2020 Map of O'Sullivan Dam

About this map

O'Sullivan Dam serves as the focal point of this arid Washington landscape, holding back the sprawling Potholes Reservoir at the edge of the Frenchman Hills. The area is defined by a sophisticated water management system crucial for the regional agricultural economy, featuring the Potholes Canal, the Goose Lake Wasteway, and the Crab Creek Lateral. South of the dam, the terrain descends toward the Royal Slope, where a chain of smaller water bodies including Upper Goose Lake, Lower Goose Lake, and Black Lake provides a stark contrast to the surrounding high desert. The map also delineates the boundary between Grant Co and Adams Co, showing how local infrastructure like Kulm Rd SE and W Phillips Rd connects these isolated water features and wildlife areas like Marsh Unit One.