MY FATHER IS walking to Lake Tahoe. He lives on the floor of the Sacramento Valley, fifteen feet above sea level. Lake Tahoe is more than 100 miles east of his home and some 6,000 feet above it. My father owns a car. He has money for a bus or a train. He is walking.

He departs from a small, ageing development just west of the Sacramento River, where venerable valley oaks tower above modest ranch houses. He is walking for these trees – for the giant natives that still stand and for those slain recently to make way for the enormous pipe that workers have begun burying a few feet beyond his back vegetable garden. This pipe, part of a growing region’s new sewage superhighway, will carry waste from points north and east past my father’s place before picking up contributions from the 5,000 houses that recently closed up the open country just south of where he lives. My father was one of three or four people on Earth who knew the locations of the wild asparagus patches that thrived there until the bulldozers came. He is walking for the sacks of wet green spears he carried home every spring.

Except for the shoes, each thing my father wears cost him less than a dollar. He outfits himself at the second-hand stores in the dreary neighbourhoods he traverses on his way to the bridge. He is walking for the people who live in these neighbourhoods and for those who live below the bridge, down on the riverbank.

My father, who grows more homeless daily, spends several mornings a week teaching science to the river people’s children. To prepare their favourite lesson, he ventures into a nearby cemetery and heads straight for a stand of mature cypress trees where barn-owls roost. These owls swallow their prey whole, then cough up the indigestible parts in compact pellets. My father gathers these pellets from the ground, and the children eagerly unpack them, the usual classroom welter subsiding as rapt students reconstruct entire skeletons of voles.

My father, too, is performing a reconstruction. Walking through Sacramento, he passes leggy old houses whose elevated floors tell of a time when citizens were wary of their wilful river. My father walks for the Sacramento, its course and currents altered for human convenience, its waters tainted by the poisons people produce.

He also walks for the American, his city’s second river. Flowing from east to west, down the green seaward slope of the Sierras, the American opens a path into the mountains. My father follows its protected parkway. Like the deer that crowd this narrow green belt, browsing bushes to the nub, and like the mountain lions that hazard suburbia to pursue their overly abundant prey, my father is responding to the pressures of growth.

Sacramento was a modest city when work first brought him here, a quiet state capital in a region of growing land and grazing land and small agricultural towns. In forty years this pleasant piece of valley has developed into a busy netherworld where buildings, roads and automobiles ceaselessly multiply beneath an ever-thickening pall. My father has patiently suffered this vast denaturing. Stoicism has seen him through the end of frog music, the paving of vernal pools, the snuffing of stars. But the slaughter of ancient shade-givers, the houses rising where asparagus grew, the sewer pipe snaking so close to his garden – these offences shake him to the roots.

And so my father is walking. He is walking in protest, as César Chávez and Martin Luther King walked before him, as Gandhi walked before them. He is walking in reverence, as John Muir walked. He is walking philosophically, in the manner of Thoreau. He is walking for his heart.

He is leaving the lowlands, entering the hills. He is eager for the hard reality of granite, the cool astringence of evergreen. He is throwing off the dingy blanket that smothers the valley. He is walking to Lake Tahoe, legendary for its clarity and depth.

What will happen when he arrives? I believe the mountain water will restore him. I believe he will return. When he returns, I believe he will fight.

Believing is necessary; but believing is not knowing.

My father is walking to Lake Tahoe.

He could be saying goodbye.

Andrew Wingfield’s novel, Hear Him Roar, deals with people and mountain lions in the sprawling suburbs of Sacramento, California.