ANTIOCH -- Appearances can be deceiving when it comes to canals.

The placid looking waters can look inviting for fishing or taking a dip, especially with the warmer summer temperatures and restrictions on water use.

But sharp currents and slick floors underneath the surface can make it treacherous for anyone in the canal to make their way out.

"It's not like going to the Lazy River, where you're on slow-moving water," said Steve Arnold, a Contra Costa Water District operations and maintenance supervisor.

Staying out of the Contra Costa Canal is a message water district officials hope sinks in, particularly in East Contra Costa, where the deeper, more isolated waters are more conducive to trespassers.

The top of the fence along the canal trail off Gentrytown Drive is bent from people trying to climb over it in Antioch on July 10, 2014. (Dan
The top of the fence along the canal trail off Gentrytown Drive is bent from people trying to climb over it in Antioch on July 10, 2014. (Dan Rosenstrauch/Bay Area News Group)

The district continues to get the message out by going to schools, distributing pamphlets, adding more warning signs along the fences around the canal and launching a video campaign that features U.S. Olympic gold-medalist swimmer and Contra Costa native Natalie Coughlin,

Contra Costa Water is also hitting trespassers harder in the wallet. The district board recently approved increasing citations for trespassing inside the fence surrounding the canal from $25 to $500.

"I think this shows we're serious about it," district spokeswoman Jennifer Allen said.

On a recent afternoon while on patrol, district patrol officer Shane Pinto pointed out that most trespassers will either cut the chain-link fence to gain access, or bend the top of the fencing down and climb over. Most who do that are there to fish, he said.

On occasion, some will find ways to meander over the fence. That happened in April, when four young teens were found swimming in the canal about a half-mile west of Gentrytown Drive in Antioch,

"They made their way down the hill, and found a platform to help them get over the fence," Pinto said.

What makes that area in the west side of the city particularly dangerous is a nearby siphon pulling the water under a creek at a high velocity, he said.

The canal also has a lot of unknowns, including tree branches, beer cans, shopping carts and other objects of varying sizes beneath the surface, Pinto said.

According to the Contra Costa Water District, the canal ranges between 6 to 10 feet deep in East Contra Costa, and is much shallower in the middle of the county. The current can be up to 12 miles per hour, while the 18-foot-wide canal tapers at the bottom.

Eight people have drowned in the 48-mile canal since 2000; people were in the water for varied reasons, including car accidents.

There were a pair of trespassing-related drownings within a week in Antioch last May. Twelve-year-old Jumai Caldwell, of Alameda, died May 25 after falling into a canal while trying to retrieve his flip-flop. Caldwell's body was pulled from the canal about two hours after he fell into the water, a quarter-mile from where he fell in.

Five days earlier, Saul Hernandez, a 48-year-old from Brentwood and a patient at Sutter Delta Medical Center at the time, left the hospital's emergency room, jumped a pair of fences and entered the water.

"The canal is very deceptive. The water appears to be moving slowly, but there is a fast current under the surface," Pinto said.

Even good swimmers can drown in the canal.

"There's no way I'd swim the canals. The current is swift, and the sides of the canal are steep and slippery," Coughlin said in the video. "It can be pretty scary."

For more information or to report someone in the canal, call the district 925-688-8307.

Contact Paul Burgarino at 925-779-7164. Follow him at Twitter.com/paulburgarino.