ROCKLAND — The city’s distinction of having one of the largest exhibits of lighthouse artifacts in the country is in jeopardy, as the U.S. Coast Guard has asked for the return of more than 700 items.

The news came in an email received by the city Friday from Arlyn Danielson, the Coast Guard’s curator from Forestville, Maryland.

“In order to properly preserve, care for, and maintain these important artifacts, we need to make arrangements to return them to the Coast Guard as soon as possible. The duration of this loan as well as the recent financial hardships have put this collection of valuable and historically significant artifacts at risk,” the curator said in her letter.

City Manager James Chaousis told the city council in a memo Friday that he had been working over the last few weeks on a way to respond to the financial difficulties faced by the Maine Lighthouse Museum and was reaching a reasonable solution when the letter from the Coast Guard curator was received.

The extent of the financial problems at the museum became known to city officials two months ago.

The Maine Lighthouse Museum exhibits the Coast Guard collection at 1 Park Drive. The museum shares the building with the city and Maine Lobster Festival through a condominium arrangement. The city announced in early March that the condominium association is broke because the museum — which occupies 50 percent of the building — has not paid its share of expenses since 2009 and owed $150,000.

The collection of lights from lighthouses was started by former Coast Guard Cmdr. Ken Black in 1971. The collection first was kept at the Coast Guard station and then the Shore Village Museum on Limerock Street before relocating a decade ago to 1 Park Drive, where the lighthouse museum initially leased and then purchased space in the building.

Dot Black, whose late husband Ken Black put together the collection in Rockland, said Wednesday she was unaware of the response from the Coast Guard. Black said the volunteer organization has been working hard to raise money to keep the museum operating this year.

The museum opened last month and is planning more fundraisers to help pay its operating expenses.

The Coast Guard curator stated in her letter that the most recent loan agreement with the city was reached in 2004, although she acknowledged many of the items have been on loan for more than 20 years.

“Our records indicate that the Maine Lighthouse Museum has over 700 items on loan from the Coast Guard. This loan, having been established many years ago and under unusual circumstances, is an outlier in terms of the number of items on the agreement,” the curator stated.

She said that in order to maintain consistent control and the ability to monitor the heritage assets of the Coast Guard, the agency generally limits its loans to 10 years.

“However, in the interests of maintaining a Coast Guard artifact presence and interpretive opportunity for Rockland, going forward, we are willing to consider a much smaller, tightly focused loan of artifacts to the museum (we are thinking only 50 to 60 items), but cannot renew the vast majority of items for extended loan,” Danielson stated in her letter.

The curator said Coast Guard representatives plan to meet with city officials in early June to discuss the issue.

“Alternatively, should you decide that a loan renewal of fewer artifacts within a professionally designed exhibition is not feasible, we can discuss the issues pertaining to the consequent return of the entire collection to the Coast Guard,” she concluded.