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Meandering the mudflats: 800 miles around Cook Inlet

A channel wanders through the mudflats along the Seward Highway and Turnagain Arm on Saturday, October 25, 2014. The low tide along the arm reveals the glacial silt carried along from receding glaciers. (Bob Hallinen / Alaska Dispatch News)

Editor's note: Author Erin McKittrick and her family made an 800-mile circuit of Cook Inlet over more than three months. One result is the new book "Mud Flats and Fish Camps: 800 Miles around Alaska's Cook Inlet," from which this is excerpted.

Tall brown reeds marked water so deep that you'd best avoid it. The flat-bladed grass tussocks weren't too wobbly for walking. Short grass bristled beneath a few inches of warm water, firm and springy underfoot. Golden rye grass sprayed clouds of silt dust with every footstep. And when the grass feathered away into salty ocean, there was nothing left but the mud.

I ran out of words that meant "gooey." It was more fun to compare this world to food. The frosting that lines the channel banks. The softened butter beneath my paddles. The layers of canned pumpkin or pureed squash, tomato sauce or heavy cream, stacked up into a sensory smorgasbord of dirtiness. The mudflats might even be lovable. But they did not, in fact, have a single dry spot to fit a tent on.

We camped on a duck shack porch. In every square inch of mud, there were bird tracks. In every moment of silence, there were bird songs. Cranes, gulls, snipes, shorebirds, ducks, and geese. They were here in the spring and they'd be here in the fall, with hunters following close behind. The state gives people permits to put up cabins out here where no one lives — perched on pilings above the tide — because the hunters can't find a dry campsite either. Across the water, Anchorage's downtown skyscrapers gleamed pink in the light of sunset. Houses sprawled up the hillside above the city, sparkling streetlamp orange beneath alpenglow peaks. Over the wind farms of Fire Island, a full moon rose. And if you're seeing all of that in late May, it means you're staying up pretty darn late.

Anchorage viewed at sunset from the far side of Knik Arm in May 2013. (Ground Truth Trekking)

"We walked at least five miles, but I think we made about two miles of actual progress," I commented later that night, squinting at the map.

"About what I thought," my husband Hig replied, dangling his bare feet over the edge of the porch, sweaty gray soup streaming between his fingers as he squeezed out the tattered remains of his socks.

"Why don't you just switch socks now?" I asked him. "I bet you could even burn those — they're wool."

"Because this environment is really hard on socks. If I can get across the Susitna Flats … "

"And the Trading Bay Flats, and the Tuxedni Bay Flats, and the Chinitna Bay Flats," I interrupted.

"We'll have it all figured out by then," he said. "We won't be wandering around like idiots, we'll be —"

"Muddy."

Hig laughed. "Mudflat experts."

Packrafting down a Trading Bay slough with an oil rig in the misty distance. (Ground Truth Trekking)

Big, messy tides

In 1896 — it was May then, too — Mr. W.A. Dickey got off a steamship, picked his way around ice blocks on the beach, clambered into an open dory with a few partners, and pushed off with the tide. Channels braided, crisscrossed, unmappable. It took them two days to find the mouth of the Susitna.

Erin McKittrick writes in her journal from the porch of a duck shack on the Susitna Flats. The shack was locked, but the trekkers made use of its porch for an unorthodox campsite to get a bit farther from the marshy grass — and the potential for going beneath the tide. May 2013. (Ground Truth Trekking)

The tide swept them upriver, until finally they reached the current that tumbled out of the glaciers, too strong for their boats. So they stopped and whipsawed lumber to make two river boats, caulked them over with spruce gum and grease, and pushed on upstream, wading through the cold, tugging a thousand pounds of supplies in each boat, hoping to make a couple of miles each day. We had digital maps, instant communication, and gear so light the miners wouldn't recognize it, but we went about as far, in a day, as they had. The miners were only here to get rich. Their goal was material wealth, their commodity was largely useless to the world, and they were one of the forces that decimated the people who lived here first. The world would probably be better off if every speck of their gold was still buried beneath a ton of gravel. Still, it was hard not to admire their ingenuity.

The next morning, I repacked the diapers and walked back inside the duck shack, our daughter Lituya on my hip. Son Katmai slept while we packed around him. He could sleep in the packraft, but who wakes such a sweetly sleeping child? That blond head, that muddy face, those unknowable dreams. Water poured down the sloughs, racing away from us as we struggled to catch up, struggled to get ready in time for the tide. It was 9:42 a.m. At 7:42 a.m. the tide had stood at 32.4 feet, leaving just a few patches of grass above the water. At 3:03 p.m. the tide would stand at minus 4.2 feet. That difference adds up to more than 36 feet of water — enough to flood the entire tip of Florida. Here it just left us with a tidal flat that seemed Florida-sized, with water in a rushing hurry to cross it, four times a day.

The loose and lagging rhythm of family camping was a grating contrast to the specificity of the tide tables. Tides feel so big and messy — as overwhelming as the weather. It has always astonished me that we can predict them so exactly. That I can look up just where the water will stand in a certain spot at a certain time, months or even years into the future.

Any periodic motion can be calculated as the sum of a number of simpler curves. In 1867, the English mathematician Sir William Thompson applied this to the tides. Only mathematicians noticed. By hand, the math was too monstrous to be of any use. In 1881, William Ferrel designed a tide-prediction machine for the U.S. Coast and Geodetic Survey. At 11 feet long and over 2,500 pounds, it was a mechanical marvel of gears and dials, capable of summing 37 components of the tide — adjustable for each tide location — to spit out the same sort of numbers now printed in a free book that fits in my pocket. The Dena'ina didn't have tide books, of course. Nor did Captain James Cook, the steam ship drivers, the gold rush prospectors, the early fishermen, or the homesteaders. In 1922, Anchorage had a part-time tidal observation station. Everyone else had to know tides for themselves.

They had to take the tides by feel. The incremental shifting — about 45 minutes later each day. The increasing drama of stronger currents, clam beds laid bare and flooding marshes as the full and new moons drew near. The tide moves across the earth as a wave, bulging, reflecting, interfering with itself as it bounces off the intricate outlines of the land and resonates in enclosed pockets like Cook Inlet. Tides can sweep you, shove you, ground you. Captain Cook filled his logs with notes on the tide, on the time the ebb began each day, the force of the current, the fathoms of water, or lack of water, beneath his ship. It flowed with the current because he couldn't fight the tide any more than our packrafts could. The highest average tidal range in the world is 38 feet, in Canada's Bay of Fundy. Cook Inlet's average range is 30 feet.

"It will appear," Cook wrote, "from what has been said occasionally of the tide, that it is considerable in this river and contributes very much to facilitate the navigation of it. It is high-water in the stream, on the days of the new and full moon, between 2 and 3 o'clock; and the tide rises, upon a perpendicular, between three and four fathoms. The reason of the tides being greater here, than at other parts of this coast, is easily accounted for. The mouth of the river being situated in a corner of the coast, the flood that comes from the ocean is forced into it by both shores, and by that means swells the tide to a great height."

The sun lights up the patterns created by water wave action in the glacial silt mud as the tide is out on Turnagain Arm along the Seward Highway on Monday, August 13, 2012. (Bob Hallinen / ADN archive)

Tidal energy

It was a full moon. More than 200 years later, our low tide was at the same time Cook's high had been, and 4 fathoms — 24 feet — was an understatement. I closed my tide book, shouldered my backpack, and grabbed Katmai's hand. It was after 11 a.m. by the time we felt our way down to the slough, slipping and sliding down the glistening mud banks, my paddle as a brake. We flopped into the packrafts and followed the slough. Ducks erupted from the water, scared up at every curve. The mud canyon became a creek, then a river whose banks we could now see over. Then, in a foaming rush, it became the ocean.

Fine mud streaked by tidal currents covers gravel. (Ground Truth Trekking)

It was 12:30 by now. We crossed a choppy eddy line where brown foam churned and boiled, gathering up sticks and logs of driftwood. We were flying. Rushing. Racing. Sprinting. Perhaps it takes a couple months of walking at the speed of a 4-year-old to appreciate it, but 5 miles an hour is really fast. The energy is overwhelming.

Calculations show that 90 percent of the tidal energy potential in the United States is in Alaska — and much of that is in Cook Inlet, where shallow constricted channels and high tidal ranges combine into the rush we were following. Alaskans might power half of the state's Railbelt (the road-connected cities from Homer to Fairbanks) with the tide. But silt scours anything you put in this brown water, as it scours our skin and our tent zippers. Ice floes shatter and crash for months out of the year. Neutrally buoyant ice chunks, as big as boxcars, have been described as "bowling balls coming down the inlet." Alaska is energetic — violently energetic.

As early as the 1950s, other engineers looked to the energy of the Susitna River itself. Its hydroelectric potential was studied and dropped, and studied and dropped again, and now resurrected in a $6 billion plan to build a 600-megawatt power plant and a huge dam, stopping the giant Susitna where rapids boil through the Wantana Canyon, 184 miles upstream. If built, the dam might be a way to cut some of the web of ties that binds Alaska to its fossil fuels. Or it might be hubris. A pork-barrel boondoggle and the sure death of salmon. Depending on which Alaskan you talk to.

Water hit the base of Katmai's sand castle. It undermined the crumbling foundation, curled around the walls, and poured into the space behind them. He clutched his paddle-shovel, watching the flood. The dropping tide had pulled us down the slough, from the duck shack to the ocean, to the sandbar. We'd paused for lunch, and now the tide was coming back. The island was gone. It was a stream of hissing bubbles ascending to the surface through the rising tide. Eruptions of water shot several inches into the air. A dozen belugas joined us at the edge of the current, whooshing and splashing as they fed in the eddy line. Their spouts arced above the rising tide. Watching them, I could imagine the salmon flooding with the tide, swimming right into those great white mouths.

The tide comes in fast, flooding a castle in just a few minutes. (Ground Truth Trekking)

"Susitna" comes from a Dena'ina word "Suyitnu," meaning "Sand River." I wonder if they named it for someplace far upstream of the mudflats, where rippled sandbars broke the river into braids. Or from when they paddled out here, where sandy islands appeared and disappeared with the tide, and river and ocean blended into one. Mirages stretched the distant mountains into a city of skyscrapers, hovering above a cushion of mirror-like water. Trees floated on nothing, some uncountable number of miles away.

We were in the middle of the ocean. That was my most precise estimate of our location. The cellphone drowned by Knik Arm had been partially resurrected by a campfire, and when I found enough power and signal to turn it on, shaded the wonky rippled screen with a hand, and turned on the online tracking app, I could sometimes actually locate us in space. Otherwise? We were mere flotsam in the currents.

Lituya displays her new attire of Trading Bay mud. (Ground Truth Trekking)

I'd told Hig the other night, "If we can cross the Susitna, we can do anything." But the Susitna wasn't something we could cross. Or fight. Or even drink. It was like a breathing giant, blowing us out in the morning, then snorting us back in at the end of the day. Exhaled with the driftwood, our packrafts streaking past mountains so fast it felt like we were one of those jets painting contrails in the sky. Then inhaled. Sucked in toward the shore, sucked back up into the Susitna, the tide rushing upstream as we tried to pick a channel that might help us get the right direction. We navigated by specks on the horizon. Nothing could tell us how far we were from shore, when the shore itself could grow or shrink by miles in a few brief hours.

We just hoped to make it from the giant's left nostril to the right.

Erin McKittrick is a writer, adventurer and scientist based in Seldovia. She's the author of "A Long Trek Home: 4,000 Miles by Boot, Raft and Ski," the children's book "My Coyote Nose and Ptarmigan Toes" and "Small Feet, Big Land: Adventure, Home and Family on the Edge of Alaska." Her latest, "Mud Flats and Fish Camps: 800 Miles around Alaska's Cook Inlet," was published earlier this year. You can find her at GroundTruthTrekking.org.

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