Michigan's sand dunes are unique in the world. They were built by the glaciers scrubbing along over a particular rock type, by the weather that followed and by specific land elevations. One constant element in the evolution of these dunes is the wind.

This is especially true at the spectacular sand dunes at Silver Lake State Park, where the winds and breezes continuously rearrange the sand at this 1800-acre complex in the northwest Lower Peninsula. Overnight, Mother Nature can sculpture an entire new landscape and hills appear where valleys were just the day before.

It is here, on the northern edge of the park, where those interested in off-road recreation have a facility that also is unique in this part of the country. The Silver Lake State Park Off-Road Vehicle Area is one of Michigan's most popular off-road riding attractions and is the only ORV area located on publicly owned sand dunes in the Midwest.

Located along the shoreline of Lake Michigan, this 450-acre facility provides area vacationers and sporting enthusiasts the rare opportunity to ride and/or drive across the desert-like landscape that borders the west shoreline of Silver Lake.

Although the ORV area is very much like its bigger brothers and sisters found along the Pacific Coast of the United States, in these particular economic times, Silver Lake State Park offers the same fun and excitement much closer to home.

"Total annual park attendance approaches one million campers and visitors, with a third of those taking direct advantage of the sand dune riding/driving experience," said Park Supervisor Charlotte Kiefer.

According to Kiefer, there's no designated trail system in the ORV area, and the "cross country" riding/driving experience takes a special sense of navigation and acute operator skills.

"Although portions of the riding area have a designated direction of travel, much of the dune and beach area is 'open' riding," Kiefer said. "The dune ridge areas, along the eastern half of the facility, prohibit north bound traffic. This is done to prevent head-on vehicle collisions at the crest of the hills and to provide the safest ride/drive across the ever-changing dune terrain."

Traffic directional signs, she added, are found throughout this area unlike elsewhere in the dunes where the orange safety flags, required on all vehicles, are the prime indicator for vehicle location and direction of travel.

Over the 50-plus years since the ORV area opened, there have been a number of changes in the riding/driving habits of visitors and the ORV equipment they use in the park.

Early sand dune vehicles included conventional water-cooled vehicles, "water-pumpers" that were stripped down automobiles with a minimal number of components: frame, seats and usually a large engine. Air-cooled, rear-engine models (Volkswagen- and Corvair-type vehicles) eventually came along to take their place.

"Later, of course, came the four-wheel drive trucks; tubular framed, rear- or mid-engine dune buggies; all-terrain vehicles; motocross and dirt bike motorcycles; sport utility vehicles; and monster trucks," Kiefer said. "We've pretty much seen anything on wheels."

Most recently, long-travel or enhanced suspension dune cars and recreational utility or side-by-side vehicles have arrived on the scene, she said.

Safety regulations and rules, along with park attendance, also have changed greatly over the years.

"Early on there were few rules," said Pete LundBorg, park manager. "The major challenge for most people was simply climbing the entrance trail grade to the dune car area."

In the 1960s and early 1970s, a weekend that found as many as 100 dune cars using the area was rare. But in the late '70s and '80s, as a result of better equipment and a rise in the popularity of off-roading, attendance increased sharply growing to 1,000-1,500 dune vehicles on summer Saturdays. And by the late 1990s, weekend attendance often exceeded 2,000 vehicles each day.

"When I first arrived at Silver Lake State Park in 1978, we had only three basic rules for the ORV area beyond the required permits and normal operational hours," LundBorg said. "All vehicles needed a safety flag that reached 10 feet in the air, flotation tires were required and no alcoholic beverages were allowed."

As the number of ORV accidents involving injuries increased over the years, several dune riding enthusiasts approached park officials about coming up with measures to make the area safer for all users.

Citizen advisory committees were set up on two occasions, LundBorg explained, to formulate recommendations which mandated the use of vehicle roll-bars and seat belts, orange safety flags, and the creation of ATV and motorcycle helmet and eye protection requirements that eventually were included in statewide ORV rules.

In addition, the park worked with the user groups to create new directional traffic zones, adopt rules covering ORV operation by unlicensed drivers, revise area boundaries and create a seven-month season for the Silver Lake ORV Area.

Most of these rules have been in force for more than 20 years, and parking and entry area refinements also have been accomplished through annual funding from the DNR's ORV Grant program based upon off-road vehicle licensing fees and additional measures to operate the facility in an orderly and controlled manner.

The biggest change was the development of the ORV Voucher System in 2000, which was developed to resolve concerns with the long, often overnight entrance waiting lines (a six-hour process by the late '90s) and which has eliminated major neighborhood congestion and resolved traffic circulation conflicts.

Most recently, the Silver Lake Sand Dunes Area Chamber of Commerce has produced a dune safety program particularly focused on first-time users of the ORV Area.

"The project is evolving," said LundBorg. "One of the program's goals is to involve local business owners and their employees in learning and promoting dune safety guidelines that can be passed on to area visitors."

For more information, visit the S.A.N.D. campaign Web site at www.thinkdunes.com.