Walk along the Coastal Trail at low tide and you’ll be gazing out at a sculpted moonscape of gray-black mud. It’s the treacherous Mud Flats, all that remains of mountains scraped into silt by relentless glaciers, then carried to sea by Alaska’s swift rivers. The rivers that feed the Inlet dump massive loads of sediment: 20 million tons a year flow into Knik Arm alone–the equivalent of 100,000 747’s! As a result, though miles wide, the Upper Inlet is only 30-50 feet deep at high tide.
You might be tempted to walk across the exposed mudflats at low tide. Don’t dream of it – the quicksand mud would trap you, and the incoming tides would finish you off. The shifting silt, however, sustains life in other forms. Salt-tolerant sedges, such as arrow grass and Silverweed, thrive along the shores between Point Campbell and Point Woronzof. They filter nutrients and provide a safe rest stop for migrating waterfowl such as whistling and trum- peter swans. Canada Geese, pintails, shovelers, and American widgeons breed on the wetlands. Shorebirds such as Yellowlegs and Spotted Sandpip- ers move their chicks onto the flats during brood-rearing. And the Inlet is critical habitat for the entire continent’s population of some shorebirds, such as the Hudsonian Godwit.