This eelgrass layer includes the maximum
extent of eelgrass beds that have been surveyed in the San Francisco Bay shown
in green. It was created by merging the Bay-wide eelgrass surveys conducted by Merkel
& Associates, Inc. (Merkel) in 2003, 2009, 2014, and a Richardson Bay survey
conducted by Merkel in 2019. Merkel has granted permission for public use of these
data. These eelgrass surveys represent the best available data on comprehensive
eelgrass extent throughout San Francisco Bay in 2021 and are developed using a
combination of acoustic and aerial surveys and site-specific ground truthing. This
layer may be used as a reference to determine potential direct and indirect
impacts to eelgrass habitat from dredging projects. These data do not replace
the need for site-specific eelgrass surveys.Data from the 2003, 2009, and 2014 eelgrass surveys and associated Merkel
reports which include information on mapping methodology are available for
download on the San Francisco Estuary Institute’s (SFEI) website. Methods for creating this layer are as follows:Downloaded the Merkel Baywide Eelgrass Surveys for
2003, 2009, and 2014 from SFEI and combined into a single layer. Obtained original Richardson
Bay 2019 eelgrass survey data from Merkel. Loaded all layers into ArcGIS Pro ©
ESRI and re-projected all data to the NAD 1983 UTM Zone 10N coordinate system. Ran union of both the SFEI
and Richardson Bay 2019 layers. Merged features to create one single attribute table
for eelgrass cover from all survey years. Removed extraneous columns in the
attribute table, recalculated area fields based on new extent, and applied
symbology.
