ANZA-BORREGO DESERT STATE PARK - A twice-postponed closure of Highway 78 in the desert east of Julian is ready to take place.

Officials with the California Department of Transportation in San Diego said Monday they will close the state highway from March 6 through the end of April at Scissors Crossing, the western gateway to Anza-Borrego Desert State Park.

The closure, intended to pave the way for reconstruction of a 60-year-old bridge over San Felipe Creek, will extend seven miles from San Felipe Road (San Diego County Road S-2) on the west to Yaqui Pass Road (County Road S-3) on the east, said Caltrans spokesman Ed Cartagena.

Cartagena said Caltrans is putting a detour in place, but it will add 40 miles to the trip through eastern San Diego County along Highway 78 - and an hour or more of driving. The detour will send motorists northwest along San Felipe Road, east on Montezuma Valley Road (S-22) through Ranchita, then south and east on Borrego Springs Road.

"We apologize in advance for the inconvenience," said Armando Garcia, Caltrans deputy director of construction. "But I encourage motorists to seek out any of the other routes to the desert that may be more suitable for them."

To save time, North San Diego County residents headed for the desert along Highway 78 may want to turn left (north) on Highway 79, right (east) on San Felipe Road and then left (east) on Montezuma Valley, instead of driving through Julian.

Southwest Riverside County residents may want to avoid Highway 78 altogether, driving southeast on Highway 79 out of Temecula before turning left on San Felipe Road at Warner Springs and left on Montezuma Valley.

Cartagena said Caltrans twice planned to launch the project earlier; initially in the middle of October, and again around Thanksgiving. Both times, he said, the state highway agency postponed the work because of concerns about timing. Area businesses complained the closure would turn away visitors at the start of the desert tourism season. Off-road enthusiasts said they worried about the impact on the busiest season of the year for riding motorcycles and all-terrain vehicles in the desert.

While Caltrans managed to steer around those concerns, the closure will create a hardship for Anza-Borrego Desert State Park visitors during the traditionally busy spring wildflower season, said Michael Rodriques, interpreter and visitor center manager.

Rodriques said tourists with motor homes and trailers try to avoid steep and winding Montezuma Valley Road, with its seemingly endless hairpin curves. But, with the closure, tourists will have little choice but to take Montezuma Valley - unless they want to detour all the way south to Interstate 8.

The closure still will create a hardship for motorcycle and all-terrain-vehicle riders, as spring is also a popular time to ride in the desert.

"I'm very upset about it," said Sherri Kukla, the Ocotillo Wells-based publisher of San Diego Off Road magazine. "They wouldn't do this in the summer, shutting down the main artery to the beach. And they wouldn't do this in the football season, shutting down the main artery to the stadium."

Garcia, however, said it is critical that the work get under way.

"Our main concern is ultimately for the safety of motorists who will travel this bridge in the future," Garcia said.

And Cartagena said Caltrans is under the gun to finish by May, to avoid disturbing endangered birds during nesting season.

For more information on the project, go to www.dot.ca.gov/dist11.

- Contact staff writer Dave Downey at (760) 740-5442 or ddowney@nctimes.com.