Maine homeowners who have trampolines on their lawns may be in for a surprise when they get cancellation notices from their insurance companies.

A new state law that took effect Friday allows insurance companies to cancel homeowners’ policies if customers who are asked to remove trampolines refuse to do so within 30 days of getting notices.

The same goes for homeowners who refuse requests to put fences around their swimming pools and those who refuse to get rid of dogs that bite.

The same law includes a number of new protections for homeowners, whose complaints about their treatment by insurance companies triggered a study and a lengthy bill enacted earlier this year.

“Overall, it’s a good consumer protection bill,” said David Bragdon, spokesman for the Department of Professional and Financial Regulation. “It’s the product of a fairly lengthy investigation and analysis.”

As of Friday, insurers that want to cancel or not renew policies because of repairs needed to a home must give the homeowner four months to make the needed repairs, said Bragdon.

Also, insurers are barred from refusing to insure solely because of the age of a house, or because of claims filed by a previous owner.

The law is among scores that took effect Friday, 90 days after the close of the legislative session.

In Portland, Commissioner Dawn Gallagher of the state Department of Environmental Protection joined Friends of Casco Bay and other supporters in celebrating a new law to regulate wastewater from cruise ships.

The law prohibits the discharge of “gray water” from ships’ sinks, showers and galleys within Maine’s three-mile limit off shore. Steps are also taken to have the federal government declare Casco Bay off-limits to treated or untreated sewage from vessels.

The law also sets a Jan. 1, 2006 deadline for the state to establish a licensing program for cruise ships’ gray water discharges.

Some laws enacted by the Legislature this year have already taken effect or have later effective dates. A law to regulate all-terrain vehicles is in both categories.

A provision allowing municipalities to bar ATVs from trails during mud season took effect earlier this year.

The bulk of the bill, including provisions setting stiff fines for riding on private property and off marked trails without landowner permission, takes effect Aug. 31. Other portions taking effect that day bar ATVs in environmentally sensitive places.