The area between the arrows would be open to personal watercraft use under a plan adopted by the National Park Service at Pictured Rocks National Lakeshore/NPS

Continued use of two-stroke personal watercraft at Pictured Rocks National Lakeshore in Michigan will disturb wildlife, generate pollution, and might intrude on the wilderness experience at the lakeshore, but the National Park Service believes those impacts will disappear as newer PWCs replace two-stroke models.

Additionally, the decision announced Wednesday, which allows continued PWC use from the western boundary of the lakeshore to Miners Beach, or roughly one-fifth of the 42 miles of shoreline in the park, does away with a past proposal to give owners of two-stroke watercraft two years to upgrade to a machine that meets 2010 EPA air quality emission standards. 

Pictured Rocks Superintendent Dave Horne said the final decision didn't come overnight.

“We went back and forth. There was a lot of discussion about that, and a lot of actual studies about that," Horne, referring to the two-stroke machines, said during a phone call. "Basically, they’ve kind of naturally phased themselves out. ... The machines that are still two-strokes are just getting really old and they’re not as prevalent.”

During the summer of 2012, 82 PWCs were counted in the lakeshore. On average, fewer than four PWCs were operating in the park on a daily basis that year, the Park Service noted. If use increases significantly down the road, the agency "will determine if additional compliance actions are necessary, and if so, complete that additional compliance."

"It’s going to be controversial either way," Horne said of the decision to remove the phase-out requirement for two-stroke machines. "It’s going to be controversial for the people who keep their machines running that long, for basically 20 years at least, to force people to get a new one when it really wasn’t that much of a problem in the first place. It seemed like the most reasonable approach.”

Back in 2000 the Park Service had determined that Jet Ski use was a “controversial, recreational” activity and inappropriate in most areas of the National Park System. At the time the agency deemed Jet Skis, a namebrand version of personal watercraft, “high performance vessels designed for speed and maneuverability and are often used to perform stunt-like maneuvers.” 

Six years later, after the Clinton administration was succeeded by the George W. Bush administration, the Park Service reversed course and began finalizing regulations to allow for PWC use in park units. The move ran into judicial turbulence in 2010 when a U.S. district judge, ruling on a lawsuit against the watercraft in Pictured Rocks and Gulf Island National Seashore on the Florida-Mississippi coastline, scuttled Park Service approval of their use.

"(W)hy has NPS issued rules allowing Jet Ski use in two beautiful and pristine national parks, acknowledging that such use will impact, to varying degrees, water quality, air quality, wildlife, animal habitats, soundscapes, visitor use and safety, etc., when the users of jet skis are perfectly free to enjoy their vehicles in other, equally accessible areas, without threatening the serenity, the tranquility -- indeed, the majesty -- of these two national treasures?" she wrote.

But the judge allowed the plan to remain in place while the Park Service went back and reexamined issues related to the impacts of the watercraft. A year-and-a-half ago the staff at Pictured Rocks came back with their revised environmental assessment on continued PWC use, and it contained some disturbing conclusions:

* The forest, dune, and lake communities at the national lakeshore provide important habitat for wildlife, including extensive numbers of mammals, birds, and fish. The presence and sound of PWCs can impact wildlife by disturbing breeding, feeding, and other wildlife behaviors. PWCs tend to have varying speeds and course, resulting in frequent changes in engine noise. PWC use can cause alarm, or flight, with avoidance of habitat and effects on reproductive success of waterfowl and shorebirds.

* PWCs can also introduce invasive species into Lake Superior, including zebra mussel, quagga mussel, and eotic grass. ... Due to the design of the PWC engine, it is more difficult to deconatminate than other watercraft engines. When PWCs and trailers are used in more than one waterbody without proper decontamination, invasive species can be easily transported.

* The national lakeshore remains a relatively undeveloped park. Summer visitors engage in activities including camping, hiking, backpacking, picnicking, boating, fishing, and swimming. One of the goals of the general management plan is to maintain natural quiet to enhance the visitor experience. The associated noise and environmental effects of PWC use can impact the experience of some visitors.

After taking public comment on that document, the Park Service again revised its PWC decision by doing away with the requirement that two-stroke machines be phased out in two years. The agency did acknowledge in the revised environmental assessment that there would be some impacts, but not great enough to rise to the level of impairment to park resources or values.

"(W)ithout a required phase-out of carbureted two-stroke PWCs, noise generated by PWCs would not be reduced after two years and would continue to disturb behaviors of special-status species, resulting in a slightly greater impact than alternative 1 (which required the phase-out)," the plan said, adding, though, that "(T)he low use of PWCs makes this impact very small. Over time, older PWCs would be replaced with newer, quieter models, further reducing the impacts to wildlife."

Wildlife that could be affected include the piping plover, an endangered species. Common loon, bald eagle, osprey, peregrine falcon, and merlin, which are species of concern in Michigan, also could be affected, the Park Service said in its report.

The final plan also notes that, "without a mandatory phase-out of carbureted two-stroke engines, PWC use would continue to contribute water and air pollutants in the PWC use area; however, the low levels of water and air pollutants would not be detectable due to the low use by PWCs and would not affect human health/aquatic organisms or regional air quality, respectively."