Sonoma Valley

Historical Hydrology Mapping Project

Phase I

FINAL REPORT Task 2.4b

Arthur Dawson, Baseline Consulting

Alex Young, Sonoma Ecology Center

Rebecca Lawton Consulting

Funded by the Sonoma County Water Agency

November 2016

Prepared by: Baseline Consulting, 13750 Arnold Drive, P.O. Box 207, Glen Ellen, CA 95442 Sonoma Ecology Center, P.O. Box 1486, Eldridge, CA 95431 Rebecca Lawton Consulting, P.O. Box 654, Vineburg, CA 95687

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CONTENTS

OVERVIEW 3 METHODS 5 RESULTS 17 DISCUSSION 22 Comparison of Modern & Historical Conditions 24 RECOMMENDATIONS 27 BIBLIOGRAPHY 30 FIGURES 1. Project Area, Sonoma Valley Watershed, Sonoma County, California 4 2. Definition of Terms and Assumptions 6 3. Wetland Designations Used in this Study 10 4. Certainty Level Standards 14 5. Data Limitations and Temporal Context 15 6. Dates of Sources Used in this Study in Relation to Long-Term Rainfall 16 7. Estimated Pre-Settlement Freshwater Channels and Wetlands 18 8. Estimated Pre-Settlement Freshwater Channels and Wetlands (LIDAR Basemap) 19 9. Estimated Pre-Settlement Freshwater Channels and Wetlands (USGS quads) 20 10. Certainty Levels for Presence of Features Mapped from Historical Sources 21 11. Average annual hydrographs for the historical watershed for Napa River 25

APPENDIXES A. Selected Historical Maps A1. Detail from O’Farrell’s 1848 Rancho Petaluma Map A-2 A2. Confluence of Agua Caliente and Sonoma Creeks in 1860 A-3 A3. Confluence of Agua Caliente and Sonoma Creeks in 1980 A-4 A4. Alternate Channels Occupied by Pythian, an Unnamed Creek, and Sonoma Creek A-5

B. Fieldwork Notes and Selected Photos B1. Field Survey Locations B-6

D. Phase II Mapping Sample D1. Sample High-Resolution Map C-1

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OVERVIEW

Rationale. Prior to extensive human modification, the Sonoma Valley watershed (Figure 1) enjoyed an abundance of surface and ground water, extensive wetlands, and high water quality. Previous studies (Lawton 2006; Micheli 2006; San Francisco Estuary Institute 2012; see also “Comparison of Modern & Historical Conditions,” pg. 24) have demonstrated that changes over the last two centuries have caused increased runoff, flooding, and sedimentation; decreased surface and groundwater; degraded habitat for salmonids and other species; and a loss of wetlands. In coming years, climate change is expected to aggravate these conditions with projected increases in both flooding and drought. Understanding how the watershed functioned before significant human modification is essential to planning projects that will reduce flooding, increase groundwater recharge, improve water quality and restore habitat. Project Goal. To complete a medium-resolution (1:72,000) historical hydrology map documenting historical freshwater channels and wetlands recorded for the Sonoma Valley watershed at the time of European-style settlement in the mid-19th century. Approach. An initial literature review was followed by a review and assessment of previous efforts in Sonoma Valley, particularly the Sediment Source Analysis (Lawton 2006) and the uncompleted Critical Coastal Areas (CCA) project begun in 2007. Geomorphologist Laurel Collins of Watershed Sciences and botanist and wetland expert Phillip Northen also provided additional guidance and feedback at various stages of the project. Drawing from, refining, and expanding on these earlier studies, the current project compiled, analyzed, integrated, and mapped data from a wide variety of sources into a computerized Geographic Information System (GIS). Sources included historical maps, documents, and photos; soil and heritage oak surveys; and oral histories from local elders. Historical channels and wetlands were mapped. The majority of sources that were consulted included data up to the 19th century, while a few also included information from the early 20th century (see Appendix A for examples). After verifying the historical presence of a feature, more recent sources were used to refine its attributes. In particular, Sonoma County’s LIDAR data was invaluable for identifying and mapping historical channel alignments to a high degree of precision. The Sonoma County Soil Survey (1972) was used to support the identification of seasonal wetlands from early aerial photos. Once the draft map was completed, field surveys were undertaken to “ground-truth” sites where historical conditions were in question and to test preliminary conclusions. In some cases, field evidence supported the mapping of features that appeared ambiguous in the historical record. In other cases, where field evidence was lacking,

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BASELINE CONSULTING, SONOMA ECOLOGY CENTER, REBECCA LAWTON CONSULTING 4 features or attributes were removed from the draft map. A rubric for assigning “certainty levels” was refined from versions used in other studies (Dawson 2010, 2013; Grossinger 2001, 2012). This rubric was based on the strength of evidence for each mapped feature’s historical presence, dimensions, and location. Certainty levels of high, medium, and low were assigned under each of these categories to all mapped features. The final maps (pages 18 - 21) are based on dozens of historical sources, informed by similar studies in Sonoma County and elsewhere in the Bay Area, years of fieldwork and local observations, and the expertise of many scientists, residents, and local elders. More than 300 channel segments and wetland features were mapped. The resulting maps are key tools in understanding how the Sonoma Valley watershed functioned before significant human modification. Next Steps. Phase I of this project, which is covered in this report, provides a medium- resolution hydrological picture of the Sonoma Valley watershed in the mid-19th century. Phase II, the second and final part of this effort, will use the information developed in Phase I to identify sites that show promise for restoring hydrological function. SONOMA VALLEY These sites will be mapped at a high WATERSHED level of detail (1:18,000 or better) to support modeling, change analysis, and multi-benefit project planning designed to reduce flooding, increase groundwater retention and recharge, improve water quality, and restore habitat. This report is intended to assist the Sonoma County Water Agency, the North Coast Water Quality Control Board, Valley of the Moon Water District, the City of Sonoma, the Sonoma Ecology Center, the Sonoma Resource Conservation District, private landowners, and other stakeholders concerned with improving the ecological health of Sonoma Valley. FIGURE 1. Project Area. Sonoma Valley Watershed, Sonoma County, California

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METHODS

The Sonoma Valley Historical Hydrology Mapping Project was carried out by Arthur Dawson of Baseline Consulting, Alex Young of the Sonoma Ecology Center, and Rebecca Lawton of Rebecca Lawton Consulting. The following sequence of methods and steps was used in developing the estimated pre-settlement freshwater channels and wetlands map of the Sonoma Valley watershed. Initial Planning and Review. Project staff held an initial meeting to refine our approach and address the following questions. What is our working definition of a “mappable channel?” How can the recently acquired LIDAR data be incorporated into this effort? Do certainty level standards need to be adjusted, refined, and/or clarified? How should distributary systems be evaluated and mapped? What is our working definition of a “mappable wetland feature”? What criteria should be used for delineating various habitat types? Is our approach compatible with that used for mapping historical aquatic resources in the EcoAtlas? What should be included in the literature review? What are our definitions and assumptions (Figure 2)? The literature review (see Bibliography) preceded a review of previous efforts to map and understand historical conditions in Sonoma Valley, particularly the 2010 draft map from the CCA project. All features from the CCA map were reviewed. After identifying needed changes, it was decided that the most efficient way to proceed was to draw and attribute all features for the current project from scratch. Technical Guidance. Before commencing the initial mapping, the project team conferred with experts Laurel Collins, geomorphologist with Watershed Sciences; and Phillip Northen, wetland delineation expert and professor emeritus at Sonoma State University. Robin Grossinger of the San Francisco Estuary Institute (SFEI) was contacted but was unable to provide direct feedback on this project. Project staff are familiar with SFEI’s approach, having worked with them on the CCA mapping effort and reviewed their work in other Bay Area watersheds (see Bibliography). Source Compilation and Georectification. With one exception, all mapping sources (see Bibliography) for this project had already been compiled and were ready to bring into GIS for mapping. The exception was a map of the upper watershed recently discovered in the private collection of Kenwood resident George MacLeod (Rowe 1871). This map was an

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Figure 2. Definition of Terms and Assumptions

Channel: a watercourse with little or no vegetation in its bed; water flows directly over soil, rocks, and woody debris. Natural channels were assumed to have been mapped as sinuous lines on historical maps. Modified channels show little or no sinuousity, often cut “across the grain” of local topography and/or are extensions of previously mapped natural channels.

Some channels mapped in this project may have been vegetated swales, which are generally smaller, more subtle features than channels. However, no evidence that swales were mapped as channels was found in the record. Swales are visible in early aerial photos, which were not used as primary sources for mapping channels.

Wetlands: the U.S. Army Corps of Engineers defines wetlands as places where soil, vegetation, and hydrology are all of wetland type. If any of these three indicators does not meet this criteria, then the location is not considered wetland (1987).

It is rare that all three criteria can be met using historical evidence. For this study, where two sources suggested the historical presence of wetland (e.g., wetland soil type + darker, wetter areas in early aerial photos; apparent marsh vegetation on early maps + wetland soil type), the feature was mapped as wetland. important find for two reasons: it shows some of the earliest mapped evidence of hydromodification, and it verifies the historical presence of two distributary channels on the Sonoma Creek fan, identified in 2008 from aerial photos and field work (Sonoma Ecology Center 2009). Using the georectification tool in GIS, all maps were aligned using persistent natural or human features in the landscape (e.g., prominent creek confluences or bends, hilltops, and the site of the original ranch house at the mouth of Adobe Canyon, which is still shown on topo maps) Other sources, such as observations by Jose Altimira in 1823 and information from oral histories, were also used to identify specific locations. The accuracy of the primary and secondary sources was reflected in the certainty levels for location and size assigned to each feature. Developing a Mapping Strategy. In defining what constituted a “mappable feature” for this project, it was decided to refine the evidence-based approach used in past efforts. With the exception of early U.S. Geological Survey (USGS) quadrangles, no maps used in this project had legends or specific metadata. Thus it was necessary to make some assumptions about what was mapped in the historical record. It is unknown exactly what criteria were used by early mapmakers. Accuracy varies widely from source to source but generally improves between the mid-19th and early 20th

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BASELINE CONSULTING, SONOMA ECOLOGY CENTER, REBECCA LAWTON CONSULTING 7 centuries. To account for possible errors in interpretation, it was decided to include only features whose historical presence could be verified by at least two sources, at least one of which dated to 1942 or earlier.

A significant difference in our mapping approach from the CCA effort is that we did not use 1942 aerial photos as a primary source for mapping channels. Identifying natural historical channels from these photos is problematical. In many cases, ditches or channels dug by humans in the century prior to 1942 were already lined with trees, thus making it hard to differentiate natural from artificial channels in these photos. Maps, and to some extent written sources and oral histories, are interpretations of the landscape made by people who were familiar with and had access to the landscape during the historical period. Stream channels drawn on different maps, even decades apart, were assumed to have certain qualities in common. Conversely, interpreting stream channels from aerial photos more than 70 years old, without direct knowledge of a landscape, requires making larger assumptions and thus is prone to error. However, the 1942 photos were used as secondary sources where another primary source existed.

The 1942 aerial photos were used as a primary source for mapping seasonal wetlands however, because earlier data is not readily available for much of the area covered by this habitat type. Darker areas on the 1942 photos, where agriculture and other land use was absent, were assumed to be wetland. This interpretation is supported by soil types mapped by Holmes (1917) and Miller (1972) and follows the approach of other studies (Dawson 2010, Grossinger 2012). The Natural Resource Conservation Service lists these soils as containing anywhere from 1% to 85% wetland (2014).

Evidence Timeline. The following framework was developed to highlight the existing historical record for Sonoma Valley and significant turning points with respect to hydrological features. Not all historical sources are included. 1823: Earliest record of hydro-modification—within weeks of the establishment of the Sonoma Mission, a ditch was dug to conduct water from a nearby spring. The written record from this year was used as a primary source for a few features (Altimira). 1837: Earliest known map of a portion of Sonoma Valley, Los Guilucos Rancho in the Kenwood area. Map shows mountain ridges, creeks, marsh, and water holes (Anonymous). 1842: Hydro-modification already described as extensive in some areas (Simpson). 1867: Mapped evidence of hydro-modification still mostly lacking (Bowers). Before 1870: Smallest subwatersheds with mapped channels cover about 160 acres (65 hectares. All pre-1870 map sources)

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1871: Earliest mapped evidence of hydro-modification: interpreted from: (1) the appearance of channels not previously mapped; (2) straightness or lack of sinuosity normally expressed by unmodified, natural channels; and (3) apparent mismatch with topography, e.g., traversing a slope as seen in the Kenwood area (Rowe). 1875: Clear evidence of hydro-modification in the City of Sonoma (vonGeldern). 1877: Clear evidence of widespread hydro-modification (Thompson). 1902 & 1916: Some previously unmapped channels do not appear to be hydro-modified (USGS). 1914: First soil reconnaissance survey identifies “hog wallows” or seasonal wetlands in the lower Sonoma Valley. Fieldwork conducted in 1914; published in 1917. (Holmes). 1942: Some newly mapped channels do not appear to be hydromodified (USGS). Accepted as primary source if field verified as a “natural-appearing channel with little apparent modification” and draining a subwatershed of 160 acres or more. (Aerial photos taken in 1942 are difficult to interpret, due to hydromodification and tree growth, which both hides channels and occurs along ditches and other modified water courses. Thus photos were not used as primary sources for mapping channels. Where supported by earlier data, these photos were valuable as secondary, confirming sources. In the case of seasonal wetlands, photos were used as primary sources if supported by a soil type where wetlands are known to exist.) 1950s – 1980s: In a few cases, USGS quads from this period were used as secondary sources. 1972: Sonoma County Soil Survey from this year was used as a secondary source for mapping wetlands in conjunction with NRCS Wetland Soils data (Miller 1972 and NRCS 2014). 2010: NAIP color imagery occasionally used as a supporting source to verify historical conditions. 2013: County LIDAR imagery used to support historical sources by delineating abandoned channels and low marshy areas and to provide more precise mapping of channel sinuosity (Sonoma County).

Mappable Features. Given the nature of the historical record for Sonoma Valley, the following criteria were established for mappable features. Channels and Perennial Wetlands. Verified by a minimum of two sources, with at least one no later than 1942 (99% of primary sources predate 1920). To keep a consistent level of detail, channels appearing after 1870 must be associated with subwatersheds of 160 acres or more, the size of the smallest subwatersheds with channels recorded before that date.

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(Aerial photos from 1942 were not accepted as primary source—see above, Evidence Timeline.) Seasonal Wetlands. Verified by a minimum of two sources, at least one of which is no later than 1942. This cutoff date, which is later than for channels and perennial wetlands, takes into account the fact that Sonoma Valley’s seasonal wetlands were rarely recorded in earlier sources.

Identification of Habitat Types. Translating habitat types from historical evidence into modern terms requires a balance between precision and accuracy. After conducting a follow-up literature review for information on habitat types, wetland definitions, and mapping distributary systems on alluvial fans, it was decided to use a few broadly defined habitat types. While combining similar habitats appears less precise, such an approach acknowledges and incorporates the uncertainties inherent in the historical record and is thus less likely to be in error. In particular, the Wet Meadow, Vernal Pools, Vernal Pool Complexes, and Wet Meadow with Vernal Pool Complexes categories used in the 2010 CCA effort were combined into a single Seasonal Wetland designation. The final wetland designations used in this project, open water, perennial marsh, seasonal wetland and broad riparian forest, are shown in Figure 3 along with their expected characteristics, sources and analogous designations from other studies. A fifth designation, Willow Shrubland or Thicket, was considered. Willows along the edges of open water are mentioned in Altimira’s 1823 journal, in an early description of the Kenwood Marsh (Boggs 1861), and may be depicted in the vicinity of El Verano on O’Farrell’s 1848 map of Rancho Petaluma. While definitely present, we decided there was not enough data to confidently map Willow Shrubland or Thicket as a wetland habitat type. It likely existed on the edges of open water and as a component of perennial marsh and seasonal wetlands. Willows are mentioned in the Napa Valley Historical Ecology Atlas, but were not mapped as a separate habitat type (Grossinger 2012).

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Figure 3. Wetland Designations Used in this Study, Expected Characteristics, Sources of Evidence, and Analogues in Other Studies and Systems Wetland Nearest analogues Designation Characteristics Evidence as defined in other studies* & Hydrology & Vegetation Historical = >50 years & California Wildlife-Habitat Relationship System (CWHR) synonymous Recent = < 50 years *all in Sonoma or Napa Counties terms

 Altimira descriptions  “Laguna lakes” (Waaland 1989) Perennial water body. Open Water  Labeled “Laguna,” (lake) or “Poso,” (water hole)  “Open Water” (CH2M Hill 1990) Submergent plants, e.g. duck-  Mapped as dark areas within larger marshy zones  “Perennial Freshwater Pond” weed, marsh penny-wort, Lake  Oral histories (2010 CCA Draft; Grossinger 2012) pondweed, widgeon grass  Field evidence  Water (CWHR) Pond

Inundated for most or all of  Altimira & other early descriptions  “Freshwater Marsh” (Helley 1979) the year; saturated all year  Depicted as covered with different vegetation in early maps  “Marsh: perennial” (Waaland 1989) Perennial Emergent plants such as tules,  Oral histories  “Perennial Marsh” (CH2M Hill 1990) Marsh cattail, bulrush, sedges,  Field evidence  “Valley Freshwater Marsh” (2010 CCA Draft; Grossinger 2012) willows  Soil survey  “Freshwater Emergent Wetland“ (CWHR)  “Vernal pools” (Barbour 2007) Seasonal  “Seasonal wetland” (CH2M Hill 1990) Seasonally inundated, surface  “Seasonal marsh” (Waaland 1989) Wetland dry for at least several months  Darker areas in 1942 aerial photos  “Freshwater Emergent Wetland“ (CWHR) each year  Recorded as “hog wallows” or “wet-land soils” in early soil Desiccated during dry season. “Wet Meadow” Vernal pool reconnaissance survey (Holmes 1917) California Oat grass, Meadow- (CCA Draft 2010; Grossinger 2012)  Oral histories foam, goldfields, Sonoma “Vernal Pools” Swale  Field evidence sunshine and other annual (CCA Draft 2010)

forbs and grasses. Willows  Soil survey Moist Grassland “Vernal Pool Complexes” possible in some areas. (CCA Draft 2010; Grossinger 2012) “Wet Meadow with Vernal Pool Complexes” (CCA Draft 2010)

Broad Sonoma Creek and tributaries.  Early maps  “Broad Riparian Forest” (Grossinger 2012) Alder, ash, willow, maple, oak,  Heritage oak survey Riparian  Riverine (CWHR) wild grape, redwood (upper  Soil survey Forest watershed)  Field evidence

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Initial Mapping. Initial mapping was approached as described below. Channels. All channels that appear in the historical record before 1870 were mapped. Channels that appear in the record between 1870 and 1920 were evaluated for inclusion. Where these emanated from subwatersheds of 160 acres or more, they were included in the map (160 acres represents the minimum size for channels mapped before 1870, so this threshold avoids adding a higher level of detail than was captured in the earlier data). The focus of this study was to map the pre-settlement planform of channels flowing over the alluvium on the floor of Sonoma Valley. This is because this pattern has been significantly altered by human activity over the last two centuries while channels in the uplands have not. We began by defining the edge of the valley floor as the place where the slope break increased beyond 5 degrees and mapped this area as a polygon (figure 7). Alluvial areas in Collin’s “Geomorphological Units of Sonoma Creek Watershed” map (2010) were clipped to this polygon. Collin’s “Quaternary Tributary Alluvium,” was further trimmed so that it did not extend above adjacent “Alluvial fan” units (tributary alluvium above this point is narrow and constrained in the lowest parts of some canyons). A few additional alluvial areas delineated by the U.S. Geological Survey in 1980 were also included to ensure complete coverage of valley floor alluvium. Channels were mapped to the uppermost point of either: (1) their highest upstream point on valley floor alluvium or, (2) the highest point to which the channel was historically mapped. Channels were mapped to their earliest documented condition. For example, Carriger Creek was mapped as it appears in O’Farrell’s 1848 map, as a disconnected tributary, not as it appears in Bowers’ 1867 map, where it is a connected tributary. Two channels mapped by the USGS in 1942, which met the 160-acre rule and appeared to be natural features during the field surveys, were included as historical features. Mapping began at the upper reaches of the Sonoma Valley watershed and worked downstream. Channels from the 2010 CCA draft were evaluated for evidence of their presence before 1943, as outlined above. Historical maps were simultaneously evaluated according to the same criteria to capture any channels not included in the 2010 draft. Where evidence confirmed the presence of a historical channel, its alignment was drawn from the earliest sources, refined using aerial photos from 1942, and finalized (at an onscreen scale of 1:3000 or better) using the recent LIDAR data developed by Sonoma County. Channel alignments in the 1942 photos were often obscured by trees and usually could not be mapped to fully reflect their sinuosity. Channel sinuosity is readily visible in the LIDAR images and can be accurately mapped from these images. While the precise channel configuration may have shifted over time, LIDAR is the only data set that does not oversimplify this channel characteristic. (LIDAR data was not available in 2010; all channels were drawn “fresh” for this project, rather than by editing vectors from previous work.) Finally, the smoothing tool in GIS

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BASELINE CONSULTING, SONOMA ECOLOGY CENTER, REBECCA LAWTON CONSULTING 12 was used to adjust channel alignments to more closely depict sinuosity seen in the LIDAR images than was possible to achieve by hand. Source attributions were recorded for each feature, with the oldest source as primary and the certainty levels determined. Where the primary source showed a channel ending without connecting to a larger channel, it was mapped as unconnected. Secondary sources were used to determine the location of the lower ends of discontinuous channels as precisely as possible: evidence included points where the channel appears artificially straightened or ditched and the location of heritage oaks in or near the channel. Uncertainties about a channel’s extent are reflected in the confidence rating it received. Unless shown in pre-1920 sources, distributary channels were not drawn. Mapping “distributary zones” was tried but proved to be difficult because these features are controlled by small variations in topography. Laurel Collins’ Geomorphic Units map (Collins 2010) was used to indicate where alluvial fans are located and thus where distributaries likely existed (see Figure 7). Wetlands. The mapping of estimated pre-settlement freshwater wetlands followed the same sequence that was used for channels, beginning in the upper watershed. Mapping perennial wetlands (ponds and marshes) was relatively straightforward because these were mapped and described in the historical record. Seasonal wetlands were occasionally described but only mapped once over a limited area before 1942 (Holmes 1917). Following the two source rule required for mappable historical features, a combination of 1942 aerial photos and the 1972 Soil Survey (Miller) were used for mapping many seasonal wetlands. Darker areas in the 1942 photos that lacked both trees and obvious marks of agriculture were mapped as seasonal wetland where they appeared on soil types identified as at least 1% wetland by the National Resource Conservation Service (NRCS). This approach is the same that was taken by Grossinger (2012) in Napa Valley. A few additional soil types, not identified by NRCS but showing clear signs of swales in 1942 as well as places where seasonal wetlands have been observed in the last 25 years, were also included. Field Surveys. During the initial mapping, locations were identified where uncertainty or ambiguity existed in our interpretation of the historical record. The uncertainties were largely concerned with channel alignments and connections, historical hydromodification, and the downstream end points of previously disconnected channels (e.g. Carriger Creek, Rodgers Creek). Laurel Collins reviewed the initial map and advised on the field survey. Two field days were spent ground truthing, i.e., refining the initial mapping from historical sources using evidence seen in the field. At each site visited, field notes, GPS points, and photos were gathered (see Appendix B). Field evidence included the distribution of cobbles on the surface of the Carriger fan (the presence of larger cobbles indicated higher capacity stream flows than at present and thus pointed to past locations of major distributaries); microtopography pointed to evidence of old channels; ditching or other evidence of

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BASELINE CONSULTING, SONOMA ECOLOGY CENTER, REBECCA LAWTON CONSULTING 13 hydromodification gave clues to former stream geometries; fluvial deposits indicated the configuration of historical confluences (e.g., Agua Caliente and Sonoma Creek); and large riparian trees, especially bays and oaks, provided evidence for historical riparian forest.

Certainty Level Standards. Standards were established and refined in an iterative process from the initial planning stages through the final mapping. The intent of establishing standards was to create an objective framework for rating each feature: e.g., two researchers working independently should come to the same conclusions and ratings (Figures 4 and 10). Final Changes. The draft map was altered to incorporate information gathered during the field surveys.

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Figure 4. Certainty Level Standards for the Sonoma Valley Historical Hydrology Mapping Project PRESENCE SIZE LOCATION HIGH  Appears in historical record before 1870  Attributes supported by at least one source before  Historical and modern  Supported by secondary source(s) before 1942 1870. sources (aerial photos, 3 Source  Supported by one or more of the following: aerial photo, modern  Attributes supported by secondary source no later topo, LIDAR, or field minimum topo, LIDAR, or field observation. than 1942 observation) align with Attributes supported at least one of the following: an estimated maximum Record before NOTE: If feature is ambiguous, downgrade to “Medium” aerial photo, modern topo, LIDAR, or field error of 100 feet. Wetlands Only: 1870 observationEstimated to be within 90 – 110% of historical dimensions. error estimated for center of feature MEDIUM  Appears in historical record before 1870  Attributes supported by one historical source  Historical and modern  Not supported by secondary sources before 1942 between 1870 & 1942 sources (aerial photos, 2 Source  Supported by one or more of the following: aerial photo, modern  Attributes supported at least one of the following: topo, LIDAR, or field minimum topo, LIDAR, or field observation. aerial photo, modern topo, LIDAR, or field observation) align with OR observation. an estimated maximum  Appears in historical record between 1870 and 1920 error of 500 feet.  Supported by one or more of the following: aerial photo, modern Estimated to be within 50 – 200% topo, LIDAR, or field observation. of historical dimensions. Wetlands Only: OR error estimated  mapped as a channel in 1942 by USGS for center of feature  Field verified as a natural-appearing channel

NOTE: Minimum watershed size of 160 acres must be met for all features mapped from sources after 1870. If ambiguous, downgrade to “Low” LOW  Feature appears to have been altered before the earlier record (e.g.  Attributes in the historical record ambiguous.  Historical and modern channels within the City of Sonoma in 1875) or the record is Mapped attributes based primarily on aerial photo, sources (aerial photos, 2 source ambiguous. modern topo, LIDAR or field observation. topo, LIDAR, or field minimum;  Supported by one or more of the following: aerial photo, modern observation) align with Estimated to be within 25 – 400% an estimated maximum topo, LIDAR, or field observation. of historical dimensions. error of 1000 feet. some NOTE: Minimum watershed size of 160 acres must be met for all features ambiguity or mapped from sources after 1870. Wetlands Only: feature error estimated modified Seasonal wetlands only: for center of feature Presence supported by two sources, at least one no later than 1942. Aerial photos from 1942 accepted as primary source with soil type as secondary.

BASELINE CONSULTING, SONOMA ECOLOGY CENTER, REBECCA LAWTON CONSULTING 15 Figure 5. Data Limitations and Temporal Context

Our goal in developing an historical channel and wetlands map for the Sonoma Valley Watershed was to show conditions prior to modification by Mexican and American settlers in the mid-19th century. To produce such a map, it was necessary to use documents created during the process of settlement. While most of the maps and other documents used as primary sources span about two decades in the mid-19th century, primary sources created well into the 20th century were also used for some features. Thus an inherent paradox is present— the oldest documents are the most trustworthy in reflecting pre-settlement conditions while also being the least precise in terms of mapping resolution and detail. Moving forward in time, the documents become more precise but are also recording a landscape that was changing from the pre-settlement conditions we were attempting to map. Land Use: Beginning in 1823, the introduction of livestock began to cause changes in drainage and channel patterns. In the very earliest map of the Kenwood area, made in 1837, Sonoma Creek is shown flowing from a “Laguna” (lake or marsh) on the valley floor in the vicinity of Lawndale Road. No channel is depicted exiting Adobe Canyon and flowing across an alluvial fan as it does today. The next map of the area, drawn fourteen years later in 1851, does show such a channel. Land court testimony recounts how the land was being overgrazed during those intervening years, having “more cattle than the ranch would hold” (Leese 1861). It’s unknown whether the 1837 map didn’t show a channel because it didn’t exist or because there was no water in it. If the channel did form at that time, it was probably due to the impacts of grazing (due to the uncertainties interpreting the earlier map, we mapped Sonoma Creek from the 1851 map for this project). Grazing may have also impacted Felder Creek before the earliest records were made. Part of its lower watershed was called “The Sheep Ranch” prior to the American takeover of California in 1846; it must supported some or all of the 3000 sheep on Vallejo’s Rancho Petaluma (Vallejo 1853). It is the only tributary in that part of the watershed shown with a direct connection to Sonoma Creek when the first map was drawn in 1848. Given the speculative nature of this possibility Felder was mapped from the 1848 map. Climate: variations in rainfall may have affected what features were mapped. In wetter years there would have been more water in the channels and wetlands, and perhaps more wetted channels. Dry years would have had the opposite effect. A comparison of the dates of this study’s primary sources against tree-ring derived rainfall data from the Russian River (Figure 6) indicates that a majority of these sources were created in years of above average rainfall. Two- thirds of the sources used date to the period between 1848 and 1877, years when rainfall was above the long-term average 72% of time. Large storms can cause creeks to move around on their alluvial fans, switching from one distributary channel to another. At least four streams moved enough during the historical period to clearly show up in the record. Three of these were between 1848 and 1867, one in the late 19th or early 20th century (see “Results” section for more on this).

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BASELINE CONSULTING, SONOMA ECOLOGY CENTER, REBECCA LAWTON CONSULTING 16

FIGURE 6. Dates of Sources Used in this Study in Relation to Long-Term Rainfall reconstructed from tree ring data

for the Russian River (Griffin 2008. This is the closest available source for historical precipitation data).

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BASELINE CONSULTING, SONOMA ECOLOGY CENTER, REBECCA LAWTON CONSULTING 17 RESULTS

Maps developed from historical research and field surveys conducted during the project are presented in the figures on the following pages. (Additional observations based on these maps and a preliminary analysis comparing historical and modern hydrologic functioning of the Sonoma Valley Watershed are covered in the “Discussion” section beginning on page 23.)  FIGURE 7. Estimated Pre-Settlement Freshwater Channels and Wetlands, Sonoma Valley Floor Alluvial Areas (Historical Data Only). Note the large number of disconnected channels, extensive perennial marsh in the upper watershed, extensive seasonal wetlands in the middle and lower valley, and the dynamic movement of several stream channels on their alluvial fans (e.g. Sonoma Creek, Rodgers Creek and others). Distributary systems, while generally not historically mapped, were watered by mapped channels and assumed to have existed below these channels.

 FIGURE 8. Estimated Pre-Settlement Freshwater Channels and Wetlands, Sonoma Valley Floor Alluvial Areas( LIDAR Basemap). See comments for Figure 7.

 FIGURE 9. Estimated Pre-Settlement Freshwater Channels and Wetlands, Sonoma Valley Floor Alluvial Areas (U.S. Geological Survey 7.5’ quad basemaps), See comments for Figure 7 above. Straightening of confluences, while difficult to see at this scale, can easily be detected at the original scale of the 1:24,000 background map (see Appendix A).

 FIGURE 10. Certainty Levels for Presence of Features Mapped from Historical Sources. This map illustrates the certainty level for the presence of each historical feature based on the available evidence. Note the higher certainty for the seasonal wetlands in the lower valley to the west of Sonoma Creek than for those on the east side. This is due to a soil reconnaissance made in 1914 which recorded “hog wallows” west of the creek (Holmes 1917), which is an earlier record than those on the east side, which were identified from darker areas in aerial photos taken in 1942 (U.S. Department of War).

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FIGURE 7. Estimated Pre-Settlement Freshwater Channels # * ?

# and Wetlands, Sonoma Valley Floor Alluvial Areas

* # #? Primary sources: 1823 - 1942. Median source date: 1860

* # Subwatersheds > 160 acres (65 hectares)

#? Sonoma Creek

* # ?

* # # Legend

#?

* #

#? * #

#? Channels

Kenwood Mainstem & Tributary Channels (earliest record) Marsh

Alternate Channels # ? # * Distributary System (no channel mapped below)

Wetlands (habitat types & equivalent terms)

Perennial Marsh (some open water possible) Calabazas Creek Open Water (perennial lake or pond)

SONOMA CREEK Seasonal Wetland (vernal pools, swales, moist grassland) Stuart Creek Broad Riparian Forest

Valley Floor Alluvial Areas (all wetlands and channels are on valley floor alluvium)

Alluvial Fan

* #

#? Other Quaternary & Pleistocene Alluvium

Other Features Sonoma Valley Floor: slope < 5 degrees (alluvial areas above also included) Salt Marsh (outside study area: not freshwater)

Sonoma Valley Watershed Boundary

* #

? * # #? #

* #

? # *

#? #

* # Agua Caliente Creek

? #

# * ?

# Nathanson Creek

* # Carriger Creek ?

# # * ? #

# * ?

#

SONOMA CREEK

# * ?

#

Arroyo Seco Rodgers Creek

* #

#?

* #

#?

#

? * #

*

#

# ? * ? #

´ # # # ?

*

0 0.4750.95 1.9 2.85 3.8 Miles # * ?

# #

? * #

SCALE 1:72,000 1" = 6000' Cartography by Arthur Dawson, Baseline Consulting Valley Floor outline derived from Sonoma County LIDAR data by Alex Young, Sonoma Ecology Center Primary alluvial areas mapped by Laurel Collins, Watershed Sciences Minor alluvial areas added from U.S. Geological Survey, Sonoma County Geology 19

FIGURE 8. Estimated Pre-Settlement Freshwater Channels # *

? # and Wetlands, Sonoma Valley Floor Alluvial Areas

* # #? LIDAR Basemap

* #

#? Primary sources: 1823 - 1942. Median source date: 1860 Sonoma Creek Subwatersheds > 160 acres (65 hectares)

* # ?

* # #

? #

*

# ?

# * # #? Legend

Kenwood Marsh Channels Mainstem & Tributary Channels (earliest record)

Alternate Channels # ? #

* Distributary System (no channel mapped below)

Wetlands (habitat types & equivalent terms) Calabazas Creek Perennial Marsh (some open water possible)

SONOMA CREEK Open Water (perennial lake or pond) Stuart Creek Seasonal Wetland (vernal pools, swales, moist grassland)

Broad Riparian Forest

* #

#?

* #

? *

? # ##

* #

? # *

#? #

* # Agua Caliente Creek

? #

# * ?

# Nathanson Creek

* # ?

Carriger Creek # * # ? #

# * ?

#

SONOMA CREEK

# * ?

#

Arroyo Seco Rodgers Creek

* #

#?

* #

? #

#

? * #

*

#

# ?

* ? # # # # ? *

# * ?

# # ? ´ * # 00.5 1 2 3 4 Miles TIDAL SALT MARSH SCALE 1:72,000 1" = 6000' Cartography by Arthur Dawson, Baseline Consulting Basemap: Sonoma County LIDAR data 20

FIGURE 9. Estimated Pre-Settlement Freshwater Channels # *

? #

*

# and Wetlands, Sonoma Valley Floor Alluvial Areas #? U.S. Geological Survey 7.5' quad Basemaps

* #

#? Sonoma Creek Primary sources: 1823 - 1942. Median source date: 1860 Subwatersheds > 160 acres (65 hectares)

* # ?

* # #

#?

* #

#? * # #? Legend

Kenwood Marsh Channels Mainstem & Tributary Channels (earliest record)

Alternate Channels # ? #

* Distributary System (no channel mapped below)

Wetlands (habitat types & equivalent terms) Calabazas Creek Perennial Marsh (some open water possible)

SONOMA CREEK Open Water (perennial lake or pond) Stuart Creek Seasonal Wetland (vernal pools, swales, moist grassland)

Broad Riparian Forest

* #

#?

* #

* ? # #? #

* #

? # *

#? #

* # Agua Caliente Creek

? #

# * ? # Nathanson Creek

* # ?

Carriger Creek # # * ? #

# * ?

#

SONOMA CREEK

# * ?

#

Arroyo Seco Rodgers Creek

* #

#?

* #

? #

#

? * #

*

#

# ?

* ? # # # # ?

*

´ # * ?

# # ?

00.5 1 2 3 4 Miles * #

SCALE 1:72,000 TIDAL SALT MARSH 1" = 6000' Cartography by Arthur Dawson, Baseline Consulting U.S. Geological Survey 7.5' quadrangle basemaps: Glen Ellen, Kenwood,Petaluma River, Sears Point, Sonoma & Rutherford 21

FIGURE 10. Certainty Levels* for Presence of Features Mapped from Historical Sources

LEGEND

Sonoma Creek CERTAINTY LEVELS

CHANNELS

HIGH

Kenwood MEDIUM Marsh LOW

WETLANDS

HIGH

Calabazas Creek MEDIUM

SONOMA CREEK LOW Stuart Creek *Levels based on the strength of evidence for a feature's historical presence using the following criteria (Simplified version; detailed criteria in report):

HIGH: supported by minimum of two sources; at least one before 1870, the other before 1942

MEDIUM: supported by minimum of two sources: one before 1870, one 1942 or later OR one before and one after 1920

LOW: supported by minimum of two sources; earliest record is before 1920 but is ambiguous in the record OR seems to show modification. Seasonal wetlands only: earliest source no later than 1942.

Agua Caliente Creek

Nathanson Creek Carriger Creek

SONOMA CREEK

Arroyo Seco

Rodgers Creek ´ 00.5 1 2 3 4 Miles

SCALE 1:72,000 1" = 6000'

Cartography by Arthur Dawson, Baseline Consulting BASELINE CONSULTING, SONOMA ECOLOGY CENTER, REBECCA LAWTON CONSULTING 22

DISCUSSION While the scope of this project did not include an analysis of the hydrological function of the Sonoma Valley watershed in the mid-19th century or the changes brought about since, some initial observations can be made (however, one of our reviewers generously put together a preliminary comparison of historical vs. modern hydrologic conditions beginning on page 24): Disconnected Tributary Channels were common. More than 20 channels were historically mapped as lacking direct channel connections with Sonoma Creek. These channels range from drainages at the lower limit of our mapping resolution (160 acres) up to some of the largest tributaries, such as Carriger Creek (Figure A1) Most of these were connected to Sonoma Creek by the late 19th century. A few disconnected channels may still exist in the lower watershed, west of Highway 121, as suggested by late 20th-century topo maps (USGS 1968 & 1980). Channels on Alluvial Fans were dynamic. Sonoma, Rodgers, Pythian, and an unnamed creek in the Kenwood area were all historically mapped with channels in locations and configurations that changed over time, suggesting that their main channels were shifting over their alluvial fans (figure A4) This dynamic channel movement was recorded for Sonoma and Pythian Creeks on maps made between 1848 and 1859, and for Rodgers Creek between 1848 and 1867 (O’Farrell 1848; Tracy 1859; Bowers 1867). Such shifts have been documented recently (Dawson 1989 – 2016) both in Sonoma Valley and in the Laguna de Santa Rosa watershed (Dawson 2009), during extreme flood events, suggesting that one or more such events probably occurred between 1848 and 1867, when the maps were made. The most likely months are December 1852, when 13.2 inches of rain fell, and January 1862, which saw a record 24.36 inches. (Golden Gate Weather Service 2016). Further research could clarify the effect that storms in these months had in Sonoma Valley. Confluences were commonly at shallow angles. Unmodified tributaries tended to join Sonoma Creek at oblique angles, in some cases nearly paralleling the mainstem for a significant distance. Two examples of modified confluences are Yulupa Creek and Agua Caliente Creek, both of which now meet Sonoma Creek at nearly perpendicular angles, hundreds of yards above their historical locations (Figures A2 and A3). Because tributary channels were longer than they are today, (other factors remaining equal) it would have taken longer for tributary stormwaters to travel the distance to the main stem. This suggests a less “flashy” main stem hydrograph and a decrease in downstream flooding (because the same volume of water arrives over a longer period of time). Longer tributaries would also have had gentler channels (same drop in elevation over a longer distance). Increasing the slope of the tributary channel causes faster flow and thus greater erosive force and increased downcutting (Manning’s Equation).

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As the ability of a stream to carry sediment is proportional to the speed of its flow, slower tributary flow under oblique confluence conditions would have resulted in more sediment deposition above the confluence and thus less sediment would have reached the main stem of Sonoma Creek. Perennial Wetlands covered about 1% of the valley floor. Nearly 400 acres of perennial freshwater wetland were mapped. Most of these wetlands were in the upper watershed and associated with the Kenwood Marsh. Most of these have been drained or turned into reservoirs, which still provide some habitat but probably support far less biodiversity than in the past. Seasonal Wetlands covered 20% or more of the valley floor. While difficult to map precisely, the evidence for seasonal wetlands strongly suggests that these covered a significant portion of the valley floor. Observations from Altimira (1823), soil scientists (Holmes 1917, Miller 1972, NRCS 2014), oral histories, and other sources support this conclusion. This project mapped about 7,600 acres of seasonal wetland, or about 12 square miles of this habitat type. Most of the seasonal wetland was in the middle and lower part of the valley, from El Verano and the Springs south. Some seasonal wetland also existed in the Glen Ellen and Kenwood areas. Intricate Vegetation Mosaic. Historical and field evidence point to very site-specific influences on vegetation at scales finer than those covered by soil maps. Previous studies have found heritage valley oaks (> 42” diam.; estimated age > 170 years), which usually avoid wetter places, growing within or immediately adjacent to existing or historical wetlands. Very subtle variations in topography may account for this condition—these trees are commonly found growing just a few feet higher than the main wetland areas (Dawson 2006, 2013; Sonoma Ecology Center 2006). Another example of this situation was tentatively identified during field work for this study (see photo at top of page B-4 in the appendix). Increasing Connectivity Since the Mid-19th Century. The evidence for increasing connectivity of drainages post mid-19th century is easily discernable in the sequence of historical to modern maps cited in this report.

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Comparison of Sonoma Creek Watershed’s Historical and Modern Hydrologic and Geomorphic Conditions (This section, which goes beyond the project’s contract, was generously provided by Jason Q. White, Fluvial Geomorphologist/Restoration Designer at Environmental Science Associates.)

The purpose of this section is to provide conceptual model of how the Sonoma Creek watershed functioned under historical conditions from a hydrologic and geomorphic perspective, and how that compares to modern conditions. This section is based largely on concepts developed by the San Francisco Estuary Institute for the Napa River (SFEI, 2012), which had a very similar historical conditions and has undergone very similar landscape conversion. More detailed hydrologic and geomorphic analysis of Sonoma Creek is recommended as future work to confirm the following hydrologic and geomorphic conceptual model.

Hydrologically speaking, overall the historical Sonoma Creek would have experienced much lower winter peak flows and higher summer base flows than modern conditions. Historically, the Sonoma Creek watershed had a tremendous capacity to store rainfall. With more than 20 tributaries lacking direct connectivity to Sonoma Creek, as flow from the tributaries entered that valley floor it spread out and dissipated into alluvial fans, and seasonal and perennial wetlands. With a much smaller contributing watershed, winter storm peak flows in Sonoma Creek were much lower in magnitude for a given storm frequency under historical conditions. Historically Sonoma Creek would have overtopped its banks frequently (1.5-year peak flow frequency, typical gravel bed natural bank full channel capacity). As flows overtopped the creek’s banks, in many places in the lower watershed this flow would have remained in the overbank areas, most of which were seasonal and perennial wetlands. Water entering the alluvial fans and wetlands percolated into the shallow groundwater aquifers and was later released into the streams as substantial cold summer flows.

Under modern conditions the Sonoma Creek is extremely efficient at conveying all rainfall downstream to the lower developed reaches all at once with very little water held back in surface and subsurface storage (ESA PWA, 2011). First of all, the watershed is highly connected with nearly all tributaries directly connected to Sonoma Creek. This drastically increases the contributing watershed, sending a larger volume of water to Sonoma Creek for a given storm frequency. Second, due to land use practices (roads, agriculture, etc) many of the contributing watersheds have much higher drainage densities than historical conditions, which enable these basins to produce more surface runoff. Finally, the current channel network is more efficient at conveying flow due to having much larger flow conveyance capacity and often in places straightened. Thus the modern Sonoma Creek watershed is extremely efficient at transporting runoff from the tributary basins to Sonoma Creek, and from upper reaches of Sonoma Creek downstream to low-lying Sonoma Valley. When rainfall runoff from the entire Sonoma Valley is essentially conveyed all at once to lower highly developed reaches of Sonoma Valley, this area becomes overwhelmed and experiences such problems as flooding and bank erosion. Additionally, very little water is held back as storage, specifically as groundwater, in the Sonoma Creek watershed. With little shallow groundwater

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being stored during the winter, in the summer time Sonoma Creek experiences poor summer water quality.

As part of their investigation of the Napa River, SFEI performed hydrologic modeling to examine the effects distributary channels, dynamic alluvial fans, and perennial and seasonal wetlands would have on watershed hydrology and what happens when tributaries are connected, wetlands drained, and floodplains are disconnected under modern conditions (Figure 11). The clear take away from their work, shown in Figure 11, is that under historical conditions winter flows were much lower and summer base flows were much higher than modern conditions.

Figure 11. Average annual hydrographs for the historical watershed (dashed line; estimated) and existing watershed (blue line) for Napa River near Napa (from SFEI, 2012). Each daily flow value for either hydrograph represent the average flow calculated for that day of the year using daily rainfall data for the periods 1987 to 2006.

From a geomorphic perspective, the increased magnitude in winter storm flows has likely contributed to significant degradation of Sonoma Creek. The lower winter peak flows found under historic winter conditions would likely have resulted in a much smaller bank full channel width (1.5-year peak flow capacity). Although local flooding would have been more prevalent as winter flows overtopped banks and had frequent access to the floodplain, the cumulative downstream flooding that we experience today would have been greatly diminished. Likewise, erosional forces would have been diminished in a pre-settlement

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hydrologic network. As flows overtop the channel’s banks this would have significantly reduced the erosive energy of high flow events helping to prevent erosion and maintain a lower channel capacity. Under modern conditions, the increased runoff provides more erosive energy during peak flow events. As a result, we observe channel incision and bank erosion throughout the watershed. Additionally, the elevated flows entering Sonoma Creek have likely been out of balance with the sediment supply, creating a positive feedback loop between channel flows and erosion. As the channel is eroded, flow capacity is increased; increased flow in the channel caused further erosion. The result is a channel that not only has geomorphically adjusted to larger flow magnitudes for a given frequency, but has adjusted to contain larger, less frequent events, (above the 100-year peak flow event) for many reaches. The modern geomorphic condition of Sonoma Creek is confined, incised (down to bedrock in many locations), and armored in numerous locations that are too erosive to store sediment.

Restoring the historical hydrologic function of the Sonoma Creek watershed will lessen the effects of cumulative downstream flooding, ground water recharge and water quality in Sonoma Valley. Across the entire watershed flow inputs to Sonoma Creek during the winter months need to be slowed and stored. Because this report clearly shows this is a watershed scale problem, this will require watershed scale cooperative management to effectively achieve the goals of decreased flooding, increased groundwater recharge, and improved water quality.

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RECOMMENDATIONS The results document Sonoma Valley as a place where the historical channel system and associated wetlands allowed for slow storm runoff and facilitated the infiltration of rainwater into the ground. Compared to modern conditions, this maximized groundwater recharge, substantially decreased winter peak flows, increased summer base flows, maintained extensive seasonal and perennial wetlands, and supported high water quality. Supporting evidence for these conclusions comes from hydrological modeling and studies done in adjacent Napa Valley (SFEI 2012). The historical conditions and landscape conversion in Sonoma Valley, as outlined in this study, were found to be similar to those in Napa. The anthropogenic increase in channel connectivity over the last two centuries was presumably created for the purpose of limiting localized flooding by shunting stormwater downstream. While this was fairly successful at the subwatershed scale, the cumulative effect of combining the runoff from previously disconnected tributaries magnified flooding downstream. Increased connectivity was likely a significant factor in catastrophic events like the New Year’s 2006 flood, which caused property damage over a large part of the watershed. The similarity to historical conditions in Napa Valley suggest that the quantity of water in the Sonoma Creek mainstem would have been significantly reduced during peak winter flows. Compared to modern conditions, flooding that did occur in the historical system was probably more localized. Because connectivity was limited, flooding would have been caused by local stream conditions. Restoring or mimicking historical patterns in appropriate locations would improve groundwater recharge, reduce catastrophic flooding, increase water quality and provide opportunities for habitat restoration. Such enhancements to the watershed’s hydrological functioning would increase local water security and resilience in the face of climate change. Phase II Modeling The information developed in this study during Phase I of the project suggests a number of actions and approaches to achieve the goals mentioned above. Phase II (proposed in 2012 but not yet funded) will build on the historical hydrology map and other information developed by during Phase I. In order to confirm and quantify the potential benefits of various actions, we recommend using computer modeling to compare historical and modern conditions and test the potential benefits of the following actions: Reducing channel connections Possible actions range from slowing a tributary’s flow by engineering step-pool configurations (such as the Sonoma Land Trust’s completed Stuart Creek Project) to directing it back into abandoned distributaries to completely disconnecting a tributary by running its flow over the ground surface where land uses permit. Road ditches also

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contribute to drainage density and hydrologic connectivity and strategies for reducing their contribution should be explored. Potential benefits: flood reduction, increased groundwater recharge, improved water quality and habitat restoration. Allowing room for channels on alluvial fans to move: Possible actions: properties in key sites could be purchased or have easements established on them to allow for this condition. Potential benefits: Anticipating such events in this way would reduce economic impacts from the larger and more frequent storms expected from climate change. Restore shallow confluence angles: Possible actions: engineering confluences to mimic historical conditions. Potential benefits: reduced erosion and downstream flooding; increased infiltration and recharge in the confluence zone; increased water quality; and restoration of riparian wetland habitat in the expanded confluence zone. Protect and restore perennial wetlands: Possible actions: protect surviving perennial wetlands through purchase or easements (limited opportunities); restore perennial wetlands through decreasing drainage and/or increasing inflow. Potential benefits: habitat restoration, improved groundwater recharge, flood reduction and increased water quality Protect and restore seasonal wetlands: Possible actions: as the wetland habitat which historically covered the largest area, there are probably many undeveloped sites which could be protected through purchase or easements. Some retain hydrological function, others would need this restored through decreasing drainage and/or increasing inflow. Potential benefits: habitat restoration, improved groundwater recharge and water quality, and flood reduction. Incorporating intricate vegetation mosaics into urban and rural planning, landscaping and restoration efforts: Possible actions: the historical landscape suggests that a focus on recreating or restoring this condition would have a number of potential benefits: improved groundwater recharge; flood reduction; and enhanced biodiversity and ecological health (ecotones, where two habitats meet, promote biodiversity through the well-documented “edge effect.” Biodiversity is a widely-used and accepted measure of ecological health.) Deliverables: Report detailing the results of the modeling effort, quantifying the benefits of general types of projects and identifying promising locations where they might be carried out.

Phase II Mapping Working from the information developed during the Phase II Modeling effort and soliciting additional input from stakeholders (e.g. Sonoma County Water Agency, Valley of the Moon

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Water District, the agricultural community, local and regional environmental organizations, Sonoma Resource Conservation District, landowners, local residents and others), Phase II Mapping will: 1) Identify sites that show promise for restoring hydrologic function. Sites will be chosen by identifying areas that historically supported patterns listed under “Conclusions” above, consulting the model, and assessing the feasibility of restoring hydrologic function within the current landscape (e.g. integrating recently completed groundwater recharge mapping with the historical map will indicate promising places for recharge) 2) Develop high-resolution maps incorporating historical and modern conditions to aid project planning and implementation for 10 chosen sites (detail similar to Kenwood Fan/Vallejo home maps. See Appendix C). Deliverables: High-resolution maps for each site, showing historical and modern channels, perennial and seasonal wetlands and other relevant features. Accompanying report including site-specific recommendations.

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BIBLIOGRAPHY

Altimira, Jose. 1823. Diario de la expedicion verificada con objecto de reconocer terrnos para la nueva planta de la Mision de Nuestro Padre San Francisco principiada le dia 25 de Junio de 1823. (Translation by Robert S. Smilie in The Sonoma Mission; The Founding, Ruin and Restoration of California’s 21st Mission. Valley Publishers. Fresno, CA.) Anonymous. c. 1837. “Tereno Nombrado Guilucos Solicitado por Juan Wilson.” Bancroft Library. University of California, Berkeley. Map. Anonymous. c. 1840. “Agua Caliente.” Bancroft Library, University of California, Berkeley. Map. B-662. Anonymous. c. 1840. “Rancho de Huichica Sonoma.” Bancroft Library, University of California, Berkeley. Map. Anonymous. c. 1852. “Rancho Petaluma.” Bancroft Library, University of California, Berkeley. Map. Barbour M, Keeler-Wolf T, Schoenherr A. 2007. Terrestrial vegetation of California, 3rd edition. Berkeley, CA: University of California Press. Beller, EE, RM Grossinger, MN Salomon, SJ Dark, ED Stein, BK Orr, PW Downs, TR Longcore, GC Coffman, AA Whipple, RA Askevold, B Stanford, JR Beagle, 2011. “Historical ecology of the lower Santa Clara River, Ventura River, and Oxnard Plain: an analysis of terrestrial, riverine, and coastal habitats.“ Prepared for the State Coastal Conservancy. A report of SFEI’s Historical Ecology Program, SFEI Publication #641, San Francisco Estuary Institute, Oakland, CA. Best, Catherine, J.T. Howell, et. al. 1996. A Flora of Sonoma County: Manual of the Flowering Plants and Ferns of Sonoma County, California. California Native Plant Society. California Native Plant Society. Sacramento. Black, G. 1854. “Mission San Francisco at Sonoma.” Map. Bancroft Library collection. Boggs, William. 1861. California Land Court Transcript, Los Guilucos Rancho. July 31. Bancroft Library, University of California, Berkeley. Describes conditions in the 1840s. Bowers, A.B. 1867. “Map of Sonoma County California, 1867” Archived at the Sonoma County Museum. Butzer, Karl W. 1976. Geomorphology From the Earth. Harper & Row Series in Geography. Harper & Row Publishers. New York, Hagerstown, San Francisco, London. California Department of Fish and Wildlife. 2010. California Natural Diversity Database. California Department of Fish and Wildlife. 2015. “Wildlife Habitats — California Wildlife Habitat Relationships System.” Web page. Accessed at www.dfg.ca.gov/biogeodata/cwhr/ wildlife_habitats.asp CH2M Hill 1990. "History, Land Uses, and Natural Resources of the Laguna de Santa Rosa." Report funded by the Santa Rosa Subregional Water Reclamation System. Santa Rosa, CA. Cowardin, L. M., V. Carter, F. C. Golet, E. T. LaRoe. 1979. Classification of wetlands and deepwater habitats of the United States. U.S. Department of the Interior, Fish and Wildlife Service, Washington, D.C. Jamestown, ND: Northern Prairie Wildlife Research Center .

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Collins, J.N., M. Sutula, E.D. Stein, M. Odaya, E. Zhang, and K. Larned. 2006. Comparison of methods to map California riparian areas. Final report prepared for the California Riparian Habitat Joint Venture. SFEI Contribution 522. Oakland and Costa Mesa, CA: San Francisco Estuary Institute and Southern California Coastal Water Research Project. Collins, Laurel, Donna Morton & Paul Amato. 2002. “Geomorphic Changes in the Lower Reaches of Carriger Creek, Sonoma County.” Study by Watershed Sciences. Collins, Laurel & David O’Donnell. 2010. “Morphological Units of Sonoma Creek Watershed.” Map published by Sonoma Ecology Center. Conner, Glen. 2005. “History of Weather Observations, San Francisco, California. 1848-1948.”Prepared for the Midwestern Regional Climate Center under the auspices of the Climate Database Modernization Program. NOAA’S National Climatic Database Center. Asheville, North Carolina. Dark, Shawna; Eric D. Stein, Danielle Bram, & Joel Osuna. 2012. “Historical Ecology as a Living Resource for Informing Urban Wetland Restoration.” In Urban Coast. March. Dawson, Arthur. 1989-2016. Personal observations over many years of residence in Sonoma Valley. Dawson, A. 2004. "Synopsis of changes in geomorphology, hydrology, fisheries and related topics for the Sonoma Valley Watershed c. 1823 - 2004." Sonoma California, Sonoma Ecology Center. Dawson Arthur. 2006. “Oaks Through Time: Reconstructing Historical Change in Oak Landscapes.” Presented at the Sixth Symposium on Oak Woodlands: Today’s Challenges, Tomorrow’s Opportunities. October 9-12, 2006, Rohnert Park, California.” Published in the Conference proceedings. U.S. Department of Agriculture. Dawson, Arthur. 2009. “Historical Alignment Study of Champlin Creek for the Stage Gulch Road Curve Improvement and Realignment Project.” Funded by WRECO. Sonoma Ecology Center. Dawson, Arthur, and C. Sloop. 2010. “Laguna de Santa Rosa Historical Hydrology Project: Headwaters Pilot Study.” Santa Rosa, CA, Laguna de Santa Rosa Foundation and Sonoma Ecology Center. Santa Rosa, CA. Dawson, Arthur. 2011.”Review of Historical Habitats Draft Map” and “Review of Historical Channels Draft Map.” Prepared for the San Francisco Estuary Institute, Critical Coastal Areas Project. Contracts No. 714 and 925. SEC Report No. 20110315. Dawson, Arthur. 2013. “Montini Open Space Preserve and Vallejo Home, Sonoma State Historic Park, Historical Hydrology Study.” Baseline Consulting. Funded by the Sonoma County Water Agency. Environmental Science Associates (ESA), Daniel B. Stephens & Associates, and Parker Groundwater. 2012. Sonoma Valley Stormwater Management and Groundwater Recharge Scoping Study: Screening Evaluation and Prioritization Memorandum. For the Sonoma County Water Agency. Garcia & Associates. 2005. “Preliminary Delineation of the Wetlands and Waters of the United States for the Sonoma-Marin Area Rail Transit Project.” Prepared for the Sonoma –Marin Area Rail Transit Commission. Golden Gate Weather Services. 2016. Monthly rainfall record for San Francisco, 1849 – 2016. Accessed online via http://ggweather.com/sf/monthly.html. August 2016. Gray, Nick. 1864. County Road Survey. Sonoma County Surveyors Office. Book A. Gray, Nick. 1864. Survey for John Rodgers. Book 1, Sonoma County Surveys. Sonoma County Surveyors Office.

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Gray, Nick. 1866. Survey for Mrs. Catherine Lewis. Book 1, Sonoma County Surveys. Sonoma County Surveyors Office. Griffin, Daniel, Connie A. Woodhouse, and David W. Stahle. 2008. “Russian River Valley Precipitation and Streamflow Reconstructed from Blue Oak Tree Rings.” Poster. Grossinger, R. M. 2001. “Documenting Local Landscape Change: The San Francisco Bay Area Historical Ecology Project.” In The Historical Ecology Handbook, edited by D. Egan and E. A. Howell, 425–41. Washington, DC: Island Press. Grossinger, RM. 2012. Napa Valley Historical Ecology Atlas: Exploring a Hidden Landscape of Transformation and Resilience. University of California Press and San Francisco Estuary Institute. Grossinger RM, Striplen CJ, Askevold RA, et al. 2007. “Historical landscape ecology of an urbanized California valley: wetlands and woodlands in the Santa Clara Valley.” Landscape Ecology 22:103-120. Helley, E.J., K.R. LaJoie, et. al. 1979. "Flatland Deposits of the San Francisco Bay Region, California-- Their Geology and Engineering Properties and Their Importance to Comprehensive Planning." U.S. Geological Survey (USGS) Paper 943. USGS, San Francisco, California. Holmes, L.C. and J.W. Nelson. 1917. Reconnaissance Soil Survey of the San Francisco Bay Region, California. U.S. Department of Agriculture, Bureau of Soils. Government Printing Office. Washington, D.C. Holstein G. 2000. Plant communities ecotonal to the baylands. In “Baylands ecosystem species and community profiles: life histories and environmental requirements of key plants, fish and wildlife.” Ed. P.R. Olofson, p. 49-68. Oakland, CA: San Francisco Bay Regional Water Quality Control Board Lawton, Rebecca. 2006. “Sonoma Creek Watershed Sediment Source Analysis.” Contributors included: Watershed Sciences; Martin Trso, P.G.; Talon Associates LLC; and Tessera Consulting. Prepared and published by the Sonoma Ecology Center. Administered by the California Water Quality Control Board, San Francisco Bay Region. Laguna de Santa Rosa Foundation. 2006. “Vernal Pools of the Santa Rosa Plain.” Accessed online at: http://www.lagunafoundation.org/knowledgebase/?q=node/166. Leese, Jacob. 1861. Testimony to the U.S. Land Court on Rancho Los Guilucos. ND 94. Bancroft Library Collection. Lewis, W.J. 1870. “Plat of the Two Parts of Agua Caliente finally confirmed to Mariano G. Vallejo.” Surveyed under instructions from the U.S. Surveyor General. LSA Associates. 2006. “Charles M. Schulz Sonoma County Airport Biological Assessment, Sonoma County, California. Prepared for the Sonoma County Department of Transportation and Public Works to the Federal Aviation Administration Hawthorne, California. LSA Project No. MHN530. Luzzi, Lynn. 2012. Personal communication. Lynn is a maintenance worker at the Vallejo Home and has several years of direct observations of conditions there. Her comments were supported by her colleague, Bill Ballow. Mandeville, J.W. 1859. “Plat of Survey of Rancho Agua Caliente.” Map. .” Surveyed under instructions from the U.S. Surveyor General. Archived at the Sonoma County Recorders Office, Santa Rosa. Micheli, Elisabeth (Editor). 2006. “Sonoma Creek Watershed Limiting Factors Analysis. Final Report.” Sonoma Ecology Center with Stillwater Sciences and UC Berkeley Dept. of Earth and Planetary Sciences.

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Miller, Vernon. 1972. Soil Survey of Sonoma County California. U.S. Department of Agriculture, Soil Conservation Service. In cooperation with the University of California Agricultural Experiment Station. National Agriculture Imagery Program. 2010. Aerial photos of study area. Provided through the U.S. Department of Agriculture. Nelson, Stephen A. 2012. “Streams and Drainage Systems.” Physical Geology Department web page. Tulane University. Accessed at: www. www.tulane.edu/~sanelson/eens1110/streams.htm Natural Resource Conservation Service (NRCS). 2014. “Hydric Soils of the United States.” Accessed online at: www.nrcs.usda.gov/wps/portal/nrcs/main/soils/use/hydric/. U.S. Department of Interior. Northen, Phillip. 1996. “Wetland Delineation for Vallejo Home State Historic Park, Sonoma, California.” Prepared for Marla Hastings, California Department of Parks and Recreation (Included as an appendix in Bradley 2007). O’Farrell, Jasper. 1848. “Map of the Land of Petaluma.” Sonoma County Recorders Office, Santa Rosa, California. Ornduff R, Faber PM, Keeler-Wolf T. 2003. Introduction to California plant life. Berkeley, CA: University of California Press Orr BK, Diggory ZE, Coffman GC, et al. 2011. “Riparian vegetation classification and mapping: important tools for large-scale river corridor restoration in a semi-arid landscape.” In Proceedings of the CNPS Conservation Conference: strategies and solutions, 17-19 Jan 2009, California Native Plant Society. Ed. B.K. Orr, J. W. Willoughby, K. Schierenbeck, and N. Jensen. Sacramento, CA Peabody, E.J. 1851. “Guilucos Rancho, Surveyed & Drawn for Hood & Petit.” Bancroft Library, University of California, Berkeley. Map. Ratliff, Raymond D. 2007. California “Wet Meadow Vegetation.” Wildlife Habitat Relationships System.California Department of Fish and Game, California Interagency Wildlife Task Group. Accessed online at: http://www.dfg.ca.gov/biogeodata/ Reynolds and Proctor. 1898. Illustrated Atlas of Sonoma County, California. Published by Reynolds and Proctor, Santa Rosa, CA. Rowe, E.H. 1871. “Taken from the plan of Rancho Guilicos. Surveyed for the Sonoma Valley Land Association.” Private collection of the MacLeod family, Kenwood. San Francisco Estuary Institute. 1999. “The Bay Area EcoAtlas.” Published by the San Francisco Estuary Institute. Richmond, California. San Francisco Estuary Institute 2006. "Coyote Creek Watershed Historical Ecology Study: Historical Condition, Landscape Change, and Restoration Potential in the Eastern Santa Clara Valley, California." San Jose, California. San Francisco Estuary Institute (SFEI). 2012. Napa River Watershed Profile: Past and Present Characteristics with Implications for Future Management for the Changing Napa River Valley. Contribution number 615. Richmond, CA. Sawyer J, Keeler-Wolf T, Evens J. 2009. A Manual of California Vegetation. Second Edition. Published by the California Native Plant Society in collaboration with California Department of Fish and Wildlife. Sacramento.

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Simpson, Sir George. 1847. An Overland Journey Round the World during the years 1841 and 1842. Lea and Blanchard. Philadelphia. Smilie, Robert . 1975. The Sonoma Mission, San Francisco Solano de Sonoma; the Founding, Ruin, and Restoration of California’s 21st Mission. Valley Publishers. Fresno, California. Includes translations of Altimira’s 1823 journal. Trotta, Marcus, Bryan Sesser, Deanne DiPietro and Rebecca Lawton. 2011. “Sonoma Valley Watershed Groundwater Recharge Potential Map.” Published by Sonoma County Water Agency. Sonoma Ecology Center. 2002. The Oral History Project: A report on the findings of the Sonoma Ecology Center’s Oral History Project, focusing on Sonoma Creek and the historical ecology of Sonoma Valley. Includes interview transcripts, appendixes & maps. Sonoma Ecology Center. 2009. "Modern and Historical Channels and Associated Wetlands, Sonoma Creek Alluvial Fan, Kenwood, California." Map developed by Laurel Collins of Watershed Sciences, Arthur Dawson of the Ecology Center and the San Francisco Estuary Institute. Sonoma Veg Map. 2013. LIDAR imagery provided by the county of Sonoma. Stanford B, Grossinger RM, Askevold RA, Whipple AW, Leidy RA, Beller EE, Salomon MN, Striplen CJ. 2011. East Contra Costa County Historical Ecology Study. Prepared for Contra Costa County and the Contra Costa Watershed Forum. A Report of SFEI’s Historical Ecology Program, SFEI Publication #648, San Francisco Estuary Institute, Oakland, CA. Thompson, Thomas H. 1877. Historical Atlas of Sonoma County. Published by Thomas H. Thompson & Co. Oakland, California. Reprinted by the Sonoma County Historical Society. Tracy, C.C. 1860. “Plat of Part of the Rancho Agua Caliente finally confirmed to T.M. Leavenworth.” Surveyed under instructions from the U.S. Surveyor General. Bancroft Library reference: B-673. Tracy, C.C. 1859. “Plat of the Rancho Los Guilucos finally confirmed to Juan Wilson.” Surveyed under instructions from the U.S. Surveyor General. Bancroft Library. Tracy, C.C. 1855. “Plat of the Huichica Rancho confirmed to Jacob Leese.” Surveyed under instructions from the U.S. Surveyor General. Archived at the Sonoma County Recorders Office, Santa Rosa. U.S. Army Corps of Engineers. 1987. “Corps of Engineers Wetland Delineation Manual.” Technical Report Y-87-1. U.S. Department of War. 1942. Aerial photos of Sonoma Valley taken at the beginning of World War Two. Archived at the Sonoma Resource Conservation District, Petaluma. U.S. Geological Survey. 1902. “Napa Quadrangle.” 30-minute quad surveyed in 1896 and 1899. U.S. Geological Survey. 1916. “Santa Rosa Quadrangle.” 30-minute quad surveyed in 1914. U.S. Geological Survey. 1942. “Sonoma Quadrangle.” 7.5-minute quad. U.S. Geological Survey. 1968. “Sears Point Quadrangle.” 7.5 minute quad. U.S. Geological Survey. 1980. “Glen Ellen Quadrangle.” 7.5 minute quad. U.S. Geological Survey. 1980. “Kenwood Quadrangle.” 7.5 minute quad. U.S. Geological Survey. 1980. “Sonoma Quadrangle.” 7.5-minute quad. Vallejo, Salvador. 1853. Testimony to the U.S. Land Court on Rancho Petaluma. Bancroft Library Collection.

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APPENDIXES

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APPENDIX A. Selected Historical Maps

FIGURE A1. Detail from O’Farrell’s 1848 Rancho Petaluma Map.

NOTES: Starting near the top, Dowdall, Carriger, Felder, and Rodgers Creeks are shown to the left (west) of Sonoma Creek (which runs from top to bottom). Note how O’Farrell seems to differentiate wet channels (blue) from dry channels (black) and how most of the tributaries are shown with no direct connection to Sonoma Creek (Felder’s connection is not visible in this detail).

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FIGURE A2. Confluence of Agua Caliente and Sonoma Creeks in 1860

NOTES: Confluence recorded at an oblique angle (Tracy).

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FIGURE A3. Confluence of Agua Caliente and Sonoma Creeks in 1980

NOTES: Confluence has been modified to a much more perpendicular configuration (blue arrow below. U.S. Geological Survey) and shifted 500 feet upstream. As a consequence of modification, Agua Caliente Creek has been shortened by several hundred feet of channel since 1860.

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FIGURE A4. Alternate Channels Occupied by Pythian, an Unnamed Creek, and Sonoma Creek

1916

1859

1851 & current channels

1859

NOTES: Going from upper left to lower right, creeks are Pythian, an Unnamed Creek, and Sonoma, as mapped at various times. Channels on alluvial fans are especially dynamic and prone to “channel switching.” (Background map: U.S.G.S. Kenwood quad 1980; 1851 channels as mapped by Peabody; 1859 channels as mapped by Tracy; 1916 channel as mapped by U.S.G.S. 1859 and 1916 channels corroborated by other sources.)

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APPENDIX B. Fieldwork Notes and Selected Photos

Field notes and photos by Rebecca Lawton—February 25, 2016 Sonoma Valley Historical Hydrology Present: Arthur Dawson, Alex Young, Becca Lawton (additional photos to be submitted electronically with final deliverables)

Meet 9 a.m. El Verano

Stop 1 – Carriger Fan (photos 1-9)

Alluvium in fields indicative of Diameter-50 of fan material. Reworked fluvial deposits (cobbles and boulders rounded enough to be riverine in origin). Photos of material in vineyards, walls, ditches, roots of bay trees beside ditches.

Inboard ditching running N-S as old as oldest historical maps that show channels terminating at Carriger Road. Combination of flow petering out in coarse material and rerouting in inboard ditches.

Stop 2 – Orange Avenue (photos 10-13)

Natural channel that still flows intermittently. Up to 150-year-old streamside trees include bay, oak, buckeye. Riparian corridor looks more robust than flow that remains in channel—distributed away into ditches possible.

Stop 3 – Maxwell Park (photos 14-24)

Bays dominate the old abandoned Agua Caliente Creek channel area south of El Verano Avenue. Black walnut = ecotone species here. Marks edge of riparian where snowberry abundant. Root mass in top of bank in terrace above Sonoma Creek 100+ year old bay.

continued

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Backhoe digging in fan material near Finnish American Housing. Arthur counting rings on recently cut bay tree on second of three terraces, 50 to 60 years old, 24-inch diameter, 55 years estimate.

Stop 4 – Hyde-Burndale Road (photos 25- 26)

Standing water where creeks connect in a swale rather than maintaining channel integrity through area mapped in 1942 as seasonal wetland.

Stop 5 – Arroyo Seco and tributary (photos 27-31)

Confluence of trib with Arroyo Seco incised below 100-year-old oak tree and culvert perched above stream bottom.

Stop 6 – Oak savannah and another tributary to Arroyo Seco (photos 32-33)

One natural channel in grazed area with scattered oaks, likely previously savannah.

Stop 7 – Felder Fan (photo 34)

Standing water on Sperring Road also matches 1942 wetlands mapping.

Stop 8 – Felder Fan natural channel (photos 35-37)

With old wooden intake and concrete culvert.

Stop 9 – Felder Fan (photos 38-39)

More ponded water. This in vineyard. Across Felder Road from Felder Creek.

Stop 10 – Temelec (no photos)

Mapped tributary not found, perhaps buried. Only the barest swale there.

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Field notes & photos by Rebecca Lawton—March 4, 2016 Sonoma Valley Historical Hydrology Present: Arthur Dawson, Alex Young, Becca Lawton (additional photos be submitted electronically with final deliverables)

Meet 9 a.m. Baseline office, Glen Ellen

Stop 1 – Butler Creek (photos 1-4, 6-11, 13-17)

Visit to Will Bucklin farm. He has heard that Butler Creek used to run year round “here” prior to now, even recently if you go higher up the stream. He also said it “ran year round on a property ¼ mile away” [he pointed but it wasn’t clear which property].

He said the State [implying SDC] has a dumpsite right by the creek—“sort of their composting.”

The drainage upstream from the horse valley at SDC is wet until June. He says it’s all Johnson’s grass now and has the most beautiful oak tree he’s ever seen. “It needs protection from the horses.” The perennially wet area in the middle of SDC would make a “nice little wetlands.” It’s the only valley left in Sonoma Valley that “doesn’t have a highway running through it.”

Will said that his mother takes water from Butler and “has a dam that doesn’t hold water.”

Photos show Butler Creek, a Sonoma County Water Agency monitoring station. Field checking shows that oaks are cleared over much of the property but remain along creeks and property lines.

One photo shows a bend in the streambed into which coarser and somewhat angular material from alluvial fan has been placed into streambed (not along banks). There is a good stand of mature buckeye at this same location.

Continued to look for Butler Creek on Little Vineyards property. Butler may be discontinuous between mapped reaches.

continued

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Photo from the road between Little and BR Cohn property show ponding. Not clear whether there is a barrier impounding it on downstream (northwest) end of ponding.

Stop 2 – St Jean Winery area and coalesced fans from Sonoma Creek and Creek 823 (photos 18-22)

Oaks and walnuts well established in riparian belt flowing north-south, except where clearing done for vineyards. One 58-inch diameter oak Arthur estimated to be 230 years old. Photo shows this oak and the measuring of it.

There is a point on the channel where upstream looks natural and downstream looks ditched. We marked this point on Arthur’s map. Photo in ditched channel.

Stop 3 – Fisher Creek in Kenwood (photo 23)

May have been ditched from where line ends on old map. Photo of close-planted redwoods along engineered channel in city park.

Stop 4 – Egg Farm Creek in Kenwood neighborhoods (photos 24-25)

Marshy slow water area. Good sized oak, wild cherry that travels creeks by rootstock, walnuts, other nut trees. Property for sale through Sotheby’s. Looks like last to develop because most wet part of this neighborhood. Weeping willow on several properties (non native but naturalized in wild) Plenty of blackberry.

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Stop 5 – Photo of Kenwood Marsh outlet (photos 26-27)

Low place in this part of Sonoma Valley. Also photo of ditch near Creek 645. Field verified as plausible. Below restoration area on Warm Springs Rd, creek was not this incised even in recent times, as in old-timer Mr. Rossi’s memory you could drive a horse and wagon across an Arizona Crossing where the bridge is now at the Warm Springs end of Lawndale Road.

Stop 6 – Bennett Valley Road near Warm Springs Road (photos 28-32)

Creek here in fairly fine-grained material of this gentle fan. Upstream of our stop at residential bridges is multichanneled floodplain that has been constricted. Gravel-sized partially rounded clasts are the largest material we see in the streambed. Downstream from this point channel looks straightened and reinforced with concrete. May be straight shot to Sonoma Creek from here; old meander would be through current home southwest of confluence between two creeks.

Stop 7 – Snag Creek (photos 33-36)

Upstream and downstream views. Tributary channel coming in from direction of Yulupa, and aligned with the old, braiding, more southerly flow of historical Yulupa, has been rocked up.

Stop 8 – S-Curve in Sonoma Creek on Warm Springs Road (photos 37-38)

Fine material as if there were slow, ponded water here at least at some time of this reach’s history. Wider floodplain up higher before constriction (where residence is close to stream on east side of creek) probably the level at which the S-curve developed, possibly in response to a slug of sediment out of Snag (just speculation, could be further investigated). Photo 39 shows nearby perched culverts on west side of Warm Springs Rd.

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FIGURE B1. Field Survey Locations

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APPENDIX C. Phase II Mapping Sample

Figure C1. Sample High-Resolution Map

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