WALLA WALLA DISTRICT 2024 MINIMUM OPERATING POOL (MOP) OPERATIONS AND SPRING SPILL OPERATIONS

Notice Number: 206433-1/24-03
Date: 04/01/2024 07:00 thru 09/01/2024 06:45

From April through August 2024, the lower Snake River reservoirs will operate within the Minimum Operating Pool (MOP) ranges. During this time, all lower Snake and lower Columbia River dams will spill for fish passage in accordance with the 2024 Fish Operations Plan. The Fish Operations Plan is posted to the following website: https://safe.menlosecurity.com/doc/docview/viewer/docNBD0DA39B2B99781474b003931b92659d0a36169259da3df80b3cf57ad697c6b50d3876472818

Facilities affected: McNary Lock & Dam (Columbia River mile 292); Ice Harbor Lock & Dam (SN River mile 9.7); Lower Monumental Lock & Dam (SN River mile 41.6); Little Goose Lock & Dam (SN River mile 70.3); and Lower Granite Lock & Dam (SN River mile 107.3).

MOP ranges for each Snake River pool are listed below. Elevations are in NGVD 29 datum.

Pool Elevation (in feet)

Ice Harbor, Lake Sacajawea 437-438.5

Lower Monumental, Lake Herbert G. West 537-538.5

Little Goose, Lake Bryan 633-634.5

Lower Granite, Lower Granite Lake 733-734.5

Due to recent changes in fish passage spill requirements, the Corps anticipates a higher rate of discharge through the spillways compared to previous years, and river navigators may experience strong currents and eddies in the dam tailraces and forebays. If navigators believe river conditions inhibit safe navigation to or from a lock, they may request a temporary adjustment to spill using the contact information below. Contact with lock and dam shift operators should be initiated at least 30 minutes prior to arriving at the lock, as a requested redistribution or reduction of spill may take as long as 30 minutes to attenuate. Additionally, downstream departures may be delayed for the requested spill change to be implemented and take effect.

McNary Operator at (541) 922-2231. Call Sign WUJ41 McNary.

Ice Harbor Operator at (509)-543-3231. Call Sign WUJ42 Ice Harbor.

Lower Monumental Operator at (509) 282-7231. Call Sign WUJ43 Lower Monumental.

Little Goose Operator at (509) 399-2233 x231. Call Sign WUJ44 Little Goose.

Lower Granite Operator at (509) 843-2231. Call Sign WUJ45 Lower Granite.

Navigators are encouraged to contact dam operators and report any unsafe navigation conditions. District staff will evaluate the effects of this year’s operations in conjunction with feedback from river users and coordinate adjustments to spillway gate positioning as appropriate.

For additional information contact the NWW Operations Division at (509) 527-7364.

//signed//

Koebberling, Kenneth E, Navigation Business Line Manager