The technical memorandum focuses on describing the historical (i.e., prior to substantial Euro-Am... more The technical memorandum focuses on describing the historical (i.e., prior to substantial Euro-American modification) characteristics of the valley floor portion of South Santa Clara County, including Uvas, Carnadero, Llagas, and Pacheco creeks and the upper Pajaro River, and including the intervening, hydrologically connected San Felipe Lake area in north San Benito County. Preliminary Status It should be recognized that this assessment is preliminary to the South County Historical Ecology Study report (which will incorporate additional data, analysis, and review) and is thus subject to some adjustment and modification over the next 12 months. The scope of this document, therefore, will be limited to the more well-documented aspects of the historical landscape. This information should provide a conceptual framework for conservation planning as well as the incorporation of subsequent, more detailed information during the course of the project. Data Sources This assessment is based upon the examination and synthesis of a wide range of historical data sources. We consulted dozens of maps associated with the Mexican Land Grant Ranchos, including the original diseños (circa 1840), and reviewed court transcripts of testimony about the land grant boundaries (1850s-1860s). Along with the Public Lands Surveys of the General Land Office (1850s-1870s), these documents provided extensive evidence for landscape features prior to most Euro-American impacts. We also consulted early written accounts, soil surveys, other early maps (e.g. Thompson and West 1876), local histories, and County surveys. We created a photomosaic of the earliest available aerial imagery (1939) which, while reflecting substantial land use impacts, nevertheless provides illustration of landscape characteristics before post-World War II development. Natural Landscape Patterns Understanding how individual habitat types fit together to form a larger landscape is essential to a conservation plan. Documenting the landscape-level spatial patterns of the region prior to Euro-American modification can indicate functional relationships between habitats, such as the proximity of ecological support functions for target species. A map of landscape patterns can also help identify underlying physical controls on habitat formation and maintenance by revealing basic relationships to topography, soils, groundwater, and other factors. This section thus provides a landscape ecological overview of the area (Figure 1). Historical quotes and images are used to provide contemporary illustration of ecological and hydrological conditions.
San Francisco Bay wetland managers are looking landward for ways to accommodate accelerated sea l... more San Francisco Bay wetland managers are looking landward for ways to accommodate accelerated sea level rise due to climate change. A major concern is that sea level rise will drown existing tidal marshes except for a narrow ring of marshland between the Bay and the built environment. This would eliminate many of the Bay's ecological services, as well as many of the ecological connections to the terrestrial environment upon which these services depend. Emerging plans therefore call for the conservation and reconnection of a tidal-terrestrial transition zone (T-zone) where tidal marshes and their terrestrial connections can be created or allowed to naturally evolve. Planning the future T-zone requires knowledge of its natural form and structure-how its physical dimensions and habitat composition varied around the Bay due to natural drivers such as climate and topography, and how they might respond to future conditions. However, the T-zone was severely and extensively altered in this region during the early stages of Euro-American colonization. Information about its historical character-its width, the diversity and relative amount of habitat types that comprised it, the associated ecological functions, and the physical drivers that controlled these patterns-is fragmented and scattered among many sources within the region and elsewhere. Historical ecology can be a useful tool to assemble this information into a coherent and scientifically-sound picture of historical conditions to inform T-zone planning for the future. In this pilot project we investigated several aspects of historical T-zone form and structure for a subset of the Bay. We found that the South Bay tidal-terrestrial interface was dominated (nearly 70%) by low-gradient seasonal wetlands grading into high marsh. Within this overall pattern, however, the T-zone was quite diverse. Seasonal wetlands included wet meadow, alkali meadow, and vernal pool complexes-each with distinct ecological characteristics and functions. Willow thickets, depressional wetlands (freshwater marsh), and alluvial grassland and riparian forests also contributed to the diversity of the T-zone. Relatively steeply-sloped grasslands bordering tidal marsh-the historical interface type most similar in composition to the levee faces that constitute most of the T-zone observed today in the South Bay-comprised less than 10% of the South Bay tidal-terrestrial interface. The T-zone included variation on the tidal side as well, with fresh-brackish tidal marshes associated with major creek mouths interspersed within a broad salt marsh context. Our study also suggests that the width of the T-zone varied dramatically with physical setting, from several meters to thousands of meters. The zone was broadest in areas with significant fluvial influence and in the most gently-sloping portions of the region. The findings from this study suggest several immediate and longer-term management implications. For example, it will be important to consider the variability in and relative proportions of T-zone types in Bay restoration planning to conserve the full range of the T-zone's ecological services. In addition, a regional approach will be necessary to match local settings with the most appropriate T-zone types. Because distinctive soil characteristics play a key role in forming many T-zone habitat types, it will be important to preserve and enhance the areas scattered throughout the region with soils that retain this potential. To develop this adaptive design capacity, several next steps are recommended. Extension of the historical T-zone analysis to the rest of the Bay will be important to develop the full T-zone restoration palette. For example, research in the North Bay has documented additional T-zone types that may be applicable to other parts of the Bay (e.g., valley oak savanna-tidal marsh transitions on coarse soils may be applicable to engineered slopes; Grossinger 2012). In addition, it will be useful to develop this understanding into a set of conceptual models linking T-zone types to physical drivers and target ecological functions (as has been initiated through the Baylands Ecosystem Habitat Goals Update). Relating these T-zone types to their geophysical setting-e.g., soils, slope, groundwater and surface water hydrology-will allow their translation into landscape designs using a combination of natural and engineered processes. The emerging understanding of the character and function of the Bay's T-zone can help us re-integrate it into the contemporary and projected future landscape.
Figure 1.1. Proposed subregions for nutrient analyses. These subregions are derived from operatio... more Figure 1.1. Proposed subregions for nutrient analyses. These subregions are derived from operational landscape units (OLUs), which are a proposed planning tool for landscape-scale ecosystem restoration in the Delta (Grenier & Grossinger 2013).
This report describes baseline information about the amount and distribution of aquatic resources... more This report describes baseline information about the amount and distribution of aquatic resources, and evaluates that overall ecological conditions of streams using the California Rapid Assessment Method (CRAM), for the Lower Peninsula watershed in Santa Clara County; consisting of Stevens-Permanente Creek, Adobe Creek, southern extent of San Francisquito Creek, and their tributaries. The Lower Peninsula watershed covers approximately 98 squaremiles with creeks flowing from the Santa Cruz Mountains into southwest San Francisco Bay and its tidal wetlands. The Santa Clara Valley Water District's (District) Safe, Clean Water and Natural Flood Protection Program has many priorities, including Priority D for restoring and protecting vital wildlife habitat, and providing opportunities for increased access to trails and open space. The D5 Project focuses on ecological data collection and analysis at a watershed scale to support the District, other County agencies and organizations in making informed ecological asset management decisions. The key performance indicators (KPIs) for D5 are to: 1. Establish new or track existing ecological levels of service for streams in 5 watersheds. 2. Reassess streams in 5 watersheds to determine if ecological levels of service are maintained or improved.
Southern California's coastal wetlands are an interrelated set of resources that collectively pro... more Southern California's coastal wetlands are an interrelated set of resources that collectively provide a broad suite of ecological, hydrological, and biogeochemical functions. Managing and restoring these systems requires a regional perspective that can inform holistic decision making. Knowledge of historical conditions provides a baseline of the extent and condition of wetlands lost, and is important to guide regional planning. The U.S. Coast and Geodetic Survey topographic sheets (T-sheets) provide the most important single source for understanding the physical and ecological characteristics of the US shoreline prior to Euro-American modification. Their depictions of coastal wetlands and other estuarine habitat types can provide relatively consistent information about the extent and distribution of those systems along the southern California Bight (SCB) prior to substantial human alteration. Although most appropriately used in conjunction with other data sources, the T-sheets can provide a foundation for regional analysis and a platform on which future, more detailed investigations can be based. This project builds on earlier efforts to provide comprehensive analysis of the 40 T-sheets that cover the SCB from Point Conception to the US-Mexico border. High quality scans of the original T-sheets produced between 1851 and 1889 were obtained along with the surveyor notes. T-sheets were digitized, georeferenced, and interpreted in order to provide a map of coastal estuaries (both large and small) and coastal drainage systems representing conditions along the SCB coast in the mid-late 19 th Century. This analysis was used to answer the following questions: 1. How much total estuarine habitat was there historically (i.e., as mapped on the T-sheets) compared to today? 2. How many total coastal systems occurred historically? 3. What has happened to historical estuarine habitat types? Extent of coastal estuarine habitats The SCB coast supported approximately 19,591 hectares of estuarine habitats. Approximately 40% of this area was vegetated wetlands (e.g., salt marsh), 25% was unvegetated wetlands (e.g. salt flat and mudflat), and the remaining 35% was subtidal water. In addition to these habitat types, an additional 5,496 hectares of "other wetlands" were mapped on the T-sheets. These included dune and beach, woody vegetated wetlands, high marsh habitat, isolated ponds, and riverine habitat. Over half (~57% or ~11,000 hectares) of all historical estuarine habitats were found in San Diego County, mostly associated with Mission and San Diego Bays. Both Los Angeles and Orange Counties contained about 15% each of the total historical estuarine area. The largest expanses of historical salt flats occurred in Los Angeles County. Number of estuarine systems A total of 331 coastal systems occurred along the SCB coast. Approximately 2/3 of these systems consisted of small coastal drainages without any associated terminal wetlands. Individual coastal systems were relatively evenly distributed along the coast, with each county having between 60 and 90 systems. The distribution of systems by size was also relatively uniform across the counties. The exceptions were a slightly higher concentration of medium and large systems in San Diego County and slightly more channel only systems in Los Angeles County. On a regional scale, larger systems occur in three areas ii distributed along the SCB coastline, south San Diego, Long Beach, and Southern Ventura County. These three nodes were connected through strings of medium and smaller wetlands. The 331 systems can be grouped in 15 distinct archetypes (or distinct compositions) representing combinations of size and dominant habitats. These archetypes tended to be spatially aggregated along the coast into loose "families" of systems. Change over time Since ca. 1850 there has been an overall loss of 9,317 hectares, or 48% of historical estuarine habitat types along the SCB coast. Estuarine vegetated wetlands have experienced the greatest loss in terms of absolute area (-5819 ha, 75% loss), while estuarine unvegetated wetlands have experienced the greatest proportional loss of 78% of historical extent (Figure ES-1). In contrast, the contemporary landscape represents a 5% increase in subtidal habitat from historical extent. These differential losses have shifted the proportional composition of southern California estuaries. Historically there was a relatively even split between estuarine vegetated (40%), estuarine unvegetated (25%), and subtidal water (35%). Currently the proportional composition is heavily weighted towards subtidal water (71%) while estuarine vegetated (19%) and unvegetated (10%) make up less than ⅓ of the total area combined. Declines in estuarine area vary by county. Total losses across all counties range from 62% in Santa Barbara to 31% in San Diego. Additionally, the composition of estuaries in the counties has shifted. In the southern most counties (Los Angeles, Orange, and San Diego) there has been a significant increase in subtidal water while both intertidal and vegetated wetlands have decreased. Santa Barbara and Ventura Counties have maintained an estuarine composition similar to that seen in ca. 1850. Figure ES-1. Change in overall extent and composition of estuarine habitat types between ca. 1850 and ca. 2005 Our estimated estuarine habitat losses, although substantial, are significantly lower than previously reported estimates of over 90% total wetland loss in California. Overall estuarine habitat area changes reflect and, to some extent, hide the disproportionate impacts to different estuarine habitat types. For example subtidal habitat has increased slightly while other types have decreased dramatically. Differences from other estimates may also be explained by the fact that our analysis is more precise than that used to produce previous estimates and/or that previous estimates may have included other wetland types or iii locations not included in this study. Lower than "expected" rates of loss may also reflect policies and programs over the last 40 years aimed at protecting and restoring coastal wetlands. Looking to the future, knowledge of historical wetland extent and patterns of loss can be used to inform future planning for diverse and resilient coastal landscapes. This report provides a synthesis of the main results of our analysis. Scanned images of the T-sheets, GIS and Google Earth layers of the maps, and the underlying data from this project are available at www.caltsheets.org. Acknowledgements Funding for this work was provided the California State Coastal Conservancy (Agreement 06-061), U.S. Fish and Wildlife Service (Co-op Agreement #80211AJ111), and the California State Wildlife Conservation Board. Dr. John Cloud was instrumental in helping us obtain high resolution scans of the Tsheets that formed the basis for much of our analysis. We thank the Wetland Recovery Project Wetland Managers Group for their input and feedback at key junctures of this project. We also thank Wayne Engstrom, Walter Heady, Megan Cooper, David Jacobs, and Richard Ambrose for their insightful and constructive comments on the draft report. Finally, we are indebted to the talented surveyors and cartographers who produced the T-sheets that have provided valuable insight into historical conditions along the Southern California Bight.
This report proposes a new multi-benefit approach to flood management along Upper Penitencia Cree... more This report proposes a new multi-benefit approach to flood management along Upper Penitencia Creek. Recognizing the creek's complex history, land use, and challenges, this report explores a suite of actions that could help meet flood management objectives while improving ecosystem functioning, expanding recreational opportunities, and supporting water supply needs. The San Francisco Estuary Institute-Aquatic Science Center (SFEI-ASC) and the Santa Clara Valley Water District (District) worked with technical advisors and a group of local stakeholders to explore a range of multi-benefit management opportunities along Upper Penitencia Creek, culminating in this Resilient Landscape Vision. The vision focuses on ways to expand flow conveyance and flood water storage from the Coyote Creek confluence upstream to the Dorel Drive bridge in a manner that works with the existing landscape features and supports habitats for native species. The management measures described here fall into two main categories: • In-channel improvements & riparian enhancements includes floodplain excavation, setting back levees, and managing vegetation in modified channelfloodplain areas to better support native wildlife • Multi-benefit off-channel detention includes creating high-flow floodplain basins that have multiple uses (e.g., sports fields and flood detention) and provide habitat features to support native wildlife Additional management measures related to modifying flow and sediment delivery from the upper watershed are also discussed. The next steps for implementing the vision measures include developing design alternatives, conducting feasibility analyses, continued collaboration with local stakeholders who own and manage land along the creek, and garnering regulatory agency support. Although situated in a highly developed landscape, the Upper Penitencia Creek channel-floodplain corridor retains a considerable amount of open space that provides opportunities for multi-benefit flood management. This Vision can be used as guidance in similar landscapes around the region, where managers are seeking to implement a nature-based approach to flood management that leverages existing open space features and benefits both people and wildlife. VISION FOR UPPER PENITENCIA CREEK • v sycamore and oaks along upper penitencia creek VISION FOR UPPER PENITENCIA CREEK • 3 This Upper Penitencia Creek landscape vision is intended to serve as a roadmap for supporting ecosystem functions to benefit people and wildlife. It is intended to assist the District, its partners, and other regional stakeholders in planning adaptation approaches to ecological stewardship, flood risk management, recreation, and water supply for Upper Penitencia Creek during the coming decades. The District is seeking to develop a new management approach in coordination with local partners who own and operate land adjacent to the creek (e.g., City of San José, County of Santa Clara, and local school districts), explicitly incorporating the partners' goals into the approach, and managing the areas adjacent to the creek to provide multiple benefits.
This report describes baseline information about the amount and distribution of aquatic resources... more This report describes baseline information about the amount and distribution of aquatic resources, and evaluates that overall ecological conditions of streams using the California Rapid Assessment Method (CRAM), for the Lower Peninsula watershed in Santa Clara County; consisting of Stevens-Permanente Creek, Adobe Creek, southern extent of San Francisquito Creek, and their tributaries. The Lower Peninsula watershed covers approximately 98 squaremiles with creeks flowing from the Santa Cruz Mountains into southwest San Francisco Bay and its tidal wetlands. The Santa Clara Valley Water District's (District) Safe, Clean Water and Natural Flood Protection Program has many priorities, including Priority D for restoring and protecting vital wildlife habitat, and providing opportunities for increased access to trails and open space. The D5 Project focuses on ecological data collection and analysis at a watershed scale to support the District, other County agencies and organizations in making informed ecological asset management decisions. The key performance indicators (KPIs) for D5 are to: 1. Establish new or track existing ecological levels of service for streams in 5 watersheds. 2. Reassess streams in 5 watersheds to determine if ecological levels of service are maintained or improved.
As sea level rise accelerates, our shores will be increasingly vulnerable to erosion. Particular ... more As sea level rise accelerates, our shores will be increasingly vulnerable to erosion. Particular concern centers around the potential loss of San Francisco Bay's much-valued tidal marshes, which provide natural flood protection to our shorelines, habitat for native wildlife, and many other ecosystem services. Addressing this concern, this study is the first systematic analysis of the rates of marsh retreat and expansion over time for San Pablo Bay, located in the northern part of San Francisco Bay.
Upper Penitencia Creek drains a 24 square mile area within the Coyote Creek watershed in Santa Cl... more Upper Penitencia Creek drains a 24 square mile area within the Coyote Creek watershed in Santa Clara County, California. Like many creeks in the Santa Clara Valley, Upper Penitencia Creek has experienced extensive modifications to its hydrology, geomorphology, and ecology over the past 250 years, particularly along its course across the valley floor. This report uses archival data to document historical (mid-19th century) conditions along Upper Penitencia Creek as it flowed through the Santa Clara Valley. Findings confirm and advance the historical analyses of the Coyote Creek Watershed Historical Ecology Study (Grossinger et al. 2006) and the Upper Penitencia Creek Feasibility Study: Draft Functional Assessment (DeJager and Martel 2006). We found that Upper Penitencia Creek exhibited several heterogeneous reaches characterized by distinct riparian communities and dry season hydrology: moving downstream, conditions transitioned from mixed riparian forest and perennial flow in the canyon reach (Alum Rock Park) to a sycamore-dominated riparian corridor and intermittent flow conditions to at least the upstream Mabury Road crossing. At the historical terminus of the creek, an extensive wetland complex composed of freshwater marsh, seasonally flooded wetlands, and large willow thickets separated Upper Penitencia Creek from Coyote Creek and Lower Penitencia Creek. Throughout, we found that the creek exhibited a relatively low sinuosity, though we did document the loss of former side channels. Our findings detail numerous aspects of Upper Penitencia Creek that have changed over time, the most notable arguably being the shift to a more perennial hydrology (sustained by summer releases and imported water) and the diversion of Upper Penitencia Creek into Coyote Creek in the early 1850s. Despite the many modifications, however, aspects of the former creek have persisted in even the most urbanized reaches of Upper Penitencia Creek. In particular, the persistence of a sycamore-dominated riparian canopy on the valley floor upstream of Capitol Avenue is notable, as is the relative stability of channel planform over this time frame. This study reveals the wide range of local conditions found along the creek historically, providing context for understanding the current system and suggesting possibilities for how to manage the creek in the future. upper penitencia creek • 1
The technical memorandum focuses on describing the historical (i.e., prior to substantial Euro-Am... more The technical memorandum focuses on describing the historical (i.e., prior to substantial Euro-American modification) characteristics of the valley floor portion of South Santa Clara County, including Uvas, Carnadero, Llagas, and Pacheco creeks and the upper Pajaro River, and including the intervening, hydrologically connected San Felipe Lake area in north San Benito County. Preliminary Status It should be recognized that this assessment is preliminary to the South County Historical Ecology Study report (which will incorporate additional data, analysis, and review) and is thus subject to some adjustment and modification over the next 12 months. The scope of this document, therefore, will be limited to the more well-documented aspects of the historical landscape. This information should provide a conceptual framework for conservation planning as well as the incorporation of subsequent, more detailed information during the course of the project. Data Sources This assessment is based upon the examination and synthesis of a wide range of historical data sources. We consulted dozens of maps associated with the Mexican Land Grant Ranchos, including the original diseños (circa 1840), and reviewed court transcripts of testimony about the land grant boundaries (1850s-1860s). Along with the Public Lands Surveys of the General Land Office (1850s-1870s), these documents provided extensive evidence for landscape features prior to most Euro-American impacts. We also consulted early written accounts, soil surveys, other early maps (e.g. Thompson and West 1876), local histories, and County surveys. We created a photomosaic of the earliest available aerial imagery (1939) which, while reflecting substantial land use impacts, nevertheless provides illustration of landscape characteristics before post-World War II development. Natural Landscape Patterns Understanding how individual habitat types fit together to form a larger landscape is essential to a conservation plan. Documenting the landscape-level spatial patterns of the region prior to Euro-American modification can indicate functional relationships between habitats, such as the proximity of ecological support functions for target species. A map of landscape patterns can also help identify underlying physical controls on habitat formation and maintenance by revealing basic relationships to topography, soils, groundwater, and other factors. This section thus provides a landscape ecological overview of the area (Figure 1). Historical quotes and images are used to provide contemporary illustration of ecological and hydrological conditions.
San Francisco Bay wetland managers are looking landward for ways to accommodate accelerated sea l... more San Francisco Bay wetland managers are looking landward for ways to accommodate accelerated sea level rise due to climate change. A major concern is that sea level rise will drown existing tidal marshes except for a narrow ring of marshland between the Bay and the built environment. This would eliminate many of the Bay's ecological services, as well as many of the ecological connections to the terrestrial environment upon which these services depend. Emerging plans therefore call for the conservation and reconnection of a tidal-terrestrial transition zone (T-zone) where tidal marshes and their terrestrial connections can be created or allowed to naturally evolve. Planning the future T-zone requires knowledge of its natural form and structure-how its physical dimensions and habitat composition varied around the Bay due to natural drivers such as climate and topography, and how they might respond to future conditions. However, the T-zone was severely and extensively altered in this region during the early stages of Euro-American colonization. Information about its historical character-its width, the diversity and relative amount of habitat types that comprised it, the associated ecological functions, and the physical drivers that controlled these patterns-is fragmented and scattered among many sources within the region and elsewhere. Historical ecology can be a useful tool to assemble this information into a coherent and scientifically-sound picture of historical conditions to inform T-zone planning for the future. In this pilot project we investigated several aspects of historical T-zone form and structure for a subset of the Bay. We found that the South Bay tidal-terrestrial interface was dominated (nearly 70%) by low-gradient seasonal wetlands grading into high marsh. Within this overall pattern, however, the T-zone was quite diverse. Seasonal wetlands included wet meadow, alkali meadow, and vernal pool complexes-each with distinct ecological characteristics and functions. Willow thickets, depressional wetlands (freshwater marsh), and alluvial grassland and riparian forests also contributed to the diversity of the T-zone. Relatively steeply-sloped grasslands bordering tidal marsh-the historical interface type most similar in composition to the levee faces that constitute most of the T-zone observed today in the South Bay-comprised less than 10% of the South Bay tidal-terrestrial interface. The T-zone included variation on the tidal side as well, with fresh-brackish tidal marshes associated with major creek mouths interspersed within a broad salt marsh context. Our study also suggests that the width of the T-zone varied dramatically with physical setting, from several meters to thousands of meters. The zone was broadest in areas with significant fluvial influence and in the most gently-sloping portions of the region. The findings from this study suggest several immediate and longer-term management implications. For example, it will be important to consider the variability in and relative proportions of T-zone types in Bay restoration planning to conserve the full range of the T-zone's ecological services. In addition, a regional approach will be necessary to match local settings with the most appropriate T-zone types. Because distinctive soil characteristics play a key role in forming many T-zone habitat types, it will be important to preserve and enhance the areas scattered throughout the region with soils that retain this potential. To develop this adaptive design capacity, several next steps are recommended. Extension of the historical T-zone analysis to the rest of the Bay will be important to develop the full T-zone restoration palette. For example, research in the North Bay has documented additional T-zone types that may be applicable to other parts of the Bay (e.g., valley oak savanna-tidal marsh transitions on coarse soils may be applicable to engineered slopes; Grossinger 2012). In addition, it will be useful to develop this understanding into a set of conceptual models linking T-zone types to physical drivers and target ecological functions (as has been initiated through the Baylands Ecosystem Habitat Goals Update). Relating these T-zone types to their geophysical setting-e.g., soils, slope, groundwater and surface water hydrology-will allow their translation into landscape designs using a combination of natural and engineered processes. The emerging understanding of the character and function of the Bay's T-zone can help us re-integrate it into the contemporary and projected future landscape.
Figure 1.1. Proposed subregions for nutrient analyses. These subregions are derived from operatio... more Figure 1.1. Proposed subregions for nutrient analyses. These subregions are derived from operational landscape units (OLUs), which are a proposed planning tool for landscape-scale ecosystem restoration in the Delta (Grenier & Grossinger 2013).
This report describes baseline information about the amount and distribution of aquatic resources... more This report describes baseline information about the amount and distribution of aquatic resources, and evaluates that overall ecological conditions of streams using the California Rapid Assessment Method (CRAM), for the Lower Peninsula watershed in Santa Clara County; consisting of Stevens-Permanente Creek, Adobe Creek, southern extent of San Francisquito Creek, and their tributaries. The Lower Peninsula watershed covers approximately 98 squaremiles with creeks flowing from the Santa Cruz Mountains into southwest San Francisco Bay and its tidal wetlands. The Santa Clara Valley Water District's (District) Safe, Clean Water and Natural Flood Protection Program has many priorities, including Priority D for restoring and protecting vital wildlife habitat, and providing opportunities for increased access to trails and open space. The D5 Project focuses on ecological data collection and analysis at a watershed scale to support the District, other County agencies and organizations in making informed ecological asset management decisions. The key performance indicators (KPIs) for D5 are to: 1. Establish new or track existing ecological levels of service for streams in 5 watersheds. 2. Reassess streams in 5 watersheds to determine if ecological levels of service are maintained or improved.
Southern California's coastal wetlands are an interrelated set of resources that collectively pro... more Southern California's coastal wetlands are an interrelated set of resources that collectively provide a broad suite of ecological, hydrological, and biogeochemical functions. Managing and restoring these systems requires a regional perspective that can inform holistic decision making. Knowledge of historical conditions provides a baseline of the extent and condition of wetlands lost, and is important to guide regional planning. The U.S. Coast and Geodetic Survey topographic sheets (T-sheets) provide the most important single source for understanding the physical and ecological characteristics of the US shoreline prior to Euro-American modification. Their depictions of coastal wetlands and other estuarine habitat types can provide relatively consistent information about the extent and distribution of those systems along the southern California Bight (SCB) prior to substantial human alteration. Although most appropriately used in conjunction with other data sources, the T-sheets can provide a foundation for regional analysis and a platform on which future, more detailed investigations can be based. This project builds on earlier efforts to provide comprehensive analysis of the 40 T-sheets that cover the SCB from Point Conception to the US-Mexico border. High quality scans of the original T-sheets produced between 1851 and 1889 were obtained along with the surveyor notes. T-sheets were digitized, georeferenced, and interpreted in order to provide a map of coastal estuaries (both large and small) and coastal drainage systems representing conditions along the SCB coast in the mid-late 19 th Century. This analysis was used to answer the following questions: 1. How much total estuarine habitat was there historically (i.e., as mapped on the T-sheets) compared to today? 2. How many total coastal systems occurred historically? 3. What has happened to historical estuarine habitat types? Extent of coastal estuarine habitats The SCB coast supported approximately 19,591 hectares of estuarine habitats. Approximately 40% of this area was vegetated wetlands (e.g., salt marsh), 25% was unvegetated wetlands (e.g. salt flat and mudflat), and the remaining 35% was subtidal water. In addition to these habitat types, an additional 5,496 hectares of "other wetlands" were mapped on the T-sheets. These included dune and beach, woody vegetated wetlands, high marsh habitat, isolated ponds, and riverine habitat. Over half (~57% or ~11,000 hectares) of all historical estuarine habitats were found in San Diego County, mostly associated with Mission and San Diego Bays. Both Los Angeles and Orange Counties contained about 15% each of the total historical estuarine area. The largest expanses of historical salt flats occurred in Los Angeles County. Number of estuarine systems A total of 331 coastal systems occurred along the SCB coast. Approximately 2/3 of these systems consisted of small coastal drainages without any associated terminal wetlands. Individual coastal systems were relatively evenly distributed along the coast, with each county having between 60 and 90 systems. The distribution of systems by size was also relatively uniform across the counties. The exceptions were a slightly higher concentration of medium and large systems in San Diego County and slightly more channel only systems in Los Angeles County. On a regional scale, larger systems occur in three areas ii distributed along the SCB coastline, south San Diego, Long Beach, and Southern Ventura County. These three nodes were connected through strings of medium and smaller wetlands. The 331 systems can be grouped in 15 distinct archetypes (or distinct compositions) representing combinations of size and dominant habitats. These archetypes tended to be spatially aggregated along the coast into loose "families" of systems. Change over time Since ca. 1850 there has been an overall loss of 9,317 hectares, or 48% of historical estuarine habitat types along the SCB coast. Estuarine vegetated wetlands have experienced the greatest loss in terms of absolute area (-5819 ha, 75% loss), while estuarine unvegetated wetlands have experienced the greatest proportional loss of 78% of historical extent (Figure ES-1). In contrast, the contemporary landscape represents a 5% increase in subtidal habitat from historical extent. These differential losses have shifted the proportional composition of southern California estuaries. Historically there was a relatively even split between estuarine vegetated (40%), estuarine unvegetated (25%), and subtidal water (35%). Currently the proportional composition is heavily weighted towards subtidal water (71%) while estuarine vegetated (19%) and unvegetated (10%) make up less than ⅓ of the total area combined. Declines in estuarine area vary by county. Total losses across all counties range from 62% in Santa Barbara to 31% in San Diego. Additionally, the composition of estuaries in the counties has shifted. In the southern most counties (Los Angeles, Orange, and San Diego) there has been a significant increase in subtidal water while both intertidal and vegetated wetlands have decreased. Santa Barbara and Ventura Counties have maintained an estuarine composition similar to that seen in ca. 1850. Figure ES-1. Change in overall extent and composition of estuarine habitat types between ca. 1850 and ca. 2005 Our estimated estuarine habitat losses, although substantial, are significantly lower than previously reported estimates of over 90% total wetland loss in California. Overall estuarine habitat area changes reflect and, to some extent, hide the disproportionate impacts to different estuarine habitat types. For example subtidal habitat has increased slightly while other types have decreased dramatically. Differences from other estimates may also be explained by the fact that our analysis is more precise than that used to produce previous estimates and/or that previous estimates may have included other wetland types or iii locations not included in this study. Lower than "expected" rates of loss may also reflect policies and programs over the last 40 years aimed at protecting and restoring coastal wetlands. Looking to the future, knowledge of historical wetland extent and patterns of loss can be used to inform future planning for diverse and resilient coastal landscapes. This report provides a synthesis of the main results of our analysis. Scanned images of the T-sheets, GIS and Google Earth layers of the maps, and the underlying data from this project are available at www.caltsheets.org. Acknowledgements Funding for this work was provided the California State Coastal Conservancy (Agreement 06-061), U.S. Fish and Wildlife Service (Co-op Agreement #80211AJ111), and the California State Wildlife Conservation Board. Dr. John Cloud was instrumental in helping us obtain high resolution scans of the Tsheets that formed the basis for much of our analysis. We thank the Wetland Recovery Project Wetland Managers Group for their input and feedback at key junctures of this project. We also thank Wayne Engstrom, Walter Heady, Megan Cooper, David Jacobs, and Richard Ambrose for their insightful and constructive comments on the draft report. Finally, we are indebted to the talented surveyors and cartographers who produced the T-sheets that have provided valuable insight into historical conditions along the Southern California Bight.
This report proposes a new multi-benefit approach to flood management along Upper Penitencia Cree... more This report proposes a new multi-benefit approach to flood management along Upper Penitencia Creek. Recognizing the creek's complex history, land use, and challenges, this report explores a suite of actions that could help meet flood management objectives while improving ecosystem functioning, expanding recreational opportunities, and supporting water supply needs. The San Francisco Estuary Institute-Aquatic Science Center (SFEI-ASC) and the Santa Clara Valley Water District (District) worked with technical advisors and a group of local stakeholders to explore a range of multi-benefit management opportunities along Upper Penitencia Creek, culminating in this Resilient Landscape Vision. The vision focuses on ways to expand flow conveyance and flood water storage from the Coyote Creek confluence upstream to the Dorel Drive bridge in a manner that works with the existing landscape features and supports habitats for native species. The management measures described here fall into two main categories: • In-channel improvements & riparian enhancements includes floodplain excavation, setting back levees, and managing vegetation in modified channelfloodplain areas to better support native wildlife • Multi-benefit off-channel detention includes creating high-flow floodplain basins that have multiple uses (e.g., sports fields and flood detention) and provide habitat features to support native wildlife Additional management measures related to modifying flow and sediment delivery from the upper watershed are also discussed. The next steps for implementing the vision measures include developing design alternatives, conducting feasibility analyses, continued collaboration with local stakeholders who own and manage land along the creek, and garnering regulatory agency support. Although situated in a highly developed landscape, the Upper Penitencia Creek channel-floodplain corridor retains a considerable amount of open space that provides opportunities for multi-benefit flood management. This Vision can be used as guidance in similar landscapes around the region, where managers are seeking to implement a nature-based approach to flood management that leverages existing open space features and benefits both people and wildlife. VISION FOR UPPER PENITENCIA CREEK • v sycamore and oaks along upper penitencia creek VISION FOR UPPER PENITENCIA CREEK • 3 This Upper Penitencia Creek landscape vision is intended to serve as a roadmap for supporting ecosystem functions to benefit people and wildlife. It is intended to assist the District, its partners, and other regional stakeholders in planning adaptation approaches to ecological stewardship, flood risk management, recreation, and water supply for Upper Penitencia Creek during the coming decades. The District is seeking to develop a new management approach in coordination with local partners who own and operate land adjacent to the creek (e.g., City of San José, County of Santa Clara, and local school districts), explicitly incorporating the partners' goals into the approach, and managing the areas adjacent to the creek to provide multiple benefits.
This report describes baseline information about the amount and distribution of aquatic resources... more This report describes baseline information about the amount and distribution of aquatic resources, and evaluates that overall ecological conditions of streams using the California Rapid Assessment Method (CRAM), for the Lower Peninsula watershed in Santa Clara County; consisting of Stevens-Permanente Creek, Adobe Creek, southern extent of San Francisquito Creek, and their tributaries. The Lower Peninsula watershed covers approximately 98 squaremiles with creeks flowing from the Santa Cruz Mountains into southwest San Francisco Bay and its tidal wetlands. The Santa Clara Valley Water District's (District) Safe, Clean Water and Natural Flood Protection Program has many priorities, including Priority D for restoring and protecting vital wildlife habitat, and providing opportunities for increased access to trails and open space. The D5 Project focuses on ecological data collection and analysis at a watershed scale to support the District, other County agencies and organizations in making informed ecological asset management decisions. The key performance indicators (KPIs) for D5 are to: 1. Establish new or track existing ecological levels of service for streams in 5 watersheds. 2. Reassess streams in 5 watersheds to determine if ecological levels of service are maintained or improved.
As sea level rise accelerates, our shores will be increasingly vulnerable to erosion. Particular ... more As sea level rise accelerates, our shores will be increasingly vulnerable to erosion. Particular concern centers around the potential loss of San Francisco Bay's much-valued tidal marshes, which provide natural flood protection to our shorelines, habitat for native wildlife, and many other ecosystem services. Addressing this concern, this study is the first systematic analysis of the rates of marsh retreat and expansion over time for San Pablo Bay, located in the northern part of San Francisco Bay.
Upper Penitencia Creek drains a 24 square mile area within the Coyote Creek watershed in Santa Cl... more Upper Penitencia Creek drains a 24 square mile area within the Coyote Creek watershed in Santa Clara County, California. Like many creeks in the Santa Clara Valley, Upper Penitencia Creek has experienced extensive modifications to its hydrology, geomorphology, and ecology over the past 250 years, particularly along its course across the valley floor. This report uses archival data to document historical (mid-19th century) conditions along Upper Penitencia Creek as it flowed through the Santa Clara Valley. Findings confirm and advance the historical analyses of the Coyote Creek Watershed Historical Ecology Study (Grossinger et al. 2006) and the Upper Penitencia Creek Feasibility Study: Draft Functional Assessment (DeJager and Martel 2006). We found that Upper Penitencia Creek exhibited several heterogeneous reaches characterized by distinct riparian communities and dry season hydrology: moving downstream, conditions transitioned from mixed riparian forest and perennial flow in the canyon reach (Alum Rock Park) to a sycamore-dominated riparian corridor and intermittent flow conditions to at least the upstream Mabury Road crossing. At the historical terminus of the creek, an extensive wetland complex composed of freshwater marsh, seasonally flooded wetlands, and large willow thickets separated Upper Penitencia Creek from Coyote Creek and Lower Penitencia Creek. Throughout, we found that the creek exhibited a relatively low sinuosity, though we did document the loss of former side channels. Our findings detail numerous aspects of Upper Penitencia Creek that have changed over time, the most notable arguably being the shift to a more perennial hydrology (sustained by summer releases and imported water) and the diversion of Upper Penitencia Creek into Coyote Creek in the early 1850s. Despite the many modifications, however, aspects of the former creek have persisted in even the most urbanized reaches of Upper Penitencia Creek. In particular, the persistence of a sycamore-dominated riparian canopy on the valley floor upstream of Capitol Avenue is notable, as is the relative stability of channel planform over this time frame. This study reveals the wide range of local conditions found along the creek historically, providing context for understanding the current system and suggesting possibilities for how to manage the creek in the future. upper penitencia creek • 1
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