Tulare Lake
Willow Marsh The Lagoon
The extent of the marshland surrounding Tulare Lake in 1878
Tulare Lake
Location	Amador Valley Alameda County, California
Coordinates	37°40′N 121°54′W / 37.667°N 121.900°W / 37.667; -121.900[1]
Type	Marsh (drained)
Etymology	Once characterized by tule rush
Primary inflows	Arroyo Mocho Arroyo Valle Arroyo Las Positas Tassajara Creek South San Ramon Creek[2]
Primary outflows	Alameda Creek, via Arroyo de la Laguna
Catchment area	San Francisco Bay
Basin countries	United States
Settlements	Pleasanton, California Dublin, California Pelnen (Ohlone)[3] Seunen (Ohlone)[3]

Tulare Lake was a large, shallow lake in eastern Amador Valley, surrounded by Willow Marsh (also known as the Lagoon). Tule rushes and willow trees once lined the marshes and sloughs of its shores. Drainage alterations starting in the 19th century have since reduced the marsh to the Arroyo de la Laguna,^[2][1] and the city of Pleasanton has since expanded across what was once marshland. Such rapid developments have led to tricky seasonal flow variations in Niles Canyon.^[4]

The lake was fed by Arroyos Mocho, Valle, and Las Positas (when rainfall was substantial enough for them to reach the lagoon), as well as by Tassajara Creek and other Amador Valley creeks. Its seasonal outlet was the Arroyo de la Laguna.

Tulare Lake was densely inhabited by groups of the Ohlone people prior to the 19th century.

References