Cascade Water Alliance

Lake Tapps 
Public Water Supply Project

May 2015 Lake Tapps Reservoir Refill Update

Cascade Water Alliance today issued an open letter to the Lake Tapps Community outlining the current status of the reservoir and the completion of the multi-million dollar multi-faceted set of construction projects that began in 2013.  The work was undertaken for the long term viability of the reservoir to the benefit of residents only, and it required drawing down of that reservoir.  Once the construction began and the flume was taken down in late October 2014, there was no ability to put water in the reservoir until the entire project was completed in March. Without the improvements to the 100 plus year old system, failure of any part would have meant two summers without recreation, which is why Cascade proactively did the entire project at one time. 

However, there is currently little if any allowable stream flow above the required minimum flow to go into Lake Tapps. Its refill is rain dependent, and the area is experiencing flows 30 to 35 percent below historical lows. Gov. Jay Inslee has declared drought conditions in parts of the state, including east Pierce County.  The following facts were included in the letter to the community:

FACT:  For the next 30 to 40 years, Cascade will be operating this system to provide recreational reservoir levels solely for your benefit while meeting regulatory and operational requirements.

FACT:  The system included a failing timber flume and headgates. The facilities that release water from the lake needed to be assessed and repaired.   A dike required a seismic retrofit.  The Washington State Dam Safety Office requires that Cascade be able to take a certain flow rate from the reservoir and we could not assure that we could do that to protect homeowners in case of earthquake or emergencies. 

FACT:  If Cascade had not planned for and undertaken these projects, and if the headgates or timber flume had failed, Cascade would not have been able to divert water into the reservoir for a minimum of 18 months, resulting in the likely loss of two complete recreational seasons.

FACT:  The design, planning and bidding for the 16 project $15 million upgrade began in December 2013 and was successfully completed March 16, 2015 ensuring long-term viability of the reservoir. 

FACT:  There has been historically low precipitation, which is required to fill the reservoir.  The situation is so severe that the Governor has declared a drought emergency in many areas of the state, including east Pierce County.

FACT:  Since April 1, the available flows in the White River have dropped far below even the lowest historically recorded levels.    Average historic flows have been above 1,500 cubic feet per second (cfs) above Mud Mountain Dam. This year the White River flows are at about 700-750 cfs, the lowest flows in 22 years of record keeping. 

FACT:  Cascade is legally permitted to only take water from the White River, the source of Lake Tapps, when flows exceed the minimum flow required in Cascade’s state issued water rights. This year’s historic low flows limit the amount Cascade can divert into the reservoir. Our new flume can take up to 150% of what is allowed. At present, there is no excess water to divert.

FACT:  Projections that the reservoir would be filled by Memorial Day were based on assumptions of less than average flow conditions, but nowhere near the extreme conditions now being experienced. In a normal year, the reservoir would have been filled by May 1. 

FACT:  We have our crews available 24 hours a day to divert as much available water into the reservoir as fast as possible. A typical day includes four to six diversion adjustments, many taking place between 9 pm and 4 am.  Unfortunately, the weather is not cooperating.

FACT:  Such potential occurrences were even considered and included in the Cascade’s 2009 agreement with the Lake Tapps Community, which states “. . . operational variances may be required due to forecasts or available precipitation, under the terms and conditions of the Water Rights.”

FACT:  Cascade is in constant discussions with regulatory and other partners to determine if there is any other option available for filling the lake.  This includes working to restock the lake with fish once the reservoir is full.  The drought has affected everyone.

FACT:  Cascade will continue working hard, and do everything we can to refill Lake Tapps. 

This is an extraordinary year, and Cascade appreciates your patience as it refills Lake Tapps. 

For current refill status visit 

For lake levels visit 

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Problems on Lake
Emergency: 911
253 798 4721, Option '1'

Pierce County Sheriff
Boating Hotline:
253 798 3300

Lake Tapps Hotline

253 891 5460


Cascade Water Alliance
877 299 0930


City of Bonney Lake
253 447 4344


Pierce County
Planning and Land Service
253 796 7210

Washington State
Fish and Wildlife

360 902 2200