The reservoir was created by the construction of the Alder Dam, which was completed in 1945 to provide hydroelectric power.
The park's swimming area is monitored for water safety during the peak summer season.
The reservoir sits at an elevation of approximately 1,200 feet, creating a distinct microclimate compared to the surrounding higher Cascades.
The dam itself is a concrete arch dam, standing 330 feet tall.
Alder Lake Park is a sprawling recreational facility operated by Tacoma Power along the 1,500-acre Alder Reservoir. The park features over 170 campsites, including both tent-only and RV-accessible sites with varying utility hookups. Water access is facilitated by multiple boat launch ramps, catering to motorized craft, kayaks, and paddleboards. A designated swimming beach provides a sandy area for entry into the reservoir, which is maintained by a hydroelectric dam. The grounds are forested with a mix of Douglas fir and deciduous trees, providing ample shade. Visitors can access picnic shelters and playgrounds situated near the waterfront. The site is a primary destination for water sports in the foothills of Mount Rainier. The reservoir level fluctuates throughout the year based on hydroelectric operations and seasonal water management.
The shoreline near the boat ramp at sunset, offering views of the reservoir reflecting the surrounding tree line.
Reserve campsites months in advance during the peak summer season, as they fill rapidly.
Check the current reservoir water levels on the Tacoma Power website before planning a boat trip to ensure ramp accessibility.
Bring water shoes for the swimming beach as the lake bed can be rocky.
Do not attempt to swim or boat near the restricted buoy line located directly in front of the dam intake.
The park operates on a seasonal basis, with full services typically available from late spring through early autumn; many facilities close during the winter months.
Pack out all trash and recyclables; keep pets on a leash at all times; obey posted water safety signage near the dam area.
