Hokkaidō: A Tapestry of Lakes and Rivers

Over the years I have spent time in countless environments, from equatorial rainforests to polar tundra. In my wanderings, I have come to see the sun and water as the two central determining factors in the types of ecosystems that arise in any given area. They work to gradually transform the land, providing the conditions that give rise to forests, snowfields, and deserts. This is only natural, I suppose, as water formed on the primeval earth, cooled, and pooled into oceans where life emerged and began its evolutionary journey 3.8 billion years ago.

The weather brings about sudden changes to lakes, wetlands, and rivers, transforming their appearances in the blink of an eye. The sun, too, affects landscapes, altering their appearances as it journeys across the sky. People gazing drearily from the shore at the pallid waters of an overcast lake will feel their spirits soar when a beam of light breaks through the cloud cover, turning the surface into a shimmering display. Hokkaidō is blessed with an abundance of delicate and capricious freshwater environments, which have drawn me time and again to the remote corners of this northern land.

Volcanic Origins

Many of the island’s lakes and wetlands owe their existence to ancient volcanic activity. The area in eastern Hokkaidō around the Akan-Mashū National Park, where I live, has an especially large number of caldera lakes, including Akan, Kussharo, and Mashū. The largest of these—and the largest in Japan—is Lake Kussharo, which sets in a crater measuring 57 kilometers in circumference.

Tucked deep within the Akan-Mashū National Park, Lake Penketō lies in a thickly forested area near Lake Akan that is normally closed to the public. (© Mizukoshi Takeshi)

Lake Penketō (foreground) and Lake Panketō connect to Lake Akan, which drains into the Akan River. The three bodies of water were formed by volcanic activity that filled in sections of an ancient caldera lake. (© Mizukoshi Takeshi)

A rainbow appears over the choppy waters of Lake Kussharo following an evening squall brought by a cold front. (© Mizukoshi Takeshi)

A dawn mist drifts over Lake Shikaribetsu in the Daisetsuzan National Park. Formed by a volcanic eruption damming the Shikaribetsu River, it is the highest lake in Hokkaidō, at 810 meters above sea level. (© Mizukoshi Takeshi)

The crystal-clear waters of Kaminoko Pond are fed by underground water flowing from Lake Mashū. (© Mizukoshi Takeshi)

Lake Transformed

On a freezing morning in early February one year, I had the pleasure of witnessing omiwatari, the famous “god’s crossing” that occurs on Lake Suwa in Nagano Prefecture when the ice expands on the surface, creating a crack that propagates dramatically across the surface of the lake. The frozen lake emitted a squeaking noise like the cry of a small animal as the strong wind, gusting at times, blew the snow into the air, exposing the icy surface. As the ice began to creak again, a spout of water suddenly shot into the air, followed by a large bang. In an instant, a crack split the icy surface, running into the far distance. The next day, I heard that the omiwatari had pressed the ice along the crack upward, forming a frozen ridge over a meter tall.

The lakes in eastern Hokkaidō likewise freeze over during the harsh northern winters, the ice growing as much as 30 centimeters thick. Shortly after moving to the shores of Lake Kussharo, I began taking morning walks. Just once, some three decades ago, I witnessed an omiwatari-like phenomenon there as well; since then, I have never seen it on the lake, although I have found evidence of its occurrence every year.

When I first relocated to the area, Lake Kussharo still shimmered emerald green on sunny days, an effect created by the high acidity of the water. An earthquake in 1938 opened a volcanic hot spring below the surface, changing the chemistry and subsequently the color of the lake. The acidity has since weakened, and while fish populations that were once thought to have been wiped out have slowly returned, I miss the beautiful green hue of the water.

After the morning mist clears, Lake Kussharo comes into full view. (© Mizukoshi Takeshi)

Another development I have witnessed in about the last 10 years is that Lake Mashū, located roughly 20 kilometers east of Lake Kussharo, now rarely freezes completely over in winter. The sight of the lake shrouded in silvery white was enchanting, and to think that global warming has erased such a beautiful scene is heartbreaking.

Lake Mashū, parts of which have sadly been ice-free even in the depths of winter in recent years, is one of the world’s most transparent lakes. (© Mizukoshi Takeshi)

A Treasure Trove of Wetlands

Hokkaidō is home to a host of different types of lakes, including coastal lagoons. These bodies of water are formed by a sand spit or sandbar blocking a river inlet, which traps the water and creates a lake. Over time, wetlands have formed around many of Hokkaidō’s lagoons as sea levels have dropped and river sediment has built up. The wetlands around coastal lagoons support a diverse range of flora, and in summer the blooming plants create a vibrant scene. In eastern Hokkaidō, the wetlands around Lake Fūren, Lake Tōro, and Lake Saroma, as well as those of the Notsuke Peninsula, delight the eye with their vast array of blossoms.

Lake Fūren is a birdwatcher’s paradise. Including its famous flocks of whooper swans, it is home to more than 300 types of wild birds. (© Mizukoshi Takeshi)

A type of glasswort called akkeshisō tinges Lake Tōro on the east side of the Kushiro Marsh in reddish autumn colors. (© Mizukoshi Takeshi)

The Kushiro Marsh encompasses over 268 square kilometers and accounts for 60% of Japan’s wetland area. Formed as part of an ancient coastal lagoon, in winter it is a vital stopover for geese, ducks, and other migrating waterfowl.

The Kushiro River snakes its way through the Kushiro Marsh. (© Mizukoshi Takeshi)

One of the many alpine marshes that dot the area around Mount Asahidake in the Daisetsuzan Range. (© Mizukoshi Takeshi)

Life-Giving Rivers

I have heard that to people used to longer, more meandering rivers, the fast, turbulent waters of Japanese streams can appear more like horizontal waterfalls than typical languid waterways. Such an impression is only natural considering the geography of Japan, with the proximity of its towering mountains to the sea producing narrow, fast flows. Save for a few exceptions, most waterways that resemble the slower-moving rivers in many parts of the world are to be found in Hokkaidō, such as the Ishikari, Teshio, and Tokachi. These and other rivers have their sources in low-lying mountain ranges topping out around 1,000 meters lower than the Japanese Alps in Honshū, causing them to meander slowly across the land on their journey to the sea.

Another characteristic of Hokkaidō rivers is that they experience two periods of high water, once during the spring snowmelt in April and May and a second from heavy rains brought by the typhoons that visit Japan from July to September. The mouth of the Teshio River, for instance, fills its banks during these periods.

A third characteristic is the abundance of salmon varieties that migrate upstream from the ocean to spawn. Species such as chum salmon, pink salmon, and cherry salmon hatch in the rivers and travel as fry downstream to the Sea of Okhotsk and the Pacific, where they spend their lives before eventually returning to the rivers of their birth to spawn.

Cherry salmon from the Sea of Okhotsk navigate a waterfall on their way up the Shari River to spawn. (© Mizukoshi Takeshi)

Asian dust gives ice at the mouth of the Teshio River a yellow hue. Mount Hakkōda in Aomori Prefecture used to be the northernmost extent of the meteorological phenomenon, but it has started to be observed in northern Hokkaidō as well. (© Mizukoshi Takeshi)

Flowers of the aquatic plant baikamo bloom in early summer in the Nishibetsu River. (© Mizukoshi Takeshi)

Rapids on the upper reaches of the Akan River. (© Mizukoshi Takeshi)

Snow falls near the headwaters of the Kushiro River. (© Mizukoshi Takeshi)

The Setsuri River meanders through the Kushiro Marsh. In winter, the trees along the banks are encased in blowing snow and water vapor, creating juhyō, or “snow monsters.” (© Mizukoshi Takeshi)

Japan’s freshwater ecosystems change with the seasons, presenting an array of scenes to enjoy. Winter is a particularly stunning time of year, as temperatures remain below freezing even in the daytime, transforming the lakes, wetlands, and rivers of Hokkaidō into spectacular displays of snow and ice.

(Originally published in Japanese. Banner photo: Red-crowned cranes gather on the Setsuri River, which never freezes over even in the dead of winter. © Mizukoshi Takeshi.)