The Earth Aggregate Soil and Mulch treatment addresses the erosion and progression of a head

cut by filling the eroded, incised channel up to the slope of the original channel and its floodplain

with a combination of rock, straw, or woody debris such as tree limbs. The surface area can be

seeded with native seed, seed mats, or left unseeded to allow natural re-seeding. This treatment’s

maintenance needs will the assessed by periodic site visits. Maintenance for this treatment

includes re-seeding, re-mulching, and re-filling of any treatment area experiencing erosion.


Channel Reinstatement Treatments

Rock Plug

A Rock Plug is a rock or boulder structure installed in the incised channel which directs base stream flow

into a new channel or onto an abandoned wet meadow. The size of the material used is based on, and

seeks to match, depth of stream base flow. The structure will allow flood waters to enter the abandoned

channel resulting in increased flood plain and wetland area. Generally, one channel plug is installed at the

channel diversion and one at the downstream confluence with abandoned channel. The downstream Rock

Plug keeps the base flow from migrating up the abandoned channel. By allowing the stream access to its

original flood plain elevation, this treatment can also be used to treat headcuts upstream of the structure.

This effect is realized when the return to the original stream elevation eliminates or reduces the vertical

drop of the steam at and immediately below the spillover point of the headcut.


Plug and Pond

The Plug and Pond treatment is a method of slowing channel flow enough with a channel fill plug that

will temporarily pond water upstream of the plug.

Worm Ditch (see see diagram and description above in Headcut Treatments section)


Historic Meander Channel Reinstatement

A Historic Meander Channel Reinstatement uses a single-layer rock or boulder structure installed in

the incised channel to direct base stream flow into the original channel or wetland. The size of the

material used is based on, and seeks to match, the depth of stream base flow. The structure will allow

flood waters to enter the abandoned incised channel resulting in increased flood plain and wetland area.

Generally, one channel plug is installed at the channel diversion and one at the downstream confluence

with abandoned channel. The downstream channel plug keeps the base flow from migrating up the

abandoned channel.


Deflector Treatments

Post Vanes are used for two different results. They may be used to deflect high velocity flow away from

a cut bank of a meander bend in order to lessen bank erosion or they move the highest velocity of water

flow away from the bank. Another use of post vanes is to induce channel meandering by directing flow

into the opposite bank causing bank erosion and widening the channel in that direction.


A Picket Baffle acts as a deflector to create lateral erosion of a streambank to widen the channel. It

concentrates flow on the opposite bank and increases stream velocity, thereby decreasing stream velocity

on the adjacent bank. This increases sediment deposition along the adjacent bank which initiates the

formation of a point bar.


A Boulder Baffle acts as a deflector to create lateral erosion of a streambank to widen the channel. It

concentrates flow on the opposite bank and increases stream velocity, thereby decreasing stream velocity

on the adjacent bank. This increases sediment deposition along the adjacent bank which initiates the

formation of a point bar.


Live Vegetation

Willow Plantings are used to increase or decrease the erosion or deposition of parts of the channel

depending upon the meander design objectives.


Drawing from Riparian Management on the Bosque del Apache National Wildlife Refuge, J.P. Taylor

and K. C. McDaniel

Pole Plantings will be used to establish Narrowleaf cottonwood trees in select locations.

Willow Fascine

Diagram from http://prairiepiece.wordpress.com/

Willow Fascines are long bundles of willow stems buried in shallow trenches that run parallel to stream

flow. The bundles are constructed from live stems that are tied together. When the plant bundles sprout,

they develop a root mass that anchors the streambank.


Fencing Treatments

Post and Wire Exclosure Fence

A Post and Wire Exclosure is constructed to keep large animals out of the riparian area while allowing

small animals to move through the exclosure. The exclosures keep both cattle and elk off the creek banks

to allow for recovery of native herbaceous vegetation and willows.

Channel Crossings are designed to allow for passage of water and flood-borne materials along the

stream channel without damaging the exclosure fence.


From Zeedyk and Wells, 2006

Hemi Fence is placed on the outside edge of stream meanders to protect riparian vegetation from grazing

impacts by large ungulates. The design exploits the behavioral tendency of cattle to graze the vegetation

in these meander bends and riffle areas rather than areas with deep pools and steep banks. Another

advantage is that these can be used instead of full exclosures.

Drift Fence

Drift Fence, or livestock fence, prevents livestock movement into areas that that are restricted based on a

grazing management plan. A section of drift fence can be placed on the meander bend of a creek to

prevent cattle trampling the creek bank.


Roads

Rolling Dip

Rolling Dips are created in roads to modify the drainage patterns. They allow surface flows to be

dispersed across the roads frequently enough to prevent large, concentrated flows.

Sediment Trap

A Sediment Trap is constructed for the temporary collection of storm water. Sediments in the storm

water settle during water infiltration in the trap.


Road Crossing/Hardening Repair (Armored Cross Drains)

Road Crossing/Hardening Repair (Armored Cross Drain) functions to capture water draining from

the road and release the water in a controlled manner. A dip in the road that is approximately the width of

the channel is armored to prevent scouring. These should be placed at intervals that are close enough to

diffuse concentrated volumes of water draining from the road surface.

Water Bar

From Moench and Fusaro, 2012, www.colostate.edu/Depts/CSF

Water Bars are soil or rock berms that channel water flow off roads and trails. The berms (or bars) are

angled downslope to the outlet side.

http://www.colostate.edu/Depts/CSFS

appendix aa123.g.akamai.net/.../11558/www/nepa/80624_fsplt2_149045.pdfcomanche creek native trout...

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