Please add the name, a description and if possible a map of said trail/park. Thank you.
-Santa Ana River Trail. An asphalt bike trail that goes all the way from the edge of Yorba Linda/Corona to the Pacific Ocean right on the edge of Huntington and Newport. There are some parts of it where there are dirt trails to accompany the asphalt bike trail which is very nice.
http://www.trailsafetypatrol.com/Santa_Ana_River_Bike_Path_Map.pdf
-Fullerton Trails. Start at the courthouse off of Harbor Blvd. for public parking. You can do so many variations and so many different loops.
http://www.ci.fullerton.ca.us/depts/parks_n_recreation/map_of_parks_n_trails.asp#bodyTop
-Peter's Canyon. You can't do a lot of variations here, but there is a big hill that will be a challenge to any runner. Very fun run. Trail is mostly dirt.
(no map available)
-Chino Hills State Park. It's starts on the edge of Brea on Carbon Canyon Rd. and ends in Chino Hills. If you enter from Carbon Canyon, the two main trails you will have are Telegraph Canyon and Northridge. Telegraph Canyon is actually the flatter one despite its name. It branches off into several other trails. Northridge is a very hilly which is tough and challenging. Another popular entrance is from Rimcrest Dr. in Yorba Linda which will lead you right to Telegraph Canyon. WARNING: you will need a permit to park on Rimcrest or else you may get towed. Most of the time you will get away with it though. You have been warned.
http://www.parks.ca.gov/pages/648/files/ChinoHillsMap.pdf
-Irvine Regional Park. This is where Orange County XC Championships are held. Concrete/asphalt, dirt and grass. Very cool place to run.
(no map)
-Fairview Park. Fairview Park can actually connect to the Santa Ana River Trail. Mostly Dirt. There's a hill that's about 1/4 mile, and very challenging. Orange Coast College and Vanguard University host their invitationals there. There are also some HS meets there as well.
(no map)