From I-5 take exit 773
Turn west off the freeway, then take a right at the stoplight. Head north for about 1/2 mile on Highway 3. Turn west (left) on Greenhorn Rd. Go about 1/2 mile and turn left into Upper Greenhorn Park. There is a lot of parking there, but if the lot is full, you will be diverted to Lower Greenhorn Park for additional parking. (It's on the other side of the lake)