Opponents of a state plan to dump dredge spoils in the Chesapeake Bay are launching a $50,000 television advertising campaign portraying the proposal as hazardous to fish, crabs and children.

The 30-second ad will run during Sunday morning talk shows on all three network channels in Baltimore and during news broadcasts on cable channels in suburban Maryland, according to Patrick Welsh, director of Citizens Against Open Bay Dumping Inc., a group based on Kent Island.

The ad campaign marks an escalation in an 18-month struggle between environmentalists and state officials. At issue is how to dispose of sandy silt that will be scooped out of the approach channels of the Baltimore harbor in coming years.

Maryland Gov. Parris N. Glendening (D) and the Maryland Port Administration want to dispose of the dredge material in an four-mile-long area north of the Bay Bridge known as Site 104. Opponents say the muck should be disposed of on land.

The ad shows an older man walking with several children on a Kent Island beach while talking about efforts to clean up the bay.

"Now the Maryland Port Administration wants to dump 18 million cubic yards of dredge spoils right here. They contain arsenic, lead and mercury . . . and nitrogen and sediment that could kill fish and bury crabs alive."

"The port is important, but so are they," the speaker says, pointing to the children. The ad ends by urging viewers to call Glendening's office to express opposition.

State officials criticized the ad, saying the muddy soil being collected contains only traces of contaminated material, at levels below state standards. The material is clean enough that it is being used to expand the wildlife habitat on Poplar Island, said Judi Scioli, a spokeswoman for the Maryland Port Administration.

"A good information campaign sets out to create light, not heat and hysteria," Scioli said.

Welsh defended the claims by citing the work of Jen Aosa, a staff scientist for the Chesapeake Bay Foundation. In an interview, Aosa said that the sediment contains levels of arsenic, lead and mercury and other heavy metals that could be harmful to bay wildlife if they were stirred up.

The U.S. Army Corps of Engineers initially circulated an environmental review that found no significant problems with the dump site but then backed off and ordered more studies this fall after objections were raised by environmentalists and the U.S. Fish and Wildlife Service.

Welsh said the ad campaign, paid for with donations from 500 contributors, is the first phase of what he hopes will be a $250,000 media campaign. It is intended to rally opposition to Site 104 before the Corps of Engineers completes the new environmental impact statement and the Maryland General Assembly convenes in January.