{"id":2517,"date":"2020-02-06T13:53:49","date_gmt":"2020-02-06T21:53:49","guid":{"rendered":"https:\/\/mlml.sjsu.edu\/ccwg\/?page_id=2517"},"modified":"2020-07-13T14:17:02","modified_gmt":"2020-07-13T21:17:02","slug":"estuary-map","status":"publish","type":"page","link":"https:\/\/mlml.sjsu.edu\/ccwg\/estuary-map\/","title":{"rendered":"Bar Built Estuary info page and Map"},"content":{"rendered":"
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\n\t\t\t\t\t\tBar-Built Estuaries of California\t\t\t\t\t\t<\/h1>\n\t\t\t\t\t\t\t\t\t\t\t
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\n\t\t\t\t\t\tBar-built estuaries (BBEs) are located at the terminus of creeks and rivers where a wave-built sand barrier restricts connection with the ocean.\t\t\t\t\t\t<\/p>\n\t\t\t\t\t\t<\/div>\n<\/div><\/div><\/div>

What are Bar-built Estuaries?<\/h3>\n
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Bar-built estuaries (BBEs) are located at the terminus of creeks and rivers where a wave-built sand barrier restricts connection with the ocean.\u00a0 The formation of this sand barrier is driven by a dynamic set of processes that vary regionally and seasonally depending on watershed and <\/span>climate<\/span><\/a>, river inflows, <\/span>river<\/span><\/a> sediment load, tidal flows, nearshore sediment supply, wave exposure, and development (including transportation infrastructure). The constricted mouths of BBEs constrain tidal exchange between the estuary and the ocean and modify estuary hydrology.\u00a0 These mouths close periodically, completely separating the estuary from the ocean and impounding water within a lagoon (a coastal lake), with water surface elevations that may rise above high-tide levels in the ocean (Behrens et al. 2015b). The frequency and duration of inlet closure varies naturally across BBEs and across years. The mouth state is not binary (fully open or fully closed) as these systems transition among multiple mouth states, including non-tidal phases (closed mouth), perched overflow, tidal choking (muted tides relative to ocean), and fully tidal (fully open mouth).\u00a0<\/span><\/p>\n

\u00a0<\/span>The salinity regime of a bar-built estuary can be highly variable, exhibiting tidal fluctuations when open and different BBEs can be entirely fresh, vertically stratified or entirely hypersaline when closed, dependent on the hydrological balance and the condition of the sand barrier at the mouth of the system.\u00a0 There is a trend toward lower salinities in more northern estuaries where a positive water balance is the result of higher rainfall and river inflow, and higher salinities in southern California estuaries \u2013 but conditions also depend on watershed size and yield. Intense, two-layer salinity stratification is common in these systems when the mouth is closed or in transition (perched or muted mouth states).<\/span><\/p>\n

\u00a0<\/span>California\u2019s bar-built estuaries afford unique habitats with a wide range of special ecological services.\u00a0 Further, a suite of species listed as threatened or endangered under the federal Endangered Species Act (ESA) depend on these habitats, including the tidewater goby, Belding\u2019s savannah sparrow, steelhead trout, and Western snowy plover. In addition, benefits accrue to local human communities such as recreation, flood attenuation, and water filtration.\u00a0 Depending on the local geology and the degree of confinement by adjacent uplands, these systems may support spatially extensive wetland habitats and resources, or they may support only a narrow estuary comprised of an open water channel.\u00a0<\/span><\/p>\n<\/div>\n<\/div><\/div>

BBE Management Considerations:<\/h3>\n
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Water impoundment behind the sand barrier can conflict with some site-specific environmental or land-use objectives.\u00a0 Municipalities and resource managers routinely manage mouth state to protect specific environmental conditions or adjacent property.\u00a0 When undesirable water elevation or water quality triggers active management, there are limited options other than implementing a managed breach.\u00a0 Permits are applied for and issued on a case-by-case basis to address a variety of management purposes (<\/span>e.g<\/span><\/i>., alleviate impacts of flooding, improve estuary water quality, improve conditions for wildlife, improve public access).\u00a0<\/span><\/p>\n

CCWG, in collaboration with Bodega Marine Lab, authored a report describing Considerations for Management of the Mouth State of California\u2019s Bar-built Estuaries<\/a><\/p>\n

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\n\t\t\t\t\t\tInteractive Map of BBE data\t\t\t\t\t\t<\/h1>\n\t\t\t\t\t\t\t\t\t\t\t
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