1 the Oldman River Basin

1 The Oldman River Basin Everyone has a river in their life. – Kevin Van Tighem, Coming West: A Natural History of Home1 The Oldman, the Crowsnest, and the Castle Rivers rise in the front ranges of the Rocky Mountains in southern Alberta. The three rivers flow east from the mountains and through the foothills, converging about ten kilometres northwest of the town of Pincher Creek. From there, the Oldman continues its eastward journey through the Peigan Indian Reserve, past the city of Lethbridge, and across the prairie to a point south of the town of Brooks that the early European settlers called the Grand Forks. There, its flow combines with that of the Bow River to become the South Saskatch- ewan River, which meanders past Medicine Hat and into Saskatchewan, where it joins with the North Saskatchewan River to flow into Lake Win- nipeg, the Nelson River, and finally into Hudson Bay (see Map 2). The fact that the Oldman is a part of the Saskatchewan-Nelson River system adds another dimension to consideration of the Oldman Dam. The mean annual volume of flow in the Oldman River is about three and one-half million cubic decametres.2 By comparison with rivers in other parts of the country, that is not a lot of water. It is 10 percent of the mean annual flow of the Ottawa River in Ontario, and 5 percent of the mean annual flow of the Fraser in British Columbia. Variable is the word that Alberta water managers choose to characterize the flow of rivers like the Oldman that rise in the mountains and flow eastward across the dry southern plains. The annual cycle of flow in these rivers begins in early spring, when the snow begins to melt on the plains and foothills. By mid- June, when the weather warms enough to melt the snowfall that accumu- lated in the mountains over the preceding winter, the river flows begin to rise. Streamflows peak in early July, then recede steadily into late summer as the mountain snowpack disappears, and are sustained through the fall by run-off from glacier melt and whatever rain happens to fall. Winter sets in around mid-November, the ground freezes, the rains turn to snow, and river flows drop to their yearly minimums, where they remain until spring H U D S O N A L B E R B A Y T S A S A K A v e r T C R i H E W River A N l e North N Nelson Sask. M A N I T O River B A Red River Saskatchewan L a k e Calgary Deer W i n n i p e g Bow River River Sask. River Oldman R. South Lethbridge Lake Diefenbaker Regina A s O N T A R I O s in ib Aos r ins i n v e e i b i o i nRivere R Sourisr R i v e i r Winnipeg U s Lake of S R A River the Woods e d R i v Red e r River Map 2 The Saskatchewan-Nelson River system 14 The Oldman River Basin returns. About 60 percent of their annual flow passes down these rivers in the months of June and July. The flow in these rivers can also vary dramatically from year to year. Depending on the amount of snowfall in the mountains, streamflow can fall from near-record highs in one year to near-record lows the next. On occasion, streamflows remain well below average for periods of several years. When this happens, for example in the 1930s and again in the 1980s, summer rainfall is also well below the norm. Because of this vari- ability, dams have been the favourite tool of the region’s water managers. Water stored during the high flow period in early summer is available for use later in the year when the rivers begin to dry up or, in theory, during the next year should it be dry. In practice, so much of the water in most river systems is allocated for irrigation that there is rarely enough remaining in storage to meet demands in the second year of a dry cycle. That is why irrigation farmers are hit hard by water shortages during periods of drought and invariably raise the cry for more dams to capture and store the streamflow that is ‘wasted’ by being allowed to flow on through the system to Hudson Bay. In the expanding economic conditions that followed the Second World War, irrigation and hydroelectric development proposals in the three prairie provinces posed the potential for conflict over the use and man- agement of the river system. In 1948, the three provinces and the federal government established a Prairie Provinces Water Board (PPWB) to recom- mend the best use of the waters of the Saskatchewan River system, and how it should be allocated amongst the provinces. This arrangement, which began in a spirit of cooperation, broke down when provincial interests overcame the concept of an integrated plan for the development and use of the rivers. Because the PPWB was unable to agree on the relative merits of proposals put forward by the provinces, it was decided to adopt a for- mula for sharing the flow. The sharing arrangement was formalized in 1969, when the four governments reconstituted the PPWB, and ratified the Master Agreement on Apportionment.3 Although somewhat more complex in its details, the basic proviso of the apportionment agreement is that Alberta and Saskatchewan are each enti- tled to consume 50 percent of the flow of the Saskatchewan River system that flows into or originates in that province. The residual flow must pass to the downstream province. The agreement does not constrain the use of water in Manitoba. The agreement affords Alberta the option of consider- ing the Red Deer River to be tributary to the South Saskatchewan in Alberta for the purpose of apportionment.4 Alberta has exercised this option continuously since the agreement came into effect and, in 1976, the province adopted the policy of managing the three tributaries that contribute to the flow of the South Saskatchewan – the Red Deer, Bow, and The Oldman River Basin 15 Oldman – ‘in concert’ to meet its flow commitments to Saskatchewan.5 Because of these arrangements, the Oldman River Dam Project will have implications not only in the Oldman River system but also in the Bow and Red Deer systems. In particular, taking more water from the Oldman system to support the irrigation expansion that was the rationale for the project will limit future withdrawals from the Bow and Red Deer systems and threaten instream uses of water in those rivers. The South Saskatchewan system in Alberta is intensively used and highly regulated. Each of the headwater tributary systems features one or more large onstream dams or diversion works, the operation of which affects the pattern of downstream flow in a major way. As of 1999, there are twenty of these with more in the offing. These dams and diversions are, as a general rule, operated to satisfy the water requirements of their owners or of the predominant water use that the dam or diversion was built to serve. For example, TransAlta Utilities’ dams on the Bow River system are operated almost exclusively for the generation of hydroelectricity. Virtually all of the remaining structures, most of which are owned and operated by the provincial government, are operated primarily to support irrigation. Though the government claims that the provincially owned structures are operated for ‘multi-purpose use,’ when the weather is hot and dry and natural streamflow is low, they are only rarely operated for purposes other than to supply water for irrigation. Under Alberta’s water law, instream uses are of the lowest priority, and structures are operated to provide flow in excess of what these uses require for bare survival only at times when natural streamflow is abundant. During low flow periods, extreme public pressure sometimes forces managers to operate structures on some rivers to maintain flow at some minimum level at which the destruction of fish and other aquatic organisms is ‘minimized.’ The Oldman River Basin, the land area drained by the Oldman River and its tributaries, encompasses an area of about 26,000 square kilometres (see Map 3). The upper one-third of the basin lies in the mountains and foothills, where the river valley is deeply incised. The well-vegetated banks and bottomlands provide habitat for large and diverse populations of wildlife. Black bear, mule deer, and white-tail deer, moose, elk, fox, coyote, and various smaller mammals range the valley and the surrounding uplands, while beaver and muskrat make their homes in the river and its banks. The cold water in the streams in the upper reaches of the watershed are home to mountain whitefish and various species of trout, of which the rainbow, an introduced species, provides the greatest attraction for anglers, who consider these rivers among the best trout streams on the continent. The bull trout, a species increasingly rare in southern Alberta streams, is found in limited numbers in the Oldman. The river also has one threat- ened fish species, the shorthead sculpin. High River Little Bow Nanton River Bow Little Travers R O Willow Reservoir River 2 Creek C K Y Claresholm L E T H B R I D G E N O R T H E R N I R R I G A T I O N Oldman D I S T R I C T Porcupine River M O U N Oldman River Hills 3 Taber Fort Macleod Lethbridge Oldman PEIGAN River INDIAN T A I N S BLOOD C Dam 3 ro 3 w River s RESERVE 2 nest RiverCowley Brocket INDIAN NO.

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