Kelly Ditch Trail
Especially right now, this is one of our most enjoyable hikes. It combines a good morning's workout with some of the best fall foliage you're likely to see. If you go the suggested way, it's a mix of moderate uphill, level and downhill, so it fits many levels of fitness. That way starts at Lake Cuyamaca and goes to San Diego County's Heise Park, thus requiring a two-vehicle shuttle.
The hike, almost entirely through forested areas, is 5.5 miles and takes 3-4 hours. You can reverse the direction (e.g., start in Heise) for a definitely tougher workout. And, finally for those who are hardy hikers, this makes a great 11-mile round-trip hike, starting from and ending at Cuyamaca or Heise.
The trail head, marked with a small sign, starts from the northern end of Lake Cuyamaca. The trail follows an old walled ditch, gently upward as it goes just to the west of North Peak. (A variation is to take the side trail up the peak.) It's a good, well-marked trail through oaks, cedars, pines, manzanita and -- maybe -- mountain flowers (come back in May or June to really see a display). Some meadows and great views. You'll make an easy crossing on rocks over Cedar Creek. There's some more moderate uphill hiking, then a long downhill stretch. You'll see a sign directing you to Heise Park, with the trail ending at the parking lot, conveniently next to a lovely picnic area. If you left your first vehicle well-stocked with a cooler and snacks, this is about as fine a way to end a delightful hike as it gets. (Plan B, with a late lunch and cool drink back at the Lake Cuyamaca restaurant, isn't bad either.)
Now about that ditch. Referencing Jerry Schad's Afoot & Afield In San Diego County, 1st (not 2nd) edition, the Kelly Ditch was built a century back to divert runoff from North Peak into the lake.
Suggestions: As for any backcountry hike, I strongly recommend good shoes with lug soles. This is not a complicated hike, but it's always good to take a map. Water and snacks, of course. Horses yes, but not dogs nor bikes.
Directions: For the two-vehicle shuttle. Take Highway 67 through Ramona, to 79 and through Santa Ysabel to Pine Hills Road, right. To Deer Park Road, left to Frisius, to end at entrance to campground. Pay small fee and leave vehicle in lot to right. To drive other vehicle to Lake Cuyamaca, go back to 79 and right to Julian. Stay on 79 (south) to Lake Cuyamaca. Park at main lot by restaurant or get parking sticker and park in lot just north of the dam. Trail starts just west of Engineer Road. Later, after your picnic at Heise, drive everybody back to the other vehicle at Lake Cuyamaca.