The 2015 Minnesota Legislature should think long and hard before reneging on a promise made three years ago to further protect the state's waters from destructive zebra mussels and other invasive species.

A law it passed in 2012 — the last time Republicans controlled the House — requires those hauling boats or boat-docking equipment to buy new decals for their trailers as proof that they've passed a 10-question quiz aimed at teaching compliance with state laws that require boaters to drain ballast tanks, inspect hulls and take other similar steps to further prevent invasive hitchhikers from infesting Minnesota waters.

But now, as the law's July 1 effective date approaches, Republican legislators have launched an effort to repeal the law, citing the fears of some resort owners that the online training course is too burdensome. It will prompt reservation cancellations, they predict, and otherwise diminish the summer tourism season.

The law, they contend, is a classic example of government overreach. "This is like taking a sledgehammer to an ant," Joel Carlson, lobbyist for the Congress of Minnesota Resorts, told Star Tribune reporter Tony Kennedy.

The law is clumsily crafted. And there's a kind of "nanny state" element to it that conservatives detest — in this case, the presumption that boaters are negligent children, ignorant about the dangers of invasive species, and that the state's environmental officials are eager to slap another layer of cost on peoples' weekend enjoyment.

The critics are right to a point. After a 20-year awareness campaign by the Department of Natural Resources, the state's boaters are generally well-informed about the dangers of invasive aquatic critters and about the preventive steps the law requires. Spot checks by the DNR show that 86 percent to 91 percent of boaters are already complying with the rules.

But the margin for error is extremely small. All it takes to ruin a lake for generations to come are a few careless or unknowing boaters, most often those who haul their boats from lake to lake or state to state. That explains why, despite strong compliance, the number of invasive infestations has risen by 47 percent over the past three years to 691. Altogether, 518 Minnesota lakes and streams are now infested.

"This is mainly about risk reduction," said April Rust, the DNR's invasive species training coordinator. The risk is environmental, yes, as Rust asserts. But economic risk is closely involved. All lakeside property owners, not just resorters, have a huge financial stake in the health of the state's waters. Those who like to emphasize private property rights should understand that their property values are linked inextricably to the health of lakes and other public waters. There's a cultural aspect, too. Water defines Minnesota. This state has more registered boats per capita — some 800,000 — than any other. Legislators would be wise to take the longer view on this issue.

It's a curse of modern life that a few outliers can cause so much hassle, cost and inconvenience for everyone else. Airport security, racial profiling, and the need for layer upon layer of computer passwords are just a few troubling examples of the few spoiling things for the many. It's not uncommon nowadays for auto insurance companies to require extensive online training courses as a condition to qualify for lower rates. Those courses can take as long as four hours.

By comparison, Minnesota's new test is a trifle. The training course in invasive species will be available starting Feb. 2 at www.trailers.mn.dnr.gov. It takes less than 30 minutes to complete. The fee amount hasn't been decided. It's unlikely that anyone arriving at a Minnesota resort without a decal will be ticketed this summer; they'll be granted seven-day extensions and an opportunity to register and take the course online or on paper.

Are there tweaks for legislators to make? Probably. It makes little sense to require decals for out-of-staters transporting boats across Minnesota to Canada or other destinations, for example.

By its nature, this will be a cumbersome law to enforce. Some 500,000 boat trailers are involved. But zebra mussels, milfoil, bighead carp, faucet snails, spiny waterfleas and other invasive organisms cannot be allowed free passage into Minnesota's public waters.

The risks — environmental, economic and cultural — are just too great.