Lake Tapps Is Already Close to Its Winter Level. The February Refill Is the Bigger Question.

On Oct. 14, the USGS gage on Lake Tapps near Sumner showed a provisional reading of 540.00 feet. Cascade Water Alliance aims to hold the reservoir at about 538 to 539 feet through fall and winter, and active drawdown starts Nov. 1. That leaves the official drawdown somewhere between one and two feet of water to remove. Most of the drop has already happened.

The drought that drained the lake this summer also controls how it refills. Cascade plans to start refilling in mid-February, and that plan depends on the same White River flows that kept the lake from refilling all summer. For people who live on or near the lake, the date to watch this winter is in February, not Nov. 1.

A smaller drawdown than last year

Last fall's notice described a drawdown of a little more than three feet. This year the lake starts much closer to the target.

Under its water rights and its agreements with the Lake Tapps community, Cascade's recreational target is 541.5 to 543 feet, measured as gage height, from April 15 through Sept. 30. When Cascade issued its Sept. 29 notice, the reservoir was already a foot below that floor. The Oct. 14 reading was half a foot lower again.

The last row of the table matters for anyone who still has a boat in the water. In 2025, Cascade told residents to pull boats by mid-October at the latest. The 2026 notice gives no date. It asks residents to watch reservoir levels and decide for themselves when to take boats and other property out of the water. Last year's deadline doesn't carry over to this year.

Why the White River sets the schedule

Cascade can't divert water to Lake Tapps on any day it chooses. Its state water rights prohibit diversions when the White River is below set levels called minimum instream flows. As of the Sept. 29 notice, the river was below them.

The summer followed that rule. Cascade did capture some White River water in August, when a warm spell melted glacier ice and raised the river. Through September, with the statewide drought continuing and the river running low, Cascade couldn't add any significant water, and the lake kept dropping. On July 31, the reservoir stood at 541.28 feet, and Cascade warned it could drop another full foot by the end of August. By mid-October, the gage was about 1.3 feet below that July reading.

According to Cascade, the reasons for the November drawdown are the same every year: it allows needed maintenance on the dikes, and it protects the reservoir from wind, storms and waves over the winter. The 538 to 539 foot target is Cascade's normal fall level. Cascade says that level is enough to protect the dikes and handle routine inspections. Specific dike or maintenance projects can require going down to about 533 to 535 feet, or lower. This year's notice names only the normal range, so it isn't a deep-drawdown year.

The refill depends on the river

Cascade expects to start the 2027 spring refill in mid-February and to bring the reservoir up to about 543 feet during the spring. That's the highest level Cascade can operate at under its agreements with the Lake Tapps Community Council. The notice doesn't give a date for reaching 543 feet, and it doesn't say when the lake will get back to the 541.5-foot recreational floor.

That gap matters because refilling runs on the same rules as the summer did. Cascade's general reservoir-management page explains that it keeps the fall drawdown modest partly to reduce "the risk of problems refilling the Lake Tapps Reservoir during periods of water shortage." A lake that starts winter near 538 feet needs about five feet of White River water to reach full pool. Getting that water depends on the river running above its minimum instream flows during the refill window.

The White River's flow is public. Cascade links to the USGS White River gage from its lake-levels page. Because diversions stop whenever the river is below its minimum instream flows, that river gage is the other number to watch once February arrives.

The boat launches that closed this summer

The low water closed both public ramps on the lake this summer. KIRO 7 reported that the City of Bonney Lake closed the Allan Yorke Park boat launch on July 27 because the low water made it unsafe. KIRO also reported that the city planned to monitor levels and reopen the launch when conditions allowed. In a July 31 alert, Pierce County scheduled the North Lake Tapps Park launch to close on Aug. 14. The county cited the drought, unsafe shallow water and the hazard of submerged logs.

Neither agency has announced a reopening. Since the lake is now below the level it was at when both launches closed, and drawdown starts Nov. 1, it's reasonable to plan as if both ramps will stay unavailable until the refill brings the water back. The city's boating page and the Pierce County alert center are where any change would appear.

Lakefront owners: a work window that requires approvals first

Low water exposes shoreline that is usually underwater, and Cascade points to the drawdown as a time for property work. The Sept. 29 notice says this is a good time for residents to get the required permits and a Cascade license before starting any work.

Here is what Cascade publishes about the approvals involved:

• Who owns the shoreline. Cascade owns the lakebed and shoreline up to the 545-foot contour. It requires a license before anyone adds or modifies a bulkhead, dock, boat lift, ramp or boathouse. Its licensing page also lists insurance requirements and other applicable permits.
• Local permits. Cascade's 2026 homeowner guide sends owners to the Bonney Lake Permit Center or the Pierce County Development Center, depending on location. It notes that projects may need shoreline review, building, grading or filling, land-clearing, or SEPA approvals.
• State approval. The same guide says some projects may need a Hydraulic Project Approval from the Washington Department of Fish and Wildlife.
• Building for full pool. Cascade has authority under its water rights to raise the reservoir to 543 feet. It says any new or modified bulkhead should be built with that level in mind.

The last point ties back to the refill. The shoreline you see in December is two feet or more below the waterline Cascade plans for in spring. This section is general information and not legal advice. Confirm what your project needs with Cascade, your permitting office and a qualified contractor before any work starts.

One more lake program has a fixed calendar. Cascade's milfoil page shows the 2026 treatment ran in two phases: Phase 1 on June 22, and Phase 2, completed on Aug. 10. Homeowners or HOAs who pay to treat their own frontage through Cascade's permit and its contractor, Aquatechnex, have to schedule the treatment on Cascade's treatment days. Weed treatment is done for the year, and any private treatment will have to wait for Cascade's 2027 schedule.

What to check between now and spring

1. The lake gage. USGS gage 12101000 reports the reservoir level. Cascade itself sends residents to this page to track water levels. Remember that recent readings are provisional.
2. The White River gage. In February, river flow tells you whether the refill can go ahead.
3. Cascade's lake-levels page. This is where Cascade posts its drawdown and refill notices, including the Sept. 29 announcement.
4. TappsWise. Cascade's TappsWise program, run with the Tacoma-Pierce County Health Department, offers homeowner workshops, site visits and a certification on topics like natural yard care, septic maintenance and pet-waste pickup.

Cascade will drop the lake to its winter level starting Nov. 1. How far the lake comes back by summer depends on White River flows from mid-February on.

If you own on Lake Tapps and want to know how this year's low water and refill timing could affect a sale, a purchase or a planned dock project, the team at Elton Home Team follows Cascade's notices every season and is glad to walk through your property's situation with you. Start Your Home Search, or just call us with your questions about the lake.