Lake Levels

Current Reservoir Levels

Lake Tapps Levels Update (12/19/18)

Residents may have noticed that the Lake Tapps Reservoir is higher than anticipated during the winter months. Because of the work being undertaken by the Corps of Engineers on the Diversion Dam, where water is sent from the White River into Lake Tapps, it is necessary to keep the reservoir higher (about 539.5 feet) now to ensure Cascade is able to fill the reservoir in the spring – regardless of the Corps’ progress on the dam.  The reservoir may remain at this level, or even higher with seasonal rains, for the remainder of the winter months.

Lake Tapps Levels Update (10/16/18)

Cascade was able to keep the Lake Tapps Reservoir at about elevation 542.55 feet or above through Sept. 12.  Levels have steadily declined since then and are today approximately elevation 541.5 feet; the low end of “Normal Full Pool.”

Cascade’s agreement with the Lake Tapps Community Council is to maintain lake levels between elevation 541.5 and 543.0 feet through Sept. 30, and to make the best effort to maintain this level into and through October.

The combination of dry weather and historical low flows in the White River have prevented Cascade from maintaining higher lake levels over the past month. Even so, Cascade has maintained levels within the Normal Full Pool range for more than two weeks longer than required by the agreement with the Lake Tapps Community Council. Since mid-September, flow in the White River has been below 500 cfs, the minimum flow requirement set in Cascade’s Lake Tapps’ water rights (see graph). Cascade cannot divert any water into Lake Tapps unless White River flows are above the minimum.

2018 Fall Drawdown Scheduled (9/26/18)

The reservoir, which is full now, will continue to gradually become lower as no additional water is being added.

On Thursday, Nov. 1, Cascade will begin to actively lower reservoir levels to approximately elevation 538.5 feet, where it will likely remain for the rest of the fall and winter. This drawdown is necessary for the integrity of the dikes and to ensure safety from wind, storm and wave action during the winter months.

As usual, residents should watch the drawdown and make appropriate decisions regarding watercraft and other property, but it is recommended that boats be out of the water over the next week to ensure their safety.

Because the US Army Corps of Engineers is working on the Mud Mountain Dam Fish Passage Project in the White River, Cascade will not be reducing the reservoir levels during the winter much beyond this level, unless there is a significant need to do so.

Active fill will begin in early March with the anticipation of reaching minimum recreational level of elevation 541.5 feet by mid-April. Cascade will, for a short time during the spring, raise the level up to elevation 543 feet, which is the maximum permissible level for Lake Tapps, to remind residents of the legal high water mark.  This is done every year during the spring. Cascade will maintain Lake Tapps at an approximately elevation of 542.5 and 542.8 feet throughout the summer and early fall.

If homeowners are considering any improvements to their property or begin new projects, they should plan to do so between early February and early March.  Cascade reminds residents they must obtain all appropriate permits as well as a Cascade license prior to beginning any construction.  The time to apply is now.

USGS Links:

Lake Tapps Level Gage

White River Gage

General Reservoir Level Management

Cascade has owned and operated the Lake Tapps Reservoir since 2009. During that time, Cascade has managed lake levels in accordance with the provisions of the Lake Tapps Reservoir Water Rights, which incorporate relevant provisions from the 2009 Agreement regarding Lake Tapps between Cascade Water Alliance and the Lake Tapps Community and the 2008 White River Management Agreement between the Puyallup Tribe of Indians, the Muckleshoot Indian Tribe and Cascade Water Alliance.

The Water Rights and the agreements provide for Cascade to maintain recreational reservoir levels or normal full pool, between elevation 541.5′ and 543.0′ (gage height) from April 15 through Sept. 30.

Typical fall drawdown to a lake level of approximately elevation 538′ – 539′ is sufficient to protect the integrity of the Lake Tapps dikes and for any routine inspections. This minimizes the wear on the valves in the power house during fall drawdown and the risk of problems refilling the Lake Tapps Reservoir during periods of water shortage.

Specific dike or other maintenance projects will require Cascade to reduce the lake level in the fall and winter to approximately elevation 533′ to 535′ (some projects may require the level to be lower).

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