The "Seven Pools hike" into the upper reaches of Harding Canyon will simply amaze you -- assuming you go before summer's heat and drought dries up the canyon's lively, crystalline, spring-fed stream. It's almost unbelievable that such a pristine place can exist just a few miles away from south Orange County's densely populated communities. The canyon bottom features potentially ankle-busting terrain, so wear boots with ankle support. Also, poison oak grows in fair abundance along the banks of the stream, so consider applying a poison-ivy block to any exposed areas of your skin. You should budget four or more hours of strenuous hiking for the round trip to the falls and pools.
To reach the trailhead, exit Interstate 5 at El Toro Road and proceed 7.5 miles east to Cook's Corner (famous for its "biker bar"). Continue, without making any turns, on Santiago Canyon Road for 1.5 miles and then veer right on Modjeska Grade Road. Proceed for a mile up and over a curvy summit and down to the woodsy community of Modjeska. There, Modjeska Canyon Road joins from the left. Continue straight (east) on narrowing pavement for one more mile. Park your car either outside CSU Fullerton's Tucker Wildlife Sanctuary, where the hike begins, or back along the road wherever you can find a legal parking spot off the pavement. That may be easy on weekdays, but tough on weekends when hikers and especially mountain bikers arrive en masse by midmorning.
Across the road from the Tucker Sanctuary, find and follow Harding Truck Trail. Squeeze around the vehicle gate, and ascend 0.4 mile to a saddle in the ridge to the north. Cleveland National Forest land lies ahead. Leave Harding Truck Trail at the saddle by veering left on a descending dirt road. It takes you down to Harding Canyon's broad flood plain. Turn right, go upstream alongside the tumbling creek, and enter the canyon proper within about 0.2 mile.
Abandon the notion of trying to keep your feet dry (at least during this month and next). A sketchy use trail darts along either the right or the left bank, but you'll encounter plenty of ankle- to knee-deep stream crossings in between the trail segments. At present, every ravine of any consequence along both sides of the canyon supports a lively brook rushing down to join the main stream. Live oaks, willows, and sycamores in the lower canyon are joined by aromatic bay laurels and straight-trunked white alder trees as you climb into the canyon's progressively narrower, higher reaches.
At about 1.5 miles into Harding Canyon, notice how the canyon walls morph from tan- and beige-colored sedimentary rock to light-gray-colored granitic rock. At an abrupt bend to the left, where water sprays down a clifflike ravine on the right, notice two mining prospects pocking the canyon wall on the left. In 1878 prospectors discovered nodules containing lead and silver ore in Harding Canyon. Soon, according to a newspaper account of the day, a man could hardly swing a pick without "perforating his neighbor."
For a distance of several hundred yards ahead, cascades and deep aquamarine pools line the canyon bottom. The clarity of the water is remarkable, without a hint of turbidity or sudsing despite the churning flow. Enjoy the sights and sounds, take a dip if you like, then head back home.