The Silver River cuts a deep gorge early on, way upstream near its Herman-Nestoria swampy headwaters. One of the creeks that gets impacted by this gorge is Harley Creek, a relatively short creek draining the eastern flank of Mount Curwood. To reach the bottom of the gorge Harley Creek has to drop almost 200 feet down a series of plunges, chutes, and cascades that collectively form Harley Falls.
The lowermost falls is a group of cascades over boulders and solid rock that split and reform the creek multiple times. A short distance upstream is one of the more impressive drops, a wide slide down flat rock that creates a solid curtain of whitewater in the spring. The middle falls is a shorter sideways chute along a jagged, narrow chute surrounded by moss. Further up is another group of cascades around and over boulders and the upper falls is a set of stairs in a sudden box canyon. There are even more, smaller drops further upstream as well.
Take Lahti Road out of Herman as it turns into Summit. Continue as it narrows and becomes a two-track at Haikkinen Road. Turn left at a small gravel pit and follow this track north as long as possible. If the road becomes impassable park on the side and continue on foot.
This unnamed track eventually runs straight into Silver River. Follow the river upstream for a quarter mile, crossing over to the east bank when possible. After the quarter mile there are two creeks that head up the river bank, one that is much larger than the second. Follow the larger one, which is Harley Creek, upstream. The falls should all be with a half mile or so of Silver River.
Upper Silver Falls is upstream on Silver River from here. If you have a GPS you can chart a nice circle route, heading from the uppermost waterfall on Harley Creek straight over to the falls on Silver River, then following the river upstream past more waterfalls back to Summit Road. If you don't you can still make a circle, backtracking to Silver River and sticking to the river, although the banks can get quite overgrown in the summer and you'll be adding some distance to the hike.