SULPHUR
CREEK WATERSHED RESTORATION STRATEGY
FEATHER RIVER COORDINATED
RESOURCE MANAGEMENT GROUP
AND
MOHAWK VALLEY WATERSHED
RESTORATION COMMITTEE
PLUMAS CORPORATION
550
Crescent Street
P.O. Box
3880
Quincy,
California 95971
(530)
283-3739
March 2005
TABLE OF CONTENTS
Introduction 1
Watershed Description 1
Stream Channel Conditions 2
Causal Agents 3
Strategy
Development 4
Desired
Conditions 4
Opportunities 5
Constraints 5
Watershed
Delineation and Ranking 6
Ranking of
Roads 8
Restoration
Priorities 9
Potential
Projects 10
Estimate
Project Costs 13
Monitoring
and Maintenance 14
Bibliography 17
Figures
1.
Stream
Channel and Floodplain Cross-section, Entrenchment and Widening
2.
Transport
Channels (Type A, B, &C), Response Channel (Type C)
3.
Development
of an Inset Stream Channel Within an Entrenchment
4.
Gravel
Bar and Eroding Bank Along Lower Sulphur Creek
5.
Sulphur
Creek Watershed and Subwatersheds
6.
Project
Locations
7.
High
Priority Roads
Tables
1.
Ranking
by Sensitivity 6
2.
Ranking
by Condition 7
3.
Combined
Ranking 8
4.
Ranking
of Roads by Impacts to the Total Watershed 9
5.
Potential
Projects and Estimated Costs 13
Appendix
1.
Sulphur
Creek Subwatershed Ranking Criteria and Ranking Results
2.
Sulphur
Creek Road Systems Priority Ranking
3.
Potential
Sulphur Creek Projects Preliminary Budget
INTRODUCTION
Watershed Description
Located on the eastern edge of the Sierra-Nevada crest (Mohawk Ridge), the
Sulphur Creek watershed abuts the headwaters of the North Yuba River to the west and the Carman Creek watershed
to the east. Sulphur Creek flows
directly to the Middle Fork Feather River at Clio.
The Sulphur Creek watershed is distinctly divided into a western half and an eastern half by the Mohawk Fault. This fault is part of the larger, active system defining
the Sierra-Nevada mountain range.
Sulfur hot springs flow from one of the several parallel faults at
the White Sulphur Springs Ranch, on the east side of Highway 89.
The west side slopes
draining to the main stem of Sulphur Creek rise from the valley floor at an
elevation of 4500 feet to over 8000 feet at Haskell
Peak. This contrasts sharply with the east-side, where the elevation rise is
2000 feet less, ranging from the valley floor to just over 6100 feet. The effect is the formation of a
“rain-shadow” on the eastern half with an average annual precipitation amount
of 30 to 40 inches. To the east lies Sierra Valley,
which receives an average of 12 inches annually. The average annual
precipitation along the western half is from 40 inches near its base to over 60
inches near its summit, much in the form of snow.
Another striking
difference between the two sides of the watershed is their aspect, the general
compass direction and angle to the suns rays. The western side generally faces
north and east, receiving much less direct sun throughout the year than the
eastern side, which generally faces south and west. The eastern side also
contains gentler slopes that are exposed to the suns rays’ overhead, during the
hottest time of the day. The east side
of the Sulphur Creek watershed not only receives less precipitation, but the
greater evaporation and vegetation transpiration leads to less runoff than that from the west side of the watershed.
The west side receives more snow and it lasts longer into the year. There is
also more water available on the west side to percolate into the ground,
feeding more springs and streams with more water. Most of the streams on the
west side tend to flow year-long, while even the two main tributaries draining
the east side (there are only two draining the entire east side) become dry or
nearly so most years.
The west side is still
rising (tectonically active), while the east side
appears to be standing still and is slowly eroding away. This has very
important implications on how these two very different sides of the Sulphur
Creek watershed behave. The east side is mostly experiencing surface erosion
while slope failures are common on the steep westside. Massive slope failures are random and
episodic in occurrence, responding to either rain-on-snow or seismic
events. The 1997 rain-on-snow event
caused flooding in the valley and slides and debris torrents that deposited
large amounts of coarse material into Sulphur Creek above the Whitehawk Ranch
and onto the landscape where each tributary channel drains into the valley.
Rock types within the
Sulphur Creek watershed are metamorphic, granitoid and volcanic. Granitic rock
types are exposed on both sides of the watershed and the soils associated with
this rock type are very erosive. Highway 89 was constructed in highly weathered
granitic rock and soil where it traverses the eastside along the middle reach
of Sulphur Creek. Soils from the other
rock types are composed of much finer material that decay into sand and smaller
sized soil particles. These soils are much less erosive, but still provide
large quantities of sediment where flows are concentrated or on steep slopes
where vegetation, litter, or rock is sparse.
An arm of Lake Mohawk
extended into what is now the lower and middle reaches of Sulphur Creek. Lakebed deposits topped out at the 5000-foot
elevation (Durrell 1960). Erosion of
these lakebeds continues today and forms the sloping meadowlands on both sides
of the Sulphur Creek valley. Sulphur
Creek has become entrenched within its valley.
Entrenchment is the process, or results of the process,
whereby a stream erodes downward so as to form a trench (Figure 1). An
entrenchment is commonly referred to as a gully.
Before Lake Mohawk drained
(as recently as 20,000 years ago), the climate of the region had been cooling
and drying, culminating in the formation of glaciers. The lower ends of these glaciers rode out into the lake, leaving
behind glacial moraines (mounds or ridges of unsorted, unstratified glacial drift (heterogeneous
mixture of clay, silt, sand, gravel, and boulders)) as they receded. Several of these moraines deposited onto the
lakebeds along the westside.
Because of the gently
sloping sides from the eroding lakebed material, the valley is not a typical,
nearly flat meadow floodplain. The
floodplain of Sulphur Creek is much more narrow than the valley width. The width of the historic floodplain was
about 400 feet while the valley is up to 8000 feet wide. The westside is
drained by several, nearly parallel stream channels, as opposed to the two,
highly branched systems draining the east side (Barry Creek and Calfpasture Creek). This contrast in drainage patterns supports the idea that the east side is older and
more stable. Parallel drainage patterns usually
denote a young landscape while highly branching patterns
usually denote a mature landscape.
Where each
stream channel opens out into the valley, large fan shaped deposits of sediment
called alluvial fans have formed.
The alluvial fans associated with the two tributaries of the watershed’s
eastside are generally composed of fine material and the fans associated with
the westside channels are generally composed of loose rock material. The historic flood of January 1, 1997,
deposited large amounts of this coarse sediment onto these westside fans as a
result of debris flows (a moving mass of rock, soil, and mud)
that started high up in headwater areas.
Landslides and slumps are common, naturally occurring erosion processes
that provide abundant sedimentary material to the west side streams. Much of
this sediment is carried downstream as debris flows, a common and very important,
natural transport mechanism.
Stream Channel Conditions
There are in general two
types of streams (Figure 2), those that move sediment because they are steep
and narrow (transport channels) and those that collect sediment and
respond to changes in the watershed (response channels). The stream channels
draining the Sulphur Creek watershed are classic examples of these two general
types. Most, if not all, of the stream channel degradation (entrenchment and
widening) occurs in the fragile environment occupied by the response channels. Once
vegetation is lost or water flows concentrated in these fragile, highly
erodible environments, the entrenchment (gully) process progresses with
earnest. At the headward expansion of each entrenched channel is a headcut (an abrupt change in
elevation marked by a rapidly eroding waterfall). Downstream of each headcut is a narrow
trench, acting as a very efficient sediment transport channel. Further
downstream, the trench has widened and the channel slope (energy gradient) has
decreased and the capacity to transport sediment has diminished. Further
widening results in the development of an entrenched valley with an inset
channel system (Figure 3). Although a
lot of sediment is still transported through such a development, large
depositional features of coarse material called gravel bars form. Gravel bars
force streamflows into adjoining banks of fine material and accelerate valley
widening (Figure 4).
Streams flowing into the valley from the east are delivering much less
coarse sediment.
Several headcuts are migrating up Calfpasture Creek in the valley,
dewatering that portion of the meadow and sending fine-grained sediment to
Sulphur Creek. The lower Barry Creek
channel has entrenched and is in the process of widening.
The degradation of the
main Sulphur Creek channel has progressed upstream to a short bedrock-control
section at an elevation of approximately 5000 feet. Surface water no longer flows on top of the historic valley meadow
and its floodplain, but passes through the valley within the entrenchment,
accentuating flood flows and decreasing groundwater recharge and storage. The valley aquifer is currently maintained
by water input from tributary channels and water diversions. Most of the sediment generated in the upper
and middle Sulphur Creek drainage areas eventually moves through the entrenched
valley and channel system before entering the Middle
Fork Feather River (MFFR). This
change in water and sediment flows will continue to force adjustments to the
entrenched valley and channel with continued widening, bank loss, and
disruption of the aquatic and riparian ecosystems.
Causal Agents
There are few obvious,
direct causes for the conditions described above. Channel entrenchment can
usually be traced to some instability and drop in the base elevation
downstream. The MFFR has certainly
downcut where Sulphur Creek flows into it.
The mouth of Sulphur Creek (the location where it discharges in the
MFFR) was apparently relocated from immediately south of where the Clio bridge is presently located to upstream of the
bridge. The MFFR and its floodplain was also truncated at this location.
Other factors either
played into the many potential causes or are aggravating the degraded conditions. Upper watershed areas are
potentially delivering water faster than historically, leading to higher and
more frequent peak flows. This in turn
causes adjustments downstream mainly to the response channels in the valley
bottom. Upper watershed areas are not only delivering water differently but
also delivering more sediment than historically. Changes in water and sediment flows are
now causing continued channel instability and slowing natural recovery
processes.
The paramount disturbance
in the headwater areas is the road system.
Roads located next to and crossing stream channels contribute sediment
and runoff directly to those streams.
Roads in the Sulphur Creek watershed were primarily constructed and are
currently maintained in such a way that they intercept surface and subsurface
water, concentrate it into inboard ditches, and then drain that water directly
to stream channels. There are few cross
drains and out-sloped road segments. As
a result, the stream system is adjusting to or is aggravated by the change in
the amount and timing of water and sediment.
Debris flows, common on the westside, are enhanced by poor road
locations and design. Several roads and
road sections have been identified that probably contributed to increasing the
magnitude of debris flows and to an increased risk of future interactions. A large segment of the Mohawk-Chapman Road
is the most notable example of this problem.
Other causal agents, or
impacts, that both slow recovery and aggravate unstable conditions include
livestock overgrazing, especially within riparian areas, increases in
impervious surfaces (houses and other buildings, access roads, parking lots,
etc.), mineral mining, gravel extraction, water diversions, channel
straightening and realignment, bridges spanning the main Sulphur Creek channel,
and, possibly, wildfire suppression and ignition.
STRATEGY DEVELOPMENT
To develop a restoration
strategy, several items were identified and developed in order to focus our
attention on the important needs and desires.
To do this we identified (1) a set of desired conditions for the
Sulphur Creek watershed, (2) opportunities within the watershed that
will help us attain the desired conditions, and (3) constraints that may
hinder or reduce achievement of the desired conditions. Finally, a ranking system was
developed to help guide us to the highest priority areas and projects,
realizing that it is only a guide and that it must be periodically updated to
meet social and economic changes, changes in watershed condition, and to
accomplish other projects approved by the Steering Committee.
Desired Conditions
The desired conditions identified
so far for the Sulphur Creek watershed are:
- Stream channel, floodplain and riparian areas that
are fully functional and aesthetically pleasing.
- Minimal flood damages, including loss of property
from bank erosion.
- Sediment production and loads reduced to levels
that aid stream restoration efforts and improve water quality.
- Water quality levels (sediment and water
temperature) that enhance all life stages of a coldwater fishery and other
cold water biota.
- Maintain off-channel livestock forage production
while protecting and enhancing stream and riparian areas.
Opportunities
Several opportunities for
improving, rehabilitating, and restoring watershed conditions that strive to
meet desired conditions are listed below.
This list is not all-inclusive and can be changed at any time.
·
Several landowners (and managers) wish to improve
stream and meadow conditions on their properties.
·
The Sulphur Creek streamflow is perennial, affording
the greatest opportunity for vegetation recovery.
·
There’s an ample supply of large woody material (fallen
trees) in the middle reach of Sulphur Creek (subwatershed 10) that can be used
to help trap bedload sediment.
·
No homes and few structures have been constructed
within the historic floodplains, allowing the consideration of a wide array of
rehabilitation options.
·
Much of the main Sulphur Creek entrenchment, especially
below the Whitehawk Ranch, is sufficiently wide for it to naturally develop a
stable channel and floodplain system at the existing, lowered elevation with
only minor assistance from us.
·
A channel and floodplain system is developing through
the Whitehawk Ranch reach that can be enhanced to reduce bank erosion damages.
·
The Highway 89 crossing of Barry Creek is currently
maintaining a base level elevation for Barry Creek that is higher than that of
the adjacent Sulphur Creek channel.
Constraints
Constraints limit or reduce
restoration and rehabilitation accomplishments. Like the list of opportunities, the following list of constraints
is not necessarily all-inclusive and can change.
- Developments in the Whitehawk Ranch reach have
occurred on the original floodplain of Sulphur Creek.
- Livestock management within the newly forming
channel and floodplain area downstream of the Whitehawk Ranch reach does
not currently support rehabilitation efforts.
- The main Sulphur Creek channel is moderately or
severely constricted at four bridge locations, the lower Loop Road bridge,
the two Whitehawk Ranch bridges, and the Highway 89 bridge. The River’s Edge RV Park bridge near is
within the high flow backwater area of the Clio Bridge over the Middle
Fork Feather River.
- Barry Creek is confined within levees as it
approaches Highway 89.
- Threatened, endangered, and sensitive plant and
animal species may be present in the Sulphur Creek watershed.
- Archaeological sites have been reported within the
Sulphur Creek watershed.
Watershed Delineations and Ranking
The watershed was divided into 12
subwatersheds by simply delineating each tributary channel’s watershed area,
beginning where each discharges into the main Sulphur Creek channel (Figure
5). The main Sulphur Creek channel was
subsequently divided into three reaches and their subwatersheds
delineated: subwatershed 1, the valley
bottom reach; subwatershed 10, the middle reach; and subwatershed 11, the
headwater reach. On the watershed’s
eastside, Calfpasture Creek is further subdivided into its north and south
branches (subwatersheds 3a and 3b) and Barry Creek is subdivided into upper and
lower reachs (subwatersheds 9a and 9b).
McNair Meadow (subwatershed 12) includes both an eastside channel and a
westside channel (Sulphur Creek).
A system for ranking the
subwatersheds was developed using systems developed by the Forest Service. The first system scores and ranks each
subwatershed according to its sensitivity to disturbance (both natural
and human). Next, the system scores and
ranks each subwatershed according to its existing condition. Lastly, the scores are combined for an
overall ranking. A weighting system was
also applied because some of the elements evaluated can cause more changes to
the stream and riparian system than others (See Appendix 1 for a full display
of the scores and rankings). Priority 1
should be given the highest consideration for treatment.
The assessment of subwatershed
sensitivity was based on the following:
·
Existing and potential occurrence of landslides and
slumps.
·
Occurrence of sensitive stream channels, those prone to
degradation or aggradation when changes or disturbances occur in the watershed.
·
Potential soil erosion hazard following disturbances.
·
Potential for large, intensive wildfires.
·
Potential vegetation recovery.
Table 1.
Ranking by Sensitivity
Rankings of 1, 2
and 3 are considered to be the most sensitive (highlighted).
|
Subwatershed Number
|
Name
|
Rank
|
|
1
|
Lower Sulphur Creek
|
4
|
|
2
|
Bear Wallow Creek
|
4
|
|
3a
|
South Calfpasture Creek
|
5
|
|
3b
|
North Calfpasture Creek
|
5
|
|
4
|
Wash Creek
|
3
|
|
5
|
McKenzie Creek
|
3
|
|
6
|
Boulder Creek
|
1
|
|
7
|
Raap/Guidici Creek
|
1
|
|
8
|
Haskell Creek
|
1
|
|
9a
|
Lower Barry Creek
|
7
|
|
9b
|
Upper Barry Creek
|
5
|
|
10
|
Middle Sulphur Creek
|
1
|
|
11
|
Upper Sulphur Creek
|
2
|
|
12
|
McNair Meadow
|
6
|
The subwatershed condition
elements are:
- Number of sensitive stream channels in unstable
condition.
- Potential to connect natural sediment transport
channels with the existing gully system.
- Measured volume of soil and rock that has eroded
from the road segments that are in direct contact with stream channels.
- Measured length of road drains connecting directly
to stream channels.
Table 2.
Ranking by Condition
Rankings of 1, 2,
3and 4 are considered to be the worst condition (highlighted).
|
Subwatershed
Number
|
Name
|
Rank
|
|
1
|
Lower Sulphur Creek
|
2
|
|
2
|
Bear Wallow Creek
|
11
|
|
3a
|
South Calfpasture Creek
|
3
|
|
3b
|
North Calfpasture Creek
|
4
|
|
4
|
Wash Creek
|
5
|
|
5
|
McKenzie Creek
|
9
|
|
6
|
Boulder Creek
|
4
|
|
7
|
Raap/Guidici Creek
|
4
|
|
8
|
Haskell Creek
|
7
|
|
9a
|
Lower Barry Creek
|
2
|
|
9b
|
Upper Barry Creek
|
8
|
|
10
|
Middle Sulphur Creek
|
1
|
|
11
|
Upper Sulphur Creek
|
6
|
|
12
|
McNair Meadow
|
10
|
Table 3.
Combined Ranking
Rankings of 1, 2,
3and 4 are considered to be the highest priority (highlighted).
|
Subwatershed Number
|
Name
|
Rank
|
|
1
|
Lower Sulphur Creek
|
3
|
|
2
|
Bear Wallow Creek
|
11
|
|
3a
|
South Calfpasture Creek
|
4
|
|
3b
|
North Calfpasture Creek
|
7
|
|
4
|
Wash Creek
|
7
|
|
5
|
McKenzie Creek
|
8
|
|
6
|
Boulder Creek
|
4
|
|
7
|
Raap/Guidici Creek
|
2
|
|
8
|
Haskell Creek
|
6
|
|
9a
|
Lower Barry Creek
|
5
|
|
9b
|
Upper Barry Creek
|
9
|
|
10
|
Middle Sulphur Creek
|
1
|
|
11
|
Upper Sulphur Creek
|
7
|
|
12
|
McNair Meadow
|
10
|