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2021 Map of Union Island

Name: 2021 Topographic Map of Union Island
Creator: U.S. Geological Survey
Published: 2021
License: https://creativecommons.org/publicdomain/mark/1.0/

USGS Topo · Published 2021

About this map

The intricate waterways of the San Joaquin Delta define the landscape of Union Island and Roberts Island, where reclaimed land is protected by an extensive levee system including S Wing Levee Rd. This 2021 survey highlights the engineered hydrology of the San Joaquin Valley, dominated by the Old River and Middle River. Navigational and drainage infrastructure is prominent, featuring the Grant Line Canal, the Fabian and Bell Canal, and several man-made channels like Sugar Cut and Paradise Cut.

The southern portion of the map shows the northward expansion of Tracy toward the delta, while Lathrop sits to the east near the junction of these historical water routes. The density of rural roads like Bacchetti Rd and Corral Hollow Rd reveals a grid-based agricultural economy reliant on the complex network of sloughs, including Salmon Slough and Tom Paine Slough, which remain central to the region's geography.