Few landowners would agree to hold water on their land without compensation — but one farmer is working with the Seine Rat River Conservation District (SRRCD) to buck convention.
Dairy farmer David Wiens owns a quarter of a section — the rest is provincial Crown land — encompassed by a mile-long dike, constructed to hold water on the entire area for as long as three weeks during peak flows.
The largest water retention project undertaken so far by the district, located south of Grunthal and east of St. Malo, was built for water storage capacity up to 376 acre-feet of water, meaning it will hold water to the depth of a foot over the same number of acres.
The RM of De Salaberry approached Wiens in 2009 with a proposal to build an upstream water retention structure to reduce flooding downstream. High-speed water flows from the Rat River into the lake at St. Malo were causing erosion, flooding and even public safety concerns.
Engineers designed the site to control peak flows from upstream wetlands, allowing only a controlled flow to leave the area, including a culvert plus a five-metre-wide emergency spillway to protect against excessively high precipitation and potential culvert blockages. The culvert will passively draw the water down out of the basin over 16 days.
“In principle I thought the idea made a lot of sense,” Wiens told more than 100 visiting delegates viewing the site during a Manitoba Conservation Districts Association tour.
The theory bore out in practice. The temporary water storage occurs only in wet years, and has worked out well for his farm as well as the surrounding area, he said. It was frequently wet pasture before and cows couldn’t cross it anyways. Now they graze the berm to move through it.
“It was one of those things that was a win-win,” he said. “We knew when we started talking about this project how we would also benefit. Yes, there’d be water on the land for a few weeks, but to some extent there was anyway and we feel it has improved this pasture that we have here. The drain going through here was also cleaned out and improved.
“For holding the water, there was some other mitigating factors that made it quite attractive for us. And it’s good to know it has a positive effect on the surrounding communities,” Wiens said.
“This is the kind of thing we just need a lot more of throughout the region.”
SRRCD manager Jodi Goertzen, who guided visitors to half a dozen other watershed management projects during the tour, calls the Skyline Dairy/De Salaberry Crown Lands project an important feat of engineering as well as an example of what partnerships can achieve.
It proved much less expensive than first estimated too. Ballpark figures before engineering studies were completed initially suggested construction would cost $1 million.
“It first looked like a daunting cost. When we actually priced it out with our engineer, who is a specialist in wetland engineering and construction, what he found was we’d actually be able to use the soil type on site, which is a fine sand. That way we didn’t have to haul in clay.”
But the engineer assured them that well-compacted sand would do the job. In total the cost turned out to be $300,000. It was all paid through the conservation district and its 16 member partners over three budget years.
It’s also significant in that it represents a project constructed on agriculturally leased Crown lands, where until now water retention structures have rarely been attempted.
The project wasn’t built without controversy however. Neighbouring landowners were apprehensive about the volume of water to be stored and the potential for a breach, Wiens said.
Public hearings were key to getting those concerns aired and addressed, he said.
“I think by the time we were through that process and the hearings everyone understood quite well that the water is secure, and that there’s an emergency outlet, and that it would only hold back so much,” Wiens said.
Delegates on the June 16 tour saw other local projects in the Seine-Rat River region where stakeholders have figured out mutually beneficial solutions to mitigate flooding risks, intercept downstream nutrient loading and improve the overall health of the watershed.
This included a wetland project on property owned by Cliff and Dorothy Freund near Steinbach, where a gated backflood on the edge of a existing swamp creates over 100 acre-feet of storage for water that would otherwise be spring run-off, flooding farmland and municipal infrastructure to the west.
Compared to the De Salaberry/Skyline Dairy project, that’s a comparatively long three-month drawdown, noted Goertzen.
Another project is geared to holding water back just three days. It’s on low-lying pasture and hayland in the RM of Ste. Anne, owned by farmer Grant Edel, and includes a one-km dike and spillway designed to hold 20 acre-feet of water for 72 hours, before slowly releasing it into a nearby drain.
The water covers a wider area, to ensure it minimizes the impact to Edel’s hayfield and farm operation before its release.
That project, which was given a special award at the 2015 MCDA awards banquet, was funded by Growing Forward 2 and supported by staff with Manitoba Agriculture, Conservation and Water Stewardship, and Agriculture and Agri-Food Canada.
Other projects viewed included an RM of Tache private property where small wetlands were made from borrow pits to serve as wildlife habitat and twin dikes hold back nearly 100 acre-feet of water that would otherwise spill through the Fish Creek affecting farmland and residents near Lorette and Prairie Grove.
The tour also stopped at the Edie Creek retention basin in the RM of Springfield where three basins built between 2010 and 2012 have stemmed the flooding that used to damage local roads. Other sites on the tour included the Tourond Creek Discovery Centre, an 80-acre public park in the RM of Hanover’s decommissioned Kleefeld landfill site, and Rosenthal Nature Park where a former borrow pit to build the Mitchell lagoon now captures run-off from nearby developed land and surrounding area serves as a picnic and recreational area.