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Worthwhile trade-off

New drainage and water management initiatives announced earlier this month will make it easier for Manitoba farmers to drain low spots in their fields, but harder — much harder — to convert wetlands into annual crop production.

It may seem like a nuanced distinction and it will undoubtedly make many in the farming community nervous — especially since the penalties for undertaking unapproved drainage will also become stiffer.

But the economics and social benefits behind this approach are compelling, from the provincial standpoint and quite frankly for farmers too. It is farmers and rural Manitobans, after all, who are on the front lines of excess water woes. This year’s unseeded acreage is a case in point.

Newly released Saskatchewan-based research on the linkage between wetland drainage and flooding has confirmed what many have long suspected. A long-term monitoring and computer modelling study by the University of Saskatchewan Centre for Hydrology shows wetland drainage is indeed “a major factor in increasing Prairie streamflows and increasing flooding in wet years,” the so-called Pomeroy report says.

“Draining wetlands adds permanent surface connections, reducing the ability for wetlands to store surface water and increasing the land area contributing to streamflow when snowmelt run-off is generated,” the report says. “The land area contributing to streamflow increases in wet conditions and decreases in droughts because of the changing storage of water in wetlands.”

Earlier research conducted here in Manitoba also found wetland drainage contributed significantly to flushing nutrients into streams and lakes.

This latest hydrology work was done in the Smith Creek watershed near Yorkton, Sask., which has undergone substantial drainage over the past 50 years. In 1958, wetlands made up 24 per cent of the basin area. Today they have been reduced to 11 per cent.

These researchers found that the wetland drainage since 1958 increased the 2011 flood peak by 32 per cent and the 2011 yearly streamflow by 29 per cent. Continued drainage of those wetlands would increase the peak flows in future flood events by 78 per cent and the yearly volume by 32 per cent over 2011.

Restoring those wetlands to the 1958 levels would decrease those peak flows by 26 per cent.

It’s unlikely that’s going to happen. Once land has been “improved” or “developed,” which is how our society rationalizes valuing only those things we can draw revenue from, there are currently no mechanisms for returning it to natural services.

But these new proposals will at least stem the losses and form a basis for a much more co-ordinated and strategic approach to water management in both times of excess and shortages. Toward that end, we hope the Saskatchewan government is paying as much attention to this research as its downstream neighbour.

The federal government’s Canvec system categorizes wetlands according to a scale of 1 through 5.

The province is lessening its oversight over Categories 1 and 2 — those low spots — but adding Class 3, which tend to be seasonable wetlands that dry out in some years to the restricted list along with 4 and 5. Most of the Class 3 wetlands are less than two acres in size but there’s a lot of them; Ducks Unlimited officials said there are 275,000 acres of Class 3 wetlands left in Manitoba and a total of 1.42 million acres in Classes 3 to 5.

It’s awfully tempting for a farmer to get in there and consolidate, not only freeing up more cropland but to lessen the burden of working around them.

But if these regulations go ahead, farmers or other developers who want to drain these potholes will need a permit and to replace the wetlands lost by a ratio of three to one. That will consist of either finding another spot on the farm or purchasing wetland “credits” so that wetlands can be developed elsewhere, preferably within the same watershed. In other words, the cost of drainage is going up to reflect the broader costs associated with that drainage.

So protecting Class 3 wetlands comes at a cost to agriculture — that’s 275,000 acres of potential farmland lost. Based on land rental rates of $55 per acre per year, that’s more than $15 million worth of productive capacity lost.

But Scott Stephens, director of regional operations for the Prairies with Ducks Unlimited Canada, said the benefits by way of flood storage (11 times the current capacity of Lake of the Prairies), the carbon and nutrients stored add up to net benefit ratio of nearly nine to one, or $490 per acre per year.

It’s a trade-off all right. Farmers will be restricted from developing more land that they can farm some of the time, given the rising incidents of overland flooding. But in the future, it could mean they can get back to farming the acres they have today all the time.

About the author

Editorial Director

Laura Rance is vice-president of content for Glacier FarmMedia. She can be reached at [email protected]

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