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Water Today Title December 14, 2019

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Update 2019/7/26
Flooding


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DAM FLOODS AND DROUGHTS – PART 3: DROUGHT PROOFING THE PRAIRIES



By Gillian Ward


In the last instalment of this series, WaterToday reported how some of the more experienced nations across the pond have been successfully managing floodwater with permanent manufactured solutions, and how these solutions could help mitigate flood losses in Canada. In this instalment, WaterToday looks at drought risk, and the steps being taken toward water security in the face of climate change.

Damming up a waterway serves to mitigate a region’s drought risk, providing for municipal water, recreation, irrigation and biodiversity, but presents serious risk to humans and the environment in the event of a breach or failure.

As previously reported, Canada’s dam engineers are considered among the best in the world, contributing to the body of knowledge and experience at the International Commission on Large Dams (ICOLD). We looked to ICOLD to understand the risks associated with dams, within Lessons Learned from Dam Incidents, A study on Failures and Accidents to Large Dams up to the end of 1965. This report did not include the massive dam failure that occurred in China, in 1975 when the Banqiao Reservoir Dam was breached by Typhoon Nina. Over 170,000 people lost their lives in that single failure, with millions rendered homeless.

With extreme weather events increasing, the necessity to store and divert waterways remains, and dam safety becomes a greater issue.

WaterToday checked in with the Canadian Dam Association to find out how our waterworks stack up in the safety department. Executive Director for CDA, Don Butcher says Canadians can rest assured that large dams in Canada are carefully monitored and maintained.

“While that is not to say that a large dam in Canada will never fail, it is highly unlikely to happen,” adds Butcher, “The greater risks are actually with smaller dams – dams that might not be monitored and managed closely enough because they have been forgotten by the owners, or they are perceived to have little consequences of environmental damage or low likelihood of human casualties.”

Butcher went on to explain, “Dams are like any other pieces of infrastructure: they provide benefits to society, but they have serious functions and need constant attention and investment”.

One such investment in dam safety is a novel boom technology that protects the dam structure from incursion by floating and sunken debris, logs and ice. Andy Peters at Pacific Netting Products says that the patented MultiFunction BoomTM was developed through a contract with Brookfield in June 2018. The new design improves upon the previous technology in use, which had gaps between the boom sections, allowing a certain amount of debris to get past the barrier.

The previous generation of barrier equipment had plastic, wood or aluminum boom sections connected with chain. The connectors, being the weakest element of the system, had to be inspected, maintained and repaired frequently for wear and tear. The new booms are flange bolted together, solving the serious problem of a weak link giving way at an inopportune time.

ICOLD notes that dam failure incidents declined initially after the group formed and began the work of sharing best practises in dam design, construction and maintenance between nations. Emmanuel Grenier told WaterToday that incidence of failure is on the rise again, over the last decade. The group is calling for a Worldwide Declaration on Dam Safety, which is expected later this year. Dam security is also prioritized and codified in International Humanitarian Law, to ensure the destructive forces held back by dams are not unleashed on populations and environment in acts of war.

As more severe weather events continue to build in frequency and intensity due to climate change, we need dams more than ever to mitigate periods of drought between the floods.

When geographer John Palliser explored the northern great plains region, he declared a large area overlapping Manitoba, Saskatchewan and Alberta “an uninhabitable desert”. Settlers to the region broke the land in spite of this warning, going on to make Canada one of the top agri-food producers in the world. Today this region is threatened by a persistent and worsening water shortage.

In a statement issued by Western Economic Diversification, the prairies based, water-dependent plant protein industry is valued at $4.5 billion per year and could create an estimated 4,500 jobs over the next ten years. Planning is underway to ensure water security for this important industry, with the federal government doing its part to help out.

“Weather patterns are becoming increasingly more severe and unpredictable, as we see more storms and larger floods, and longer droughts with larger wildfires that affect people and communities. The Government of Canada will work with all parties to find the best ways of managing the water available to us, and building the infrastructure necessary to provide for water quality and quantity that will serve the residents of the Prairies in future years, “ says the Honourable Ralph Goodale, Minister of Public Safety and Emergency Preparedness.

Another drought-prone zone exists in the southernmost part of Alberta. The Milk River flows from headwaters in Montana’s Rocky Mountains, picking up snow melt and runoff before crossing the 49th parallel into Canada. The Milk and its tributaries meander over 500 km of semi-arid Alberta farmland before returning to the USA, joining the Missouri, then the Mississippi, and eventually spills into the Gulf of Mexico.

The Milk River is, in and of itself, a seasonal flow. Flow modeling from the Milk River Watershed Council indicate that the riverbed would naturally dry up in four out of every ten years. Fortunately, the Milk River has received diverted water from another river system, granting continuous flow for the past one hundred years. That supply of water may now be in jeopardy due to wear and tear on the dam and diversion works on the US side.

The Milk River Watershed supplies the town of Milk River with municipal water and over 100,000 acres of irrigation in Southern Alberta, a number that nearly matches the scale of irrigation in Saskatchewan, Canada’s most prolific agricultural zone. The flow in this system is diverted from St. Mary’s River, at its headwaters on the Blackfeet Nation in Montana. The diversion sends 1200 cubic feet per minute up and over into the Milk system before it reaches Canada.

In 1917, the US government dammed up and diverted flow from St. Mary’s Lake, the headwaters of the St. Mary’s River, located on the Blackfeet Tribal lands. Loren Bird Rattler is the Agricultural Lands Manager for the Blackfeet Nation, with a role in natural water resource management. “Of course, the Blackfeet did not approve of the diversion”, said Bird Rattler. But, since it was built, so many people depend on it downstream, the Blackfeet have come to accept its necessity.

According to Jeff Pattison, Chair of the Milk River Watershed in Montana, the St. Mary’s diversion is failing. “Two siphon tubes, 8ft across carry the water out of St. Mary’s up three quarters of a mile and over into the Milk River, adding 1200 cubic feet per minute of flow to that system”, says Pattison. The diverted flow supplies water to a large portion of southern Alberta, irrigation on both sides of the border and the City of Havre.

“The diversion itself is over one hundred years old, built with horse drawn wagons and men with shovels. If you go up there, you will see, the concrete is worn, the rebar is showing, and the tunnels are leaking terrible.” Pattison is concerned about the imminent failure of the siphon tubes, which he says have been patched up with tarps, tin and tires. He paints a gloomy picture, to be sure.

“The biggest challenge is to educate the irrigators. Many farmers don’t know where their water comes from, and what failure of the diversion will mean for them”. The City of Havre, Montana and several smaller centres rely on St. Mary’s Diversion, over 12,000 people will be directly impacted by a failure.

Bird Rattler says he understands the urgency for those downstream that would be devastated by the failure of the St. Mary’s Diversion, but has confidence that the upgrade will be prioritized and built, saying “They won’t let it fail. I don’t believe it will come to that. Too many people downstream rely on this flow, its too valuable to let it fail.”

“We are at the headwaters, so we have our needs met here”, he says. The Blackfeet Nation went to court and battled forty years for a settlement for the diverted flow, and now have an annual allocation through the Blackfeet Nation/Montana/USA Water Compact.

Natural Water Resource Management is the practise of the Blackfeet Nation, where the priority is on restoring the natural floodplain. “I just wish the natural water resource management would catch on downstream, as what we are doing here on the Blackfeet Reservation, with more priority on wetlands preservation and restoration of the late season flows,” added Bird Rattler.

Pattison is not as optimistic about his government coming through for Montana, telling WaterToday “Washington (DC) seems to care less about the Montana high-line $2 billion-dollar economy than Canada cares about Alberta.” The Milk River group on the US side has produced a video explaining the urgent need for the upgrade to the diversion, hoping to raise awareness of the looming crisis, along with the $200 million the project is estimated to cost. Pattison is adamant that the situation is urgent, telling WaterToday the upgrade needs to be done as soon as possible to avoid apocalyptic scenario.

“If the (Milk) river dried up in August, there would be five days of water supply for the town (Milk River, Alberta). It’s a scary situation,” says Tim Romanoff, Executive Director of Milk River Watershed Council Canada (MRWCC).

This is a unique case for water security, as the headwaters of this system are on the US side of the border, but through the TransBoundary Water Protection Act, some co-management of the resource takes place. MRWCC works closely with the watershed council in Montana, but just to be safe, the Alberta based stewardship group is “seeking alternative water sources”, Romanoff advises. Water security plans are published on the MRWCC website.

Alvin First Rider works in the Lands Department of the Blood Tribe, located in Southern Alberta. With over 12,000 members, the Nation is situated across a few scattered community centres, having been shifted out of their traditional lands along the St. Mary’s River. “Even though the land claim has been settled, we got a cash payout, but we don’t get our traditional land back. Still, we care about the river, and all the animals that rely on that flow. We care about our neighbours. The St. Mary’s diversion is an important subject,” said First Rider.

For the Town of Milk River and all the irrigators, the fish and wildlife that would be impacted by the loss of this important water source, we hope that the St. Mary’s Diversion can be upgraded successfully. In our next instalment, we look into the Regenerative Agriculture movement, and ways that agricultural soils can be managed to improve water holding capacity and reduce the nutrient leaching from farm fields that contributes to toxic algae blooms in our lakes.

gillian@watertoday.ca

Related

Successive floods: Preparing for the new normal
Dam floods and droughts: Preparing for floods - part 1
Dam floods and droughts: Adapting for climate change - part 2




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