SPANISH CREEK ASSESSMENT AND REHABILITATION STRATEGY

Public Meeting, March 12, 2007

Welcome and please feel free to ask questions and make comments. We encourage your participation.

Because of concerns over land loss due to accelerated bank erosion following the 1997 flood, several landowners along Spanish Creek in American Valley requested assistance from the Feather River Coordinated Resource Management Group (FRCRM) in 1999 to deal with their problems. It was agreed that everyone had a common problem and that a whole systems approach was needed.

Following an assessment of the Upper Spanish Creek Watershed condition, a strategy was developed that provides long-term stream rehabilitation guidance for Spanish Creek in American. It also provides a framework for dealing with the Upper Spanish Creek Watershed. Neither the Lower Spanish Creek nor the Greenhorn Creek Watersheds was included in this work.

Funding for this work was provided through an Agreement with the State Water Resources Control Board pursuant to the Costa-Machado Water Act of 2000 (Proposition 13).

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MEETING AGENDA

Introductions

Objective of the Meeting: To review and discuss the Spanish Creek watershed assessment and the rehabilitation strategy for Spanish Creek in American Valley.

Presentation: Assessment of the Spanish Creek watershed and rehabilitation strategy.

Review of Requested Projects and Priorities: Handout of maps and aerial photo display of Spanish Creek in American Valley.

Conclusion: What has been accomplished and where do we go from here.

SPANISH CREEK IN AMERICAN VALLEY

PROJECT REQUESTS AND PROPOSALS

All maps referenced can be found in the Spanish Creek Watershed Assessment available on our website www.feather-river-crm.org. Map 7 shows the location of the different proposals with the existing features and the table below lists each project, their projected costs, and priorities (See Appendix B, Project Concept Description).

Table 2. Proposed Channel Treatments, Priority and Cost Estimates

Map Number	Priority	Treatment Proposals**	Estimated Cost
1	Moderate	1, 2 & 6	$80,000
2	Moderate	1, 2 & 6	$100,000
3	High	1, 2 & 6	$30,000 (funded)
4	Moderate	3, 4 & 6	$90,000
5	High	1, 2 & 6	$50,000
6	High	1, 2, 6 & relocate 650 ft of Spanish Creek Road	$100,000
7	High	1, 5 & reconstruct water diversion intake	$50,000
8	Moderate	1, 2, 3, 4 & 6	$160,000
9	High	1, 5, 6	$20,000
10	Low	3, 4 & 6	$100,000
11	High	Grade-drop structure	$80,000
12	Moderate	1, 2 & 6	$50,000
13	Moderate	1, 2 & 6	$40,000

The total estimated cost for treating channel banks and enhancing channel morphometry is $900,000 to $1,000,000. The high priority projects, excluding the Dyrr Bank, would cost an estimated $300,000. These costs include those associated with all surveys, final designs, environmental studies, and permits.

**Treatment Proposals. Treatment proposals would use naturally occurring materials like whole trees, boulders, living vegetation, and existing stream channel and valley bends, bars, and bedrock outcrops. Treatment proposals would be designed to work with the energy of flowing water to maintain a balance between stream discharges and flow velocities to minimize the stress of streamflow against channel banks, bottom, and project features. The proposed treatments would include:

1. Sloping and vegetating vertical banks to improve floodplain capacities and reduce flow velocities against channel banks.

2. Installing boulder or log “vanes” to deflect the center of streamflow away from channel banks and to enhance the distribution and dissipation of streamflow energy.

3. Installing boulders, tree boles with root wads, and live vegetation to help regulate stream flow velocities and establish riffles and pools to enhance aquatic habitats.

4. Where needed and possible, allowing further recession of channel banks to increase floodplain capacities.

5. Removing, replacing, or modifying existing in-channel and bank structures that are causing channel and streamflow instability.

6. Controlling bank erosion using biotechnical erosion control techniques (NRCS 1996).

GRAVEL MANAGEMENT

Primary gravel management activities would take place on Spanish Creek at the head of American Valley, Map 6. Its location is based on fluvial geomorphic principles governing sediment transport and deposition evaluated in the EnSed2D computer model developed by Dr. Jennifer Duan and modified for this study (Duan 2006). Jen Weller, Graduate Student at the University of Nevada, Reno, conducted research necessary to adjust and calibrate the model for Spanish Creek (Weller 2005).

EnSed2D is a depth-averaged, two-dimensional hydrodynamic flow model, a sediment transport model, and a bank erosion model. It is also used to predict bed aggradation and degradation. The model accurately predicted that the highest bedload transport channel reach is upstream of American Valley and that transport is significantly reduced in the valley where channel slope is significantly reduced.

Parameters Used to Locate the Gravel Management Sites:

· The rate of replenishment from upstream.

· Ability to maintain stable streambed elevations.

· Historical patterns of sediment transport, bar formation, and bank erosion.

· Prediction of the local effects of gravel removal on bed elevation and on the stability of banks and bars and the desirability or acceptability of anticipated effects.

Primary Gravel Management Sites (Map 6):

1. The large gravel bar located approximately ¾ mile upstream of the head of American Valley. It is easily accessed from Bucks Lake Road using an existing road with a locked gate.

2. The former “Spanish Creek Aggregate” site located at the head of the valley and extending to the entrenchment bend at Feather River College. The reach is approximately 1.5 miles long.

General Operating Plan. The gravel management reach will be managed to maintain areas where bedload can deposit and removal will not damage the recovery of the stream channel. The alignment of Spanish Creek would be designated and all heavy equipment kept from the active channel area, except for designated crossings. Gravel would be removed as deemed necessary, not to exceed once a year. The methods for extracting gravel must not interfere with the integrity of the stream channel and its floodplain functions. Gravel excavation will not lower elevations below the stream bankfull elevation (as determined by cross-sectional surveys and annual monitoring results).

Responsible Parties. The party or parties responsible for removing gravel will be the respective owner(s) of the property from which gravel is to be removed. Gravel removal will take place in consultation with the Spanish Creek Technical Advisory Committee (TAC). This committee would meet approximately once a year to review all data and information and to formulate recommendations for future gravel removal.

Permit Process. The purpose for removing gravel from the Spanish Creek gravel management zone will be to maintain the function of floodplains and to reduce the risk of magnifying gravel-bars within downstream reaches, thereby maintaining the stream channel in an at-grade state (neither aggrading nor degrading) and minimizing erosion stresses against channel banks. An exemption will be sought from the State Mining and Geology Board that would allow excavation and grading for the purpose of repairing and restoring floodplains and their connection with the active stream channel and because it is an integral part of rehabilitating the Spanish Creek channel.

Other permits will be obtained, as required, including those required by the Clean Water Act, Sections 401 and 404, and Stream Alteration Agreements from the California Department of Fish & Game.

Estimated Cost. An annual inspection of the gravel collection/extraction areas would be required to assess compliance with the General Operating Plan. The inspection would focus on specific requirements and attributes, such as extraction elevation, channel alignment, gravel accumulations above bankfull elevation, damage to the stream channel and floodplain from the extraction activities, and general success of the program. It is expected that the FR-CRM staff and California Department of Fish & Game personnel would perform these inspections with the property owners and gravel operators. An annual inspection report would also be produced. The estimated cost to conduct the inspection and write the report is $500 to $1,000 per year.

SPANISH CREEK REHABILITATION

PROJECT CONCEPT DESCRIPTION

The following is a brief description of the conceptual treatment for each project reach, beginning at the head of American Valley and ending at the mouth, downstream of the confluence with Greenhorn Creek. These project concepts were used to determine cost estimates to rehabilitate each stream reach. Basically, two treatment techniques are proposed. The FR-CRM has found that these treatments are very successful when treating streams and entrenchment banks.

Meander Bend Boulder Vanes, Floodplain Enhancement and Revegetation (Figure B1). Boulders aligned in an upstream row and striking into the stream channel would be used along channel outcurves to hold the centers of flow convergence and high velocities away from the bank. This along with reconstructing floodplain areas to perform properly would allow vegetation to not only stabilize the bank but also to reduce flow velocities against the bank to near zero at all flow levels, thereby dramatically reducing bank erosion and channel migration.

Channel Constrictions and Revegetation (Figure B2) would be used between meander bends to facilitate the energy of flowing water and bedload transport within sequences predetermined for the type of stream being treated. The treatment would be designed to create (1) a minor backwater effect immediately upstream of each constriction so that sediment can be deposited along the banks and (2) an increase in flow velocities at the constriction and high flow turbulence immediately downstream in a scour hole. The effects would be to help center stream flows, dissipate excess energy, transport bedload sediment and induce vegetation growth along the margins of the channel.

The following is a brief description of the treatments proposed for Spanish Creek in American Valley by treatment reach (Refer to Map 7):

1. Gravel Management Reach. Total reach length is 6000 feet (1.1 miles). Approximately 2000 feet of eroding channel banks would be treated with a combination of floodplain enhancement, boulder vane construction, bank sloping, vegetation transplanting, and biotechnical erosion control, including vegetation plantings. Approximately 830 feet of the Feather River College channel bank was treated several years ago with rock riprap.

2. FRC – Upper Dyrr Reach. Total reach length is 3400 feet (0.64 miles). Four eroding channel banks, approximately 1700 feet, would be treated using a combination of floodplain enhancement, boulder vane construction, bank sloping, vegetation transplanting, and biotechnical erosion control, including vegetation plantings.

3. Dyrr Reach (immediately upstream of Highway 70). Total reach length is 1500 feet (0.28 miles). Two channel banks, totaling 450 feet, is scheduled to be treated in 2006 using a combination of floodplain enhancement, boulder vane construction, bank sloping, vegetation transplanting, and biotechnical erosion control, including vegetation plantings.

4. Spanish Road – Beskeen Lane Reach. Total reach length is 3200 feet (0.61 miles). Eight channel-constrictions would be constructed at approximately 450 foot intervals in combination with bank sloping, vegetation transplanting, and biotechnical erosion control, including vegetation plantings. Boulders and naturally occurring material would be used to construct each constriction. Existing trees and shrubs would be used as much as possible, as would existing boulder riprap banks located next to Spanish Creek Road.

5. Beskeen Lane at Channel Outcurve. A single entrenchment outcurve is threatening Beskeen Lane and a power pole. Approximately 350 feet of channel bank would be treated with a combination of floodplain enhancement, boulder vane construction, bank sloping, vegetation transplanting, and biotechnical erosion control, including vegetation plantings.

6. Entrenchment Bend Reach. The total length of this reach is 650 feet and includes the major bend in the entrenchment, a rock riprap bank, a concrete rubble dam, and approximately 650 feet of Spanish Creek Road. The bend has been treated with rock riprap to stop further channel migration. Stream flows are now eroding the bend at the upstream end of the riprap bank and threaten Spanish Creek Road. Treatment would include relocating approximately 650 feet of the Spanish Creek Road away from the bend and treating approximately 200 feet of the bend with a combination of floodplain enhancement, boulder vane construction, bank sloping, vegetation transplanting, and biotechnical erosion control, including vegetation plantings.

7. Concrete Rubble Dam. This dam supports a pond for pumping water to an irrigation diversion. The dam and some extraneous pieces of concrete rubble are forcing water against the bank immediately downstream of the riprap bank and then stream flows are directed against the opposite bank by the dam, causing excessive erosion of that bank. All of the concrete rubble would be removed, a channel constriction constructed to create a small pool for water diversion and the eroding bank would be sloped and further treated with vegetation transplants.

8. QCSD – Christenson Family Ranch Reach. Total reach length is 3800 feet (0.72 miles). Seven channel-constrictions would be constructed at approximately 450 foot intervals in combination with bank sloping, vegetation transplanting, and biotechnical erosion control, including vegetation plantings. Boulders and naturally occurring material would be used to construct each constriction. Existing trees and shrubs would be used as much as possible. Approximately 500 feet of channel bank would be treated with a combination of floodplain enhancement, boulder vane construction, bank sloping, vegetation transplanting, and biotechnical erosion control, including vegetation plantings. This bank, located at the Pence house and horse pasture, was previously treated with concrete rubble and channel straightening. A single power pole is also threatened. The concrete rubble would be made a part of the treated bank by burying it into the bank and using some of it as “footers” for the boulder vanes.

9. Historic RR Xing. Approximately 450 feet of channel length is affected by sheet-piling located in the center of the channel. A diversion dam was located here and now the channel is diverted around the pilings on both banks. A large gravel island has formed downstream of the pilings and erosion of both banks is occurring. Treatment would include removal of the pilings, bank sloping, vegetation transplanting, and biotechnical erosion control, including vegetation plantings.

10. Bengard - Bresciani Reach. Total reach length is 4500 feet (0.85 miles). Ten channel-constrictions would be constructed at approximately 450 foot intervals in combination with bank sloping, vegetation transplanting, and biotechnical erosion control, including vegetation plantings. Boulders and naturally occurring material would be used to construct each constriction. Existing trees and shrubs would be used as much as possible.

11. Clear Stream Headcuts. Clear Stream flows from its relatively shallow channel on top of the meadow terrace to the bottom of the entrenchment downstream of the historic RR crossing. Approximately 250 feet of the Clear Stream channel would be treated with a rock, grade-drop structure, eliminating the headcuts.

12. Bresciani - Bengard Outcurves. Three entrenchment outcurves are accentuating the erosion of existing meander bends. Approximately 700 feet of channel banks would be treated with a combination of floodplain enhancement, boulder vane construction, bank sloping, vegetation transplanting, and biotechnical erosion control, including vegetation plantings.

13. Pourcho Bank. A single entrenchment outcurve is accentuating the erosion of a meander bend. Approximately 350 feet of channel bank would be treated with a combination of floodplain enhancement, boulder vane construction, bank sloping, vegetation transplanting, and biotechnical erosion control, including vegetation plantings.