Lower Yakima River

The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border.

There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011.

The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.

Geography

Watersheds/Reaches and corresponding 12-Digit Hydrologic Unit Codes (based on USGS 2024 Watershed Boundary Set)

1. Prosser Reach - Yakima River Mainstem (City of Prosser-Yakima River, 170300031007)
2. Lower Mainstem Reach (Yakima River, 170300031205; Webber Canyon-Yakima River, 170300031203; Badlands Lakes-Yakima River, 170300031202)
3. Spring and Snipes Creeks (Spring Creek,170300031005; Snipes Creek,170300031006)
4. Corral Creek (Corral Creek,170300031201)
5. Amon Creek Wasteway (Coyote Canyon, 170300031204)
6. Cold Creek (Cold Creek, 170300031109; Lower Cold Creek, 170300031108; Middle Cold Creek, 170300031107; Upper Cold Creek, 170300031106; Headwaters Cold Creek, 170300031101)

Washington State designated this area as part of Water Resource Inventory Area (WRIA) 37, see PDF

Lower River Flow

USGS stream gage at Kiona, see USGS Gage.

Tributaries to the Lower Yakima River

Spring/Snipes Creek

Corral Creek

Amon Creek

Cold Creek

Facilities

Prosser Dam

Prosser Hatchery and Enumeration Facility

Chandler Power Plant

Horn Rapids Dam/Wannawish

Yakima Delta

The Yakima delta and confluence is a critical link to the entire Yakima River both today and historically. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.

It still provides an important link for fish as an adult and juvenile migration corridor.

However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.

The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.

For more info see the Yakima Delta page.

For more info on the Bateman Island/Causeway Project, see the Bateman Island page.

Water Stargrass (Heteranthera dubia)

Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam.

See separate page on Water stargrass