For the first time in living memory, Wasque Point on Chappaquiddick, a famed spot where riptides attract thousands of saltwater fishermen each year, will be inaccessible for much of the summer. The reason is the ferocious erosion now eating away huge chunks of the southeastern corner of Chappaquiddick at a rapid rate. The once-wide sandy beach at Wasque Point has been replaced by 20 to 28-foot sheer cliffs, with truckloads of uprooted pine and oak trees stuck in the crashing surf at their base.

“People need to understand that there is no pedestrian access now to Wasque Point and will not be for several years,” The Trustees of Reservations southeast regional director Chris Kennedy said on Thursday during a tour of the transformed property, which in some areas has lost up to 50 feet over the winter. Mr. Kennedy said the shoreline is eroding too quickly to put up temporary stairs or even a ladder down to the beach.

“It’s pretty astounding,” he said. “There’s nothing to block the waves. As you can see, they’re crashing right against the cliffs which are just sand. So we can lose 10 to 15 to 20 feet overnight.”

Mr. Kennedy said even if part of the beach could be reached by four-wheel-drive vehicles, that will not be allowed, due to the fact that three pairs of piping plovers are nesting on Leland Beach, south of the Dike Bridge. When the protected birds begin to fledge this summer, likely in June, the beach north of Wasque Point will be closed to vehicles as part of a land conservation effort, effectively closing access to the area.

Maps reflect dramatic erosion over time at Wasque. — Dana Gaines

Mr. Kennedy expects to hear criticism about the closures from fishermen and nature enthusiasts accustomed to driving on the beach. “People will really be upset and I can’t blame them,” the longtime superintendent said. “But these are things that are beyond our control. We’re basically standing by and being spectators to the natural world here.”

Mr. Kennedy said in the stretch of beach from Wasque Point to the Wasque swimming beach, 20 to 25 feet of land had been lost in the past two weeks alone, much of it during a 48-hour period of high winds in late April. The fishermen’s parking lot, once safely nestled in forested woodland hundreds of feet from shore, now has clear ocean views.

“I drove down there the other night and there was this guy standing right in front of the snow fencing with a fishing rod in his hand and a tackle box just staring. He was shaking his head; I went up behind him and said, ‘A lot of change, huh?’ He turned around and he could barely talk. He said, ‘What happened?’ ”

That snow fencing was 10 feet from the edge two weeks ago. On Thursday it was in a pile of trees in the surf at the bottom of a 25-foot cliff. New fencing had been put up once more, again 10 feet from the cliff’s edge, but Mr. Kennedy did not expect it to last long.

On Thursday, a gray seal on an excursion from Skiff’s Island, a seal-speckled sandbar in the distance that occasionally forms southeast of Chappaquiddick, inspected the scene.

“He’s swimming on what was terra firma a few weeks ago,” Mr. Kennedy said.

Once a well for private home, now out to sea. — Dana Gaines

Evidence of dramatic erosion abounds nearby in this windswept outpost where the Trustees have owned and managed hundreds of acres of conservation land for many decades. At the home of Sue and Jerry Wacks at the corner of Katama Bay and the Atlantic Ocean, the freshwater well that once serviced the house now sits in pieces in the surf (the Wacks have installed a temporary well elsewhere on the property). As recently as this past fall, after hurricane Irene, which took 22 feet of beach from the southern coastline, the well was 50 feet from the shoreline. The Wacks house now sits not much more than that distance from the shore.

But the seeds of the erosion’s end are also visible in the surf. The breach at Norton Point is driving much of the changes through complex oceanographic processes that are even adding beach in some areas. The Wasque swimming beach has gained 150 feet of sand since last fall. That new beach has had to be continually cleared of snarled pitch pine and debris by volunteer workers from the county corrections department. A maze of sandbars meanders just offshore and at one point even connects to the shore of the beach.

“At low tide this looks like a lagoon,” Mr. Kennedy said. The strange sandbars make for even stranger currents as evidenced by the disorganized whitewater off the beach.

“One of questions we have to answer before the summer is, how safe is swimming at Wasque?” said Mr. Kennedy. He is attempting to answer that question with help from Edgartown fire chief Peter Shemeth and Peter Wells of the Chappaquiddick fire department.

“They have one of these crash test dummies that we can throw in and see, just where does it go. Does it go straight to Portugal or does it get curled back in to shore?” Mr. Kennedy said.

The sand bars will become only more pronounced in the coming years as the Edgartown end of Norton Point, which now sits 800 feet from Chappaquiddick, will continue to migrate west, running parallel to the south side of the island before eventually reconnecting to land somewhere near the property of Richard Schifter (which lost 15 feet of lawn in the most recent storm) at the extreme southeastern end of Chappy.

Mr. Kennedy said he expects the process to take two to five more years to complete, after which he believes the area will see some respite from the dramatic erosive episodes of late.

Since he began working for the Trustees two decades ago, Mr. Kennedy said Wasque Point has lost at least 500 feet, including its salt marsh and swan pond, which were still visible on the Google Maps aerial shot of the Vineyard until only recently.

“We’ve got a lot more to lose,” he said.