Cowles Mountain, the centerpiece of Mission Trails Regional Park, stands 1591 feet above sea level, making it the highest point within San Diego's city limits. On a warm springtime day, hundreds of people -- maybe even a couple of thousand -- walk up the main, south-side trail to reach its view-rich summit. Relatively few try the more challenging northeast route from Big Rock Park in Santee, involving some 1200 feet of ascent from the start to the top of the mountain.
March and April showers have saturated the mountain, and its flanks are positively weeping with moisture. On the northeast side especially, velvet-green grasses have popped up, blue-blossoming ceanothus (wild lilac) is blooming, and some of the normally dry ravines are alive with the sound of trickling water.
You can start hiking either at Santee's Big Rock Park, at the corner of Mesa Drive and Prospect Road in Santee, or start from the south dead end of Big Rock Road. Either way, you'll encounter right away a little brook sometimes known as "Big Rock Creek" that tumbles through a V-shaped ravine, down from the very summit of Cowles Mountain. The water appears clean and clear, as it arises from a pristine watershed. With a fair bit of bush dodging, boulder hopping, and possibly wading in shallow water, you can follow Big Rock Creek upstream from the end of Big Rock Road for 10 or 15 minutes and reach several enchanting little cascades and shallow pools.
The main trail to the summit, however, stays east of the creek and gradually diverges from it. The stony path continues relentlessly for a tough uphill mile, whereupon you reach the steep, unpaved service road going up Cowles' east flank. To finish the climb, follow that road to the summit, one more mile away.