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| Big Flat Meadow Re-Watering Project |
Plumas County, California |
Primary Project Type: Instream Restoration
Secondary Type: Riparian Restoration |
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The broken water surface in the constructed E channel at Big Flat Meadow indicat... |
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Primary Problem: Channel Incision, Headcutting
Secondary Problem: Overgrazing, Timber Harvest |
| Main Restoration Action(s): Floodplain reconnection, Pond and plug, Redirect flow into remnant channel, Riparian revegetation |
| Native Fish Focus: N/A |
Is this project part of a watershed scale restoration? Yes
Click here for the description. |
| Project Dates: June 1995 to August 1995 |
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Initial Monitoring: 1994
Restoration Implementation: June 1995 to August 1995
Follow-up Monitoring: 1995 - 2004 |
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Lead Agency:
Feather Coordinated Resource Management (FRCRM) group
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| Project Partners: |
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| Project Location:
Big Flat Meadow is located in the 10,919 acre Cottonwood Creek watershed two and a half miles upstream from the confluence with Last Chance Creek, which drains into Indian Creek, a tributary to the East Branch North Fork Feather River. The site is on public land administered by the Plumas National Forest in Northeastern California near Honey Lake, approximately 60 miles Northwest of Reno, Nevada and 25 miles South-west of Susanville, California.
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Project Description:
The information and text for this case history was taken from the Feather River Coordinated Resource Management website at http://www.feather-river-crm.org/index.html.
Mountain meadows play a key role in effecting watershed condition and water flow in the northern Sierra Nevada. Restoration of degraded meadows is the first step in improving overall watershed function and could have major effects on surface and subsurface flow regimes, which influence water delivery downstream. This is especially important in the Feather River watershed since there are over 250,000 acres of meadow and small mountain valleys of which an estimated 98 per cent are degraded. Qualitative observation indicates that fully functioning meadows can moderate flow by storing water in soils, vegetation, streambanks and subsurface aquifers, reducing peaks and extending late season flow – all beneficial for fish population survival.
Cottonwood Creek once kept Big Flat meadow watered as it flowed through on its way from the east side of the Sierra Nevada mountain range to join the Feather River. The cumulative effects of livestock grazing, fire, road building and timber harvesting led to severe erosion causing the channel to cut down from its former meadow height into a gullied channel, 15 feet deep in some places. As the new channel eroded and incised, subsurface meadow aquifers drained, vegetation converted from wet meadow species to xeric species, and the summer stream flows were modified from perennial to intermittent. Because the creek was dry during the summer months, spawning and rearing habitat for rainbow trout was eliminated. Continued heavy grazing impeded the establishment and vigor of vegetation and increased mechanical breakdown of soils on the streambank. The resulting entrenched channel was a major source of elevated sediment supply downstream. Loss of meadow function led to a dramatic change in hydrology, diminishing subsurface water storage and flood attenuation capacity. |
| Project Goals: The Feather River CRM initiated the Big Flat Meadow re-watering project in order to restore Cottonwood Creek's original channel form into a stable narrow channel with meanders and a flood plain. The objectives of the project were to: 1) reduce the amount of sediment produced or downstream deposition and improve water quality, 2) restore spawning and rearing habitat for rainbow trout by prolonging summer stream flows, 3) elevate meadow groundwater increasing production of moisture loving plants, and extending length of the season in which the stream is flowing, and 4) demonstrate an innovative stream restoration technology, which can be applied to other degraded watersheds. |
| Project Methods:
Re-watering the Big Flat meadow entailed designing a project which combines an innovative technique of stream and meadow restoration with changes in the grazing system of the Forest Service's grazing allotment. The project design consists of: 1) abandonment and “ponding” of the creek's old incised gully, 2) diversion of the creek into a new 4,050-foot long section of shallow channel on the meadow floor above, 3) establishing rock step pools to minimize erosion on the new channel, 4) revegetation of disturbed areas as a result of construction, and 5) grazing management.
Click here for more information on project methods.
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Rock step-pool treatments are used to stop the process of headcutting in a strea... |
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Figure 2: Pool types constructed at Big Flat Meadow, based on observations of na... |
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| Monitoring Data and Collection
Methods: Feather River CRM members designed a monitoring plan to test the effectiveness of the project at restoring the Big Flat Meadow. Information was collected on stream and meadow characteristics in 1994 and 1995 to have a baseline against which to measure the project effectiveness. CRM members tracked changes in the stream's flow, groundwater level, channel stability and structure, and vegetation. Because CRM members wanted restoration of rainbow trout spawning and rearing habitat, fish population data was also collected.
For detailed information on the Big Flat Meadow monitoring program, click here.
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Was this project effective
and how was this determined? Returning Cottonwood Creek and Big Flat Meadow to full hydrologic function through this unique geomorphic approach was the first-in-kind demonstration in California. The technique has already been implemented on 16 other restoration projects in northeastern California, with successful results. The approach is also broadly applicable to semi-arid montane meadows in other areas.
Project monitoring results indicate that the successful reconnection of the channel to its naturally evolved floodplain has extended the period of stream flow, moderated the magnitude and duration of peak flow events, reduced seasonal ground water fluctuation indicating increased groundwater storage, and restored trout populations within the stream. Meadow vegetation is more productive and has shifted to wetter site species. The modified grazing system has encouraged vegetation establishment and minimized mechanical streambank damage along the new channel.
Channel size was derived from calculated bankfull discharge and bedload size/quantity. While this was fortuitous to the advancement of the technology, the design channel was too large. Extended monitoring of the new channel showed that the streambed was aggrading very slowly; therefore, the decision was made to intervene and rectify the error. The treatment was a riffle augmentation using a nearby rock source. The riffle augmentation made a tremendous difference in the vegetative recovery of the meadow and it influenced further improvement in the base flow conditions. Monitoring results have also showed recharge from the meadow aquifer doubles the total flow in the channel and has reduced water temperature by 3 degrees Centigrade.
The project was tested during the major January 1, 1997 flood which was recorded as the flood of record at all Feather River gages. Peak flows were measured at 485 cfs. Water flow in the channel, which was designed to accommodate 40 CFS, inundated the meadow to depths of 6”-18” and widths of 200’-600’. There was no significant erosion of concern to the project's new channel or any adverse affects on the floodplains or seven new ponds.
Plumas Corp. professionals have written a publication - “Evaluation of Geomorphic Stream Restoration Techniques Applied to Fluvial Systems” - giving their evaluation of the diversity in stream restoration techniques used in the past 25 years in the Feather River watershed. To view the entire publication on-line, click here. For the discussion in the publication evaluating the success of the pond and plug technique in reconnecting the stream channel to the floodplain, click here.
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(Before) A before-restoration aerial photo of the Big Flat Meadow "pond and plug... |
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(After) An after-restoration aerial photo of the Big Flat Meadow "pond and plug"... |
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| Confounding Effects/Additional
Information: After completing similar projects to the Big Flat project, the Feather River CRM has determined a more cost effective, and efficient method of reconnecting the floodplain with the stream channel. Frequently, the historic meadow and floodplain still contains a system of intact remnant channels. The CRM has implemented several projects where flows were diverted onto the floodplain and into remnant channels of the meadow. Channel reaches were constructed only where necessary, at the upstream and/or downstream end of the project area. |
| Project
Specs (all specs are estimates): |
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Overall Estimated Cost:
$185,590
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| For more information on this project
contact: |
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Jim Wilcox, Plumas Corp., Email: jim@plumascounty.org
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| This information
was collected by: Kristin Keith |
| Project last updated on: 7/5/2007 |
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