Head east on I-90. About 44 miles west of Seattle, take Exit 45 (Forest Road 9030.) The pavement is short and be careful for large potheads. At a fork 0.8 miles from I-90 take the left branch onto Road 9031. (On another day take the right branch, Road 9030, and that takes you to the Talapus Lake trailhead.) At about 3.8 miles from I-90, you will reach the large parking area for the Ira Spring Trail (#1038.) A privy is available, but there is not any regular water source so bring you water filter on a hot day. A Northwest Forest Pass is required.
Take note that this is a very popular trailhead and parking can be quite busy here on a weekend. The Forest Service regularly checks this area and will issue tickets for violations, so take notice of the no parking signs.
The trip up to Mason Lake is great for backpacking, day hiking, trail running, families, and dogs. Ira Spring Trailhead has lots of parking and decent bathrooms. This trail is perfect for a summer day and are in the mood for a swim.
The climb is not so bad until you hit the bridge to cross Ira Springs and a quarter mile from there you will notice the serious incline. This is great for backpacking training or a good run! You will definitely feel the burn.