Carol Cowan and her husband, Ken Anderson, live just outside the greenbelt in the stone house Carol’s great-grandfather bought in 1874. They moved to the 80-hectare farm southwest of Waterloo four years ago when Carol’s father turned eighty-seven. Ken commutes to a Toronto law practice; Carol raises calves organically. “We didn’t want the farm to go out of the family, and we didn’t want it to become part of the housing development going on as a result of the Toyota plant down the road,” Carol told me last spring. Serene in a blue denim smock under a halo of short white hair, she had just delivered the first of some fifty calves she would midwife over the coming days.

Ontario’s greenbelt, like BC’s Agricultural Land Reserve, was drawn on the map of the politically possible. Nature’s map follows a different terrain. The creek that crosses the pasture behind Carol Cowan’s weathered brown barn, like scores of other brooks trickling over southern Ontario’s farm country, is the functional equivalent of Mexico’s mountain “water factory.” It collects nature’s supply of rain and snow from the couple of hundred hectares of farmland it drains, and delivers it to the Nith River, a kilometre down the concession road. Along with the waters of other creeks, the Nith flows into the Grand River. More than 800,000 residents in the surrounding four counties rely mainly on the Grand for water; 500,000 more are expected to join them by 2030. The importance of the creek coursing through Cowan’s pasture land to their future is no less for its being excluded from the official greenbelt.

Nor does inclusion in the agricultural greenbelt keep the capillaries of Ontario’s water factory from becoming clogged. When cattle gather at a creek to drink, they churn the banks to mud. Fields worked to the water’s edge afford no shade for cool-water-loving native fish. Rain that falls on soils laced with fertilizers or pesticides becomes infused with them from furrow to stream. All three factors contribute to the dead zones that have returned to Lake Erie, to which the Grand River contributes a quarter of Canada’s share.

Ontario’s Grand River Conservation Authority enjoys a reputation as a leading model of watershed governance. Like Mexico, it’s been taking a little of the money it receives to maintain recreational areas and manage the river, and giving it to farmers to help keep the basin’s water capillaries clean. Carol and Ken received about $5,000 to erect fences along their creek to keep cattle a few metres back from the bank. Inside the fences, the authority planted a hundred burr oak, silver maple, and tamarack saplings that are now growing future shade. Despite her pro-conservation leanings, the fourth-generation farmer swallowed hard before agreeing to give up any of her working land to creekside repair. “People whose income comes solely from their farms,” Carol says, “[are] going to need to get a lot of money to change.”

And more change will be needed. Ontario has already lost many of its water-capturing capillaries. Some eighty species at risk live in the Grand River watershed, along creeks like the one Cowan maintains. But it would take only one farmer upstream or down who doesn’t buy into the same standard of stewardship to undo her good work.

I asked the conservation authority’s Martin Neumann whether enough of southern Ontario’s natural water factories were being preserved to carry its bursting suburbs through the summer droughts that are growing longer and more frequent. “No,” he replied. “We’d better crank it up, significantly.”

DOZING BY SATELLITE

Flying across the country, the Prairies seem comparatively wide-open, virgin territory. But touch down in Winnipeg and drive west, and you are soon disabused of this impression. Here, too, almost every inch of the Prairie Pothole Region is spoken for. The shallow marshes and vernal pools that give the area its name shelter the deer, waterfowl, and less-charismatic creatures whose variety is the definition of biodiversity. And like riverbanks farther east, they protect watercourses and communities downstream from the leakage of industrial agriculture. The same runoff cocktail depleting oxygen in Lake Erie contributes to soupy blooms of blue-green algae in Lake Winnipeg. But with grain prices up at last, many farmers eye the income locked beneath the few remaining sloughs and fire up the dozers. Potholes are shrinking fast, both in number and size.

“There was more brush broken last winter than I’ve seen in many years,” Cam Henry told me one spring morning as we sat in his tidy farm office, forty-five minutes northwest of Brandon, Manitoba. Henry’s granddaughters, aged two and three, could one day be the fifth generation of the family to work the land. This operation is on another scale than Cowan’s: about 1,700 cultivated hectares produce seed barley, wheat, canola, and flax. After breaking and draining most of the farm’s potholes over the years, the Henrys have left 200 or so hectares of slough, creek bottom, and woodlots untouched — for now. But piles of new slash down the road are a ready reminder that their neighbours continue to drain the prairie.

There’s an understandable eagerness to take advantage of the return of good grain prices, but that’s not the only change threatening the potholes that remain. There’s technology, too. “Automated steering,” Henry tells me. “It’s run off satellite, and it’s driving machinery for us. You go to the end of the field, you turn it on, it goes to the other end of the field; it’ll turn itself around and come back. But it wants to run in straight lines. Every time you come to an obstacle, you have to turn it off. You can’t drive around a slough. So there is a suasion to take those things out.”