Stream and Riparian Inventory

Introduction

The Stream and Riparian Inventory is dedicated to the memory of Garrett Gibson. Garrett was an enthusiastic botanist, a gourmet cook, and a good person. He is missed.

The objective of the Stream and Riparian Inventory is to determine and quantify existing conditions on Big Chico Creek and its major tributaries, Mud, Rock and Sycamore Creeks. Specific attributes, demonstrated to be indicative of stream condition, were tested using accepted scientific protocols. The seasonal sampling of these attributes can be expected to be useful in describing physical condition differences with a moderate to high level of confidence (Stream Condition Inventory 3.4, 1996, pg8). In the future, it is expected that volunteers will conduct this inventory.

This Stream and Riparian Inventory utilizes two established survey protocols: The Stream Condition Inventory, and The Greenline Protocol. The Stream Condition Inventory (SCI), a survey methodology developed by the United States Forest Service (USFS), is a way to measure stream conditions with statistical validity. The Greenline Protocol, which is in the process of being implemented nationally, monitors riparian plant community composition to determine the overall health of the stream corridor.

Methodology

Stream Survey Inventory

Surveys were completed at 8 stream reaches with 3 permanent cross-sections installed per reach (see Map Valley Study Sites).

Stream Reaches:

BIG CHICO CREEK - UPPER BIDWELL PARK REACH

BIG CHICO CREEK - LOWER PARK REACH

BIG CHICO CREEK - BIDWELL AVENUE REACH

LINDO CHANNEL - FIVE-MILE REACH

LINDO CHANNEL - MADRONE REACH

SYCAMORE CREEK REACH

MUD CREEK REACH

ROCK CREEK REACH

These permanent cross-sections will help in the long term monitoring of stream and channel trends, as well as monitor the creek's suitability as salmonid and other wildlife habitat. Stream cross-section measurements taken include: percent of banks that are stable, pebble size, percent of shade by vegetative cover, and numbers of large woody debris. Pool measurements taken consist of maximum pool depth, water depth at end of pool, and percent of fine particles in the pool tail. Floodplain measurements include bankful width and depth and size of the streamside floodplain.

Stream Type

Cross-section measurements contribute to the ability to classify the stream using Dave Rosgen's system. Rosgen identifies 7 major stream types, A-G, and uses modifier numbers to indicate the dominant bed material (e.g., A1). Stream types A, B, C and F are found in this inventory:

• An A stream has a steep slope, little or no floodplain and is narrow
• A B stream has less slope, more floodplain, and is wider compared to its depth: a mountain stream with a more defined valley
• A C stream is quite flat, with a channel that tends to be wider than B's and a wide floodplain: a classic meandering valley stream
• A F stream is a valley stream that has downcut to the point it can no longer access its floodplain and is in the process of building new floodplains by eroding away its banks.

Pebble Count

Pebble size is, among other things, indicative of the stream's power to move material and to cause erosion. Salmonids need gravel of about 2-4"in diameter in order to spawn. High concentrations of fine materials deposited in stream gravel reduce the amount of oxygen available to the eggs, causing them to be smothered.

Measurement: substrate composition (pebble count).

Large Woody Debris

Large woody debris (LWD) is an important component for fisheries habitat when available (Rosgen, 1996, pg.5-72). LWD provides nutrients to aquatic insects, encourages the formation of pools, and provides shelter and cover for fish.

Measurement: # Large Woody Debris.

Pool Measurements

Pools are essential habitat for fish. Deeper pools provide cover from predators and help maintain the cool water temperatures necessary for salmonids. Pool tail fines (particles <2mm) were measured, as the pool tails are a favored spawning area for salmonids. Fines in pool tails clog gravel and prevent water from flowing through, limiting oxygen supply to salmon eggs.

Measurements: maximum and pool tail depths, pool tail fines, pool residual depth.

Shade

Shade is essential to keep water temperatures low, as well as providing cover for fish. Fallen leaves and large woody debris from trees growing along stream banks provide food and cover for aquatic insects and fish. Historically, the United States Fish &Wildlife Service (USFWS) has used 70% shade as an optimal goal for salmonid streams.

Measurement: percent shade.

Bank Stability, Width/Depth

A high width/depth ratio (shallow stream) may be an indicator of unstable bank conditions. Water flowing in a stream always has a certain amount of energy, which is used for 1) overcoming internal friction (turbulence) and 2) overcoming friction with the bed and banks or vegetation. If the energy available to the stream is not fully used in overcoming internal friction, bed, banks or vegetation friction it will be used for transporting sediment or eroding the bed or banks (J. Castro, NRCS unpublished handout, 4/24/98). When the stream reach is very wide and shallow, it has a tendency to deposit gravel and can easily transfer that energy to eroding banks. Unstable banks are a major source of fines.

Measurement: transect.

RIPARIAN VEGETATION INVENTORY

The Greenline monitoring method was selected for documenting vegetation characteristics along Big Chico Creek and its tributaries. The U.S. Bureau of Land Management (BLM) and the U.S. Forest Service (USFS) originally developed the methodology. The greenline is defined as that specific area where a more or less continuous cover of vegetation is encountered when moving away from the center of an observable channel. The percent of each different plant community type along the greenline is determined and then used to evaluate the riparian vegetation. The advantage of the Greenline method is that it is a variable plot method, repeatable independent of peak flow events. In fixed plot methods, the plots are vulnerable to being washed out or silted over.

The Greenline method has three components:

• Greenline transect
• Woody species regeneration
• Riparian cross-section

Note: A modified BLM/USFS protocol was instituted, so that the Greenline method could be used in conjunction with the SCI.

Recording plant community types is an integral part of the Greenline method. Extensive work has been done in portions of the Western United States to classify the community types and determine stability class ratings for each type. In those areas, each community type has been assigned a stability class rating, which indicates its ability to anchor and protect the stream bank from the erosive action of flowing water. The scale for stability classes ranges from 0 to 10 where 10 has the greatest stabilizing ability. Unfortunately, the plant community types and stability class ratings have not been developed specifically for the Big Chico Creek study area. Stability class ratings were assigned based on tentative recommendations noted in the course of gathering data in the field and in follow-up meetings with local botanists and stream restorationists.

Vegetation studies for each reach began with the compilation of a species list. Most of the reach was traversed (on foot along the banks and/or in the stream), and all of the plant species were noted, or collected for later identification. Thorough familiarity with the flora was helpful when data for the actual transects was collected (see Appendix A. Stream and Riparian Inventory Species List).

The standard BLM/USFS protocol for the length of a Greenline transect is 363 feet along one bank, and then 363 feet back along the opposite bank. A typical SCI study reach is about 1,600 feet in length. SCI data collection includes selecting and measuring channel cross-sections at three sites within the 500-meter study reach. To adapt the Greenline method for use with SCI, the Greenline transect footage was divided into thirds. Specifically, the plant community types were recorded for 121 feet along the banks, with each 121-foot segment beginning at one of the three SCI cross-sections. Plant community types were described in the course of collecting the data, based on the dominant and subdominant species present along the transect. A result of adapting the Greenline method to SCI is that Himalayan blackberry and other dense vegetation types are probably under-represented in the percentages of community types. The exact location of SCI channel cross-sections is partly determined by ease of accessibility, thus creating a bias in the vegetation data results when that data is collected in the vicinity of dense blackberry thickets.

The Woody Species Regeneration data is collected by retracing the greenline transect, and recording the individual trees and shrubs rather than the community types. The individual plants are tallied by age class (i.e., seedling, and sapling, mature, decadent, dead) and species. Blackberries and California pipevine were not considered woody species in the Woody Species Regeneration portions of the Stream Inventory.

A riparian vegetation cross-section was established 15 feet from each of the three SCI channel cross-sections in each of the study reaches. The SCI cross-sections were completed first as a precaution against any trampling or other vegetation disturbance created by data gatherers. The end-points for each of the riparian vegetation cross-sections were selected based on site-specific features such as the top of a levee, a road or other constructed feature, or the point on a slope where upland vegetation community types occur. The riparian vegetation data was recorded in the same manner as the greenline transect and Woody Species Regeneration portions, except that the transects cut across the stream rather than running along it.

Throughout this document, the riparian cross-section located furthest downstream in the study reach is referred to as the lower cross-section, and the one located furthest upstream within the study reach is referred to as the upper cross-section.

BIG CHICO CREEK - UPPER BIDWELL PARK REACH

Stream Inventory

The Upper Bidwell Park Reach (Upper Park) is located just upstream of the 5-Mile pedestrian bridge in the 5-Mile Recreation Area and extends upstream to the 17th Hole on the Bidwell Golf Course. The reach is 548 m long.

Table Average SCI inventory for Upper Park Reach

Large woody debris (LWD) counts in the Upper Park Reach were low at 31 pieces/mile, with one aggregate of 3 pieces. The January 1997 storm, estimated to be a 75-100 year event, moved out a considerable amount of LWD and placed it against the Lindo Channel Diversion Dam and the Wildwood Avenue Bridge. If the Wildwood Avenue Bridge were made "Large Woody Debris Friendly", LWD might move downstream to the "Sycamore By-Pass Canyon", where it could be beneficial in resisting the large active erosion taking place.

The pebble count found 13% of the substrate composition to be fines. This reach has 3.1% pool tail fines. This low number of pool tail fines can be considered a base line from which to compare lower reaches.

This reach has an average maximum pool depth of 1.5 m with an average pool tail depth of 0.3 m. Pools are long, with only four being found throughout the reach.

Big Chico Creek - Upper Bidwell Park

According to Rosgen's classification system, The stream type is B4c. Entrenchment decreases and slope increases as the survey progresses upstream. This would be expected as the stream ascends higher into its canyon, thus increasing confinement. At the lowermost cross-section, the north bank is composed of erosion-resistant materials while the south side has a wide accessible floodplain. Progressing upstream the north bank is riprapped in several areas as it flows along the golf course and the stream becomes more entrenched with a less accessible floodplain. The result is the stream assuming more B-type characteristics of confinement and entrenchment.

This reach's width/depth ratio is higher than Rosgen's statistics for B4 streams. The very high Width to Depth ratio may reflect the stream exiting the canyon and depositing bedload (Maslin, 1999, pers. Comm.). It may also be a result of channel scouring during the 1997 storm. A high width/depth ratio has the result of spreading water over shallow riffles, which may cause it to heat up, especially when coupled with very low (26%) shade for this reach. The high width/ depth however, may be beneficial rearing habitat for salmonid fry.

According to the USFS, a stream bank stability problem exists if stability is less than 80% in response reaches (generally C streams) or less than 75% in transport reaches (generally B streams). The upper park reach may be 52% stable, 23% below the USFS threshold. The instability in this reach may be partially due to the January 1997 storm event and from impacts of recreation.

The variability in shading in this reach is characteristic of meandering streams. In this reach the mean shade is 26%. Shade may be low in this reach partially because of the 1997 storm event, which swept away dozens of alders. The proximity of the paved road on the south side of the creek and the golf course on the north also limits the shading in this reach.

Riparian Vegetation Inventory

The vegetation along this reach of Big Chico Creek can generally be described as riparian forest. The most noticeable plants are towering sycamores and valley oaks, alders, and gray pines and live oaks in the adjacent uplands. Shrub and herbaceous vegetation types are present where the tree canopy is thin, or in gaps of the tree canopy. Gravel bars, and similar areas of exposed substrate immediately adjacent to the stream, are nursery sites for large numbers of riparian tree and shrub seedlings.

A total of 116 plant species were observed at the Upper Park reach. One third of these were trees or shrubs, and two thirds were herbaceous species. Of the 37 woody species, 22% were non-native species. In the herbaceous category, 79 (53%) were non-natives. Such a high percentage of non-native herbaceous species is typical for much of the California Central Valley and surrounding foothills (see Appendix A for a detailed species list).

Several highly invasive wildland plant species exist in this reach including giant reed, Yellow star-thistle, English-ivy, and Himalayan blackberry.

The giant reed, star thistle, and blackberry were present in sufficient amounts to be considered community types in the Greenline transect. The English-ivy is not common at this time. Other potentially degrading exotic species include Eastern hackberry, edible fig, privet, and white mulberry.

GREENLINE TRANSECT

A diverse mix of plant community types was encountered in the course of the Greenline transect, and is a reflection of the large number of species present at the Upper Park Reach. To summarize, 24%of the transect was essentially un-vegetated (although the right bank of the lower section, which was all bedrock, did support a noticeable amount of deergrass). Native trees and shrubs accounted for 31%, and the corresponding value for non-natives was 19 percent (giant reed is included in this value due to its unusually large stature for a herbaceous species). At the herbaceous level, native species community types constituted 15½ % of the transect, while 12% was non-native. The left bank of the lower section of the transect had some un-vegetated public trails accessing the stream. This bare ground is approximately 4% of the transect, however, these sections were ignored, and the transect was extended an equivalent distance for vegetation data gathering purposes.

The stability rating for the Upper Park Reach is 5.67; thus the vegetation along this section of stream has a moderate ability to stabilize the banks.

BIG CHICO CREEK - LOWER PARK REACH

Stream Inventory

The Lower Park Reach begins just downstream of the Madrone Avenue Bikeway Bridge and extends downstream 532 m just above the Cedar Grove Bike Bridge. This well-shaded stretch is 63.2% shallow pools, with a significant amount of LWD and steep banks. The average maximum pool depth (which is affected by cobble dams created by recreationists) is 0.79 m with an average pool tail depth of 0.41m. Pool depth is not optimal for salmonid habitat and bears monitoring. Pool tail fines are low in this reach, but should be monitored due to the percentage of unstable banks.

Table Average SCI inventory for Lower Park Reach

The substrate consists primarily of small cobbles with a significant amount of gravel. Bank stability is rated as low. This reach is characterized by deeper entrenchment than expected for this stream type (B3c). This could indicate that the stream is down cutting below the point where it can access its floodplain. This could bring about a significant cycle of degradation where the stream erodes the banks extensively and creates a new streamside floodplain incised well below the existing one.

City of Chico Park Management has decided to leave LWD in the system unless it threatens infrastructure. The resulting increase in LWD may lead to variability in shade figures as channel meandering takes place. This may also open the canopy in patches for willow and alder regeneration. The existing 82.3% shade may limit regeneration of shade intolerant riparian species such as willows and cottonwoods.

Riparian Inventory

Both surrounding residential landscaping and managed stream flows in the Lower Park Reach have, in different ways, promoted non-native tree and shrub species. Since Lower Bidwell Park is contiguous to the backyards of many residences, the introduction of horticultural species is inevitable. The relevance of managed flows is discussed in the section on woody species regeneration.

The stream here is lined with mature trees, with mature canopies reaching completely over the channel. Typical tree species immediately adjacent to the stream are alder, ash, sycamore, and catalpa. The vegetation here falls within the California sycamore series vegetation type (A Manual of California Vegetation).

Outside the immediate stream margins is a riparian forest type categorized as valley oak series. This series typically becomes established where the soils are intermittently flooded, but only seasonally saturated. In this reach, the valley oaks and other tree species, such as sycamore and northern California black walnut, form a towering canopy covered with wild grape. Below the high canopy, the shrubs present are scattered thickets of elderberry, pipevine, and other species. The herbaceous layer is dense with annual grasses and forbs.

The plant list for this reach has 65 species; 27 are herbaceous and 38 are tree or shrub species. This is quite different than the findings in the Upper Park Reach which had nearly twice the number of species, and where herbs outnumbered trees and shrubs two to one. Forty percent of the tree and shrub species and 48% of the herbaceous species in the Lower Park Reach were non-native.

The number of non-native herbaceous species present is similar to results found during biological assessments conducted on Deer Creek, Toomes Creek, Mill Creek, Dye Creek, Antelope Creek and Butler Slough. However, the number of woody species, 40%, is significantly higher than the 18% reported in the comparable assessment. This comparison suggests an unusually high level of non-native trees and shrubs in the Lower Park Reach.

Non-native species are so prominent in this reach that they are addressed separately below. Northern California black walnut is categorized as a native species in this report, however its status as a native or non-native is currently a matter of debate. Re-analyzing the data with black walnut as non-native would not substantially alter the results, although this species does appear regularly in the Lower Park Reach data set.

NON-NATIVE SPECIES CONCERNS

The flora of the Lower Park Reach, and Lower Bidwell Park in general, has been significantly infiltrated by non-native species. The level and type of impact of each non-native species is different, but exotic species are seldom ecologically beneficial.

All of the non-native species observed in the course of the field studies are indicated on the list of plants in Appendix A. Some of the more invasive or rampant species are discussed here. It should be noted that there are numerous other non-native species in Lower Bidwell Park beyond the borders of the study area. They have not been included on the plant list.

Periwinkle (Vinca major) often forms a nearly continuous ground cover below the tree canopy along the stream. It and Himalayan blackberry have displaced nearly all native herbaceous species in this densely shaded, relatively moist environment.

Big Chico Creek - Lower Bidwell Park Reach

Himalayan blackberry (Rubus discolor) is widespread, and probably underrepresented in

This study due to the previously discussed bias against it in the selection of Stream Condition Inventory cross-section sites. The park roads do appear to serve as a deterrent to the vegetative spread of periwinkle and Himalayan blackberry in many instances.

A substantial infestation of a thorn-less blackberry cultivar was encountered in this study. It is of particular concern because it has a much more clambering growth habit, spreading substantially and unusually high into the tree canopy, in comparison to the Himalayan blackberry or native California blackberry. The infestation is located on the south side of the stream in the vicinity of Picnic Site 8.

English-Ivy (Hedera helix) was only documented in the Lower Park Reach during the initial botanical survey. While it was not significantly represented in the study reach, large (often over a hundred feet in diameter) infestations were noticed in other areas of Lower Bidwell Park. Two specific sites are 1) the south side of Big Chico Creek just west of the freeway and 2) on the north side of the stream, downstream from the Cedar Grove Bicycle Bridge (just downstream from the study reach).

Numerous non-native tree species are present and competing with the native species. The non-natives present in higher numbers include catalpa, hackberry, hawthorn, fig, mulberry, privet, and pistachio. There are at least five more species present in lower numbers.

A potentially useful management suggestion would be to census the English-Ivy and privet in the winter, as their evergreen habit makes them readily visible in comparison to the majority of the other riparian species which are deciduous.

On a positive note, tree-of-heaven (Ailanthus altissima) was absent. This is an admirable result of the park management non-native, eradication program.

GREENLINE TRANSECT

Nearly 90% of the stream margin is lined with riparian tree and shrub community types (70% tree, about 20% shrub). This is quite high, and for comparison, the Upper Park Reach had only 50% tree and shrub community type footage along the greenline.

In Lower Park, 73% of the transect intercepted native community types, and 25% was vegetated with non-native species community types. The non-native woody species in this study area are generally not as tall as the natives, thus they often get recorded as subdominant and their significance is underestimated. Looking at the data in a slightly different perspective to compensate for this limitation of the Greenline Protocol, non-native species were dominant or subdominant for 40% of the transect length.

Tree species are generally good at stabilizing stream banks; thus the stability class rating in the Lower Park Reach was relatively high among the reaches in this study at 6.77.

BIG CHICO CREEK - BIDWELL AVENUE REACH

The Bidwell Avenue Reach begins 72 m downstream of the Nord Avenue Bridge, and extends 534 m. Big Chico Creek is more entrenched here than in other reaches, with floodwater unable to access a floodplain. This sensitive reach is actually less entrenched than downstream towards Rose Avenue. Banks are generally fine soil particles or riprap.

Table Average SCI inventory for Big Chico Creek - Bidwell Ave. Reach

The reach cross-sections are on the cusp between B4c and F4. This reflects the F4 stream type process of forming a new geomorphic floodplain at its current level. Overall cross-section characteristics correspond with Rosgen's description of the F4 stream type, "...incised in alluvial valleys resulting in the abandonment of former floodplains... slopes less than 2%, ...and have width/depth ratios that are high to very high" (Rosgen 1996, pg5-154). Width/depth ratios though, fall slightly higher than the mean for an F4 stream.

The pebble count showed significant concentration of fines in this reach (particles < 2mm). In fact, 27% of the total substrate was surveyed as fines, second only to the Sycamore Creek Reach for fine levels. This is indicative of the reach's deep entrenchment in fine depositional soils. Rosgen describes F4 sediment supply as "moderate to high depending on stream bank stability. " Stream bank erosion rates are very high due to side slope rejuvenation and mass wasting processes, ".unless, riparian vegetation ... covers the entire slope face of the channel banks"

Big Chico Creek - Bidwell Avenue Reach

(Rosgen, pg. 5-154). Pebble size here is smaller than Lower Park. LWD count for this reach was 113 pieces/mile, and could be regarded as generally good.

This reach is 57% pools, higher than the USFS ratio for transport reaches. The stream is well shaded. The percentage of wood formed pools is also high at 75%. Large wood contributes to pool formation. Residual pool depths are substantially greater than Lower Park's, averaging 0.9 m deeper. This may be partially because of the additional storm drain flows added to the creek between the two reaches, and may also reflect the additional confinement of this reach which is over 1.6 m more entrenched in valley soils.

In this reach only 15% of the banks are stable. Since it tends to form a new geomorphic floodplain at its lower level, the creek cuts into its banks. The high width/depth ratio is indicative of and contributes to this process. The stream tends to be shallow and wide, especially at riffles and runs, putting more erosive pressure (shear stress) on its banks. The percentage of unstable banks is also evidence of the process of floodplain formation. According to Region 5 USFS data, a problem of stream bank stability exists if the percentage of stable banks is less than 75% in transport reaches (generally B streams), which include the F4 stream type.

The stream is bound by Bidwell Avenue to the north. Since Butte County is obligated to protect the road from undercutting, riprap has been placed at several locations, making the bank progressively "harder" and more resistant to erosion. That riprap design does not usually provide for vegetation or soil in the voids, riparian canopies are usually absent. It was difficult to locate riffles for the cross-section and still avoid north bank riprap. Private property owners to the south have backyards that are deep and thus far have not hardened their banks with riprap. This has allowed the stream to create some streamside floodplain to the south and has limited down cutting.

Significant levels of fines were discovered in this reach. It is second only to the Sycamore reach in terms of fines. Additionally, 85% of its banks rated unstable or vulnerable.

Rosgen describes the F4 stream type as, ".extremely sensitive to disturbance with a poor recovery potential, . a very high sediment supply and stream bank erosion, .vegetation's controlling influence on stream bank erosion and stream stability is moderate due to the difficulty of vegetation growing up the entire inner banks." Therefore, preliminary indications show that Big Chico Creek is very sensitive to changes in stream flow magnitude, timing, and/or sediment increases.

A critical problem that complicates the analysis of the Bidwell Avenue Reach and the Lower Park Reach is the altering of the natural water flow cycles below the Five-Mile Diversion Dam. The peaks are cut off. The diversion structure only allows flows up to 1500 cfs to pass. Determining bankfull flow level is difficult because the water volume never exceeds a certain level.

Standard bankfull determination methods were used. One difference between the Lower Park Reach and the Bidwell Avenue Reach is that a number of storm drains enter the creek upstream of the Bidwell Avenue Reach, ultimately increasing water levels.

Riparian Inventory

This reach is the lowest site on Big Chico Creek, located immediately downstream from the Nord Avenue Bridge (State Route 32). It is surrounded by residential development. The northwest side is bound by Bidwell Avenue with residences immediately behind it. There is also a small area of abandoned floodplain on this side. The southeast side has residential development often reaching to the top of the bank, and a short stretch of commercial development just off of Nord Avenue. In this reach the banks are very steep.

The vegetation can be described as riparian forest, though only a few mature specimens of native trees remain. Like the Upper Park Reach, this reach would best be described as a community of exotic invasive vegetation including the Tree-of-Heaven (Ailanthus altissima) which is moving aggressively into the mix from the upper end of the reach.

Greenline Transect

The coverage of the transect by woody community types is 88%. Of this coverage, 69% is still dominated by native trees and shrubs. This high percentage of native plants reflects the long-lived valley oaks that remain on this site.

Only 32% of the 22% in herbaceous coverage are native. This native coverage is one native species, rice cutgrass.

The stability rating was 5.69. This is a moderate level of stability in terms of the vegetation's ability to protect the banks from erosion or disturbance.

LINDO CHANNEL FIVE-MILE REACH

Stream Inventory

The Lindo Channel - Five-Mile Reach is located immediately downstream of the Five-Mile Recreation Area, extending for 470 m. This reach connects Big Chico Creek with Lindo Channel. The upper portion of this reach is affected by gravel removal by Butte County for flood control purposes. The surveys were performed in late November 1998 and April 1999.

Table Average SCI inventory for Lindo Channel - Five-Mile Reach

This reach has no large woody debris, as it is washed through to the Lindo Channel Diversion Dam and Wildwood Avenue Bridge. Lindo Channel is a wide and shallow gravel stream. The first cross-section was placed in the area affected by gravel removal, the second just beyond the area and the third above the Lindo Channel diversion dam.

The first cross-section data reflects the influence of gravel removal; the channel is undeveloped and wider (34.7m) in proportion to its depth than any of the other 27 cross-sections. Its stream side floodplain is only 1.56 times as wide as the channel although the floodplain is nearly 60 m wide. It is a B4c stream, and is 3 times as steep as the rest of the reach (1.56% slope).

The channel is more developed at the second cross-section. It's 30% narrower here (24.6 m) and twice as deep. The channel is almost exactly the same width at the third cross-section (24 m) and slightly deeper still. When the channel is deeper it can move more gravel in the bed. When a channel is allowed to maintain itself, it provides for deeper water. Deeper water can move more of the bedload through the reach, thus lowering costs for gravel removal and replacing some of the gravel that has moved downstream in Lindo Channel.

Water flowing in a stream always has a certain amount of energy available and can be used for:

• Overcoming internal friction
• Overcoming friction with the bed and banks or vegetation
• Transporting sediment
• Eroding the bed or banks

(J. Castro, NRCS unpublished handout)

Since the reach is very wide and shallow (width /depth Ratio average 84), it has a tendency to deposit gravel and can easily transfer that energy to eroding banks.

The Five-Mile Reach's pool/non pool ratio (p/np) is very low at 28.9%, considering the USFS average pool/non-pool ratio for C streams is 71.1%. Pool residual depth depends on many factors but the 0.38 m figure is a baseline figure and very low for a stream of this size. For example, the Bidwell Avenue reach is 8 m wide and has pools 2 m deep. At a very low 2%, fines are not currently a problem in the reach.

Lindo Channel - Five-Mile Reach

A problem exists if stream bank stability is less than 80% in response reaches (generally C streams). Only 38% of Lindo Channel's banks are stable in this reach, a very low stability rating. This is partially due to gravel manipulation, which have destroyed the channel in the past, and also because of the immense amount of gravel that Big Chico Creek deposits at 5-Mile after a large event like the January 1997 storm. It takes a series of smaller events to cut through the remaining gravel to recreate a new channel.

There is only 11.2% shade in this reach, much lower than the 70% that USFWS recommends. Management of Lindo Channel for flood capacity removes vegetation, leaving little shade, and not much cover for rearing salmonids, or other aquatic life.

Riparian Inventory

This 5-mile reach of Lindo Channel has many mature trees including valley oaks, cottonwoods, and sycamores. They are mostly on the streamside floodplain set back from the creek and do not shade it. Himalayan blackberry is beginning to invade here.

Greenline stability rating for this reach is 5.43 or moderately resistant to erosion. By far the largest percentage of stream bank vegetation is annual grasses 40.9%, followed in abundance by Pale spike rush 12.5%, cottonwood 8.3%, and willow leafed Baccharis 6.6%. Increasing the abundance of cottonwood and willow leafed Baccahris could help to shade and prevent bank erosion.

NON-NATIVE INVASIVE PLANTS

Spanish broom is present on the floodplain. Botanists observed approximately 100 juveniles and a few adults up to 9 feet high. A few giant reed (Arundo donax) clumps exist. It is normally spread by high water events that spread corms and canes which then root.

Privet also occurs here, apparently spreading from the landscaped area by the Five-Mile Recreation Area where several large trees are located near the restrooms. Close to a large privet tree in the reach, the ground is carpeted with seedlings. Ripgut brome was also present in appreciable quantities.

LINDO CHANNEL AT MADRONE REACH

Stream Inventory

The Lindo Channel - Madrone Reach is located downstream of the Madrone Avenue Bicycle Bridge, and is 492 m long. The reach has no LWD. Here, Lindo Channel is a gravel stream with very few fine soil particles. The stream in this reach is very wide and shallow. In the area close to the bridge it is a relatively flat, meandering gravel stream (C4c). It can flood onto a wide streamside floodplain where sand and fines deposit. The floodplain contains an overflow channel that flows to a pond that remains filled into the summer, providing habitat for the mallards and frogs that were observed in April. The stream is also wide here because of changes in the stream that have occurred the last few years.

Table Average SCI inventory for Lindo Channel - Madrone Reach

As it flows downstream the channel narrows by 50%. This constriction is due to old tailing piles at the First Avenue and Verbena open space area, and also because some of the gravel has settled out. Here the stream changes to a B4c stream, a straighter (less meandering) stream. The total streamside floodplain changes in width from 123 m near Madrone to only 33.7 m near Verbena.

Lindo Channel - Madrone Avenue Reach

The Madrone reach was the most dynamic of all the reaches on Lindo Channel. In November, during the course of the survey, a 1.7 meter pool filled and another 1.7 meter pool was created almost 100 m upstream during a storm. Possible explanations for these manifestations are:

• California Department of Water Resources cut willows the previous summer. Many willows died. The willows previously had slowed stream flows. Killing them increased water speed, thus moving more gravel.
• The new bike bridge restricts the stream's access to its stream side floodplain, again, increasing the depth and speed of flows during storms. Approximately 2 foot additional down cut in the stream gravel was observed under the bridge.
• A cement bike path was removed from the channel after the bridge was installed. This had been stabilizing the stream's bedload. Removed, it allowed a gully to travel upstream moving more gravel.

Moving gravel have moved two riffles downstream 20 m and buried 3.2 m of rip rap since 1990. So far this has created only minor problems for the stream or adjacent property owners.

The reach has a good number of pools and they are adequately deep. Only 58% of Lindo Channel's banks are stable. There is less than 5% shade in Lindo Channel, much lower than the 70% that USFWS recommends. Management of the channel over the years has removed quite a bit of vegetation, leaving little shade, and not much cover for rearing salmonids. In fact, where there were willows or cottonwoods growing next to the water, the field staff found schools of young salmon.

Riparian Inventory

Lindo Channel currently is used as a diversion for flood waters from Big Chico Creek. It is an intermittent stream with its flow controlled by the dam at the Five-Mile Recreation Area and the Lindo Channel Diversion Dam. The reach is bounded by what may be a natural bank on the southeast side and extensive areas of fill. The northwest side is a stabilized high bank that is bordered by residential housing.

In this reach there are fairly well-developed willow thickets and some different-sized cottonwoods. However, the most striking feature is the open dry meadows of annual grass, johnsongrass, star-thistle and mugwort. There are several groups of giant cane and a fair number of Spanish broom from two to six feet in height spread over the left bank floodplain. One tamarisk was found in a storm drain channel. The number and dispersion of Spanish broom shows a developing problem with this invasive exotic plant.

Because it is a diversion, the stream dries up as the flow of Big Chico Creek declines in the spring. There is active ground flow during the summer that sustains the riparian trees and shrubs. There is only one seasonal pond and a small seasonal wetland dominated by deer grass.

Most active seed regeneration of woody vegetation occurs in the streambed where lingering moisture allows seedlings to establish themselves sufficiently to pursue the water table as it drops. This reach and the Sycamore Creek Reach are the driest, most intermittent, sections in this survey.

However, active runoff from yards and streets, and even watering by homeowners, has created some mesic, or wet, areas on the northwest bank. In addition, active planting of native and non-native species by homeowners has added to the complexity of the site.

GREENLINE TRANSECT

Trees and shrubs, all native species, compose 36% of the greenline coverage. Of the remaining coverage (64%) of herbaceous community types, 27% of these are dominated by native species.

The stability rating of 4.23 for this reach is in the poor range. As such, the vegetation offers only "poor" ability to stabilize the banks against erosion.

THE RE-SURVEY OF THE GREENLINE PROTOCOL

As a requirement of the funding agency one reach was to be re-surveyed using the standard Greenline protocol that was modified for use in this study. The Lindo Channel Madrone reach was chosen for this re-examination.

The re-survey yielded a stability rating of 4.23. This value is only 0.09 more than the original value of 4.14. This verifies the accuracy and repeatability of the modified Greenline protocol that was used. Below is a rough breakdown of the results of the two trials on this reach. Since they were completed a month later, little water remained in the stream save for a few isolated pools.

Three variables likely account for the variation in the feet per general community type. First, warm season perennial grasses and forbs, and actively growing grapevine and roses displaced annual grasses. Changes in the lay of the greenline and alternative interpretation by the examiners are the other two possible variables.

SYCAMORE CREEK REACH

Stream Inventory

The Sycamore Creek Reach is just upstream of Cohasset Road. Surveys were performed in December 1998 and May 1999. Sycamore Creek joins the Sycamore by-pass Channel at the upper boundary of this 392 m reach. The Sycamore By-Pass Channel contains water from a small (unnamed) drainage and overflow water from Big Chico Creek and Lindo Channel.

Table Average SCI inventory for Sycamore Creek Reach

This reach had three pieces of LWD. Overflows from Big Chico Creek and Lindo Channel sweep all large pieces of wood downstream to the Cohasset Road Bridge where it is normally removed by equipment during and after large storms. The design of the bridge is such that it catches most of the large wood during high flow. Sycamore Creek is a gravel stream with many fines; 18% of the pebble count were fines.

At the upper end of this reach, Sycamore Creek cuts through a large gravel and cobble floodplain/bar. The stream is more confined here by this gravel bar than elsewhere in the reach. It forms a B4c stream. The rest of the reach has a much wider streamside floodplain, which averages 3.4 times the width of the stream channel. This type of stream, a C4c, or relatively flat meandering gravel stream, tends to deposit gravel and create meanders in some areas. Sediment supply in this type of stream has a tendency to be moderate to high unless stream banks are in very stable condition. The stream's lowest cross-section has a narrower channel.

Sycamore Creek Reach

Only 24% of Sycamore Creek's banks are stable in this reach. It is interesting to note that the upper section of the reach where the stream is more of a transport stream (B4c) it is much more stable. In the lower two-thirds the banks are much more unstable.

At a mean shade value of 0.74%, shade is very low in Sycamore. This reach dries up much earlier than the other reaches studied. It generally ceases flowing by mid-May.

Fines were at 71% in our pool tails, by far the highest figure in the survey. Fines are mobilized elsewhere in the system and drop out where ever the stream flattens out. These fines are then colonized by vegetation, such as reeds and sedges. One large source of fines is the new "Sycamore By-Pass Canyon" forming upstream about 1/2 mile of this reach. Overflow waters from Lindo Channel and Big Chico Creek flow into what was a small stream (before By-Pass was completed). At times, this overflow can reach 8,000 cfs. These waters have cut a channel 6 m deep by 12 m wide. This reach is one area where these fines drop out of suspension. Other fines come from unstable banks.

Reeds, sedges and annuals, grasses, and star thistle dominate vegetation here.

Riparian Inventory

The Sycamore Creek Reach is the only reach still under heavy grazing as pastureland. The site is generally barren. Only a few large cottonwoods and willows remain on the northwest bank. The upland area is exclusively grassland with annual grass and a heavy star thistle component.

The southeast side is a "natural" slope rising to Eaton Avenue, which has not yet experienced urban development. The northwest side has a steep bank that rises from the channel to a fairly level upland that has a small service road setback about 100 to 150 feet.

GREENLINE TRANSECT

The few trees on this site are all native, making 7% of the total coverage. Of the total herbaceous coverage of 92%, only 17% are native with the remaining 83% dominated by non-native species.

Cattle have trampled the upland areas under the few trees. By the time the lower greenline transect section had been performed the vegetation was trampled that the composition and location were to some extent estimations.

This reach was found to have a very low stability rating of 3.03, which is at the very bottom of the "poor" category. This indicates that the ability of the vegetation to stabilize the banks of this reach is very poor. This correlates with the stream survey finding of only 24% stable banks.

The lower third of the greenline has more mesic or moisture dependent vegetation. This is reflected in the cross-section with rushes, perennial grasses and mugwort growing in the channel. This is due to a rise in the water table that is a result of runoff from the local residential areas and roads.

The major factors in the condition of this reach's vegetation are intermittent flows, the large amount of fines washing in from above, and cattle grazing. The stream stopped flowing in early May, about when the cattle arrived. As the area dried down, the cows spent more and more time adjacent to and in the stream. Perennial herbaceous plants like Eleocharis macrostachya, which formed 14.4% of the Greenline, can become well established in this regime. They thrive in an area where fines are deposited and moisture is seasonal.

MUD CREEK REACH

Stream Inventory

The Mud Creek Reach is located several hundred meters upstream of the Sycamore /Mud Channel confluence and extends for 560 m. The surveys were performed in late April and early May. Mud Creek was where the team repeated the SCI portion of our survey (as required by EPA), in order to evaluate the consistency of survey techniques. In general, repeat figures followed very closely the original survey figures.

Table Average SCI inventory for Mud Creek Reach

This reach has no large pieces of wood. Since it is part of the flood control system, large wood is removed or burned by California Department of Water Resources. This is done because large wood tends to get caught on bridge pilings. Unfortunately, this deprives the stream and its ecosystem of an important food and energy source. Mud Creek is a gravel stream with 15% fines.

The floodway appears to have plenty of capacity to carry flood flows here, with its average width of 101.7 m.

Pool/non-pool ratio for this reach would be considered quite good for fishery purposes.

There are significant numbers of fines in Mud Creek, though the percentage is not high enough to present a problem at this time. Since the stream has excellent access to its floodplain, the fines may be settling out on it. Due to large wood removal from the creek, only one of the pools was formed by wood.

Only 45% of Mud Creek's banks are stable in this reach, which is a little more than half the optimum percentage. This may be contributing some of the fines found in the pebble count.

Mud Creek Reach

The USFWS has recommended 70% shade for salmonids. The USFS has documented 30% shade occurs in response reaches (like this C stream). The shade on Mud Creek is very low at 47.5%. Management of the creek for floodway capacity has destroyed quite a bit of vegetation, leaving little for cover for fish. Indeed, wherever willows or cottonwoods were growing next to the water, young minnow schools were found.

Riparian Inventory

This portion of Mud Creek is bounded by setback levees. Outside the right bank levee, or north side, is a residential development. The south side is in agricultural use as a recently planted orchard.

Visually the levees are the dominating feature of this reach. However, despite maintenance for flood control, the stream banks and some portions of the floodplain within the levees have begun to develop towards a riparian forest. Upstream from the reach large cottonwoods and willow thickets are well-developed and moderately extensive in coverage. This vegetation thins downstream, through the reach, and becomes largely absent by its end. The riparian forest tree and shrub species are largely native.

Introduced grasses -- johnsongrass, ripgut brome, medusa-head and other annual grasses -- dominate the floodplain. There are scattered patches of mugwort and lower wet areas have extensive population of iris-leafed rush, both native species. Only one small Himalayan blackberry was observed while the presence of yellow star-thistle seed stocks from last season shows it occurrence in this reach. For unknown reasons this season star thistle has not survived and is present only as scattered plants. It is unclear if this is a result of spraying for noxious weed control, an effect of the severe cold spell of December 1998, or due to other causes.

Despite its confinement in a flood control structure the stream meanders somewhat naturally within its channel and has a small floodplain. It is one of the more "natural" reaches in the valley portion of the watershed and it may provide a unique opportunity to recreate a native riparian forest as long as flood control concerns are addressed.

GREENLINE TRANSECT

The tree and shrub species encountered on the greenline were all native, although they have only 14% of the total coverage. Only one non-native tree, an Osage orange, was observed on the floodplain outside of the greenline. The coverage occurred primarily in the upper segment of the greenline.

Of herbaceous coverage of the greenline, 32% was of communities dominated by native species and 45% by non-native. The remainder of the greenline, 9%, was bare ground, johnsongrass, thatch and cobble.

The stability rating of 4.32 for this reach is in the poor range. As such, the vegetation offers only "poor" ability to stabilize the banks against erosion.

ROCK CREEK REACH

Stream Inventory

The Rock Creek Reach is off Keifer Lane, close to where Keifer Slough crosses. Surveys were performed in late May 1999. The reach is 435 m long

This cobble stream reach is 57% shallow pool, with no large woody debris and moderate shade. Fine particles are present in the pool tails in only small amounts. In the upper end of the reach the stream has a well-maintained bankfull channel, with willows on some of the banks and a very well vegetated overflow channel. Downstream the creek is wider and shallower, as it is in other areas observed while searching for a reach to survey. Here, with a high width to depth ratio averaging 48.37, it is wider than 82% of Rosgen's C3 streams.

Table Average SCI inventory for Rock Creek

The landowner explained that this reach has not been modified for 25 years with the exception of the lowermost 50 m where he had pushed stream gravel up against the banks to protect a large oak tree and orchard from bank erosion. Just above the reach, the landowner has done the same thing for approximately 25 m. Pushing gravel against the banks has in some ways protected the banks. The bulldozing has helped to create the wide flat channel observed in the lower end of the reach. In this wide flat channel, stream gravel tends to be deposited. This can force the stream to put more stress on its banks. This is countered by the energy it takes Rock Creek to remove the stream gravel from the bank.

Rock Creek Reach

This C3c stream, or relatively flat meandering cobble stream, tends to deposit gravel and create new meanders in some areas. Sediment supply in this type of stream has a tendency to be low unless stream banks are in a very erodible condition (Rosgen, 1996, pg. 5-92).

Only 46% of Rock Creek's banks are stable in this reach. It is interesting to note that the upper and middle sections of the reach are more stable in general. The lower third banks are much more unstable. Examination of entrenchment figures show that in the stable section the streamside floodplain is wide, whereas at the lower end the streamside floodplain is 25% narrower. This narrower floodplain coupled with fewer willows, means the stream has more energy to put into eroding the banks. The C3 stream channel explains Rosgen "... is susceptible to accelerated bank erosion".

At the upper end of the reach mature willows are common. Part of the streamside floodplain is in a well-vegetated overflow channel. Other reaches of Rock Creek have only a few mature trees. The landowner indicated that the ranch had little vegetation 25 years ago.

Riparian Inventory

This stream has seen a substantial impact by human activity. Immediately upstream of the reach, all shrub and tree vegetation has been removed from the channel in an attempt to improve flood control. The land owner along this reach, however, has refused access to allow vegetation clearing.

Just above the reach the streambed has been entered with heavy equipment to plow cobble and gravel from the channel. Mounds of stream deposits form the right bank of the creek. In addition, a windbreak composed of non-native species of cypress, cottonwood and Osage orange tops the left bank. These provide most of the shade on the stream.

Despite these factors, the streambed itself has native willows and to some extent has a "natural" feel. The south bank is un-leveed with willow, valley oak and California wild grape in front of the windbreak. Behind the windbreak is a large kiwi orchard. The right or north bank has evidence of some plowing in the past, and now has extensive willow thickets and other riparian vegetation. Just beyond the top of the north bank is a dirt road and extensive open grasslands that are used for grazing.

GREENLINE TRANSECT

Woody species are dominant in a total 56% of this reach's vegetation. Of this, 77%, was of woody community types dominated by a native species. Herbaceous communities covered 42% of the reach with only 7% of that dominated by natives. The remaining 1% was bare ground.

The stability rating of this reach is 5.63, which is considered to be "moderately" stable in terms of vegetation development. The better condition of this reach is likely due to the remaining vegetation in place as well as wise ranching management on site.

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