TOMHEGAN TOWNSHIP, Maine — The owners of a $15 million seasonal home on the western shore of Moosehead Lake could face a fine of up to $157,500 for allegedly violating federal wetland protections.

Robert and Gayle Greenhill of New York, N.Y., who own more than 3,200 acres of property in Tomhegan Township, violated federal law when they filled in 1.5 acres of freshwater wetlands to expand a private airstrip and to develop a rock quarry, according to the federal Environmental Protection Agency.

The Greenhills neither obtained the necessary permit for the most recent work, which occurred between mid-2001 and 2005, nor did they obtain a permit for a trout pond they constructed in 1997. To resolve the latter violation, the Greenhills applied for and were issued an after-the-fact permit but were required to do mitigation work. A permit for such work is required under the federal Clean Water Act, according to Dave Deegan, a public affairs spokesman for the EPA’s New England Region.

Messages left at the couple’s seasonal home seeking comment were not returned Thursday.

Deegan said recently that it was his understanding that the earlier remediation work required for the pond violation has been completed and that the U.S. Army Corps of Engineers oversaw the project. He wasn’t immediately able to say what that remediation involved.

A resolution to the latest violation concerning the airstrip and the rock quarry is still pending, according to Deegan. He said an administrative order issued by the EPA in January 2006 for that violation required the Greenhills to restore about 1 acre of the filled wetlands and to create wetlands on another one-half acre.

When asked whether any of the work had been done yet, Deegan replied, “I can confirm that there has not yet been any resolution to this case, but that it has not been referred to an administrative law judge.”

According to an EPA press release issued earlier this summer, a 985-foot expansion of the western end of an existing runway and the development of a rock quarry off the eastern end of the existing runway disturbed property containing “a mosaic of evergreen and deciduous forest which contained freshwater wetlands.”

The EPA stated in its complaint that from August 2001 to 2003 the Greenhills or people under their supervision used an excavator and front loader during the airport expansion to fill in wetland areas with sand and gravel. The wetlands on the eastern end of the runway are part of a large wetland system that’s adjacent to and connected to an unnamed tributary to Socatean Stream that flows into Moosehead Lake, according to the complaint.

As for the rock quarry, the complaint says that an access road and equipment corridor for the quarry were developed through several wetland areas using an excavator and bulldozer. Wetland areas also were affected by blasting and rock removal and some materials from the rock quarry were placed in wetland areas, according to the EPA.

The complaint indicates that a fine of up to $157,500 could be assessed.

According to the Maine Revenue Services Property Tax Division, the Greenhills have a complex in Tomhegan that includes a main home and some outbuildings. The buildings and 3,230 acres have a combined value of $17,425,143. The buildings alone are valued at $15,553,400.

The EPA lists the Greenhill’s home address as 23rd Floor, 300 Park Ave. in New York City.

Robert Greenhill is chairman of Greenhill & Co. LLC, an independent global investment banking firm headquartered in New York City. According to the company’s Web site, Greenhill founded the firm in 1996. Before that he had worked for 30 years with the Morgan Stanley investment firm, where he served in various capacities, including as director of its investment banking division, and later as president and vice chairman of the company. He left Morgan Stanley in 1993 to become chairman and chief executive officer of Smith Barney Inc.