ON SHELL KEY — Suzi Kinter picked her way down the white sandy beach, noting the stagnant, murky water pooled nearby."The water here used to be crystal clear," she said. "You could see 10 feet down."Kinter stood in the middle of what had been Shell Key's northern channel. Now clogged with sand, the channel had been hundreds of yards across, where pristine water flowed swiftly between the island and nearby Tierra Verde.Mounds of shifting sands have transformed a vibrant ecosystem into a kill zone. Sea grass withers in the listless water. Coyotes and wild dogs scamper across the newly formed sand bridge and gobble up nesting shore birds.Florida's dunes and shoreline are constantly sliding this way and that, pushed by wind and waves. What has made this migrating beach unusual is that it has jeopardized a popular island nature preserve."I don't think there's any question the preserve is dying," said Kinter's Tierra Verde neighbor, Morrie Goldman.The president of Tampa Bay Watch, an estuary protection group, agrees. Peter Clark has helped plant much of the sea grass near the 1,800-acre preserve on one of the county's largest undeveloped barrier islands to provide habitat and food for marine life. Now he can only watch as the sea grass fades away. Flowing water that kept the sea grass healthy sits as still as if it were in a bathtub because the channel is closed, choking off access to the Gulf of Mexico.Clark has called a public meeting on Tierra Verde on Monday to discuss possible solutions. But fixing the problem is complicated by Shell Key's own history.Aerial photos of the area from the 1950s reveal that Shell Key didn't exist. At most there's a clump of mangroves and a sandbar. But by the 1990s, swirling sand washing southward from Pass-a-Grille Beach had accumulated enough in that spot to form an island popular with boaters and campers, according to Jack Coletti of St. Petersburg, who runs Friends of Shell Key. Such an island, by law, belongs to the state. But in 2000 the Florida Department of Environmental Protection agreed to lease it to Pinellas County to manage as a preserve, a rare bit of undeveloped property in the state's most densely populated county. So who would be in charge of saving the preserve: the state or the county? Sen. Jack Latvala, R-Clearwater, took a boat ride last week to see the situation for himself. He cautioned that "we're way down the pike from knowing how to fix the problem. It's a county problem."But the county's coastal manager, Andy Squires, doesn't see any point in reopening the channel.Four years ago, the last time the channel closed, the Tierra Verde Homeowners Association got a county permit to dredge it open, Squires said. Within months the reopened channel clogged up again, he said. "I don't think it's a good idea to spend county money — or anybody's money — fighting Mother Nature," he said. It's better, he said, "to just let Mother Nature take its course."But Coletti doesn't see the problem as a force majeure."Blaming Mother Nature seems kind of convenient," Coletti said. It's not an act of God that repeatedly spends millions in taxpayer dollars to dredge and pump sand back onto the eroding beaches of Pinellas' barrier islands, such as Pass-a-Grille.Coletti, Clark, Kinter and Goldman are convinced that the sand that closed up Shell Key's channel came from those Pinellas beach nourishment projects, where the funding is split between the federal government, at 60 percent, the state at 20 percent and 20 percent from the county.The county's own figures show that thousands of cubic yards of sand dumped on those beaches soon washed away. For instance, in the summer of 2014, new sand was pumped onto Upham Beach, a park off Gulf Boulevard north of St. Pete Beach. In the past year, about 140 feet of the beach washed away. Squires says he doesn't know the origin of the sand. University of South Florida coastal geology expert Ping Wang said the sand choking the Shell Key Preserve did not come from those beaches. The island's creation by the natural flow of sand shows the channel's closure is a natural process, he said.But another USF professor, ocean current expert Bob Weisberg — who lives in Tierra Verde — contends that the southward flow of water from those beaches shows that the beach projects are the likely source. County officials want to know for sure, so next year they'll conduct a study, according to Commissioner John Morroni. Of course, by the time it's done, it might be too late to salvage the preserve, he acknowledged.If the study shows the sand that closed the channel "is from our beach nourishment sand, then that's not Mother Nature doing it" and it should be dredged, Morroni said. But if it's not, "then I would say leave it alone."Regardless of the source, Coletti and others believe that the solution to preserving the preserve is for someone — county, state or federal government — to dig up all the sand that has clogged the channel and use it the next time Upham, Pass-a-Grille or one of the other beaches needs more sand.And if the government won't take action, Goldman said, more desperate measures might at least help: "A bunch of our neighbors want to come out here with shovels one night and open it up."Times researcher Caryn Baird contributed to this report. Contact Craig Pittman at [email protected] Follow @craigtimes.