Level 1 Water-Quality Inventory of Baseline Levels of Pesticides in Urban Creeks - Golden Gate National Recreation Area and the Presidio of San Francisco, California

AbstractSuspended-sediment flux at the ocean boundary of the San Francisco Estuary—the Golden Gate—was measured over a tidal cycle following peak watershed runoff from storms to the estuary in two successive years to investigate sediment transport through the estuary. Observations were repeated during low-runoff conditions, for a total of three field campaigns. Boat-based measurements of velocity and acoustic backscatter were used to calculate water and suspended-sediment flux at a location 1 km landward of the Golden Gate. Suspended-sediment concentration (SSC) and salinity data from up-estuary sensors were used to track watershed-sourced sediment plumes through the estuary. Estimates of suspended-sediment load from the watershed and net suspended-sediment flux for one up-estuary subembayment were used to infer in-estuary trapping of sediment. For both post-storm field campaigns, observations at the ocean boundary were conducted on the receding limb of the watershed hydrograph. At the ocean boundary, peak instantaneous suspended-sediment flux was tidally asymmetric and was greater on flood tides than on ebb tides for all three field campaigns, due to higher average SSC in the cross-section on flood tides. Shear-induced sediment resuspension was greater on flood tides and suggests the presence of an erodible pool outside the estuary. The storms in 2016 led to less export of discharge and sediment from the watershed and greater sediment trapping within one up-estuary subembayment compared to that observed in 2017. Results suggest that substantial trapping of watershed sediments occurred during both storm events, likely due to the formation of estuarine turbidity maxima (ETM) at different locations in the estuary. ETM locations were forced nearer the ocean boundary in 2017. Additional measurements and modeling are required to quantify the long-term sediment flux at the Golden Gate.

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Let There Be a Firmament in the Midst of the Waters

Boom A Journal of California ◽

10.1525/boom.2016.6.1.130 ◽

2016 ◽

Vol 6 (1) ◽

pp. 130-136

Author(s):

Brock Winstead

Keyword(s):

International Relations ◽

San Francisco ◽

San Francisco Bay ◽

World's Fair ◽

Golden Gate ◽

Design History ◽

International Exposition ◽

History Of ◽

The Creation ◽

Treasure Island

Treasure Island in San Francisco Bay was created to host the Golden Gate International Exposition, a World’s Fair, in 1939-40. The fair was an expression of an idealized order of both design and international relations. Neither survived much longer than the fair itself. The author considers the creation and re-creation of Treasure Island and the problem of building for an uncertain, ultimately unknowable future. This article is a critical appreciation of Andrew Shanken’s Into the Void Pacific, a design history of the fair.

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