Lakes / Oregon / Morrow County / McCormack Slough
McCormack Slough, Oregon
248 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Oregon
45.89 degrees N, 119.58 degrees W - Morrow County. State and county outlines drawn from Census boundary data; the lake marker is placed by its USGS National Hydrography Dataset coordinates, not by eye. Schematic - not a survey map.
How McCormack Slough Stacks Up
- Larger than 75% of the 642 lakes counted in Oregon.
- About 152 miles from Portland, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Lake Umatilla | Morrow | 18 mi | 50,042 acres |
| Carty Reservoir | Morrow | 18 mi | 1,025 acres |
| Cold Springs Reservoir | Umatilla | 21 mi | 1,440 acres |
| Willow Lake | Gilliam | 22 mi | 307 acres |
| Willow Creek Reservoir | Morrow | 38 mi | 154 acres |
| McKay Reservoir | Umatilla | 44 mi | 1,174 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About McCormack Slough
How Big Is McCormack Slough?
McCormack Slough covers 248 acres in Morrow County, Oregon.
What Is the Largest Lake in Morrow County?
Lake Umatilla is the largest lake in Morrow County, at 50,042 acres.
Largest Lakes in Oregon
| # | Lake | County | Surface Area | Max Depth |
|---|---|---|---|---|
| 1 | Upper Klamath Lake | Klamath | 62,095 acres | - |
| 2 | Lake Umatilla | Morrow | 50,042 acres | - |
| 3 | Lake Abert | Lake | 37,137 acres | - |
| 4 | Summer Lake | Lake | 31,602 acres | - |
| 5 | Harney Lake | Harney | 31,290 acres | - |
All 642 Oregon lakes ranked by surface area
Sources: USGS NHD (The National Map NHD MapServer layer 12) named waterbodies FTYPE 390/436; counties via Census point-in-polygon lake data (ID 167136053). Verified October 30, 2026.