The Proposed Ardley Dam: Potential Impacts on the Red Deer River Watershed

The idea of constructing a dam near the hamlet of Ardley on the Red Deer River has been contemplated for nearly a century, with studies dating back to the 1940s. In 2024, the Alberta government allocated $4.5 million for a comprehensive feasibility study to assess the potential construction of this long-considered water infrastructure project. This report examines the possible environmental, ecological, hydrological, and socioeconomic impacts that the proposed Ardley Dam could have on the Red Deer River Watershed. The dam would be located approximately 35-40 kilometers east of the city of Red Deer, creating a reservoir that could significantly alter river dynamics while potentially offering benefits for water security, flood control, irrigation, and recreation in an era of climate change and growing population demands.

Background and Context of the Ardley Dam Proposal

Historical Development of the Ardley Dam Concept

The idea of a major water engineering project near the hamlet of Ardley extends back to at least 1914, when irrigation engineer William Pearce first devised plans to divert water from the Red Deer River for livestock and agricultural purposes1. This concept evolved over decades as various studies were conducted, governments changed, and public finances fluctuated. By the 1940s, a formal dam project was proposed, with sites surveyed and core samples taken1. Cost estimates for construction were prepared by 1951, yet the project never materialized despite additional studies conducted in the 1960s1.

In 1983, the Dickson Dam was built upstream on the Red Deer River, southwest of the city of Red Deer, creating Gleniffer Lake1. The Dickson Dam was constructed to address many of the same concerns that are now driving renewed interest in the Ardley Dam proposal: ensuring reliable water supply during low winter flows, providing flood control, and creating recreational resources1. Despite the Dickson Dam's presence, continued population growth, increased water demand from agricultural and industrial users, and recurring drought conditions—exacerbated by climate change—have prompted reconsideration of the Ardley Dam proposal1.

Current Proposal and Feasibility Study

In 2024, the Alberta government announced funding for a new feasibility study of the Ardley Dam project in its provincial budget2. The two-phase, multi-year study will explore the costs and benefits of constructing and operating the reservoir, as well as its impact on downstream communities, farmers, ranchers, and businesses2. The first phase of the study, expected to be completed by December 2025, will review existing geotechnical and hydrotechnical information while exploring conceptual dam options23. The second phase, scheduled for completion by March 31, 2026, will assess whether an effective dam can be safely designed and constructed, including detailed analyses of potential environmental impacts23.

The Request for Proposals (RFP) for the study specifies a study area of approximately 15 square kilometers, about 35 kilometers east of Red Deer1. The province has contracted Hatch Ltd., a Canadian multi-disciplinary professional services firm, to undertake this comprehensive study2. While the primary purposes of the proposed dam would be irrigation, drought management, water security, and flood protection, the study will also consider secondary benefits such as hydroelectric power generation and recreational opportunities12.

Hydrological Impacts on the Red Deer River System

Alteration of Natural Flow Regimes

If constructed, the Ardley Dam would significantly alter the natural flow regime of the Red Deer River. Dams fundamentally change river hydrology by creating barriers that transform flowing river systems into more static, lake-like environments15. Research on similar projects shows that dams typically reduce annual peak discharges, decrease the range of daily flows, increase the number of flow reversals, and alter the timing of high and low flow events11. These changes can extend for considerable distances downstream of dam structures.

The Red Deer River currently experiences natural seasonal variations, with higher flows during spring snowmelt and lower flows during winter months. The existing Dickson Dam already regulates these patterns to some extent, ensuring minimum winter flows of 16 cubic meters per second (cms) compared to natural lows of just 2 cms26. An additional dam at Ardley would further modify this regulated system, potentially creating more consistent year-round flows at the expense of natural variability1112. These altered flow patterns would affect all downstream reaches of the river through to its confluence with the South Saskatchewan River system.

Flood Control and Drought Mitigation Potential

One of the primary justifications for the Ardley Dam is its potential to enhance water security and mitigate drought conditions in Central Alberta. The Red Deer River Municipal Users Group (RDRMUG) has emphasized the vulnerability of the river system to drought, warning that "if we have two years of drought in a row, we are going to be in trouble"23. Unlike the Bow and Oldman rivers, which have multiple storage facilities, the Red Deer River currently has limited drought resilience with only the Dickson Dam providing significant storage capacity23.

The proposed dam could provide substantial flood control benefits as well. The Dickson Dam has demonstrated the value of such infrastructure during major flood events; during both the 2005 and 2013 floods, it reduced downstream peak flows by approximately 30%26. The Ardley Dam could offer similar protection for communities further downstream, including Drumheller, which has historically suffered significant flood damage3. However, while dams can effectively regulate small and medium-sized floods, their ability to attenuate extremely large flood events is limited by reservoir capacity and operational constraints26.

Ecological Implications for the Watershed

Impacts on Fish Populations and Migration

The construction of a dam at Ardley would create significant barriers to fish movement and alter habitat conditions throughout the river system. The Red Deer River hosts numerous fish species including mountain whitefish, goldeye, walleye, brown trout, and northern pike19. These species have adapted to the river's natural flow conditions and any major alteration could disrupt their life cycles.

The existing Dickson Dam has already demonstrated such impacts on fish distribution in the Red Deer River. Following its construction, the cold-water releases from the bottom of Gleniffer Reservoir extended a downstream cold-water zone that favored species like mountain whitefish and brown trout while pushing warm-water species such as northern pike, goldeye, and mooneye downstream of their historic ranges19. An additional dam at Ardley would likely create similar thermal and habitat alterations, potentially fragmenting fish populations and creating disruptions to established species distributions1822.

Fish migration would be particularly affected by the dam construction. Many river fish species undertake seasonal movements for spawning, feeding, or to avoid unfavorable conditions. Without effective fish passage facilities, the dam would block these migrations, potentially leading to isolated populations with reduced genetic diversity and resilience18. Even with fish bypass channels or other mitigation measures, the effectiveness of such structures varies widely and rarely perfectly replicates natural connectivity19.

Alterations to Riparian and Wetland Habitats

The Red Deer River is unique in Alberta as it flows through all five of the province's major ecoregions from the Rocky Mountains to the prairie grasslands6. This diversity creates a rich mosaic of riparian habitats that support numerous plant and animal species. The construction of the Ardley Dam would permanently inundate a section of the river valley, transforming flowing river habitat into a reservoir and flooding existing riparian zones in the impoundment area2122.

Downstream of the dam, riparian ecosystems would face altered hydrological conditions that could disrupt established plant communities. Healthy riparian areas depend on periodic flooding and natural flow variations to maintain their ecological function20. Dam construction typically reduces peak flows and alters flooding frequency, which can lead to changes in vegetation composition and reduced riparian biodiversity22. These changes would be particularly significant in the Central Agricultural and Dry Grasslands zones of the watershed, where riparian health is already under pressure from agricultural activities20.

Wetlands connected to the river system would also face hydrological alterations. The fluctuating water levels in the reservoir itself could create new shoreline wetland habitats, but these would differ significantly from natural riverine wetlands in terms of species composition and ecological function2021. If designed with environmental considerations in mind, the dam operation could potentially incorporate flow regimes that support downstream wetland ecosystems, but this would require careful planning and management21.

Water Quality Considerations

Reservoir Stratification and Downstream Effects

The creation of a reservoir behind the Ardley Dam would transform a section of the flowing Red Deer River into a more static body of water, leading to thermal stratification and changes in dissolved oxygen levels. In reservoirs, water typically forms distinct layers with higher oxygen concentrations at the top and lower concentrations at the bottom13. These hypoxic (low-oxygen) or even anoxic (zero-oxygen) bottom layers develop as microorganisms decompose organic sediments, consuming available oxygen13.

When water is released from the bottom of the reservoir through the dam, this oxygen-depleted water flows downstream, potentially creating adverse conditions for aquatic life13. Even small decreases in oxygen content can cause complications in river ecosystems, affecting fish and invertebrate populations13. Additionally, the reservoir would alter water temperature patterns, potentially releasing colder water downstream that could impact temperature-sensitive species and ecological processes14.

Nutrient and Sediment Dynamics

Dams fundamentally alter the transport of nutrients and sediments through river systems. The Red Deer River naturally carries sediment loads that include organic materials, nutrients, and minerals. The proposed Ardley Dam would trap an estimated 70-90% of these sediments in its reservoir, significantly reducing downstream transport17. This sediment trapping would have multiple cascading effects on water quality and ecosystem function.

Research on other reservoirs has shown that dams can change nitrogen and phosphorus ratios in downstream waters, as they may facilitate nitrogen removal through denitrification while potentially increasing phosphorus loading due to internal reservoir processes14. These changes in nutrient stoichiometry can profoundly affect aquatic ecosystems by altering primary productivity patterns and food web interactions14. Additionally, the loss of sediment transport downstream would reduce natural nutrient delivery to floodplains and riparian areas that depend on periodic flooding to maintain soil fertility15.

The trapping of sediments would also affect water clarity and light penetration. Downstream of the dam, water typically becomes clearer due to reduced suspended sediment, which can increase vulnerability to algal blooms if nutrient levels remain high15. This change in turbidity could alter predator-prey relationships for fish species that rely on naturally turbid waters for protection from predators15.

Socioeconomic Implications and Community Impacts

Water Security for Growing Communities

The proposed Ardley Dam would significantly enhance water security for the growing population of Central Alberta. The Red Deer River supplies water to hundreds of thousands of Albertans across the region, and expanding storage capacity through an additional reservoir could help meet increasing demands as more families, businesses, and industries establish in the area2. A consulting report estimated that the project could provide water for an additional 1.4 million people in the region, illustrating its potential significance for long-term regional growth1.

The city of Red Deer has experienced significant population growth, increasing by more than 33,000 residents over the previous two decades to just over 100,000 today1. Surrounding Red Deer County has a population of about 20,0001. These growing communities require reliable water supplies, particularly during periods of drought or low river flows. The Ardley Dam would provide an additional buffer against water shortages, complementing the existing storage at Gleniffer Lake behind the Dickson Dam2.

Agricultural and Industrial Applications

Agriculture remains a dominant land use in much of the Red Deer River basin, with approximately 43% of the watershed used to grow crops on about 13,000 farms4. The proposed Ardley Dam could significantly expand irrigation capacity in the region, potentially supporting irrigation for an additional 51,000 hectares according to a recent report1. This expansion of irrigated agriculture could increase agricultural productivity and resilience, particularly important in an era of climate change and increasing weather variability.

Industrial users would also benefit from enhanced water security. About 46% of allocated water consumption from the Red Deer River basin currently goes to irrigation, while industrial and fossil fuel production account for approximately 29%1. The petrochemical industry is particularly significant in the region, with major facilities like the Prentiss and Joffre plants requiring reliable water supplies20. Enhanced water storage would support these existing industries while potentially enabling further economic development in the region.

Recreational Opportunities and Tourism Potential

While the primary purposes of the Ardley Dam would be water security, flood control, and irrigation, recreational opportunities represent an important secondary benefit that could generate significant economic value. Similar reservoirs in Alberta, such as Gleniffer Lake created by the Dickson Dam, have become popular destinations for boating, fishing, swimming, and other water-based activities126.

The economic value of reservoir recreation can be substantial. A case study of Chestermere Lake reservoir near Calgary estimated the total monetary value of recreational ecosystem service benefits provided to non-resident day users at between $794,000 and $980,000 annually25. If the Ardley reservoir were designed with recreational access and amenities in mind, it could potentially generate similar economic benefits for the region through increased tourism and recreational spending25.

Challenges and Controversies

Environmental Concerns and Ecosystem Impacts

Despite potential benefits, the proposed Ardley Dam faces significant environmental concerns. Flooding nutrient-rich land can result in the release of carbon into the atmosphere, while a large volume of standing water absorbing heat from the sun can increase water temperatures and decrease dissolved oxygen levels1. These changes can fundamentally alter aquatic ecosystems and potentially lead to biodiversity loss2122.

Environmental scientists have highlighted that dam construction creates "irreversible consequences for the land and biodiversity"1. Prof. Tricia Stadnyk, Canada Research Chair in hydrologic modelling, has noted that the environmental costs of dams are often inadequately calculated in cost-benefit analyses: "Where we do a poor job these days—and this is globally, not just here—is in quantifying the loss of the benefits of the ecosystem service of the land in its natural state"1. The natural fluctuations of river levels support diverse ecosystems that would be permanently altered by dam construction1.

The feasibility study will need to carefully assess these ecological trade-offs, including impacts on fish migration, changes to riparian vegetation, and effects on water quality. The loss of connectivity between upstream and downstream river sections represents a particular challenge that could fragment populations and disrupt ecological processes22.

Stakeholder Perspectives and Policy Considerations

Various stakeholders hold different positions regarding the Ardley Dam proposal. The Red Deer River Municipal Users Group has actively advocated for the project, citing water security concerns and the need for drought resilience89. Municipal leaders from communities like Didsbury, Sundre, and Olds have expressed support for a feasibility study to determine if a second reservoir is needed923.

In contrast, the Red Deer River Watershed Alliance maintains a more neutral position as a science-based organization with a multi-stakeholder board1. Their statement indicates they are "interested to find more details on the proposed project" without taking a definitive stance on the Ardley dam1. This reflects the complex considerations at play, including potential trade-offs between water security and environmental preservation.

Water management in Alberta operates within the framework of the provincial Water for Life Strategy, which aims to balance three goals: healthy aquatic ecosystems, safe drinking water supplies, and reliable water for the economy7. The Ardley Dam proposal represents a test case for how these sometimes competing objectives can be reconciled in policy decisions. The feasibility study will need to address questions about water licensing, allocation priorities, and long-term watershed sustainability in the context of climate change and growing demand1.

Conclusion

The proposed Ardley Dam represents a significant potential intervention in the Red Deer River Watershed that would have far-reaching implications for hydrological patterns, ecological systems, and socioeconomic development. The two-phase feasibility study funded by the Alberta government will provide crucial information about the viability, costs, benefits, and impacts of this long-considered infrastructure project. Based on the available information, the dam would likely enhance water security and drought resilience while creating new opportunities for irrigation and recreation. However, these benefits must be weighed against potential ecological disruptions, including alterations to fish habitat, riparian ecosystems, and natural river processes.

The complexity of the Ardley Dam proposal highlights the challenges of balancing human water needs with environmental preservation in an era of climate change and population growth. As Central Alberta continues to develop, managing water resources sustainably will require careful consideration of both immediate needs and long-term ecosystem health. The ultimate decision on whether to proceed with the Ardley Dam will need to integrate scientific assessment, stakeholder input, and value judgments about the desired future of the Red Deer River Watershed.

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