Columbia Basin
Wildlife Area Location

Chad Eidson
6653 Road K NE
Moses Lake, WA 98837
(509) 765-6641

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Columbia Basin Wildlife Area
Potholes Reservoir Unit
The 32,820-acre Potholes Reservoir unit is formed by O'Sullivan Dam south of Moses Lake in Grant County as part of the Columbia Basin Irrigation Project. Reservoir water levels are subject to wide fluctuations because the project’s purpose is to gather wastewater and return flows from irrigated lands upstream and store water for reuse on farmland downstream. At full pool in spring there are 20,000 acres of surface water. The dam initially inundated the Crab Creek channel and about 800 small ponds scattered among the sand dunes of the area. With several thousand acres of water covering the sand dune area, perhaps 1,000 islands were formed in the north and west parts of the reservoir. These seasonally flooded areas currently support a small forest of willow trees. The higher elevation wetlands on the northern and western fringes of the reservoir have cattail and bulrush communities. The western part still has many active sand dunes with shrub steppe vegetation, except for the wetland areas along the Winchester and Frenchman Hills wasteways. The Desert unit borders on the west. The east side of the unit is mostly sand, gravel and round rock soil with shrub steppe vegetation bordered by irrigated farmland. The southern area, adjacent to O'Sullivan Dam, is mostly basalt outcroppings with big sage and bluebunch wheatgrass occurring where soil exists. The original Crab Creek channel is exposed just below O'Sullivan Dam and west of Potholes Canal, the outlet of the reservoir. Wildlife use of this unit includes waterfowl, wintering bald eagles, mule deer and one of the two known populations of northern leopard frogs in Washington.
Viewing Opportunities


  • Birds of Prey
  • Eagles
  • Shorebirds
  • Songbirds
  • Upland Birds
  • Wading Birds
  • Waterfowl
  • Mammals

  • Deer
  • Small Mammals
  • Other

  • Butterflies
  • Reptiles/Amphibians
  • Wildflowers
  • How to Get Here
    Access Site #1
    Driving Directions
    From Moses Lake, Take I-90 west to the Mae Valley Road Exit 174, turn south on Mae Valley Road and cross the freeway overpass to the intersection of South Frontage Road. Turn east (left) and then straight ahead 1/4 mile to Sage Road and another 1/4 mile to Sand Dunes Road. Go south on Sand Dunes Road to access the two Moses Lake Outlets and the east Crab Creek Arm of Potholes Reservoir. Back at the end of Mae Valley Road, Turn west (right) on South Frontage Road and travel west two miles to Road D.5 NE. Take this gravel road south a couple miles to access four dead end roads with parking areas in the 'North Potholes' portion of the Potholes Unit. Farther west on South Frontage Road, there is a primitive WDFW parking area at the south end of county Road A SE, 2.5 miles south of the South Frontage Road. There are no access roads for the western portion of the Potholes Unit. The south O'Sullivan Dam and Lind Coulee portions of the Potholes Unit are accessed from Moses Lake on SR 17, 1.5 miles south of I-90 Exit 179. Take county Road M SE from SR 17, 5.5 miles south to the WDFW Lind Coulee parking area on the northwest side of the wasteway bridge. Just south of Lind Coulee, Road M SE intersects with Highway 262. Turn west (right) on that highway to access more WDFW roads and parking areas on the lower Lind Coulee. Continue west on Hwy. 262 to the the Glen Williams parking area at the southeast corner of Potholes Reservoir. Highway 262 crosses the O'Sullivan Dam from Glen Williams and Potholes Canal on the east end to MarDon Resort at the west end of the dam. Just 1/2 mile west of MarDon Resort is the WDFW parking area known as Blythe Access. West of Blythe Access is the entrance to Potholes State Park.
    Parking/Restroom Information
    The two WDFW parking areas on Sand Dunes Road, at the north and south Moses Lake outlets, both have large parking lots with outhouses. There are no outhouses in the North Potholes area or at the Road A SE parking area. The parking area at Lind Coulee Wasteway on Road M SE is large and has two outhouses and a concrete boat ramp. The Glen Williams parking area on Hwy. 262, is also a large, partially paved, parking lot with two outhouses and two concrete boat ramps. The Blythe Access has two outhouses, some pavement, an overnight parking area, a day use parking area and a concrete boat ramp.

    See listing of Potholes Reservoir Access Sites and Facility Information

    Other Information
    The North Potholes Game Reserve is within the 'North Potholes' portion of the Potholes Unit.
    Unique Features
    The Potholes Reservoir was created by the construction of O'Sullivan Dam to impound water for the federal Columbia Basin Irrigation Project. The 20,000 acre reservoir and adjoining public lands, provide great wildlife habitat for many species and offers many public recreation opportunities.
    Wildlife Area Habitat Conservation Plans
    Weekender Report
    Wildlife Viewing Guides
    Accessing Washington's Outdoors
    Find a Water Access Site
    GoHunt - Interactive Mapping
    Green Dot Maps
    No activities currently listed for this Unit.

    If you are Hunting or Fishing, remember to check all current regulations.

    Activities may include restrictions or require permits. Please see Public Conduct Rules for more information.