After years of lobbying by the Coast Guard and state and city officials, dredging to clear the mouth of the Annisquam River is set to begin Monday.

About 10,000 cubic yards of sand and silt will be removed - enough to cover the surface of the football field at Newell Stadium to a depth of 6 feet - to provide easier passage for rescue vessels and recreational boats.

The state Department of Conservation and Recreation received the green light from other state agencies earlier this week, more than four years after the Coast Guard declared the work was urgently needed.

"It's about time," said Harbormaster James Caulkett. "We're relieved."

Caulkett said the dredging, to be done by Jay Cashman Inc. of Quincy, will take only three to four days.

At low tide, the shoals leave only 5 feet of clearance from the surface. Minimum safety standards call for at least 8 feet.

"The dredging of the mouth will provide a deeper channel, which will benefit both the public boater as well as the local Coast Guard station resources," said Chief Warrant Officer Chris Sparkman, commanding officer of the Coast Guard station on Harbor Loop.

At low tide, rescue boats moored at the station must steam 12 miles around Rockport to reach Ipswich Bay, adding 80 to 90 minutes to a trip that would take only 25 minutes up the three-mile Annisquam.

Until the shoals are clear, Caulkett recommends that boaters considering using the Annisquam pass the shoals at high tide or within two hours on either side of high tide. Sparkman recommended boaters take safe-boating classes, which the Coast Guard offers, and carry depth-sounders on their vessels.

In a January 2003 letter to the Army Corps of Engineers, the Coast Guard said deepening the mouth of the Annisquam was "of utmost importance to us due to the time it saves our rescue boats."

Michael Driscoll, an engineer with the Department of Conservation and Recreation who has been working on the project, said the dredging itself will cost $192,000. The state, through the Seaport Advisory Council, freed up $550,000 for the job, enough to pay for the preliminary surveying, engineering and other work, as well as the dredging.

Richard Armstrong, executive secretary of the Seaport Advisory Council and director of port development for the state, said the money was released earlier this year.

The holdup over the summer had been the wait for a clean water certification from the Army Corps of Engineers before the four-day project was put out to bid. The document certifies that the work will not violate the federal Clean Water Act.

"The permit situation has been resolved," Armstrong said yesterday.

In May, Caulkett told the Times that the dredging would not disturb fish habitats and that the sand is clean enough that it can be deposited just past a buoy at the 30-foot line. It could not be dumped any closer because of clams off Coffin Beach, a private beach west of Wingaersheek Beach.

Various state and federal officials had been promising for at least four years to get the work done.

State Sen. Bruce Tarr said in January 2006 he believed the project would be finished by the end of that year. He attributed the delay to the length of the planning process once the state decided to pay for the project.

Dredging rivers is under the purview of the Army Corps of Engineers, though it did not make room in its budget for the project.

Ed O'Donnell, New England chief of navigation for the Corps, told the Times in January 2006 that his agency, while transferring responsibility for small river projects such as the Annisquam to state and local governments, still hoped at that time to complete the project in 2007.

O'Donnell predicted in September 2003 that the work would be done by the fall of 2004 at the latest. Former Lt. Gov. Kerry Healey, who served as chairwoman of the Seaport Advisory Council, also promised to have the work completed.

The current lieutenant governor, Timothy Murray, called for completing the dredging when he made his first official visit to Gloucester in February.

Caulkett said the city will seek to have four other areas of shoals in the Annisquam River dredged as well. They are at the entrance to Lobster Cove, off Thurston Point, at the northern entrance to the Little River and off Wolf Hill.