O’Sullivan Dam

The O’Sullivan Dam is located south of the communities of Ephrata and Moses Lake in Central Washington. It is part of the Columbia Basin Irrigation Project and helps with both irrigation and recreation.

Fun Facts About O’Sullivan Dam

-Construction on O’Sullivan Dam began in 1947 and was completed in 1949.

-O’Sullivan Dam holds back the water of Crab Creek, a small but major waterway in the area.

-The water backed up by O’Sullivan Dam forms Potholes Reservoir. This reservoir is designed to collect the return flows from all of the irrigation in the northern portion of the Columbia Basin Irrigation Project so that it can be used in the southern portion.

-O’Sullivan Dam measures in at 200 feet high.

-O’Sullivan Dam measures in at 19,000 feet in length.

-O’Sullivan Dam is one of the largest earthen dams in the entire United States.

-O’Sullivan Dam is located in Grant County.

Featured Attractions / Activities Near O’Sullivan Dam

Potholes Reservoir
MarDon Resort

Featured Lodging Near O’Sullivan Dam

MarDon Resort
The Inn at Moses Lake

Featured Restaurants Near O’Sullivan Dam

Michaels on the Lake