STREAM INVENTORY REPORT
LITTLE NORTH FORK BIG RIVER
WATERSHED OVERVIEW
Little North Fork Big River is a tributary to the Big River (Figure 1). Elevations range from 20 feet at the mouth of the creek to 1000 feet in the headwater areas. Little North Fork Big River’s legal description at the confluence with the Big River is T17N R17W Sec24. Its location is 39o18’52"N. latitude and 123o42’17"W. longitude according to the USGS Mathison Peak 7.5 minute quadrangle. Little North Fork Big River drains a watershed of approximately 8,013 acres.
HABITAT INVENTORY RESULTS
The habitat inventory of October 2 through October 11, 1995, was conducted by Chris Coyle (CCC) and Shelly Dunn, Bettina Chimarios, and Kyle Young (WSP/AmeriCorps). The portion of stream surveyed by this crew includes the section from the confluence of the East Branch of the Little North Fork to the end of the creek. Another habitat inventory was conducted by Diana Hines and Dave Wright (Georgia-Pacific) (G.P.) June 24 through June 26, 1996 and includes the portion of stream from the G.P. property line to the confluence of the East Branch of the Little North Fork Big River. This report includes a compilation of the data from the two surveys. The total length of surveyed stream in Little North Fork Big River was 25,254 feet (4.8 miles, 7.7 KM) (Table 1). Side channels comprised 210 feet of this total. Flow measured near the bottom of the survey reach in June of 1996 was 2.91 cubic feet per second (cfs).
Little North Fork Big River consists of two reaches: B4 for the first 5,603 feet and G4 for the remaining 19,441 feet.
Table 1 summarizes the Level II Riffle, Flatwater and Pool Habitat Types. By percent occurrence Riffles comprised 15%, Flatwater 31% and Pools 47% of the habitat types (Graph 1). By percent total length, Riffles comprised 8%, Flatwater 39% and Pools 49% (Graph 2).
Twenty Level IV Habitat Types were identified and are summarized in Table 2. The most frequently occurring habitat types were Mid-Channel Pools 23%, Glides 19% and Low-Gradient Riffles 15% (Graph 3). The most prevalent habitat types by percent total length were Mid-Channel Pools at 22%, Glides 18% and Step Runs 17% (Table 2).
Table 3 summarizes Main, Scour and Backwater pools which are Level III Pool Habitat Types. Main Channel Pools were most often encountered at 75% occurrence and comprised 75% of the total length of pools.
Table 4 is a summary of maximum pool depths by Level IV Pool Habitat Types. In third order streams or higher, pools with depths of three feet (.91 m) or greater are considered optimal for fish habitat. In Little North Fork Big River, 15 of the 325 pools (16%) had a depth of three feet or greater (Graph 4).
The depth of cobble embeddedness was estimated at pool tail-outs. Of the pool tail-outs measured, 8% had a value of 1, 19% had a value of 2, 39% had a value of 3 and 34% had a value of 4 (Graph 5).
Of the Level II Habitat Types, Pools had the highest mean shelter rating at 59 (Table 1). Of the Level III Pool Habitat Types, Scour Pools had the highest mean shelter rating at 66 (Table 3).
Of the 325 pools, 16% were formed by Large Woody Debris (LWD): 12% by logs and 3% by root wads (calculated from Table 4).
Table 6 summarizes dominant substrate by Level IV Habitat Types. Of the Low Gradient Riffles fully measured, 73% had gravel as the dominant substrate (Graph 6).
Mean percent closed canopy was 89%: 79% coniferous trees and 10% deciduous trees. Mean percent open canopy was 11% (Graph 7, calculated from Table 7).
Table 7 summarizes the mean percent substrate/vegetation types found along the banks of the stream. Mean percent right bank vegetated was 83% while mean percent left bank vegetated was 85%. Grass was the dominant bank vegetation type in 68% of the units fully measured. The dominant substrate composing the structure of the stream banks was Sand/Silt/Clay, found in 70% of the units fully measured.
DISCUSSION
The information gathered in the process of habitat typing will provide Georgia-Pacific with baseline data on the current condition of this creek and the available habitat for salmonids. These data can be used to identify components of the habitat in need of enhancement so appropriate conditions for Little North Fork Big River can be obtained over time.
Level II habitat types by percent occurrence and length
Flatwater habitat types comprised a moderate percentage of the units by both percent occurrence and length at 31% and 39% respectively (Table 1 and Graph 1). These unit types usually do not provide optimal spawning or rearing habitat for salmonids. Riffle habitat units comprised a low percentage of the stream by both percent occurrence and length at 15% and 8% respectively. Pools, however, comprised a much higher percentage by both percent occurrence and length at 47% and 49% respectively. Riffles usually provide good spawning habitat while pools provide important rearing habitat. In addition, Mundie (1969) reported that invertebrate food production is maximized in riffles while pools provide an optimum feeding environment for coho. In fact, the most productive streams are those consisting of a pool to riffle ratio of approximately one to one (Ruggles 1966).
Pool Depth
According to Flosi and Reynolds (1994), a stream with at least 50% of its total habitat comprised of primary pools is generally desirable. Primary pools are at least two feet deep in first and second order streams and at least three feet deep in third order streams. The information from Graph 4 on maximum depth in pools was used to determine percent of primary pools. Little North Fork Big River, a fourth order stream, is comprised mainly of shallow pools with 16% of the pools having a maximum depth of three feet or greater.
Instream Shelter
Instream shelter ratings are derived from two measurements: instream shelter complexity and instream shelter percent cover. The first is a value rating which provides a relative measure of the quality and composition of the shelter, and the second is a measure of the area of a habitat unit covered by shelter. The various types of instream shelter include LWD, SWD, boulders, root wads, terrestrial vegetation, aquatic vegetation, bedrock ledges and undercut banks. Of the Level II habitat types Pools had the highest mean shelter rating at 59. Of the Level III habitat types Scour Pools had the highest mean shelter rating at 66. These values are low as shelter values of 80 or higher are considered optimal for good rearing habitat (Flosi and Reynolds 1994).
Large Woody Debris
The presence of Large Woody Debris in streams is a significant component of fish habitat. Woody debris creates areas of low flow, providing a refuge for fish during periods of high flow (Robison and Beschta, 1990). Woody debris also provides cover for fish, lowering the risk of predation. The percent of pools formed by LWD in Little North Fork Big River was 16%. Whether these numbers are high or low, relative to the needs of salmonids is difficult to ascertain since the optimum amount of woody debris in streams has not been specified (Robison and Beschta 1990). However, based on data from Georgia-Pacific’s 1995 Aquatic Vertebrate Study, the only coho found in the Ten Mile River Basin were in stream reaches where approximately 50% of pools were formed by large woody debris. Those reaches that did not support coho had a significantly lower percentage of pools formed by large woody debris (Ambrose et al, 1996). This suggests that a low percentage of LWD formed pools could adversely affect juvenile Coho Populations (C.S. Shirvel 1990).
The above LWD analysis pertains only to pools formed by logs or root wads as described in Flosi and Reynolds (1994): Lateral Scour Pool Log Enhanced, Lateral Scour Pool Root Wad Enhanced, Backwater Pool Log Formed and Backwater Pool Root Wad Formed. Other pools containing LWD as a component were not included in the calculation. For example, plunge pools may be formed by boulders, bedrock or LWD but are not described as such by habitat unit types. Therefore, the LWD formed pool calculation is limited to four pool types and does not quantify the total amount of LWD in Little North Fork Big River.
Canopy
There are two important benefits of canopy cover in coastal streams. Canopy keeps stream temperatures cool as well as providing nutrients in the form of leaf litter and organic material (Bilby 1988). This leaf litter, organic material, and their associated nutrients are utilized as a food source by benthic macroinvertebrates (aquatic insects). The macroinvertebrates, in turn, are major food sources for most fish species in forested areas (Gregory et al., 1987). Mean percent canopy cover for the Little North Fork Big River was 89%. This is relatively high since a canopy cover of 80% or higher is considered optimum, Flosi and Reynolds (1994).
Coniferous trees occupied a larger portion of the canopy than did deciduous trees. Coniferous trees comprised 79% and deciduous trees 10% of the canopy. Wood from coniferous trees does not deteriorate as rapidly as wood from alder and most other deciduous species (Sedell, et al. 1988). Therefore, more LWD would be available in the future for fish cover and LWD formed pools in this creek and others dominated by coniferous species.
Embeddedness
High embeddedness values (silt levels), such as those found in Little North Fork Big River, have been associated with many negative impacts to salmonids. These negative impacts can be observed in important environmental components of salmonid habitat, such as pool habitats, dissolved oxygen levels and water temperatures.
The impact high silt levels have on pool habitat is that they fill in and eventually eliminate pools. As already mentioned, pools provide important habitat for rearing salmonids.
High silt levels also impact oxygen levels in the water. They do so by reducing water circulation within the substrate, thus lowering the oxygen levels needed by salmonid eggs (Sandercock, 1991). This can hinder the survival of the eggs deposited in the redds, as well as the survival of juvenile salmonids.
Water temperature is impacted by high silt levels in several ways. Hagans et al (1986) reported the following impacts to water temperatures: 1) the loss of a reflective bottom; 2) darker sediment (as opposed to clean gravels) storing heat from direct solar radiation which is then transferred to the water column; and 3) a reduction in the flow of water through the substrate interstitial spaces thereby exposing more of the water column to direct solar radiation.
Another means by which water temperatures are increased is through the widening of stream channels: over time, high silt levels increase the substrate surface level of the creek, resulting in a wider, shallower stream channel (Flosi and Reynolds 1994). In shallow streams more surface area is exposed to the sun relative to the volume of water, leading to an increase in solar heating which in turn leads to higher water temperatures.
Substrate embedded with silt in varying degrees were given corresponding values as follows: 0-25%= value 1, 26 - 50% = value 2, 51 - 75% = value 3 and 76 - 100% = value 4. According to Flosi and Reynolds (1994), creeks with embeddedness values of two or higher are considered to have poor quality fish habitat. In Little North Fork Big River, 92% of the pool tail-outs measured had embeddedness values of two or more.
It is important to consider, however, that the above embeddedness values were obtained in the summer during low flow conditions. In winter and spring, flows are usually higher due to the rainy season and the lowered evapotranspiration of the trees. This higher flow can carry away some of the previously deposited silt to sites further downstream. Therefore, embeddedness values may fluctuate throughout the year along different sections of the stream.
Substrate
In Little North Fork Big River, 73% of the Low Gradient Riffles had gravel as the dominant substrate. The relatively high concentration of gravel in riffles indicates that there is a sufficient amount of substrate available as potential spawning habitat in this creek. While this creek had sufficient substrate for spawning in the existing riffles, the overall percentage of riffles in the surveyed portions of the creek was low at 15% (Table 1). Subsequently, in areas surveyed, there may be a lack of sufficient spawning habitat. The absolute number of riffles within the Little North Fork are unknown and, resultingly, it is difficult to ascertain definitive conclusions pertaining to this creek’s potential suitability for spawning.
Overall, surveyed portions of the Little North Fork Big River appear to have low shelter values, a low percentage of primary and LWD formed pools and high embeddedness values. In addition, while there was sufficient substrate for spawning, habitat for spawning appeared to be limited. This creek does appear to have sufficient canopy.
Georgia-Pacific recognizes that there are areas of Little North Fork Big River in need of enhancement and where feasible will attempt to restore those areas over time as part of its long term management plan. The company will also attempt to facilitate a healthy environment for salmonids in this creek through sound management practices.
RECOMMENDATIONS
Little North Fork Big River should be managed as an anadromous, natural production watershed.
Where feasible, design and engineer pool enhancement structures to increase the depth of pools. This must be done where the banks are stable or in conjunction with stream bank armor to prevent erosion.
Shelter values throughout Little North Fork Big River could be increased by addition of large logs and root wads, boulder clusters, log and boulder wiers and log and boulder deflectors. These need to be placed carefully to prevent washing out in high flows. The Stream Habitat Restoration Manual, by Flosi and Reynolds, 1994, provides detailed descriptions for restoration efforts.
Log debris accumulations retaining large quantities of fine sediment should be modified if necessary, over time, to avoid excessive sediment loading in downstream reaches.
Sources of stream bank erosion should be mapped and prioritized according to present and potential sediment yield. Identified sites should then be treated to reduce the amount of fine sediment entering the stream. In addition, sediment sources related to road systems need to be identified, mapped and treated according to their potential for sediment yield to the watershed.
SURVEY MEMOS
The following memos were taken in the field at the time of survey. All distances are approximate and measured in feet from the confluence.
893 Young of year (yoy) steelhead (sthd) observed
1205 Dead lamprey carcass found. bank failure along left bank 40'h x 20'l contributing gravel and sand
2040 Old RR crossing at 106' into unit
2225 Two coho observed. hobo temp pool (Big 8). tributary entering left bank at end of pool.
2309 Two coho young observed
2766 Channel type is a B4
2885 Four coho observed, approximately 6 yoy
2943 Yoy observed
3233 Three coho observed, approximately five yoy observed
3271 Approximately six pieces lwd across pool. three coho observed and six yoy sthd.
3384 Three coho observed, two pieces lwd over pool.
3561 One redd observed, old RR crossing on right bank at 102'.
3674 Large pile of lwd and swd on left bank near edge of creek approximately 6'h x 10'l x 6'w.
3762 Six redds observed
5193 Log jam over creek, one piece lwd and many swd 12' x 4'h x 4'l
5603 End of survey. East Branch Little North Fork enters on left bank. The remainder of the Little North Fork Big River has already been surveyed by Fish and Game.
37 Fish and Game survey starts at right bank tributary just inside the Jackson State Forest Boundary
578 Fish - young of year (YOY)
675 (+5)(637') old RR tressel
1094 (+9) ? right bank tributary Dry??
2367 (+35)(2362') right bank tributary. Berry Gulch
2487 (+28) LDA 18'Wx19'Lx4'H approximately. 5' gravel retained (+32) left bank erosion 7'Hx10'W
2920 (+0)(2866') left bank erosion 6'H
3039 (+19) LDA 8'Hx20'Wx32'L, gravel retained 2'Hx5'L, right bank erosion
3203 (+130) left bank tributary, DRY
4300 (+0)(4248') right bank erosion 6'H LDA 15'Wx3'Hx10'L (+25)(4325')
4902 (+0)(4858') left bank erosion 6'H
5249 (+0)(5183') right bank erosion 10'H
5275 (+5)(5268') right bank tributary, a trickle
5838 (+5)(5810') left bank tributary. Dry
6209 (+0)(6184') right bank erosion 25'
6344 (+36)(6336') right bank erosion 9'H
6433 (+0)(6374') left bank erosion (+18)(6392') LDA 41'Lx6'Hx16'W, gravel retained 2'Hx10'L
6486 (+0)(6467'-6635')
6639 (+34)(6635') LDA 8'Lx6'Wx2'H
6735 (+30)(6705') left bank erosion 12'H
7408 (+35)(7375') right bank tributary, Ref. point on map
11570 (+11)(11500) LDA 3'Hx75'Wx15'L, retaining gravel 2'Dx50'Wx50'L, not a barrier
12286 (+3)(12215') left bank erosion 30'L contributing fines 1.5'D dug fir into channel
12340 (12310') 3' jump with 2' gravel retained
12489 (+3)(12432') 12 right bank seep
12972 (12942')Top: 4' jump over down log retaining sediment 3' deep
13412 (13318') 10'd CMP culvert, entire unit, no baffles, no barrier
13540 (13568') Top of unit: LDA 4'Hx15'Wx5'L, gravel retained 2'd at base
13725 (+7)(13674') left bank tributary approximately. 1gpm, probably not anadromous (+50)(13717') Many 4'd chunks in channel. No gravel retention. Swamp conditions
14094 (+23)(14132') right bank tributary, Dry
14420 (+15)(14401') Log raft 15'Wx47'L. NGNB
14756 (+28)(14772') Log Raft 15'Wx22'L, NGNB
15849 (+102)(15856') RR trestle, relic
15909 (15947') left bank tributary, approximately. 1 GPM, Possibly fish bearing, but very poor habitat, steep, clogged with vegetation, silty
16283 (+21)(16311') LDA 5'Hx15'Wx10'L NGNB
19441 End of Survey. Dual 4'd CMP culverts 40'L, no barrier no baffles.
DIH