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CEQA FINDINGS The California Environmental Quality
Act and County Environmental Review Guidelines require that when an EIR has been completed
which for a project identifies one or more significant environmental effects for the
project, the public agency shall not approve the project unless one or more of the
following findings can be made: 1. Changes
or alterations have been required in, or incorporated into the project which avoid or
substantially lessen the significant environmental effect as identified to the final EIR. 2.
Such changes or alternations are with the responsibility and jurisdiction of
another public agency and not the agency making the finding. Such changes have been adopted by such agency or
can and should be adopted. 3. Specific
economic, social or other considerations make infeasible the mitigation measures or
project alternatives, identified in the final EIR. The final Environmental Impact Report
for the Pajaro River and Salsipuedes and Corralitos Creeks EIR (EIR) includes the Draft
and Final EIR dated August 31, 2001 and February 2002 respectively. The EIR has identified, as significant, the
impacts described below. Changes have been
incorporated into the project or mitigations have been specified for permit conditions
which can reduce all identified impacts to levels of insignificance. Project mitigations are described directly below
each impact listed on the following pages of these findings. All mitigation measures listed on the following
pages have been incorporated into the project design or they have been made a condition of
the project. CEQA finding #1 pertains to all impacts on the following pages. Impacts which are less than
significant are listed following the significant impacts and corresponding mitigation measures. HYDROLOGY
AND WATER QUALITY Impact
H-2. Construction of bank protection measures may
reduce hydraulic capacity within the levees and increase the threat of flooding. Installation
of bank protection would reduce the cross-sectional area available for flood flows,
potentially resulting in higher flood levels and increased risk of flooding adjacent
areas. In addition, bank protection measures
could trap sediment, causing the bank to increase in width over time and reduce hydraulic
capacity. This is a significant impact. Mitigation
Measure H-2. To prevent reduction of hydraulic capacity of
project streams, bank protection measures shall not be constructed unless studies show
that; 1) hydraulic capacity would not be decreased below current (year 2001) capacity; and
2) erosion is substantial enough to threaten the adjacent levee. These studies should include the following: · A
topographic survey of the Pajaro River and Salsipuedes Creek channels to establish
baseline (year
2001) bank topography information;
· Field
observation of the affected bank vicinity to determine if previous bank armoring exists;
· Annual
monitoring after significant storm events to determine the presence and rate of bank
erosion;
· Field
measurements from new (damaged) toe of bank to toe of levee to compare to baseline
(year 2001)
conditions; and
· Engineering
analysis of channel capacity with proposed armoring in place (HEC-2 or HEC-RAS
computer models).
The
river shall be monitored annually and after significant storm events to identify the
presence of bank erosion. Erosive areas shall
be evaluated for their potential to erode further and pose a threat to the levee. The degree of threat depends upon the geometry in
the erosion areas. Factors to be considered
should include the distance of bank retreat, local geometry that suggests an increased
threat (such as the presence of bends, contractions, or abutments), and the presence (or
lack of) existing bank protection. Impact
H-3. Temporary construction activities would generate
sediment in the area of bank protection construction. Construction
activities associated with stream bank armoring would disturb surrounding areas and result
in denuded areas that are temporarily susceptible to erosion. Additionally, the proposed bank protection
features include excavation and compaction of earth materials. Until vegetation becomes established, these areas
would be prone to erosion resulting in a significant impact. Implementation of the mitigation described below
would reduce this impact to less than significant levels. Mitigation
Measure H-3. To reduce the potential for erosion and
sedimentation in the adjacent river, the final design of proposed bank protection shall
include preparation of an erosion control plan that incorporates requirements of the
County of Santa Cruz Grading Ordinance, Erosion Control Ordinance, County Design Criteria
and the Construction Activities General Permit. The
plan shall be reviewed and approved by County Planning and applicable regional and State
agencies, when required, prior to the commencement of any construction activity. All provisions of the approved plan shall be
followed during construction. Compliance
with these requirements would necessitate preparation of an erosion control plan to
minimize erosion during and following construction of bank protection. Standard best management practices shall be
included in the plan, such as placement of silt fences, straw-bale dikes, or check dams
and revegetation of barren slopes immediately following construction. The type of measures will vary depending upon
location and type of armoring proposed. Impact
H-4. Use of the herbicides Roundup and Rodeo to control
vegetation growth along levee benches and slopes could adversely impact water quality.
Roundup
and Rodeo are extensively used herbicides manufactured by Monsanto Company. Glyphosate, the active ingredient of Roundup and
Rodeo, is a wide-spectrum, non-selective herbicide that is effective against perennial
grasses, broad-leaved weeds and shrubs. Glyphosate
is absorbed almost exclusively by plant foliage and is then translocated throughout the
plant by the plant’s circulatory system. Once
in the soil, glyphosate is broken down into natural materials by soil microflora and has
little potential to move in the ground to affect nearby, untreated plants. Therefore, glyphosate-based herbicides are often
selected because of their effectiveness in killing only the plants that are directly
sprayed. Rodeo and Roundup are similar except
that (1) Rodeo contains a more concentrated form of glyphosate and (2) Roundup contains
polyethoxylated tallowamine (POEA), a surfactant (an agent that attaches itself to
suspended material) that can have toxic effects in water systems. Because Rodeo contains no POEA, the Environmental
Protection Agency’s Office of Pesticide Programs has approved its use over open water
and wetlands. Mitigation
Measure H-4. To sustain non-toxic effects to aquatic wildlife,
Rodeo and Roundup herbicides shall be applied in such a manner as to avoid over-spray or
application of Roundup in or adjacent to surface water.
Application
methods proposed by the applicant would minimize the potential for adverse impacts from
herbicide use to less than significant levels. These
methods include: · Use
of herbicide at or below concentrations recommended by the manufacturer. · Use
of proper precautions to avoid spills. · Worker
training to ensure that herbicide is sprayed only on target vegetation. · Use
of Roundup herbicide for on-land application only. · Minimal
in-channel use of Rodeo herbicide. It
is not anticipated that large quantities of vegetation would be sprayed in the river or
creek channels. Application of herbicide in
the channel would be limited primarily to “painting” the stems of woody
vegetation greater than 3 inches in diameter. If
large scale spraying of vegetation in the channel is required, however, the County would
remove the dead vegetation entirely from the channel. GEOLOGY
AND SOILS
Impacts from
Levee Resurfacing Impact
G-2. Levee maintenance may cause accelerated erosion
along levee slopes. The
proposed levee maintenance activities include minor grading to repair levee roads and
application of herbicides on levee tops and some slopes areas and on benches to control
growth of vegetation. Grading will result in
bare, un-vegetated soil that can become susceptible to accelerated erosion from wind, rain
or scour from flooding. Similarly, the
application of herbicide would kill vegetation whose root systems would otherwise
stabilize levee slopes. This would also cause
accelerated erosion from rain and scour from flooding.
Therefore, levee maintenance may significantly accelerate erosion on levee slopes. Mitigation
Measure G-2. To prevent accelerated erosion of repaired levee
slopes, graded areas shall be revegetated prior to October 15 of the same year that repair
work occurred. To
prevent rainfall or stream flow induced erosion of recently repaired or maintained levee
slopes, Public Works maintenance crews should apply grass seed and mulch material to bare
soils immediately after grading and related maintenance activities have been completed. On bare levee slopes exceeding 15%, the mulch
shall be secured with jute netting stapled into the soil according to accepted erosion
control practices. In all cases all erosion
control measures shall be completed prior to October 15 of the year the maintenance/repair
work was done. Additionally, the mitigation
measures as described in H-3 shall be implemented. Impacts
from Bank Erosion Repair
Mitigation
Measure G-3b: Construction period effects. See
Impact H-3 and G-2. Mitigation Measure H-3
and G-2 will be implemented on a site-specific basis and will consider time of year to
implement measures, soil containment during construction, slope stabilization after
construction and access for heavy equipment used for repairs.
Repairs shall
be done in late summer (June 1 to October 15) to minimize impacts to steelhead and other
aquatic wildlife from sedimentation. An
erosion control plan shall be prepared to minimize erosion during and following
construction of bank protection as in Mitigation Measure H-3. Standard best management practices shall be
included in the plan, such as placement of silt fences, straw-bale dikes, or check dams
and revegetation of barren slopes immediately following construction. The type of measures will vary depending upon
location and type of armoring proposed. Mitigation
Measure G-2 will be implemented to stabilize slopes after construction and BMPs shall
consider access routes of heavy equipment to minimize further erosion and disturbance to
vegetation. Impact
G-4. Implementation of bank erosion repairs on the Santa
Cruz County side of the Pajaro River could cause increased erosion and bank movement on
the Monterey County side. Under
the proposed project, bank erosion repairs and revegetation of channel banks will be
performed exclusively on the Santa Cruz County side of the Pajaro River. Installation of new bank protection could change
flow characteristics in the area of bank repair, including flow direction, velocity and
sediment carrying capacity. Erosion
potential on the Monterey side of the Pajaro River may change as a result of changes in
channel depth, velocity, or angle-of-attack. This
could cause an increase in erosion from scour and subsequent bank movement on the Monterey
County side. This would be a significant
impact. Mitigation
Measure G-4. To prevent increased erosion and bank movement of
the Monterey County side of the Pajaro River, mitigation H-2 should be implemented as part
of any stream bank repair on the Santa Cruz County side of the river.
The
mitigation measures described in H-2 would eliminate potential adverse impacts to the
Monterrey County side in relation to the baseline 1999-2000 conditions. This work shall include review of the results of
the HEC model (see Mitigation Measure H-2) for velocity and depth changes in relation to
the year 2000 condition. Additionally, the
engineering analysis shall consider the potential for proposed improvements to act as a
“vane” to direct flows toward the Monterey County banks. If revegetation is proposed as part of the bank
improvements or if sediment would be expected to deposit along the bank as a result of the
improvement, the hydraulic analysis should consider these factors. Impacts
from Revegetation and Channel Maintenance
Impact
G-5. Proposed tree planting along the inner channel
benches of the Pajaro River could threaten levee and/or bank stability. The
proposed revegetation activities include planting trees sporadically along benches. If the bench is too narrow or the tree is planted
too close to the edge of the bench, the tree may be unable to stabilize and could fall
over, taking portions of the bank with it as it falls.
Tree failure could increase bank erosion potential during flooding, resulting in
levee instability or infilling of the river channel.
However, under the proposed project no trees will be planted where the inner
channel bench is less than 10’ feet wide and will restrict tree planting to channel
benches that are at least 32’ wide. As a
result of these design measures, the potential for this impact would be considered less
than significant. Mitigation
Measure G-5. To ensure channel and bank stability, design
features identified in Impact G-6 shall be implemented. To ensure that bank and or/levee stability is not threatened from
tree planting along the inner benches of the Pajaro River, trees shall not be planted
closer than 8 feet to the edge of the channel bank. Impact
G-8. Installed bank protection measures could fail due
to flanking flows if not properly installed. Failure
of bank protection measures could occur from erosion behind the bank surface, due to
either inadequate placement of a filter blanket under the protection measures or flows
over the bench areas cutting substantially behind the bank.
Mitigation
Measure G-8. To protect failures of new bank protection
measures, the design of rock armoring or toe protection shall include measures to mitigate
for flanking flows. To
ensure that stream bank repairs will not fail during high velocity flow events, armoring
shall be keyed into the existing bank material. Tying
proposed improvements well into existing surfaces (buried armoring at the ends of the
treatment areas) shall be done to limit potential for flanking damage. This is particularly important at the beginning
and end of proposed bank protection areas. Filter
blanket shall be installed immediately below the bank protection to prevent material from
eroding around larger rock. The filter
blanket may be either geotextile fabric or a gradation of small rock and gravel and should
consider the size of the primary armoring rock. It
is recommended that the design be consistent with USCOE methodologies. The flexible types of bank protection proposed in
the Bank Erosion Assessment, which tend to bend without breaking, should be used for bank
protection. This type of bank protection
tends to settle and move rather than failing completely.
Impact
G-9. Bank protection measures may cause changes in
depositional or erosion patterns along the channel banks up- or downstream of the
improvements. This may result in protection
for the improved area, but also result in adverse erosion to occur in adjacent areas. Vegetation,
rock armoring, and timbers are all bank protection components that influence the roughness
(Manning’s N-value) of the channel banks. Changes
in roughness along a portion of the bank (i.e., from installation of bank protection) may
cause increases or decreases in water velocity up- or downstream of the improvements. Increases in water velocity may cause increased
bank erosion in unprotected areas while decreases in velocity may increase sediment
deposition. Increased sediment deposition may
result in decreased channel hydraulic capacity or changes in flow patterns in the channel
that lead to increased erosion elsewhere. Mitigation
Measure G-9. To prevent erosion problems upstream and
downstream of bank repair sites, the design of bank protection shall consider effects to
adjacent areas and design features to reduce impacts to up- and downstream adjacent areas. To protect
adjacent areas up- and downstream of bank repair sites, design of bank protection shall
include transition protection for adjacent areas. As
necessary to attenuate potential velocity increases, the design shall incorporate energy
dissipation features at the transition such as oversized rock, plantings, or check
structures. Hydraulic
evaluation using the HEC-2 or HEC-RAS computer simulations (Mitigation Measure H-2) shall
include an analysis of potential velocity changes in adjacent areas of the river. If necessary, additional sections may need to be
added to the model to define changes in nearby areas.
Field review of the overall condition of up- and downstream areas, including the
existing level of bank protection in those areas, shall be conducted to support the
hydraulic evaluation. Impact
G-10. Deposition in the confluence area of the
Salsipuedes Creek and Pajaro River may result in reduced capacity and increased frequency
of overtopping of the levees. The
deposition of material at the Salsipuedes confluence zone (from the Southern Pacific
Railroad bridge 3500 feet downstream of, to 500 feet upstream of, the Salsipuedes Creek
confluence [Reach D, Figure 2.3-1 and Figure 2.3-2) is anticipated based upon sediment
transport analysis and the history of past maintenance efforts. The confluence area is also the area with the
highest population density surrounding the river, and therefore is the area with the
greatest risk of flood damage. Mitigation
Measure G-10. To prevent potential flood hazards, the large sand
bars in the confluence area shall be removed during the late summer in order to remove
obstructions to flow prior to the wet season.
Only
sandbars greater than 4 feet in height (above water level) and 250 feet in length and
located in the Salsipuedes Creek confluence zone shall be removed. Sandbar removal on the Pajaro outside of the
Salsipuedes confluence zone is not part of this project.
If the County finds that sandbar removal outside of the Salsipuedes confluence zone
is necessary because of threats to flooding and or the levee integrity, the County will
obtain the necessary permits from regulatory agencies. BIOLOGICAL
RESOURCES
Impact
W-2. Removal of vegetation from the Pajaro River
channel bottom between Murphy Crossing and Highway 1 would decrease the potential for
formation of a concentrated low flow channel during the dry season and reduce shading of
the channel. High water temperature may have
an adverse impact to out-migrating steelhead smolts during their passage from rearing
areas to the ocean.
As
water level declines in the Pajaro during the dry season, a low flow channel or series of
braided channels forms across the relatively flat bottom of the Pajaro riverbed. The location and configuration of the low flow
channel(s) may change from year to year depending upon patterns of sediment deposition
during the previous rainy season. Under the
proposed project, all in-channel vegetation, with the exception of a 5-foot-wide buffer on
each side of the low flow channel, would be removed by hand and the stumps treated with
herbicide during the summer of each year. A
5-foot band of vegetation would be allowed to grow on either side of the low flow channel,
although trees or shrubs would be cut at the base (manually) when stem diameters are
greater than 3 inches. In areas where braided
channels form as water levels decline, County Public Works personnel would allow
vegetation to develop only along the deepest channel. Establishment
of the 5-foot vegetation buffer is intended to improve habitat conditions for fish by
causing water to concentrate along a defined pathway, facilitating the creation and
maintenance of a low flow channel that is deep enough to allow steelhead passage. In addition, the buffer would provide some shading
of the channel that may lower water temperature during the dry season. The buffer zone may reduce the impacts of
in-channel vegetation clearance to a less than significant level for steelhead, but
monitoring shall be conducted to evaluate the effectiveness of the vegetation management
proposal. Mitigation
Measure W-2a. To minimize loss of beneficial in-stream habitat
characteristics for steelhead, annual monitoring of the effectiveness of the vegetative
buffer along the low flow channel shall be conducted.
A
comprehensive monitoring program shall be undertaken to evaluate the effectiveness of the
vegetation buffer in facilitating the formation and maintenance of a low flow channel that
meets the minimum depth requirements (if flow permits).
The monitoring shall be done by a qualified fisheries biologist and assess how
quickly the vegetation buffer becomes established during the dry season, the effectiveness
of the buffer in creating and maintaining a concentrated low flow channel, and under what
flow conditions the buffer is ripped out during high velocity winter flows. The
Pajaro Valley Water Management Agency is required to maintain a minimum flow of 90 cfs,
corresponding to maintaining 9 inches in riffle areas, for the area from Murphy’s
Crossing to the Pajaro River mouth for one of their projects affecting the Pajaro River. Therefore, this project has recognized this
standard. In the driest of years, however,
there may not be any flow in late summer in some reaches of the Pajaro, despite a
concentrated low flow channel. A
comprehensive monitoring program shall be undertaken to evaluate the effectiveness of the
vegetation buffer in facilitating the formation and maintenance of a low flow channel that
meets the minimum depth requirements (if flow permits).
The monitoring shall be done by a qualified fisheries biologist and assess how
quickly the vegetation buffer becomes established during the dry season, the effectiveness
of the buffer in creating and maintaining a concentrated low flow channel, and under what
flow conditions the buffer is ripped out during high velocity winter flows. Monitoring shall be conducted during the 20-year
life of the project to allow for evaluation during both drought and flood cycles. If monitoring concludes insufficient low flow
channel depth, then the remedial actions specified by measure W-2c shall be implemented. Mitigation
Measure W-2b. If the vegetation buffer is too sparse during some
years to facilitate creation of a low flow channel, willow cuttings shall be planted along
the low flow channel in the spring to enhance vegetation re-establishment.
To
compensate for lack of sufficient low flow channel depth, spring willow planting shall
occur along both sides of the thalweg segments where biological monitoring has determined
is necessary to re-create adequate depth of the final thalweg. Willow cuttings shall be obtained from existing
vegetation in the immediate area and planted at 1.5-foot centers along both sides of the
low flow channel. Planting shall be conducted
in early spring or late fall and be supervised by a qualified biologist. Mitigation
Measure W-2c. Water temperatures shall be monitored to document
temperature patterns along the Pajaro River and Salsipuedes Creek and evaluate conditions
for migrating smolts.
Permanent
stations shall be established along the Pajaro River and Salsipuedes Creek to evaluate
water temperature during periods of smolt migration.
Continuous temperature monitoring devices shall be installed and set to record
water temperature between April 1 and June 15 of each year.
Temperature shall be monitored along the Pajaro River at a minimum of 3 stations
between Murphy Crossing and Salsipuedes Creek, 1 station at the mouth of Salsipuedes
Creek, and 2 stations between Salsipuedes Creek and Thurwacker Bridge. At least one station shall be established on
Salsipuedes Creek below the Corralitos Creek confluence.
The locations of the stations shall overlap with permanent transects established to
monitor vegetation and hydrologic conditions (Mitigation Measure S2a). In addition, air temperature shall be monitored at
each of the stations so that a correlation between air and water temperature can be
determined. If
monitoring determines that temperatures rise above 24 degrees C for more than one hour
during the day or the average temperature within any 24 hour period rises above 24 degrees
C, the Public Works maintenance staff shall implement one or more of the following
remediation activities listed below immediately: · Supplemental
willow planting where buffer is sparse. · In
channel earthwork to create low flow channel. · Increase
width of vegetative buffer. · Allow
buffer vegetation to grow taller. Temperature
monitoring shall continue to determine if the remediation actions are effective. If they are not, additional remediation actions
shall be implemented until monitoring concludes that temperature standards have not been
exceeded. The results of all monitoring shall
be carefully recorded and documented as specified in the mitigation monitoring and
reporting program for this project. “Mitigation Measure 6.4.3-2—Maintenance
of Flow for Steelhead Migration: Vertical wells or infiltration gallery pumps will be
operated only when flow in the Pajaro River is at least 90 cfs, which is expected to
maintain a minimum depth in riffles of 0.75 ft.” Impact
W-3. Establishment and maintenance of riparian
vegetation from the toe of slope to near the top of bank on the Santa Cruz County side of
the river would improve conditions for steelhead and several sensitive bird species and
would be a beneficial impact of the project.
Conservation
of riparian vegetation along the channel bank would shade the low flow channel and provide
overhanging escape cover and channel scour where the low flow channel flows along the
bank. This would improve conditions for
migrating steelhead and for resident warm water fishes.
This may also benefit several sensitive bird species including the Yellow Warbler
and Yellow-breasted Chat that are dependent largely on dense riparian vegetation for
nesting. Mitigation
Measure W-3. The benefit of revegetation to birds shall be
monitored with yearly surveys over the course of five years following restoration.
To
adequately assess the success of restoration efforts and to compensate for the routine
removal of vegetation with stem diameters greater than three inches, the restoration
plantings on the stream bank shall be monitored by a qualified wildlife biologist annually
for five years following the initial planting to determine how the habitat is being used
by birds and other wildlife species. This
monitoring shall quantify the use of new habitat in terms of nesting, foraging and
roosting within sample transects at representative locations along the river. These surveys shall follow a standard protocol
such as those established for Breeding Bird Surveys or Breeding Bird Atlases and be
conducted by a qualified ornithologist at least three times per year. Survey transects or blocks shall be established in
at least five locations throughout the project area including three along the Pajaro
River, one on Salsipuedes Creek and one on Corralitos Creek. The monitoring shall make recommendations to
correct any observed problems. A monitoring
report shall be prepared and submitted to County of Santa Cruz Public Works and Planning
Departments on the same date each year. This
report shall recommend management activities and be available as guidance for similar
projects. Furthermore, Monterey County should
be encouraged to establish riparian vegetation along the banks of the Monterey County side
of the Pajaro. The results of this monitoring
will provide useful guidance towards such revegetation. Impact
W-4. Periodic removal of accumulated sediment from the
channel could adversely affect fish and other aquatic wildlife by destabilizing the low
flow channel and increasing stream turbidity. Other
wildlife, such as western pond turtle, California red-legged frog and western snowy
plover, may be impacted directly by heavy equipment and maintenance workers in the channel
or indirectly by impacts to their food sources.
Removal
of sandbars every 4 to 5 years at a single location could remove or alter the low flow
channel and associated vegetation buffer and temporarily increase stream turbidity if
activities were conducted when surface water is present.
Sandbar removal could cause significant adverse impacts to migrating steelhead if
the low flow channel was removed or turbidity increased during migration periods. Other wildlife of concern, such as western pond
turtle and California red-legged frog, may be directly or indirectly impacted by sandbar
removal activities. These impacts are
addressed in Impact W-9. Mitigation
Measure W-4a. A meandering low flow channel shall be maintained
during sand bar removal or reconstructed following in-channel work.
To
prevent destabilization of the low flow channel, activities within the low flow channel
shall be avoided during sand bar removal if possible.
If impacts to the low flow channel are unavoidable, a low flow channel shall be
immediately reconstructed when sand bar removal is completed. A five-foot band of willow cuttings shall be
planted along both sides of the re-created channel to reestablish the vegetation buffer. Mitigation
Measure W-4b. Measures shall be implemented to minimize
turbidity during any in-water construction.
To
minimize water turbidity during sandbar removal activities, temporary use of cofferdams or
other measures to minimize turbidity shall be implemented if sand bar removal is conducted
in areas with surface water. Mitigation
Measure W-4c. Sandbar removal shall be conducted at the end of
the summer (June 1 to October 15).
To
further minimize water turbidity and prevent loss of special status fish species, sandbar
removal shall be conducted at the end of summer (June 1 to October 15) when sedimentation
effects would be short-lived and eliminated by winter rains. No sand bar removal shall be conducted before July
1 to avoid potential impacts to out-migrating steelhead smolts. Mitigation
Measure W-4d. Sandbar removal in the Pajaro River channel shall
be limited to the Salsipuedes Creek Confluence Zone, which begins 3500 feet downstream of
the confluence of Salsipuedes Creek and the Pajaro River at the Southern Pacific Railroad
Bridge and extends 500 feet upstream of the Salsipuedes Creek confluence (Reach D, Figure
2.3-1 and Figure 2.3-2). Only sandbars
greater than 4 feet in height (above water level) and 250 feet in length and located in
the Salsipuedes Creek Confluence Zone shall be removed.
Sandbar
removal on the Pajaro outside of the Salsipuedes Confluence Zone is not part of this
project. If the County finds that sandbar
removal outside of the Salsipuedes Confluence Zone is necessary because of threats to
flooding and/or the levee integrity, the County will obtain the necessary permits from
regulatory agencies after subsequent environmental review is conducted. Impact
W-5. Removal of fallen and leaning trees in Salsipuedes
and Corralitos Creeks would decrease shade cover, escape cover and pool formation for
resident and migrating steelhead. This
activity will also decrease estivation habitat for California red-legged frogs and basking
sites for western pond turtle.
Project
implementation would result in the removal of fallen and leaning trees that would block or
divert storm waters in Salsipuedes and Corralitos Creeks.
In Corralitos Creek, from East Lake Avenue/State Highway 152 to the Browns Valley
Bridge, these trees would be cut into 3- to 4-foot sections and left in place. Their root structures would also be left in place. This work would be conducted by hand during times
of low flow and no equipment would be operated in the channel bottom. These natural structures in the channel create
pools and provide shading and escape cover for resident and migrating fish. They also provide estivation habitat for
California red-legged frogs and basking sites for western pond turtles. Resident steelhead could be adversely impacted by
the loss of habitat features from the Highway 129 crossing to the Pajaro River confluence. Although suitable summer rearing habitat for
steelhead is not present along the reach from Highway 129 to Highway 152, vegetation
removal would reduce shade and escape cover for migrating steelhead. In
Corralitos Creek from Varni Road upstream, tree removal would have minimal effects on
steelhead because this reach of the channel serves only as a seasonal migration pathway. Between Highway 152 and Varni Road, steelhead
rearing occurs in perennial portions of the stream in wetter years. Loss
of downed trees and in-channel woody vegetation in Salsipuedes and Corralitos Creeks could
have a significant impact on the survival of steelhead smolts along reaches of the
watershed where summer rearing occurs. Mitigation
Measure W-5a. Large (3-foot) boulders or other structures
anchored to the channel bed shall be placed in the channel at the toe of the bank to
replace habitat lost by woody debris removal.
To
compensate for the removal of fallen trees, entrained logs and other cover material used
by steelhead and other aquatic species, maintenance crews shall incorporate large boulders
or other structures into the toe of the slope as part of bank protection that should scour
along the base of the rock to create pools and cover structure. The placement of boulders in the channel would
serve to create pools and escape cover for migrating and resident steelhead. Mitigation
Measure W-5b. Fallen or leaning trees removed in all parts of
Corralitos and Salsipuedes Creeks shall be cut into 3- to 4-foot sections and left in
place. Their root structures shall also be
left in place. These features will provide
habitat for steelhead, western pond turtle and California red-legged frog.
As
described above, leaving cut-up tree sections and root structures in the channel would
provide shade and escape cover for fish and habitat for frogs and turtles. Impact
W-6. Removal of vegetation on the levee slopes and
benches along Salsipuedes Creek by mowing and herbicide application would impact a number
of nesting birds.
Vegetation
management on Salsipuedes Creek would occur with herbicide application three times each
year on levee slopes (early spring, mid-summer and late summer) and twice each year on
benches (mid summer and late summer). Mowing
would occur once each year in late June or early July.
Removal of this vegetation will impact birds nesting in these areas. Mitigation
Measure W-6. No vegetation control work, including herbicide
application, shall be conducted before July of that year to maximize the growth of
vegetation for nesting birds and leave active nests undisturbed throughout the breeding
season.
To
minimize disruption of bird nesting and pre-fledging activities, maintenance crews shall
conduct all mowing and spraying of vegetation on levee benches and slopes after July 1st
each year. If vegetation control work is
conducted as described above, nesting birds in these areas may be heavily impacted. If vegetation control measures are delayed until
July each year, then birds will have the chance to complete the nesting cycle and will not
be directly impacted by removal activities. Impact
W-7. Bank stabilization and erosion control measures,
using riprap or other bank protection measures, will reduce potential nesting habitat for
the Bank Swallow and Northern Rough-winged Swallow.
The
Pajaro River 1998 Bank Erosion Study (Northwest
Hydraulic Consultants, 1998) identified 70 specific sites in need of erosion repair
along the Pajaro River. Following the 1998
flooding, USCOE repaired Priority 1 sites by installing rock riprap along the eroded
slopes. Currently, bank erosion protection
has not progressed at any of the Priority 2 or 3 sites, but may in the future depending on
conditions. The intent of erosion control is
to correct the tendency of the river channel to widen due to bank scour. However, Bank Swallows require vertical banks with
friable, sandy soils that form due to bank scour to dig their nesting holes. Their decline in the state is largely due to loss
of nesting habitat from bank protection and flood control projects. Mitigation
Measure W-7. Implementation of bank stabilization measures
shall be limited to areas that severely threaten the integrity of the levee system.
To
minimize impact to Bank and Northern Rough-winged Swallow nesting habitat along the Pajaro
River, some eroded banks shall be retained in a vertical (or nearly vertical) condition
without bank repair where these eroded slopes pose no threat to the integrity of the levee
system. If
swallows are present, appropriate mitigations should be developed in consultation with the
appropriate trustee agencies. Swallows may
not be present for some time in the project area even though they historically occurred
there because their nesting habitat (near vertical sandy banks) have been degraded by
maintenance activities for so long. Therefore,
at least 5 areas with near vertical bank comprising an area of at least 25 feet in length
and 5 feet in height will be retained on the Pajaro from Murphy’s Crossing to the
river mouth to accommodate swallow nesting. Impact
W-8. Use of herbicides Roundup and Rodeo to control the
growth of vegetation along the levee benches and slopes could adversely impact wildlife.
Roundup
and Rodeo are extensively used herbicides manufactured by Monsanto Company. Glyphosate the active ingredient of Roundup and
Rodeo is a wide-spectrum, non-selective herbicide that is effective against perennial
grasses, broad-leaved weeds and shrubs. Glyphosate-based
herbicides are often selected because of their effectiveness in killing only the plants
that are directly sprayed. Rodeo and Roundup
are similar except that (1) Rodeo contains a more concentrated form of glyphosate and (2)
Roundup contains polyethoxylated tallowamine, a surfactant (an agent that attaches itself
to suspended material) that can have toxic effects in water systems. Because Rodeo contains no POEA, the Environmental
Protection Agency’s Office of Pesticide Programs has approved its use over open water
and wetlands. The
greatest potential for impacts to water quality from use of Rodeo or Roundup would be
expected to occur from improper use of the products.
Use of Roundup in or directly adjacent to water could cause adverse affects to
aquatic life, especially if it is discharged in higher than expected concentrations. Either product could cause damage to native plant
communities along the drainages if the herbicide is over-sprayed or the wrong plants are
targeted. Mitigation
Measure W-8. Rodeo and Roundup herbicides shall be applied in
such a manner as to avoid over-spray or application of Roundup in or adjacent to surface
water. Herbicide application shall also be
limited to areas where vegetation cannot be effectively mowed to control growth.
To
protect wildlife using in-stream and riparian habitat from any toxic effects generated by
the overuse of chemical herbicides, maintenance crews shall only use Rodeo and Roundup
herbicides and they shall only be applied in the manner proposed by this project. All maintenance crew personnel working with
herbicides shall be certified in the use of chemical herbicides as required by state law. Application methods proposed by the applicant
would minimize the potential for adverse impacts from herbicide use to less than
significant levels. These methods include: · Use
of herbicide at or below concentrations recommended by the manufacturer · Use
of proper precautions to avoid spills · Worker
training to ensure that herbicide is sprayed only on target vegetation · Limited
use of Roundup herbicide on levee slopes and benches (not slopes of the stream channel) in
Salsipuedes Creek during the dry season (July 1 to October 15) · No
use of herbicides anywhere in the channel bottom Furthermore,
where vegetation can be effectively mowed, such as on levee benches where mowers have easy
access and the area is relatively flat, mowing shall replace herbicide application to
control vegetation. Impact
W-9. Vegetation removal, sandbar removal and other work
in ponded areas of Corralitos and Salsipuedes Creeks will impact the California red-legged
frog.
Adult
California red-legged frogs require dense, shrubby or emergent riparian vegetation closely
associated with deep, still or slow-moving water. Therefore,
the few ponded areas that exist within the project area provide critical refuge for frogs. Any activities in these ponded areas may have a
significant impact to frogs, if they are present, and these impacts shall be avoided. Mitigation
Measure W-9a. Vegetation removal, sandbar removal and other work
shall be avoided within ponded areas of Corralitos and Salsipuedes Creeks to avoid impact
to California red-legged frogs.
Activities in
ponded areas may directly impact frogs that are present or indirectly impact frogs through
impacts to suitable habitat. Therefore,
activities shall be avoided in ponded areas. Mitigation
Measure W-9b. Maintenance workers shall be briefed on the
potential presence of California red-legged frog and western pond turtle in work areas and
be informed of avoidance measures to be employed.
Measures to
avoid “take” of California red-legged frogs include not removing fallen logs and
branches that provide upland frog habitat, not filling in small rodent burrows or other
potential frog refuges and limiting herbicide application to dry, upland areas. Mitigation
Measure W-9c:
Conduct surveys for suitable Red-legged frog habitat 24 hours prior to vegetative clearing
or levee work and avoid identified suitable habitat areas.
In
addition to implementing mitigation W-9b, avoiding take of California red-legged frogs and
their habitat can be accomplished by identifying and avoiding suitable habitat for the
species. Twenty-four hours prior to
conducting levee work or clearing of vegetation in the stream channel or banks, surveys
shall be conducted by trained personnel to identify suitable habitat. Public Works maintenance crews could be trained to
conduct these surveys by a qualified biologist. The
location of identified habitats shall be communicated to other maintenance crewmembers and
clearing or excavation work (eg. sand bar removal) shall be avoided where these habitats
occur. Mitigation
Measure W-9d:
Annual monitoring will be conducted to determine if backwaters form because of the
established 5-foot vegetation buffer for the low channel.
If backwaters do not form, initiate a bullfrog eradication program on Hansen and
Harkins Sloughs to benefit area-wide populations of the red-legged frog.
The
Biological Assessment report prepared for BioSearch for this EIR discussed the lack of
backwaters (with low or non-existent stream flows) in the Pajaro River channel as a major
characteristic that is detrimental for the survival of red-legged frogs. The EIR preparers anticipate the new backwaters
will form as a result of establishing a permanent vegetative buffer for the river’s
low flow channel. The USFWS has requested
that the formation of these new backwaters be documented through annual surveys by a
qualified biologist. The creation of
backwaters will enhance the in-stream habitat for the species. If backwaters do not form in substantial numbers,
then other measures will be conducted to benefit area-wide populations of the frog. The off-site measure recommended by USFWS is that
Public Works maintenance crew conducts a bullfrog eradication program in Hansen Slough and
Harkins Slough to remove this primary predator of red-legged frog larvae. The Mitigation, Monitoring, and Reporting Program
will provide details on how this eradication program would be conducted. Impact
W-10. Rodent control along the Pajaro River and
Salsipuedes Creek may directly or indirectly affect the California red-legged frog.
Fumitoxin, a
Category 1 pesticide, is used by placing moisture-activated pellets in rodent burrows and
then closing the burrow entrance. During the
dry season, California red-legged frogs take shelter in landscape features that provide
cover and moisture including small mammal burrows. Rodent
control activities may directly impact frogs taking shelter within targeted burrows or
indirectly impact frogs by eliminating potential shelter areas. Mitigation
Measure W-10. Rodent control using pesticides shall not be
conducted along Salsipuedes Creek to avoid impact to California red-legged frogs. Rodent control using pesticides along the Pajaro
shall be limited to areas where rodent burrows severely threaten the integrity of the
levee wall. Rodent control activity shall
also be limited to no more than 12 feet from the base of the levee and not be conducted
along the outer benches or banks.
Rodent control
may directly impact California red-legged frogs and may also indirectly impact raptors
such as Red-tailed Hawk (Buteo jamaicensis)
and American Kestrel (Falco sparverius),
which hunt rodents on the river’s banks and benches. Impact
W-11. The Western Snowy Plover breeds on the sandbar at
the Pajaro River mouth and sandbar modification during their breeding season (late spring
and summer) would negatively impact this federally threatened species.
The Santa Cruz
County Department of Public Works has permits to open (and attempt to re-close) the
sandbar at the mouth of the Pajaro in late spring or summer if high lagoon water levels
produce flooding. The breeding season of the
coastal population of the western snowy plover extends from mid March through mid
September. Nest initiation and egg laying
occurs from mid March through mid July (USFWS,
1993). Mechanical sandbar breeching is
considered a potentially significant impact to this threatened species. Mitigation
Measure W-11. Impact to breeding Western Snowy Plovers, if
present, shall be avoided during modification of the sandbar at the mouth of the Pajaro
River.
A qualified
wildlife biologist shall inspect the sandbar area slated for removal prior to any removal
activities to determine if snowy plovers will be impacted. Impact
W-12. Maintenance equipment used within or near a wetted
channel may leak grease, oil and/or fuel into the channel and this would negatively impact
aquatic wildlife.
Oil, grease and
fuel are toxic to wildlife and their entry into the Pajaro River system from the use of
maintenance equipment shall be avoided. Oil,
grease and fuel entering the Pajaro River system will have a negative on steelhead,
California red-legged frog, tidewater goby and other aquatic wildlife. Mitigation
Measure W-12. Any maintenance equipment that within or near a
wetted channel will be inspected to be free of grease, oil and fuel that could enter the
watercourse. Heavy equipment will only cross
a wetted channel in very extreme cases. In
all circumstances, when operating heavy equipment within or adjacent to the wetted
channel, fuel and oil tanks/pans should be surrounded by secondary containment devices. Hydraulic oils will meet, at minimum,
Environmental Protection Agency aquatic toxicity requirements and be biodegradable.
Maintenance
equipment includes heavy equipment such as front loaders, excavators, dump trucks as well
as smaller equipment such as chainsaws. Impact
W-13. Maintenance activities below Highway 1 impacts
listed species in the Pajaro.
The NMFS and
CDFG commented that maintenance activity below Highway 1 does not significantly improve
the flood carrying capacity of the river, yet significantly impacts listed species in the
Pajaro. Impact W-1 (p. 103) states
“vegetation in the channel bed [below Highway 1] is presently very scarce because of
brackish water inundation by tides and sandbar development” and that “downed
trees in the wide sandy channel downstream of Highway 1 are generally scarce, even without
maintenance”. Furthermore, the Pajaro
River Management and Restoration Plan (CH2M Hill 1997, p. 26) states “vegetation
removal below Highway 1 does not significantly affect river capacity upstream of the
Highway”. Mitigation
Measure W-13. In-stream vegetation (except invasive weeds) or
woody debris in the channel bottom below Highway 1 will not be removed.
The
County has re-evaluated maintenance activities below Highway 1 and concluded that a
reduction in vegetation maintenance is appropriate.
There is an intrinsic benefit of in-stream vegetation and woody debris to listed
species in the Pajaro, and removal of this material may have a significantly impact. Therefore, the County will no longer remove
vegetation (except for invasive weeds) and woody debris in the channel bottom below
Highway 1. AIR
QUALITY
Impact
AQ-1. Levee maintenance, bank erosion repair, vegetation
maintenance and revegetation activities would generate PM10 (dust) emissions.
Under
the proposed project, levee maintenance activities along the Pajaro River and Salsipuedes
Creek would generate dust emissions from grading and equipment transport along dirt roads. Similarly, bank repairs and revegetation along the
Pajaro River and vegetation maintenance along the Pajaro River, Salsipuedes Creek, and
Corralitos Creek would generate dust emissions from equipment and vehicles traveling to
the site along dirt roads. In addition, river
maintenance would include removing silt from streambeds and flap-gates along the Pajaro
River and Salsipuedes Creek. The following
discussion addresses dust emissions associated with silt removal, travel on dirt roads,
and grading activities. Dust
Emissions from Silt Removal According
to Santa Cruz County (Reynolds, Personal Communication, 1999), up to 150 cubic yards of
silt per day would be removed from the Pajaro River during sand bar removal, 40 cubic
yards of silt per day would be removed from Pajaro River flap-gates, and 6 cubic yards per
day would be removed from Salsipuedes Creek. Removed
silt generally has high water content and would not be dried before transport to the
County of Santa Cruz Public Works maintenance yard. Table
3.5-3 provides an estimate of the amount of dust that would be generated by silt removal
activities. Dust
Emissions from Travel on Levee Roads Equipment
and vehicles driving on dirt roadways to access the project site would generate dust. To access the Pajaro River and Salsipuedes Creek,
the equipment and vehicles would travel along approximately ¼ mile of dirt farm roads. The remainder of road travel would be on paved
roads or roadways surfaced with base rock and screenings.
Calculations of dust emissions were conducted using a total travel distance of 0.5
mile per vehicle to account for the return trip and additional travel necessary to access
different areas of the river. Dust emissions
that would be generated from travel by equipment and vehicles for each activity are
presented in Table 3.5-3. Dust
Emissions from Grading Grading
during levee road maintenance or implementation of bank stabilization measures would
generate fugitive dust when equipment wheels or blades pulverize and brake down surface
material. Wind erosion or vehicle tires;
subsequently entrain the dust generated, including PM10.
The MBUAPCD assumes that grading and excavation activities generate approximately
71 pounds of PM10 per acre (MBUAPCD, 1995).
According to the County (Reynolds,Personal Communication,1999), up to one acre
would be graded on any given day. Based on
this level of activity, grading associated with levee and access road maintenance or bank
repair would generate approximately 71 pounds of PM10 per day. Summary
of Dust Emissions Dust
emission levels that would be generated by each project activity are shown in Table 3.5-3. As the results indicate, no single activity would
be expected to emit PM10 above the MBUAPCD significance threshold of 82 pounds
per day. However, two or more activities
combined could exceed the PM10 threshold. Mitigation
Measure AQ-1. Limit
grading and similar activities to those that will generate less than 82 lbs/day of
particulate matter (dust). To minimize dust
generation and its effects on nearby residential and agricultural uses, the Public Works
Department shall schedule grading and related maintenance activities so that a single area
of less than one acre is being disturbed within a single workday. If this is not possible, then the grading site
shall be watered with a spray truck constantly during the workday.
Two
or more maintenance activities that, when combined, would generate PM10 emissions
exceeding the MBUAPCD threshold (82 lbs/day), shall not be conducted on the same day. Grading operations (bank erosion repair and levee
and access road maintenance) are in terms of lbs/day/acre.
Therefore, dust generation can be reduced below tabulated values by working on
areas less then 1 acre in size. Should a
combination of activities be contemplated which would exceed MBUAPCD thresholds, then
watering 2-3 times per day for earthmoving and excavating activities will need to be
employed to reduce this contribution from 38 lbs/day/acre to 29 lbs/day/acre. NOISE
Impact
N-1. Earthmoving equipment, service vehicles, mowers,
chain saws, wood chippers and other equipment used for proposed maintenance would generate
noise.
Noise
would be generated by levee and access road maintenance along the Pajaro River and
Salsipuedes Creek from trucks and equipment traveling to the site to repair potholes and
shoulder along levee roads. Noise associated
with grading and other road repair activities would be audible by residences located
adjacent to the levees in the short reach of the river through the Town of Watsonville. Bank erosion repairs along the Pajaro River would
generate noise from service vehicles used to approach the site and the use of equipment
such as excavators, loaders and dozers. Vegetation
maintenance activities would generate noise along the Pajaro River, Salsipuedes Creek and
Corralitos Creek from the use of service vehicles, chain saws, wood chippers and mowers. These vegetation management activities and the
noise produced by them will be similar to those currently going on under the interim
Coastal Zone/Riparian Exception permit, as identified in the setting section. The
nearest sensitive receptors to the project site are homes in the City of Watsonville along
the Pajaro River and Salsipuedes Creek. The
nearest residence to proposed work areas is adjacent to the Pajaro River levee just
downstream of the Salsipuedes Creek confluence. The
residence is approximately 50 feet north of the levee and 200 feet north of the toe of the
channel bank. Residences within 50-100 feet
of the levees may experience fairly high noise levels, but the noise would be short-term
(3-5 days annually) and limited to the hours between 8 AM and 5 PM. The levee will act to attenuate noise generated as
a result of work on the banks, benches and channel areas.
Residences greater then 100 feet should not be significantly impacted. Because of the extremely limited number of homes
that lie within 100 feet, the attenuation effects of the levees, and the extremely limited
duration of project work in the area of the homes, noise impacts are expected to be less
then significant. Mitigation
Measure N-1. All equipment shall be outfitted with mufflers and
their operation limited to the hours of 8a.m. to 5p.m. weekdays.
To
minimize noise generated by maintenance activities and its effects on nearby residential
areas, the Public Works Department shall ensure that all maintenance activities comply
with the following:
· Equipment
operation onsite shall be limited to the hours of 8 a.m. to 5 p.m. weekdays (except in
emergency situations).
LESS
THAN SIGNIFICANT IMPACTS In addition to the impacts the
mitigations listed above, the EIR identified several impacts of the project which are less
than significant and therefore no mitigation measures are required. Findings are not required for less than
significant impacts. However, these less than
significant impacts are listed at the end of these findings to clearly identify which
impacts identified in the EIR result in insignificant effects and to note which impacts do
not require mitigation measures. The listing
of these insignificant impacts is also included to provide an explanation why these
impacts have been determined to be insignificant. Impact
H-1. Establishment of vegetation in the channel bottom
and along the channel banks of the Pajaro River will reduce the conveyance capacity of the
channel and therefore increase the flood risk compared to existing conditions. No
significant impact. The full implementation
of the proposed vegetation management plan results in a less then 1% decrease in channel
capacity in relation to current (July 2000) and baseline (February 1999) conditions. The proposed plan includes provisions for
monitoring to ensure that vegetation growth stays within plan guidelines. Mitigation
Measure H-1:
No mitigation is necessary. Impact
G-1. Levee resurfacing and maintenance could cause
levees to erode or fail as a result of increasing the height of the levee slope, placement
of additional load on the levee, or inadequate soil compaction. The
proposed project would involve (1) resurfacing the Pajaro River levee in Monterey County
to restore the levee to its original elevation and (2) ongoing resurfacing as needed to
maintain the Pajaro River (Monterey and Santa Cruz Counties) and Salsipuedes Creek levees
at their original 1949 elevations and to provide a consistent level of protection. This activity would increase the height of the
slope and load on the slope. As a result of
substantial increases in levee height, levees could become susceptible to static
instability, a condition in which the levees could collapse under their own weight. Poorly compacted soil could erode from wind or
flooding activity. Increased slope and height
could cause added material to topple if it is not placed and compacted adequately. Failure of the additional material could also
occur as a result of liquefaction during an earthquake.
Slope failure or erosion could result in infilling of the river channel and
reduction of the hydraulic capacity of the river or levee failure and possible over bank
flow during flood events. This would be a
significant impact. Levee resurfacing is not
anticipated to result in an elevation increase of more then 1-2 feet. An assessment of this degree of resurfacing
indicates that the quantity of material proposed to be added and the anticipated change in
height would not be enough to cause any of the above indicated consequences. Consequently, any stability or erosion impacts
related to the levee resurfacing and maintenance are expected to be less then significant.
Mitigation
Measure G-1. No mitigation is necessary. Impact
G-3. The proposed bank erosion restoration along the
Pajaro River would reduce the likelihood of bank/slope erosion, slumping and levee failure
caused by exposing bank soil to wind and scour from flooding. The
proposed project has identified 37 areas of significant erosion threat (half of which have
been armored on an emergency-basis by the USCOE). As
described under Mitigation H-2, erosion restoration will be provided to reduce bank
erosion and the threat of levee failure. Eight
alternative treatments are proposed that combine rock protection, regrading of channel
banks and biotechnical (i.e., use of vegetation) stabilization methods. None of the methods suggested increases the threat
of instability from seismic events for the treated and adjacent areas. More basic techniques of laying back (reducing the
slope angle) bench slopes to allow for greater vegetation success will only increase
stability for seismic events. All suggested
bank stabilization techniques are expected to have positive, but varying degrees, of
effectiveness. As defined under Mitigation
H-2, site-specific characteristics will need to be evaluated at the time of the repair
design and consideration given to potential for impacts to adjacent areas and the opposing
bank. Mitigation
Measure G-3a: Long-term effects.
No mitigation is necessary. In the
long-term, this is a beneficial impact.
Impact
G-6. Revegetation of the banks of the Pajaro River
would reduce bank erosion caused by soil exposure to wind and scour from flood and would
thus improve bank stability. Under
the proposed project native riparian vegetation would be established along the channel
bank from the toe of slope up to 8 feet below the top of bank on the Pajaro River from
Highway 1 to Murphy Crossing. In addition,
vegetation would be left to grow naturally on the toe of slope, along the lower channel
slope and channel bench on Salsipuedes Creek from the confluence with the Pajaro River to
State Highway 129 and on the east side of Salsipuedes Creek from Lakeview Road to East
Lake Avenue/State Highway 152. Vegetation
planting and regeneration will reduce bank erosion by providing soil cover and root
stabilization. This will decrease the
potential for bank slope failure and subsequent levee instability. This would be a beneficial impact. Mitigation
Measure G-6. No mitigation is necessary.
Impact
G-7. Vegetation management on channel banks along
reaches of the Pajaro River and Salsipuedes Creek may potentially cause bank erosion. Under
the proposed project, vegetation management along the Pajaro River from Highway 1 to
Murphy Crossing would include removing dense vegetation on the upper channel banks. The removal of vegetation from the upper channel
banks will include only the hand removal of woody vegetation with a stem diameter of three
(3) inches or greater. If water reaches the
upper channel bank where the clearance of the larger woody vegetation has occurred, there
is a potential that this area may be subject to erosion.
However, because the lower channel bank will be vegetated and the upper channel
bank will have ruderal annual grass vegetation and smaller woody vegetation there is
little likelihood that such erosion will cause bank/slope or levee instability. Because this vegetated condition is relatively
consistent with the baseline 1999 condition, this impact is considered less then
significant. Mitigation
Measure G-7. No mitigation is necessary. Impact
W-1. Clearance of downed trees on the Pajaro River
downstream of Highway 1 would remove potential escape cover and limit deepwater habitat
for steelhead and tidewater goby.
Maintenance
actions will remove downed trees and woody vegetation greater than 3 inches in diameter
from the channel bed. However, vegetation in
the channel bed is presently very scarce because of brackish water inundation by tides and
summer sandbar development. Although they
provide some escape cover for fish, downed trees in the wide sandy channel downstream of
Highway 1 are generally scarce, even without maintenance and do not provide backwater or
significantly deeper habitats. Consequently,
this potential impact is not considered significant. Mitigation
Measure W-1. No mitigation is necessary.
Impact
AQ –2. Levee maintenance, bank erosion repair and
vegetation maintenance would result in vehicle exhaust emissions from the use of
excavators, tractors, loaders, dozers, dump trucks, pickup trucks, utility trucks and
emissions from chain saws and wood chippers
Calculating
ROG and Nox emissions from construction activities is not necessary because these
temporary emissions of these ozone precursors have been accommodated in State- and
Federally –required air plans. Mitigation
Measure AQ-2. No mitigation is necessary Impact
V-1. Vegetation management along the Pajaro River and
Salsipuedes Creek may impact the scenic quality of views from scenic routes.
Under
the proposed project, vegetation management activities along the portions of the Pajaro
River that would be visible from Highway 1 would include: (1) removal of invasive weeds
and woody vegetation growing in the channel; (2) mowing or herbicide application on upper
channel banks, channel benches, and levee slopes; and (3) establishment of riparian
vegetation along the lower channel banks. Vegetation
management activities along Salsipuedes Creek that would be visible from Highway 152 would
include (1) mowing and herbicide application on channel benches and levee slopes; (2)
removal of woody vegetation from the channel bottom and banks, and (2) natural growth of
vegetation along the east side of the channel. Despite
these activities, the impact from vegetation management on views from Highway 1 and
Highway 152 is expected to be minimal and less than significant for the following reasons: · Minimal
vegetation would be removed from the Pajaro River stream channel or banks on the coastal
side (west side) of Highway 1 (Coastal Zone area); · Most
vegetation removal would occur in the river channel which is located at a lower elevation
than the roadways and obscured by levees which are above adjacent grade and therefore is
not easily viewed by motorists traveling along Highway 1 or Highway 152; Ÿ
Highway
1 and Highway 152 intersect at a minor area of the entire project area and thus, most of
the stream clearance activities will not be visible from these two roadways. Proposed
vegetation management would improve views (in relation to February 1999 conditions) of the
Pajaro River upstream of Highway 1 by planting riparian trees and shrubs along portions of
the channel banks (and/or allowing natural establishment) that are currently lacking
riparian vegetation. In addition, riparian
trees would be established along the channel benches to create a savanna-type landscape. Areas treated with rip rap during emergency USCOE
flood repairs will be slower to revegetate, but are expected to gradually increase in
vegetation coverage over time. Mitigation
Measure V-1. No mitigation is necessary.
Impact
V-2. Vegetation management and bank erosion restoration
would alter the scenic quality of the Pajaro River and Salsipuedes Creek as viewed from
the levees.
As
described in impact V-1, vegetation management along the Pajaro River and Salsipuedes
Creek will involve both vegetation removal and planting and natural regeneration and
growth. The visual quality of the view from
the levees along these streams is expected to improve from the removal of ruderal
vegetation and the planting and natural growth of native riparian vegetation. Therefore, the impact from vegetation management
on the scenic quality along the levees would be beneficial. The
bank erosion restoration along the Pajaro River would involve a combination of traditional
structural armoring methods and bioengineering techniques (i.e., planting). The artificial nature of some of the traditional
treatments would have an impact on the visual quality of the Pajaro River bank as viewed
from the levee. However, the erosion sites
are sporadic along the riverbank, and the impact would be temporary as natural vegetation
grows in. As a result, the impact from bank
erosion restoration on the scenic quality along the levees would be less than significant.
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