Natural isolated bodies of water good for cooling off in are few and far between. Beating the heat in San Diego usually means fighting for a parking spot at one of our overcrowded beaches (unless you have the luxury of owning a swimming pool). The other unwise option is to stay air-conditioned indoors and run up the electric bill.
Enter the 221-acre Santa Margarita Preserve. A river of the same name passes through the preserve, which runs through Fallbrook. (Access to the area is provided from De Luz Road.)
The Santa Margarita River cuts through the preserve on its way from its Temecula source to the Pacific Ocean, and is home to a number of species of fish, including rainbow trout and striped mullet. (Be advised that fishing is currently prohibited here.) The preserve is also home to many animal and bird species that rely on the river as a water source.
There are hiking trails that are shared with mountain bikes and horses, and we took one that involved fording the river on foot. If you do this, you'll get wet, so water shoes are recommended—especially to avoid the unpleasant experience of stepping in fresh horse manure in your bare feet. (In the spring there's a stunning variety of flowers and other vegetation.)
The preserve has a deep history. For centuries the river sustained Native Americans, and was discovered in 1769 by the Spanish Portola. One part of the site I explored was once part of a massive Mexican ranchero that stretched as far west as Camp Pendleton. We encountered ruins that appeared to have been part of the ranchero.
The preserve is open seven days a week from 8 a.m. until half an hour before sunset. If there's been a heavy rain the park will close due to the dangers of swift water and washed-out trails. That's not been a problem of late, but who knows what a Super El Niño may bring.
SANTA MARGARITA PRESERVE · De Luz Rd. & Sandia Creek Dr. Fallbrook, CA 92028