Gardeners and do-it-yourselfers are making the sparks fly, and the nation’s utilities want them to stop.

Residential customers have been blamed for most of the damage done each year to buried gas and electrical lines, something that could have been prevented by phoning ahead for the lines’ locations, officials say.

“About 70,000 incidents were reported in 2009 where people didn’t call ‘811’ before they did any digging,” said Bob Kipp, president of Common Ground Alliance (CGA), an industry-backed damage prevention group. “Somewhere between 40,000 to 50,000 of those were caused by homeowners — people trying to put in a new fence, patio, maybe some shrubs or a mailbox.”

The nationwide 811 line alerts utilities about proposed construction projects. They can respond by sending crews to locate and mark the service lines.

An estimated 100 billion feet of gas, electric, water, sewer and communications lines are routed underground in the United States. At least half of all homeowners planning to dig on their property this year will do so without knowing where those potentially dangerous corridors run, according to a recent CGA survey.

In this case, what you don’t know definitely can hurt you.

Take the case of the Muskegon, Mich., man who ruptured a gas line in April while uprooting a tree stump from his yard. “The homeowner called in the leak while standing nearby using his cell phone,” said Maureen McCaffrey, an operations analyst with DTE Energy Co. in Detroit. “That could have sparked a fire or explosion with static electricity. The tab for that incident was just over $1,600.”

Every state has a one-call law, requiring that you check with a utility before doing any digging.

“The rules are similar, although enforcement varies dramatically state to state,” Kipp said. Penalties can be steep, as much as triple the cost of repairs and losses.

“Professionals know enough to call,” Kipp said. “Homeowners is where we have to expand our message.”

The industry is using banners and billboards, direct mail and newspaper ads, speakers’ bureaus, National Safe Digging Month and Call 811 campaigns to get the word out.