SNOWMASS VILLAGE - The crews combing Ziegler Reservoir near Snowmass Village for Ice Age fossils won't find them all by July, but that's OK, according to one of the co-leaders of the excavation for the Denver Museum of Nature & Science.Whatever still lurks in the muck when the fossil dig wraps up on July 1 isn't going anywhere, reasoned Dr. Kirk Johnson, the museum's chief curator, though the prospect of fossils left undiscovered is a source of consternation for the public."A buried fossil is fine," Johnson said. "Most of the fossils in the world are buried."For a seven-week period that wraps up July 1, museum crews are digging through tons of soggy earth in a roughly 2-acre area where dam construction is scheduled to begin in earnest on July 2. Their goal is making sure anything buried there, down to the glacial till at the bottom, is excavated.While other fossils undoubtedly exist in the area, once an ancient lake, they won't be lost, Johnson said. Their discovery will simply await another day.Draining the reservoir at some point in the future isn't beyond the realm of possibility, though a lot of pieces would have to fall into place to make that happen, added Kit Hamby, manager of the Snowmass Water and Sanitation District, which owns Ziegler Reservoir."It isn't as though this is going to be lost," Hamby said Friday. "It's going to be under water, just as it was for hundreds of thousands of years. It's going to be preserved."This year's dig, which follows a two-week frenzied effort late last fall after the bones of a mammoth were bulldozed to the surface, allows the museum to make sure nothing will be destroyed by dam construction in the area where the dig is under way, Johnson said.The state owns the fossils, and the museum is the repository for them, but the district has a legal obligation to not knowingly destroy fossils in the process of enlarging the reservoir and constructing a dam. An agreement between the museum, Water and Sanitation District and the State Historical Preservation Office establishes the window for the museum to extract fossils that might otherwise be destroyed, Johnson explained.Financial considerations for both the museum and the district also dictate a finite period of fossil excavation.In addition to scientists working at the site, the museum is putting up a rotating dig crew of 40 people in Snowmass Village for nearly 50 days - one of the largest excavation efforts the institution has ever undertaken."It's a financial stretch," Johnson said. "To do this is a huge effort."This is literally a million-dollar project that we didn't know about seven months ago. It wasn't on anybody's radar seven months ago."The Snowmastodon Fund has been established through the Aspen Community Foundation to collect contributions that will compensate the museum, the district and the town of Snowmass Village for costs incurred as a result of the fossil excavation. With a $100,000 donation from the Crown family, owners of the Aspen Skiing Co., the fundraising hit the $460,000 mark last week.For the district, enlargement of the reservoir was to be a two-year project, with a break for the winter. It has a contract with a contractor for dam construction this year, and a commitment to the Ziegler family, which owns the land around the reservoir, to finish by this fall, Hamby said.Failing to honor the $2 million dam construction contract has ramifications for the contractor and its employees."In this economy, that would be really crushing," Hamby said.The district purchased the reservoir in 2005 for $3.5 million, planning to significantly expand its capacity, at an additional cost of $6 million, to serve the resort's future water-storage needs. When it's finished, the reservoir will hold about 80 million gallons of water, up from roughly 17 million gallons before work began.It will allow for the protection of Snowmass Creek, which supplies Snowmass Village with water, during the winter and in dry years, and when calls from other water-rights holders affect water supplies."It's probably the single most environmental project Snowmass Village has ever seen," Hamby said.For the museum, which recovered some 600 bones and bone fragments last fall and had topped 300 more by Friday, the fossils that are found will do much to advance scientific study, according to Johnson."We're going to have a huge cache of fossils for our efforts," he said.Last week's finds included five pelvises, two tusks and two skulls, all from mastodons, among the sediments at the bottom of the original lake bed.The skulls and pelvises, which Johnson described as each the size of a car door, are in one large "bone bed" among massive boulders.Why they are all there, together, is baffling, he said. They may be from skeletons that were on the shoreline and washed into the lake, settling at the bottom.The average mastodon pelvis weighs about 150 pounds, and increases to 400 pounds once the fossil is surrounded by a plaster jacket to protect it for removal. An average mastodon skull weighs up to 600 pounds before it is jacketed.Heavy machinery will be used to hoist the specimens onto a rented truck for transport to the museum.