The Management Areas designated for the Adaptive Management Plan for Secret Ravine are meant to be a coarse-scale description of the restoration and enhancement practices that would be appropriate for each stream reach. The management areas were derived, and boundaries delineated, based on factors such as channel morphological character (e.g. - alluvial verses bedrock confined reaches), future land-use history (e.g. - private versus public ownership), channel health, access issues, and potential for restoration. Our initial delineation of reach breaks was based on familiarity with the channel and riparian area, brief field visits, and aerial photo analysis. Further field work and analysis of channel conditions is required to refine the management areas and broaden the recommendation made for each area. From the confluence of Secret Ravine with Miners Ravine to just above Horseshoe Bar Road, five management areas were delineated.

MANAGEMENT AREA A

Management Area A extends from the confluence with Miners Ravine upstream to the downstream boundary of the Guntert Property (see Plate 1). Much of Management Area A is public land held by the City of Roseville making it an area of high priority and feasibility for restoration. This reach of Secret Ravine is characterized by an incised channel that meanders through old floodplain and hydraulic mining debris deposits. Due to incision of the channel and heavy bank erosion, large amount of highly mobile sands dominate the bed of the channel, impairing salmonid spawning gravels and reducing rearing habitat through pool filling and loss of aquatic macroinvertebrate production. It is also very difficult for riparian

Hydrology / Geomorphology /Restoration /Water Resources/ Construction Planning & Supervision

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vegetation to establish on the alternating sand bars due to deep, high velocity flood flows that have little access to, historic floodplain surfaces

Recommended treatments for Management Area A would be to stabilize existing alternate sand bars to allow them to become point bars through a process of establishing riparian vegetation, This can be accomplished by raising the elevation of the bars to bank full and armoring them with gravel and cobble-sized. material (see Site 3 and detailed engineering plans), Stable point bar development would allow a dense riparian overstory to develop and allow scout of the outside bends of the channel where pools could form for rearing habitat. Riffle gradients would also increase creating cleaner spawning areas for salmonids and should also be cut back to provide floodplain storage aid reduce velocities and shears acting an the channel bed and banks during high flow conditions.

In order for these restoration and enhancement actions to be successful, formalization of the City of Roseville‘s access road and cessation of illegal trespassers must be a top priority, Restoration actions cannot be successful if they are continually damaged by ORV uses.

MANAGEMENT AREA 8

The boundaries for Management Area B consist of the up and downstream edges-of the Guntert property (see Plate 1), This property is slated for development in the near future that may include provisions and mitigation measures to improve floodplain and channel conditions along the property.

Proposed restoration actions on this property could include rehabilitation of the floodplain and a channel realignment property that would move the channel away from Highway 80 (See Site 4), The existing floodplain surface on the property is a wide, heavily eroded area with multiple ORV trails gullies, and steep access roads from the adjacent hillside. Revegetation .and possible development of vernal pools and off-channel wetlands could be a viable option. Channel conditions in this section of stream are similar to conditions found in Management Area A. As part of this plan, we are recommending similar actions occur through Management Area B. Currently, the channel flows straight along edge of Highway 80 with riprap along the right bank of the channel (looking dowstream) There is an opportunity to meander the channel while maintaining riprap along the outside bends. An existing high flow channel adjacent to the active channel. can be filled with excess material from the channel, restoration portion of the project.

MANAGEMENT AREA C AND E

Very little is known about both Management Areas C and E due to access issues and the number of land owners that would be involved in any proposed restoration action see Plates 2 and 3). These areas have been encroached upon by commercial and residential development and may have limited restoration potential, Some pockets exist for restoration within Management Area E just upstream of Sierra College Blvd.

We recommend additional studies be conducted within these two areas to further identify restoration potential and the possibility of cooperative landowners.

MANAGEMENT AREA D

Management Area D is bounded by Rocklin Road on the downstream end and Sierra College Blvd on the upstream end (see Plate 2). Morphologically this reach of stream is quite different from the other management areas described in this report. This reach consists of steeper valley walls that confine die channel with very little floodplain surface. Riparian vegetation is dense and mature, providing a shaded canyon with the potential for cooler water temperatures. The bed of the channel has more bedrock exposures and large boulders that control the grade of the channel and provide channel roughness, reducing bank scour and erosion. Though salmonid habitat conditions are better in this Management Area compared to others, excessive amounts of sand still fill pools and cover spawning beds.

Enhancement actions in Management Area D should focus on improving pool depths, quality of spawning beds, and escape cover for salmonids by introducing roughness elements into the channel (see Site 5). Roughness elements provide obstructions to flow allowing energy to be released at the point of contact and causing pools to scour and undercut banks to form. Roughness elements can include large woody debris, rootwads, or large boulders that do not move even under high flow conditions. The Department of Fish and Game California Salmonid Habitat Restoration Manual (Flosi and Reynolds, 1998; see Section VII) outlines some of the potential treatments that could be used. We recommend a series of boulder log treatments each placed on the outside of a meander. Velocities will concentrate at these locations and the boulder log treatment will act to protect the bank from erosion but also induce pool scour, exposing buried gravel and providing a hiding spot for migrating or juvenile salmonids.

Restoration & Enhancement Plan Areas

and Locations of Conceptual Design Projects

Plate Index	Plate 1
Plate 2	Plate 3

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Project: Bank Erosion Site I

Site 1 Detail

  

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 Location: Approximately 1500 feet upstream of confluence with Miner's Ravine. Adjacent to hospital and access road (See Plate 1).

Description: This site is experiencing erosion of the outside bend of the stream. This has been exacerbated by encroachment of a dirt road, illegal offroad vehicle use, and lack of vegetation to provide support and road strength. Due to access issues, the City of Roseville would like to maintain the adjacent road. 

Treatment: The proposed treatment includes overexcavation of the toe of the failing bank allowing rock ormoring to support the toe. The bank would then be rebuilt and planted with live willow stakes and other appropriate riparian vegetation types. In addition, root wads will be added and keyed into the bank to provide cover for fish, protect the bank, and scour the stream bed.

Estimated Cost: $35,000. Cost depends on material availability and site accessibility.

Site 2	Site 3
Project: Headcut Erosion Site 2 Location: Approximately 2000 feet ups tream of confluence with Miner's Ravine. Adjacent to hospital and access road. (See Plate 1) Description: On a weekly basis, fire fighting tests occurring up the hill adjacent to the hospital dump thousands of gallons, in an uncontrolled manner, down into Secret Ravine. This water has begun to erode a section of the access road along Secret Ravine forming a heodcut along the streambank and road where the water enters [he stream. Treatment: Treatment at this site very much depends upon the direction of policy at the hospital. If the practice of allowing uncontrolled releases of water continues, we recommend collecting this water in a rock-lined channel adjacent to the road and moving the water under the road surface to allow the water to be discharged into Secret Ravine without bank erosion or headcutting. Estimated Cost: $5.400. Cost depends on material availability and site accessibility. Restoration and Enhancement Conceptual Designs Site 2	Project: Channel Restoration Location: Within Management Area A adjacent to hospital. (See Plate 1) Description: This site is indicative of the degraded habitat conditions that occur throughout Management Area A (See ADIP discussion). Channel downcutting, excessive sand, and mobile bars have resulted in pool filling and burial of spawning gravels. Confinement of the channel along Interstate 80 has straightened the channel and reduced the potential for meander development and pool scour. Treatment: Stabilization of existing sand bars to bankfull elevation with cobble and gravel will focus receding flood flows into the main channel. encouraging pool sour and riffle developnent. Cutting back existing high terraces to allow flood flows to inundate the flood plain will expand riparian width and provide flood storage, reducing high flow stresses within the primary channel. Reclaimed flood plain areas will also act to store fine sediment as flows recede, Estimated Cost: $300 per linear too!. Cost depends on material availability and site accessibility Restoration and Enhancement Conceptual Designs Site 3

 

Project: Channel Restoration at Guntert properly. Location: Within Management Area B. (See Plate 2) Description: Channel downcutting, excessive sand, and mobile bars have resulted in pool filling and burial of spawning grovels. Confinement of the channel along Interstate 80 has straightened the channel and reduced the potential for meander development and pool scour. Residential development on the Guntert property may provide the opportunity to pursue restoration through this reach. Treatment: Stabilization of existing sand bars to bankfull elevation with cobble and gravel will focus receding flood flows into the main channel, encouraging pool scour and riffle development. Cutting back existing high terraces to allow flood flows to inundate the flood piain will expand riparian width and provide flood storage, reducing high flow stresses within the primary channel. Reclaimed flood plain areas will also act to store fine sediment, as flows recede. An existing high-flow channel can filled with excess sediment from the terrace cuts. This may provide an opportunity to develop off-channel wetlands. Estimated Cost: $500 per linear foot. (Cost is higher (due to Site 3 due to more extensive channel reconstruction to develop meander pattern.) Costs depend on material availability and site accessibility. Restoration and Enhancement Conceptual Designs Site 4

Project: Habitat Enhancement Location: Adjacent to Sierra College between Sierra College Boulevard and Rocklin Road - Management Area D (See Plate 2) Description: This stretch consists of a well-shaded stream with the potential for good spawning and rearing habitat. Good salmonid habitat is limited by the lack of deep pools, escape cover, and hydraulic complexity that generates patches of spawning gravel. Treatment: Enhancement of these factors can be improved along this reach through placement of channel roughness elements such as large woody debris and root wads, as recommended in the California Department of Fish and Game's Stream Habitat Restoration Manuel (Flosi and Reynolds, 1998). A series of these treatments can be placed at the outside of the low flow channel along the entire reach to induce pool scour and provide places for rearing fish to hide. Estimated Cost: $2,500 per root wad. Cost depends on material availability and site accessibility.   Swanson Hydrology& Geomorphology 115 Limekiln Street Santa Cruz, CA 95060 831.427.0288 fax 831.427-0472 Restoration and Enhancement Conceptual Designs Site 5

  

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October 9, 2001

Dry Creek Conservancy
Attn: Gregg Bates
P.O. Box 1311
Roseville, Ca. 95678

RE: Design Report for Initial Restoration Site on Secret Ravine

Dear Gregg, 

Attached is a letter report summarizing the assumptions and methods that went into the preliminary restoration design for the initial site on Secret Ravine. If you need a more detailed description or clarification on certain elements of the design or geomorphic assumptions, feel fee to call me at 831 827-0288. We look forward to implementing this and similar restorations plans on Secret Ravine. 

Sincerely,

 

John Dvorsky
Senior Associate
Swanson Hydrology & Geomorphology

 

Problem Statement 

Historic and modem land use practices within the Secret Ravine watershed have had a long-lasting impact on the geomorphic and biological integrity of the primary stream channels. The impacts from land use practices date back to the period of time when hydraulic mining was occurring throughout the watershed. Hydraulic mining introduced millions of cubic yards of decomposed granite into the active channel system material that had historically been deposited in a series of terraces from large outwash floods following the last glacial period.

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In the period of time between the last glacial and the 50-year period of intense hydraulic mining, Secret Ravine had developed a static equilibrium between sediment supply, storage and transport. The result was a an active channel that meandered back and forth across a wide floodplain that consisted of an alternating series of stable point bars that were heavily vegetated by common riparian plants of the area such as willow and alder. These stable bars would become inundated during high flows, allowing the water to spread across the floodplain and causing fine sediment to settle out, adding additional nutrients to the riparian forest. 

During the receding limb of high flow events, sediment starved water (due to deposition on the floodplain would pour off the floodplain and concentrate in the main channel, scouring out deep pools and cleaning cobble dominated riffles, leaving high quality salmonid spawning gravels in the tail sections of the pools. These scour events would produce a longitudinal series of pools and riffles. Pools would occur on the outside of a bend with a stable point bar on the inside of the bend. Between pools, cobble dominated riffles would occur in the straight sections and act as grade control, limiting excessive downcutting during peak How ever essentially allowing deep scouring of pools on either side of the riffle Due to the presence of a riparian forest on the edge of the active channel, dense root systems would allow bars to persist and banks to be undercut, increasing the habitat value of the system for salmonids.

During the hydraulic mining period, large amounts of sand-sized decomposed granite were introduced into the primary channel from inactive terraces. The introduction of large amounts of material overwhelmed the system and induced a period of channel aggradation Channel aggradation results from the inability of the stream to carry the introduced sediment load. As the sediment load overwhelmed the system, the channel filled up with sediment along its entire length, burying existing channel and floodplain features, such as stable bars, pools, and riffles, smothering riparian vegetation, and causing water to flow across the floodplain, even during low to moderate flow events.

The impacts of channel aggradation can be devastating to the aquatic ecosystem as well as human systems. Aquatic systems are impacted through loss of critical habitat. For salmonids this includes loss of deep pools for rearing, decreased macro invertebrate production through burying of cobble substrate, and loss of potential spawning habitat. Human systems are impacted from increased flooding and reduced bridge capacity, a phenomena that has been well-documented following channel aggradation.

Following the period of hydraulic mining, sediment loads to the channel were reduced and the stream began to adjust to a condition of decreased sediment supply. This consisted of incision of a new channel through the hydraulic mining deposits and establishment of a meandering pattern with a high flow floodplain. Essentially, the channel was attempting to reestablish the static equilibrium that existed prior to the perturbation (i.e. - hydraulic mining).

Unfortunately for the salmonids and other aquatic organism, the process of recover and return to the static equilibrium that existed prior to hydraulic mining, is extremely slow. Sediment supply is still excessive within the active channel due to re-incision of hydraulic mining deposits through undercutting of unstable bank deposits. The reactivated bank deposits are composed primarily of sand that form unstable alternating

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bars. These sand bars do not support stable riparian vegetation because they are mobile and transient during peak flow events. In addition, channel incision into extensive hydraulic mining deposits (6-12 feet in some places) has resulted in reduced access of flows to floodplain surfaces during 2 - to I 0-year recurrence interval floods. Loss of floodplain access can result in higher velocities and shear stresses that can reduce the ability of the bars to support vegetation.

Over time, channel meandering and transport of fine-grained sediment out of the system would allow the system to return to the static equilibrium that existed prior to hydraulic mining. In our proposed restoration design, we plan to accelerate this process through the following treatments: 

1) Stabilize existing alternate (sand) bars by armoring them with cobble-sized substrate,altering the bar elevation by matching to the bank full flow (approximately 1.5-2.33- year recurrence interval flow), and revegetation with appropriate riparian plants,

2) Armor existing riffle locations by introducing cobble/gravel substrate and narrowing the channel at these locations to focus flow and energy into downstream pools to accelerate scour and habitat development, and

3) Cutting back existing terraces to provide additional access to floodplain surfaces.

The remainder of this report will discuss the design criteria and assumptions used to develop preliminary plans and specifications for one location within the study area on Secret Ravine. 

Geormorphic and Engineering Design 

A preliminary geomorphic and engineering design was developed for one site on Secret Ravine within the reach of interest. This site was chosen for initial study because it was an excellent example of problems that exist along the entire reach both geomorphically and biologically. In addition there was good access to the site. 

The field investigations that were conducted to develop the design included a detailed topographic survey of the site (see plan sheet) and a geomorphic investigation along approximately 1300 feet of channel. For the geomorphic investigation a longitudinal profile was developed along with a bank full survey and five detailed cross-sections. In addition, notes were made about the depth of scour at certain pools and how those conditions related to riffle slope and width. Data regarding local geomorphic conditions and channel morphology are vital when developing a restoration plan because they provide information about bank full widths and depths, pool-riffle spacing and meander pattern.

The existing alignment of the low-flow channel at the site of interest will not be significantly altered in the design including the existing meander pattern and locations of pools and riffles The majority of work will focus on the bar features, the lower riffle. and the downstream end of the right bank terrace (looking downstream). Tile three bar features within the project site will be brought to an elevation of 2.5 feet above the low flow channel. This will force water to remain within the low-flow channel area at flows less than bank full, allowing pools to scour and riffles to be cleaned. When flows exceed bank full, water will spread out onto these floodplain surfaces where lower velocities allow for deposition of fine-grained sediment. As flows recede, water will flow back into the channel, focusing flow to further scour pools and generate habitat.

The material required to bring these floodplain surfaces to the appropriate elevation will be excavated from the right bank terrace. Since most of this material consists of sand sized deposits, an additional layer of cobble/gravel substrate will be used to armor file floodplain surfaces and provide a more stable feature for growth of riparian vegetation. Initial estimates suggest a small off-site removal of sand from the right bank terrace would be required to complete the high-flow terrace restoration

Remaining Elements

In order to complete the restoration plan and allow construction to begin, the following elements need to be included.

• Completion of existing design to 100%.
• Revegetation Plan
• Erosion Control Plan
• Temporary diversion, dewatering, and fish relocation plan
• Description of proposed construction sequencing / access to site
• All required permits

Detailed Plans page 1	Page 2