RIPARIAN VEGETATION MAPPING
IN THE
SOUTH FORK AMERICAN RIVER
AND
LOWER IOWA CANYON CREEK
2010
April 2011
Prepared For: Sacramento Municipal Utility District Power Generation Department 6201 S Street, Mail Stop B355 Sacramento, CA 95817
Prepared By: ECORP Consulting, Inc. 2525 Warren Drive Rocklin, California 95677
TABLE OF CONTENTS
1.0 INTRODUCTION ...... 1
1.1 Site Location ...... 2 1.2 Existing Site Conditions ...... 2
2.0 METHODS ...... 2
3.0 RESULTS AND DISCUSSION ...... 3
3.1 Upland Communities ...... 3 3.2 Riparian Communities ...... 6 3.3 Riparian Vegetation Comparison: 2004-2010 ...... 7
4.0 CONCLUSION ...... 9
5.0 REFERENCES ...... 11
LIST OF TABLES
Table 1 – Dominant Species within Each Alliance ...... 3 Table 2 – Comparison of Alliance Acreage Between 2004 and 2010 ...... 7 Table 3 - Percent of the Total Vegetation Cover for Each Alliance Type ...... 8
LIST OF FIGURES
Figure 1. Project Site and Vicinity Figure 2. Natural Resources Conservation Service Soil Types Figure 3. Vegetation Communities within the Study Area (2010) Figure 4. Vegetation Community Comparison
LIST OF ATTACHMENTS
Attachment A – 2004 Riparian Vegetation Map prepared by VESTRA Resources, Inc.
Sacramento Municipal Utility District Upper American River Project FERC Project No. 2101
1.0 INTRODUCTION
At the request of Sacramento Municipal Utility District (SMUD), ECORP Consulting, Inc. (ECORP) conducted a riparian vegetation mapping study in support of the proposed New Slab Creek Powerhouse Project (Project).
The Project consists of modification of SMUD’s existing Upper American River Project (UARP), a 688 MW hydroelectric project consisting of eight powerhouses. The smallest is Slab Creek Powerhouse, a 0.4 MW facility lying at the base of Slab Creek Reservoir Dam on the South Fork American River (SFAR). This powerhouse generates power from the 10/36 cfs minimum release requirements under the existing license. Under the new UARP license, higher and more variable minimum releases ranging between 63 and 415 cfs will be released from Slab Creek Reservoir.
Preliminary engineering feasibility studies have demonstrated the value of adding a new powerhouse at Slab Creek Reservoir to take advantage of the new minimum releases. However, the size of the release valve at the base of Slab Creek Reservoir Dam, which feeds into the existing powerhouse, limits the volume of water to approximately 260 cfs. Under the new license, SMUD will also provide boating flows below Slab Creek Reservoir of up to 1,500 cfs. Currently, boating flows can only be provided by spilling water over Slab Creek Dam. Alternatively, boating flows could be realized by boring a new hole through the base of the dam and installing a larger pipe and release valve.
SMUD has determined the White Rock Tunnel Adit 3, a short tunnel that connects to the White Rock Tunnel, is the optimal location for a new powerhouse that can facilitate the minimum and boating releases required under the new license. Under SMUD’s proposal, a valve inserted into the White Rock Tunnel bulkhead would deliver water into a penstock leading to the new powerhouse at the end of the adit. The powerhouse would be located on the banks of the SFAR, directly downstream of Iowa Canyon Creek. A new bridge crossing the lowermost section of Iowa Canyon Creek would provide vehicular access to the new powerhouse.
The purpose of this study was to document existing site conditions (including vegetation communities) and to map the distribution of riparian areas within and immediately downstream of the ¼-mile reach of the SFAR between Slab Creek Dam and the proposed new powerhouse site. The survey area included the stream channel and the adjacent areas within 300 feet (ft) of the normal high-water line. The lower portion of Iowa Canyon Creek, a tributary to the SFAR, was included within this survey area because of the proposed bridge construction across the creek. Current site conditions, vegetation communities, and riparian vegetation mapping results were compared to data collected in 2004 as part of the relicensing studies, to evaluate relative changes in the riparian communities over the six-year period. These data will also be used to document potential changes in the riparian communities during and post construction of the proposed powerhouse and associated discharge structure(s).
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1.1 Site Location
The Project is located just north of Slab Creek Road and immediately west (downstream) of the Slab Creek Reservoir Dam, in El Dorado County, California (Figure 1. Project Site and Vicinity). The site corresponds to a portion of Section 25, Township 11 North, and Range 11 East (MDBM) of the “Slate Mountain, California” 7.5-minute quadrangle (U.S. Department of the Interior, Geological Survey 1973). The approximate center of the site is located at 38° 46’ 20” North and 120° 42’ 05” West within the South Fork American River Watershed (#18020129, U.S. Department of the Interior, Geological Survey 1978).
1.2 Existing Site Conditions
For the purposes of this study, existing riparian vegetation within and immediately downstream of the ¼-mile reach of the SFAR and other upland areas within 300 ft of the normal high water mark (including Iowa Canyon Creek) were evaluated during the summer of 2010.
Riparian areas consist of several willow (Salix sp.) and alder (Alnus sp.) dominated vegetation communities. The north and south slopes of the river consists of mature forest communities dominated by ponderosa pine (Pinus ponderosa), canyon live oak (Quercus chrysolepis) and Douglas fir (Pseudotsuga menziesii) and a variety of understory species. All of these communities are described in the Results section.
According to the Soil Survey of El Dorado County, California (U.S. Department of Agriculture, Soil Conservation Service 1974), four soil units, or types, have been mapped within the site (Figure 2. Natural Resources Conservation Service Soil Types): (AaF) Acidic rock land, (MbF) Mariposa very rocky silt loam, 50-70% slopes, (McF) Mariposa-Josephine very rocky loams, 50- 70% slopes, and (MmF) Metamorphic rock land. None of these soils units consist of listed hydric components, or contain hydric inclusions (U.S. Department of Agriculture, Soil Conservation Service 1992).
2.0 METHODS
Field surveys were conducted on 26 August 2010 by ECORP biologists Debra Sykes and Daria Snider. During this survey, each plant community within the project area was identified based on the Alliance-level CalVeg system for North Sierran - Zone 3 (USDA 2010a and 2010b). The limits of each plant community were delineated onto an ortho-rectified aerial photograph (1:200) and a list of the current conditions of each plant community was recorded. Dominant species within each plant community were noted.
Riparian plant community data collected in 2010 was compared to data obtained in 2004 (DTA 2004) as part of the UARP relicensing studies. However, a direct comparison of the 2004 and 2010 data was not possible due to differences in data collection techniques between the two data sets. The 2004 data was collected and mapped on a relatively broad scale using primarily aerial photography, which was later verified by selected ground truthing. This assessment did not include upland alliances located adjacent to riparian areas, which were mapped as barren or
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rocky shore. The 2010 community data and mapping was based on community alliance polygons obtained using GPS, and included adjacent upland alliances. To maintain consistency with the total area evaluated in both 2004 and 2010, upland alliance percentages recorded for 2010 are presented but are not compared with the 2004 data which included upland areas as part of barren or rocky shore habitat. Consequently, the 2010 data could not be directly superimposed on the 2004 data; although a comparison of the size, general shape, and location of the vegetation polygons was conducted. Additional details regarding this analysis are presented in the Results and Discussion sections. Upland vegetation community data was not collected in 2004 and as a result, a comparison of upland community data could not be performed.
3.0 RESULTS AND DISCUSSION
During the 2010 field survey, ten plant community alliances were documented within the study area (Figure 3). These alliances include both the riparian community and the adjacent upland community. Plant community alliances observed in the project area include:
• Douglas Fir-Pine/Interior Mixed Hardwood Alliance (DP-NX) • Interior Mixed Hardwood Alliance (NX) • Canyon Live Oak Alliance (QC) • Ponderosa Pine Alliance (PP) • Non-native/Invasive Forb/Grass Alliance (IF) • Non-native/Ornamental Shrub Alliance (IS) • California Buckeye Alliance (QI) • White Alder Alliance (QE) • Willow-Alder Alliance (QY) • Willow (Riparian Scrub) Alliance (WL)
Other non-vegetated surfaces found during the survey include the following:
• Non-vegetated Type (XZ) (This feature is a man-made woodpile.) • Barren (BA) (This represents the exposed bedrock on the banks of the river.) • Water (WA) (This represents standing/pooled water.) • Exposed non-water features (W9) (This represents the rocky shoreline of the river, and the riffles and runs where standing/pooled water is not present). • Dam Structure (DAM) (This is not a CalVeg category)
3.1 Upland Communities
The steep upland slopes adjacent to the river are composed of eight plant community alliances. The acreages listed below for each of the alliances includes the ¼-mile reach of the SFAR and upland areas to 300 ft from the normal high water mark. A description of each of these alliances is provided below, and the dominant species found within each of the upland community alliances is presented in Table 1.
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Table . Dominant Species Within Each Alliance Upland Communities Dominant Plants Species Douglas Fir-Pine/Interior Mixed Hardwood Pseudotsuga menziesii, Pinus ponderosa, Quercus Alliance chrysolepis, Quercus wislizenii, Heteromeles arbutifolia, Philadelphus lewisia, and Toxicodendron diversilobum Interior Mixed Hardwood Alliance Quercus chrysolepis, Quercus wislizenii, Umbellularia californica, Aesculus californica, Philadelphus lewisia, and Toxicodendron diversilobum Canyon Live Oak Alliance Pinus ponderosa, Arctostaphylos viscida, Aesculus californica, Quercus berberidifolia, and Ceanothus integerrimus Ponderosa Pine Alliance Pinus ponderosa, Quercus chrysolepis, and Aesculus californica Non-native/Invasive Forb/Grass Alliance Avena fatuta, Cynosurus echinatus, and Bromus diandrus Non-native/Ornamental Shrub Alliance Rubus armeniacus California Buckeye Alliance Aesculus californica, Avena fatuta, and Bromus diandrus Riparian Communities White Alder Alliance Alnus rhombifolia, Rubus armeniacus, Salix lasiolepis, and Mimulus guttatus Willow-Alder Alliance Salix lasiolepis, Alnus rhombifolia, Rubus armeniacus, and Baccharis pilularis Willow (Riparian Scrub) Alliance Salix lasiolepis, Rubus armeniacus, and Baccharis pilularis Non-Vegetated Surfaces Non-vegetated Type Woodpile Barren Exposed bedrock Water Standing water/pools Exposed non-water features Rocky shoreline/ riffles and runs Dam Structure1 Slab Creek Dam 1 This classification is not a CalVeg Alliance.
Douglas Fir-Pine/Interior Mixed Hardwood Alliance (DP-NX)
The Douglas fir-pine/interior mixed hardwood alliance comprises approximately 8.7 acres of the project area. This alliance type is found on the south side of the river on the north-facing slope and occurs on both slopes of Iowa Canyon Creek. This alliance is composed of a 50/50 mixture of two separate alliance types: the Douglas fir-pine alliance and the interior mixed hardwood alliance. The conifer component of this alliance is composed of Douglas fir (Pseudotsuga menziesii) and ponderosa pine (Pinus ponderosa) as co-dominants. The interior mixed hardwood component of this alliance is dominated by several upland hardwood species with no clear hardwood dominant. In this stand, the two dominant hardwood trees are canyon live oak (Quercus chrysolepis) and interior live oak (Quercus wislizenii). Understory shrubs found in this alliance include toyon (Heteromeles arbutifolia), mock orange (Philadelphus lewisia), and poison oak (Toxicodendron diversilobum).
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Interior Mixed Hardwood Alliance (NX)
The interior mixed hardwood alliance comprises approximately 3.4 acres of the project area. This alliance type is found on the southern side of the river on the north-facing slope and to the immediate west of the reservoir and dam. This alliance is dominated by two hardwood trees (canyon live oak and interior live oak) but is lacking the conifer component found in the Douglas fir-pine/interior mixed hardwood alliance described above. Understory trees and shrubs at this location include California bay (Umbellularia californica), California buckeye (Aesculus californica), mock orange, and poison oak.
Canyon Live Oak Alliance (QC)
The canyon live oak alliance comprises approximately 7.5 acres of the project area. This alliance type is found on the northern side of the river on the south-facing slope, and is the most dominant alliance on this slope. The dominant tree within this alliance is canyon live oak. Other trees and shrubs that occur in this stand include ponderosa pine, whiteleaf manzanita (Arctostaphylos viscida), California buckeye, scrub oak (Quercus berberidifolia), and deerbush (Ceanothus integerrimus).
Ponderosa Pine Alliance (PP)
The ponderosa pine alliance comprises approximately 2.3 acres of the project area, and only occurs in a small band above the canyon live oak alliance on the northern side of the river. In this location, ponderosa pine is the dominant tree. Other trees and understory shrubs occurring in this location include canyon live oak and California buckeye.
Non-Native/Invasive Forb/Grass Alliance (IF)
The non-native/invasive forb/grass alliance comprises approximately 0.8 acre of the project area, occurring in a small linear area around a disturbed walking trail to the river on the northern bank, and in a small area just west of the dam also on the northern side of the river. The dominant vegetation is comprised of all non-native and/or invasive grasses including wild oats (Avena fatua), hedgehog dog-tail grass (Cynosurus echinatus), and ripgut brome (Bromus diandrus). Other native and non-native herbaceous species growing in the alliance includes rose clover (Trifolium hirtum), small-head clover (Trifolium microcephalum), bluehead gilia (Gilia captitata), tall stephanomeria (Stephanomeria virgata), spanish clover (Lotus purshianus), summer mustard (Hirschfeldia incana), and prickly lettuce (Lactuca serriola). Although the two grasslands within the project area were categorized as this alliance based on the predominance of non-native annual grasses, some minor differences were noted between the two areas. The grassland area adjacent to the walking trail was more disturbed and contained a higher number of weedy, non-native/invasive species including sweetclover (Melilotus alba), black mustard (Brassica nigra), and summer mustard. The grassland situated closer to the dam was not as disturbed and contained a higher number of native forbs including bluehead gilia and tall stephanomeria.
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Non-Native/Ornamental Shrub Alliance (IS)
The non-native/ornamental shrub alliance occurs on the north bank of the river, adjacent to the non-native/invasive forb/grass alliance described above. This small alliance only comprises approximately 0.1 acre of the project area and is dominated by a single invasive shrub, Himalayan blackberry (Rubus armeniacus).
California Buckeye Alliance (QI)
The California buckeye alliance is located on the northern side of the river just above the bank of the river. This area comprises approximately 0.7 acre and is dominated by a single shrub, California buckeye. The annual grasses and forbs described above for the non-native/invasive forb/grass alliance are found within the understory for this alliance.
Non-Vegetated Type – Woodpile (XZ)
On the northern side of the river, a large woodpile is present adjacent to the ponderosa pine alliance. This woodpile was established in 1997 after woody debris accumulated in the Slab Creek Reservoir after a flood event. The debris was removed and left on the northern bank of the river. The portion of the woodpile that occurs within the project area is approximately 0.20 acre.
3.2 Riparian Communities
The riparian communities within the project area are found within the banks of the river. Three plant community alliances and the dam structure occur within the banks of the river. Three additional alliances are non-vegetated or sparsely vegetated. These are water (WA), barren (BA), and exposed non-water feature (W9). All seven of these types are described below. The dominant species found within each of the riparian community alliances is provided in Table 1.
White Alder Alliance (QE)
The white alder alliance comprises approximately 0.5 acre of the project area. All areas mapped within this alliance occur downstream (west) of the confluence of Iowa Canyon Creek with the SFAR. The dominant tree in this alliance is white alder (Alnus rhombifolia). Other co-occurring species include Himalayan blackberry, arroyo willow (Salix lasiolepis) and common monkeyflower (Mimulus guttatus).
Willow-Alder Alliance (QY)
The willow-alder alliance comprises approximately 0.3 acre of the project area. Two stands of this alliance are found in a narrow band along the south bank of the river. This alliance is equally dominated by arroyo willow and white alder. Other species co-occurring within this alliance are Himalayan blackberry and coyote brush (Baccharis pilularis).
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Willow (Riparian Scrub) Alliance (WL)
The willow (riparian scrub) alliance comprises approximately 1.6 acres of the project area. This alliance occurs along the lower portion of Iowa Canyon Creek to the confluence with the SFAR, and at several locations upstream (east) of the confluence. This alliance is dominated by arroyo willow and has Himalayan blackberry and coyote brush within the understory. White alders are also scattered throughout this alliance; however, they are not a dominant species within this alliance.
Barren (BA)
The barren alliance corresponds to the exposed bedrock along the river. Three areas of exposed bedrock comprising approximately 1.2 acres were mapped within the project area. In the 2004 Riparian vegetation mapping study, this area was classified as “Bedrock.”
Water (WA)
The water alliance comprises approximately 1.7 acres of the project area. Pools of standing water were mapped separately from riffle, run, and pool areas of the river. Included within this alliance is the large plunge pool at the base of the dam.
Exposed Non-Water Feature (W9)
The exposed non-water feature category includes all the rocky shore and flowing water within the river bed. This category excludes exposed bedrock areas, standing pools of water, and areas that have sufficient vegetation to be classified within another vegetation alliance. Riffle and run habitats are included within this category along with the rocky shore and the river bed which consists primarily of large cobble, and small and large boulders. This area comprises approximately 2.6 acres of the project area. In the 2004 Riparian vegetation mapping survey, this area was classified as “Rocky Shore”.
Dam Structure (DAM)
The Slab Creek Dam does not fit any CalVeg Alliance, and is represented on the map as DAM.
3.3 Riparian Vegetation Comparison: 2004-2010
In 2004, Devine Tarbell and Associates (DTA) conducted a large-scale riparian vegetation mapping effort as part of SMUD’s Upper American River Project (UARP) and Pacific Gas and Electric Company’s (PG&E) Chili Bar Project (DTA 2004). Approximately 360 acres of riparian vegetation were mapped by DTA. The 2004 mapping effort was conducted at a broad scale, and the data collection was designed for a watershed-wide analysis. As such, the 2004 vegetation polygons are not designed to be viewed at a fine scale. Data collected in 2010 provided a more detailed and accurate assessment of vegetation community boundaries. As a result, a direct comparison of the 2004 data to the 2010 data was not possible due to the
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differences in the level of detail between the two data sets. However, sufficient data was still available to conduct an assessment of the relative differences in the general size, shape, and location of the alliance types documented during both survey years (Figure 4).
The Graphic Information System (GIS) polygon dataset that provided the analysis for the 2004 DTA report was provided to ECORP from Vestra Resources, Inc. Preliminary investigation of the 2004 dataset indicted that the vegetation data was significantly shifted (+/-75m) and rotated when overlaid on a 2009 USDA NAIP 1-meter ortho-rectified aerial photo mosaic of El Dorado County. To provide a more accurate comparison of the 2010 and 2004 datasets, the 2004 data was transformed by creating a grid from the polygon data and applying a 3rd order polynomial spatial transformation, using the 2002 ortho-photo as a guide for approximate spatial locations of the 2004 vegetation classes. The transformed grid was converted to polygons and its spatial accuracy was reviewed against the 2002 ortho-photo and the 2009 NAIP ortho-photo. The corrected vegetation polygons overlaid appropriately and could then be overlain with the 2010 survey data to assess vegetation cover change. Since the 2010 study area is larger than the area that was mapped in 2004, the boundary for the comparison was based on the total area mapped in 2004 (Comparison Survey Area).
A comparison of the alliance types and acreages for all alliance types found within the study area in 2004 and 2010 is present in Table 2, and the percent of the total cover for each alliance type for 2004 and 2010 is provided in Table 3.
Table 2. Comparison of Alliance Acreage Between 2004 and 2010 Upland Communities 2004 (acres) 2010 (acres) Canyon Live Oak Alliance NA 0.16 Douglas Fir-Pine/Interior Mixed Harwood Alliance NA 0.10 Interior Mixed Hardwood Alliance NA 0.09 Riparian Communities White Alder Alliance 1.62 0.25 Willow-Alder Alliance 0.0 0.23 Willow (Riparian Scrub) Alliance 0.29 0.93 Non-Vegetated Surfaces Barren1 0.46 0.37 Water 0.53 0.94 Exposed non-water feature2 2.56 2.39 1 This was classified as Bedrock in the 2004 report. “Bedrock” is not listed as a CalVeg Alliance, so it was reclassified as Barren. 2 This was classified as Rocky Shore in the 2004 report. “Rocky Shore” is not listed as a CalVeg Alliance, so it was reclassified as Exposed non-water features.
Table 3. Percent of the Total Vegetation Cover for Each Alliance Type Upland Communities 2004 (%) 2010 (%) Percent change Canyon Live Oak Alliance NA 3 NA Douglas Fir-Pine/Interior Mixed Harwood Alliance NA 2 NA Interior Mixed Hardwood Alliance NA 2 NA Riparian Communities
2010-026.2 Riparian Surveys/Rip_Veg_Map_Study_v2 8 Sacramento Municipal Utility District Upper American River Project FERC Project No. 2101
White Alder Alliance 30 5 -25 Willow-Alder Alliance 0 4 +4 Willow (Riparian Scrub) Alliance 5 17 +12 Non-Vegetated Surfaces Barren1 8 7 -1 Water 10 17 +17 Exposed non-water feature2 47 44 -3 1 This was classified as Bedrock in the 2004 report. “Bedrock” is not listed as a CalVeg Alliance, so it was reclassified as Barren. 2 This was classified as Rocky Shore in the 2004 report. “Rocky Shore” is not listed as a CalVeg Alliance, so it was reclassified as Exposed non-water features.
The presence of upland communities in the 2010 data that are not represented in the 2004 data is likely due to minor differences in data collection methods between the two survey years and to the higher level of detail obtained during the 2010 survey. The 2004 survey was conducted at a broad scale and did not include upland vegetation communities. The small fringe of upland communities identified within the Comparison Survey Area in 2010 was mapped as “Barren” or “Rocky Shore” in 2004. These differences account for the slight variations in acreage recorded for the barren (bedrock) and water and exposed non-water feature (rocky shore) alliances.
Within the riparian communities, a shift in vegetation alliances has occurred between 2004 and 2010, and willows (most notably arroyo willow) have increased in abundance over this time period. In 2004, the dominant alliance was the white alder alliance (1.6 acres and 30% of the total cover); while in 2010, the dominant alliance was the willow (riparian scrub) alliance (0.9 acre and 17% of the total cover). In 2010, the white alder alliance occupied only 0.25 acre and 5% of the total canopy cover within the Comparison Survey Area. The alliances are defined by which species (willow or alder) accounts for 50% or more of the canopy cover, and both of the alliances have the other species co-occurring (but with less than 50% canopy cover). In both survey years, these two alliances were present, but the white alder was more abundant in 2004 and the willow (riparian scrub) was more abundant is 2010. In addition, in 2010 an “intermediate” alliance, the willow-alder alliance, was documented within 0.2 acre (4%) of the Comparison Survey Area. This “intermediate” alliance is defined by equal dominance of willow and white alder, and occurred on the southern bank of the river, adjacent to open water areas. In 2004, these areas were classified as white alder alliance.
The shift from white alder alliance to willow alliance appears to have occurred downstream of the confluence with Iowa Canyon Creek and in an area closer to the dam. The white alder alliance has remained in the same general locations downstream of the confluence, as those areas mapped in 2004. The variation in polygon size and shape is likely due to differences in the scale of the two mapping efforts.
4.0 CONCLUSION
On 26 August 2010, ECORP conducted a vegetation mapping study within and immediately downstream of the 1/4-mile reach of the SFAR (including the lower portion of Iowa Canyon
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Creek) located immediately downstream of the Slab Creek Reservoir Dam. Vegetation community alliances were mapped, according to the CalVeg alliance system, on an aerial photo of the study area. Vegetation community data collected by ECORP was compared with data collected in 2004, which represented a subset of the 2010 study area (Comparison Survey Area). To evaluate the relative change in the type and location of vegetation communities between the two data sets, the general size, shape, and location of the riparian vegetation alliances mapped in 2004 were compared with the riparian vegetation polygons obtained in 2010. The 2004 survey was conducted at a broader scale and did not include upland vegetation communities. The small fringe of upland communities included in 2010 was mapped as “Barren” or “Rocky Shore” in 2004.
In general, a shift from alder dominated communities to willow dominated communities appears to have occurred along the SFAR within the ¼-mile reach between 2004 and 2010. This shift has occurred mainly on the south side of the SFAR, downstream of the confluence with Iowa Canyon Creek. The alliance types documented upstream (west) of the confluence have not changed since 2004. In addition, a new alliance (the willow-alder alliance) is now present along the southern bank of the river and adjacent to some open water areas. Other minor differences between the 2004 and 2010 vegetation community data are likely due to differences in data collection between the two survey periods.
Since a direct comparison of the 2004 and 2010 data was not possible, the 2010 data represents a new baseline for the ¼-mile reach that can be directly compared with and future studies or monitoring requirements. Potential future changes in flow volume and water velocity within the ¼-mile reach is likely to occur as a result of implementation of this project, which may influence the size, shape and vegetation community types currently present within the study area.
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5.0 REFERENCES
DTA (Devine Tarbell & Associates, Inc.) 2004. Riparian Vegeation and Wetland Technical Report. Unpublished report prepared for Sacramento Municipal Utility District and Pacific Gas and Electric Company.
U.S. Department of Agriculture, Soil Conservation Service. 1974. Soil Survey of El Dorado County, California. U.S. Department of Agriculture, Soil Conservation Service. Davis, California.
U.S. Department of Agriculture, U.S. Forest Service. 2010a. Field Key to CalVeg Alliances North Sierran – Zone 3. Accessed on 2 August 2010 from http://www.fs.fed.us/r5/rsl/projects/classification/zone-map-key.html
U.S. Department of Agriculture, U.S. Forest Service. 2010b. Vegetation Descriptions, Northern Sierran – Zone 3. Accessed on 2 August 2010 from http://www.fs.fed.us/r5/rsl/projects/classification/zone-map.html
U.S. Department of the Interior, Geological Survey. 1973. “Slate Mountain, California” 7.5- Minute Quadrangle. U.S. Geological Survey.
U.S. Department of Interior, Geological Survey. 1978. Hydrologic Unit Map, State of California. Geological Survey. Reston, Virginia.
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LIST OF FIGURES
Figure 1. Project Site and Vicinity
Figure 2. Natural Resources Conservation Service Soil Types
Figure 3. Vegetation Communities within the Study Area (2010)
Figure 4. Vegetation Community Comparison
Scale in Feet §25, T.11N., R.11E., MDBM Latitude 38° 46 20 N 0 2000 Longitude 120° 42 05 W Slate Mtn, California, South Fork American 7.5 minute topographic quadrangle, Watershed (18020129) US Geological Survey, 1973.
FIGURE 1. Project Site and Vicinity
2010-026.2 SMUD UARP - Slab Creek SOIL KEY AaF Acidic rock land MbF Mariposa very rocky silt loam, 50-70% slopes McF Mariposa-Josephine very rocky loams, 50-70% slopes MmF Metamorphic rock land * Soil units do not contain listed hydric components or inclusions. Scale in Feet Natural Resources Conservation Service 0 1000 Soil Survey of El Dorado Area, California 1974.
FIGURE 2. Natural Resources Conservation Service Soil Types
2010-026.2 SMUD UARP - Slab Creek Figure 3. Vegetation Communities within the Study Area (2010) Map Features
Study Area (+/- 32.5 ac.) Vegetation
Code, Alliance Name BA, Barren (1.214 ac.) IF BA DAM DAM, Dam Structure (0.587 ac.) XZ SS l l a a b b QI CC r r e e e e k k DP-NX, Douglas Fir-Pine/ RR e e s s e e r r v v o o i i r r Interior Mixed Hardwood Alliance (8.735 ac.) PP WL WA IF, Non-native/Invasive Forb/Grass Alliance (0.834 ac.) W9 IS, Non-native/Ornamental Shrub Alliance (0.119 ac.) WL WL BA NX, Interior Mixed Hardwood Alliance (3.394 ac.) WA QY PP, Ponderosa Pine Alliance (2.297 ac.)
QC BA QC, Canyon Live Oak Alliance (7.526 ac.) NX QE, White Alder Alliance (0.522 ac.)
IS QI, California Buckeye Alliance (0.698 ac.) WA WL IF QY QY, Willow-Alder Alliance (0.331 ac.) (JSwager 11/18/2010) W9, Exposed Non-water Features (2.581 ac.)
WA, Water (1.728 ac.) BA DP-NX WL, Willow (Riparian Scrub) Alliance (1.696 ac.) QE XZ, Non-vegetated (0.249 ac.) W9 QE WL QE IF WA BA QE
DP-NX
Sl ab C re d e Roa k oir Re s erv USGS 7.5' Quadrangle: Slate Mountain Location: N:\2010\2010-026 SMUD\002_Lower_Slab_Creek_Powerhouse\MAPS\Vegetation\Vegetation\v2\LSC_Vegetation_v2.mxd
2010-026.2 Lower Slab Creek Powerhouse Scale in Feet Photo Source: USGS June 2007 Map Date: 11/18/2010 1 " = 200 ' 0 200 I SS l l a a b b Figure 4. 2010 Vegetation (ECORP) CC r r e e e e k k RR e e s s e e r r v v o o i i r r Vegetation Community Comparison Map Features
Comparison Area (+/- 5.46 ac.) Vegetation_Comparison
ECORP 2010 QC, Canyon Live Oak Alliance DP-NX, Douglas Fir-Pine/ Interior Mixed Hardwood Alliance NX, Interior Mixed Hardwood Alliance QE, White Alder Alliance QY, Willow-Alder Alliance d a o WL, Willow (Riparian Scrub) Alliance R ir o v WA, Water r e s e BA, Barren R k e e W9, Exposed Non-water Features r C
b
a DTA 2004 l
S White Alder Alliance Willow Alliance
(JSwager 12/20/2010) Open Water, (WA, Water) 1
1 SS l l a a b b Bedrock, (BA, Barren) 2004 Vegetation (DTA) CC r r e e e e k k Rocky Shore, (W9, Exposed Non-water Features) 1 RR e e s s e e r r v v o o i i r r 1 CalVeg Alliance Name 2 2010 2004 Vegetation Alliance Acres % Acres % Upland Communities Canyon Live Oak Alliance 0.16 3% N/A N/A Douglas Fir-Pine/Interior Mixed 0.10 2% N/A N/A Hardwood Alliance Interior Mixed Hardwood Alliance 0.09 2% N/A N/A Riparian Communities White Alder Alliance 0.25 5% 1.62 30% Willow-Alder Alliance 0.23 4% 0.00 0% Willow (Riparian Scrub) Alliance 0.93 17% 0.29 5% Non-vegetated Surfaces Barren 0.37 7% 0.46 8% Water 0.94 17% 0.53 10%
d Exposed Non-water Features 2.39 44% 2.56 47% a o Grand Total 5.46 100% 5.46 100% R ir o N:\2010\2010-026 SMUD\002_Lower _Slab_Cr eek_Power house\MAPS\Vegetation\Compar ison\v2\Tables\[Veg_Comp_20101019.xlsx]Results v r 2 e The 2004 survey was conducted at a broader scale and did not include s upland alliances. The small fringe of upland included in the 2010 survey e R was mapped as barren or rocky shore in 2004. k e e r C
b
a l
S Location: N:\2010\2010-026 SMUD\002_Lower_Slab_Creek_Powerhouse\MAPS\Vegetation\Comparison\v2\LSC_Vegetation_Comp_v2.mxd
2010-026.2 Lower Slab Creek Powerhouse Scale in Feet Photo Source: USGS June 2007 Map Date: 12/20/2010 1 " = 200 ' 0 200 I
ATTACHMENT A
Riparian Vegetation Map (2004)
Prepared by VESTRA Resources, Inc.