A wetland is the general term we use to describe parts of the landscape where water and land meet and intermingle.

Wetlands include the edges of streams, rivers and lakes, as well as springs and a whole range of soggy lands from sloughs to peat bogs and fens. Although the degree of stability of wetlands varies naturally, all wetlands perform ecological functions, whether they contain water on a seasonal or year-round basis.

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“Lack of understanding is one of the major threats to wetland health and longevity. Filling in or draining a single hectare of wetland can negatively impact the surrounding landscape. The negative effects of wetland loss are cumulative. Every time a wetland is lost, or allowed to degrade, the entire watershed loses value to humans, animals and plants.”

– Wetlands Alberta

Ecological Services

Wetlands provide a great variety of valuable ecological services, including the following:

detoxification of pollutants
inactivation of pharmaceutical drugs
silt filtration
sewage breakdown
removal of excess fertilizers
general water purification
recharging of groundwater
provision of a buffer against both floods and droughts
storage of atmospheric carbon and accompanying moderation of greenhouse gas levels
habitat for rich biodiversity and abundant life

Wetland Types

Approximately one-fifth of Alberta’s landbase is covered in wetlands. In Alberta, wetlands can be divided into two broad categories: peatlands and non-peatlands.

Peatlands

Peatlands, such as bogs and fens, are characterized by their peat-based soils and are found mostly in the forested northern part of the province. In fact, 90 percent of Alberta’s wetlands are peatlands located in the boreal region.

Bogs, also known as muskegs, are poorly drained and filled with mats of peat moss (sphagnum moss). They are acidic and surrounded by boreal forest black spruce and tamarack trees.
Fens, a unique feature of the Boreal Region, are a type of peatland that has some water flow, sometimes causing patterns through the peat masses. They are less acidic than bogs and therefore support different types of flora and fauna. Fens are generally surrounded by sedges, grasses, shrubs and tamarack trees.

The northern part of Alberta, known as the boreal forest, contains more than 100,000 km² of bogs and fens, amounting to about 11 percent of Canada’s peatlands. Until very recently, these were considered to have little value except for the production of peat used by gardeners and in industrial filtration. Peatlands are now being recognized as representing unique ecosystems that provide habitat for over 400 species of plants, many of them threatened or endangered. Many wildlife species are associated with peatlands as well, including the endangered woodland caribou. The role these vast peat bogs play in climate stability is just beginning to be understood, and this may be their greatest ecological service.

Non-peatlands

Non-peatlands, comprising mostly marshes, ponds, swamps, and shallow open water, are found primarily in the more settled Parkland and Prairie Regions of the southern half of the province.

Marshes, also called sloughs, are areas of open, slow-moving water dominated by plants like reeds, rushes, cattails, and grasses.
Shallow open water, also called ponds and potholes, usually have no obvious rate of flow and contain water plants like duck weed and water lilies.
Swamps are forested ponds with little obvious flow that are fed by spring floods and snowmelt. They are surrounded by shrubs and trees like black spruce, willow, and tamarack.

Wetland Loss

Up to 70 percent of Canadian prairie wetlands have been drained and filled in, mainly to facilitate agriculture. In Alberta, 64 percent of wetlands in the White Area have been lost. The estimated wetland loss in Alberta’s Parkland Region alone is 61 percent. Today we have a better understanding of the vital role wetlands play in maintaining wildlife and ecosystem health and in storing, cleaning, and replenishing vital water supplies. Unaltered wetlands are one of the most cost-effective means of controlling floods and cleaning water.

While there has been some success in restoring prairie wetlands disturbed by agriculture and industrial activities, it is generally acknowledged that a restored wetland does not function as optimally as an original intact wetland. In the Wetland Consultation Workbook, 2007, produced by the Alberta Water Council, it is acknowledged that “it is almost impossible to fully replicate the complexity of a natural wetland ecosystem.” Peat-based wetlands are especially complex. They develop over thousands of years and there is currently scientific consensus that once damaged, they are impossible to restore to their original ecological functionality.

Nature’s Filters

Wetlands are nature’s kidneys, functioning on a broad scale to filter and clean water and to recharge surface and underground water supplies. Cities like Calgary are moving toward retaining and even building wetlands. Wetlands are gaining increasing regard for their ability to settle and clean storm water, which is often very contaminated with dog feces, spilled solvents, paint and oil, salt from winter streets, and so on. Wetlands also provide urban wildlife habitats and enhance city aesthetics.

Prince’s Island Park in downtown Calgary is home to a constructed wetland designed to help filter storm water. Many groups collaborated to build an interpretive trail to help educate Calgarians about the many benefits wetlands provide and what we can all do to reduce the amount of contaminants making their way into the Bow River through the storm sewer system.

The real workers in wetlands are plants, mud bacteria and fungi, and filter feeders like freshwater mussels. Research shows that the plants in healthy wetlands located in agricultural areas can remove up to 92 percent of nitrogen and 95 percent of phosphorous from over-fertilization of fields. While drawing water through their systems, plants chemically alter or filter out many toxins and detrimental chemicals. Bacteria and fungi in wetland muds gradually convert most filtered toxins, except for heavy metals, into benign materials.

Wetlands in the Prairie Pothole Region

Over 10,000 years ago, shallow depressions were left across the Great Plains of North America by glacier activity. Covering an expanse of ~800,000 km² and spread across Alberta, Saskatchewan, Manitoba, and five U.S. states, they form the Prairie Pothole Region (PPR), a massive wetland complex and key source of water in an otherwise dry, windy, and temperature-extreme climate. As snow melts in the spring, the water naturally drains and collects in these depressions, creating seasonal and temporary wetlands that contribute outsized benefits to regional hydrological functions and biogeochemical processes.

Recent research finds wetlands are “active regulators of ecosystem water balance”, playing a dominant and direct role in setting the rate, extent, and timing of runoff in the Great Plains and PPR[1]. Wetlands located here determine “not only how much water leaves a catchment each year, but also whether that response unfolds gradually or abruptly”[1]. In an area characterized by limited precipitation and frequently afflicted by drought, this makes protecting PPR’s wetlands particularly critical.

Prairie potholes contribute base flows to streams, reduce peak flows during flood, facilitate exchange between groundwater and surface water stores, increase habitat connectivity and support movement of wildlife. Rich in biodiversity, they also provide prime breeding and nesting habitat for waterfowl and other water dependant species as they migrate across the region. Prairie potholes help prevent soil erosion, retain sediment, sequester carbon, and absorb, transform, and remove excess chemicals like phosphorus, nitrate, nitrite, and pesticides.

Alberta’s agricultural industry is concentrated within the PPR and historically has been the main threat to the region’s wetlands. Through conversion and drainage, an estimated 70 % of wetlands have already been lost.

Wetlands play important roles in agricultural fields

Excess nutrients and chemicals from fertilizers, pesticides, and other agricultural applications are a known threat to watersheds, contributing to algal blooms, eutrophication, and reduced water quality downstream. The retention of wetlands within agricultural fields is known to provide effective mitigation, as wetlands function as natural filters on the landscape. Researcher have found the ecosystems remove on average 53% of nitrate and 68% of phosphates from agricultural drainage[2].

Wetlands also provide important habitat for native pollinators, who in turn increase crop yields through their pollination services[3],[4]. In canola and cereal fields within the Prairie Pothole Region, the abundance and diversity of native bee species was found to increase with proximity to wetlands[5].

When comprehensive cost-benefit analyses are undertaken that factor in the many ecosystem services associated with wetlands, retaining these ecosystems makes both environmental and financial sense[6],[7]. Research on canola crops in Alberta found that “hydrologically intact basins had higher average profit/acre values than drained or consolidated wetlands”, with 70 % of the basins with impacted or degraded wetlands producing less than the producer’s desired benchmark profit of $100/acre[6].

Encouraging producers to retain wetlands in their fields is beneficial for increasing crop yields and profits, for protecting water quality, watershed health, biodiversity, and for retaining essential ecosystem services like filtration and pollination in agricultural landscapes.

Tile drainage impacts wetland ecosystems and the watershed

When soil is too wet to grow crops, tile drainage is one technique used to remove excess water. Once installed below the surface, tile drains rapidly remove and direct groundwater away from agricultural fields. In doing so, they are associated with a number of environmental impacts.

Tile drainage impacts regional hydrology, reducing watershed storage. It is associated with “increased duration and severity of stream flow droughts”, a specific type of hydrological drought that occurs when streams experience abnormally low flows[8]. The depletion in water resources incurred by hydrological droughts is associated with “widespread implications for hydropower, water supply, industry, agricultural productivity, and ecosystem services”[7].

Because tile drainage facilitates the movement of subsurface water to streams more quickly than natural drainage, it influences the “flashiness”, or how quickly water flows increase and decrease within steams. In relatively flat watersheds, where the topography is less than a 2% slope, the flashiness of streams increased with increased tile drainage[9].

Tile drainage increases the concentration of selenium in aquatic ecosystems and benthic invertebrates. Compared to control sites, researchers found selenium levels in those impacted by tile drainage to be “on average twice as high and at times over 32 times higher”[10]. Aquatic insects at impacted sites contained selenium concentrations “at or above levels of dietary concern… high enough to cause impairment in birds”. The researchers found the selenium remains in insect tissues through metamorphosis from their larval state to their adult forms, which means they can be a source of selenium in both aquatic and terrestrial food chains[9].

Tile drainage also has an impact on water temperature. In watersheds where tile drainage covers more than 15% of the drainage basin, median and quartile stream temperatures increased by 3°C[11]. The researchers attributed this change to tile drainage “lowering the water table and reducing cool waters fluxes into streams and rivers”, with impacts particularly apparent during the summer[10]. This has serious implications for Alberta’s native fish populations, who require cool water temperatures to thrive.

Drainage tiles negatively impact wetlands, reducing their depth and permanency[12]. This threatens their function, particularly their ability to provide habitat, as many wetland organisms require at least 70 – 130 days (~10 – 19 weeks) of standing water to complete their life cycles[11].

Draining wetlands reduces resiliency to natural disasters and climate change

Draining wetlands is associated with increased flood damage downstream[5]. Researchers find that retaining existing wetlands provides a high social return on investment (ratios of 3.17 – 7.70), particularly in the long term and “is an economically viable solution to limit the financial, social and environmental damages of flooding in… the Prairie Pothole Region”[5].

Wetland drainage is an unaccounted source of greenhouse gas emissions in the atmosphere. The “mean annual wetland loss in the Canadian Prairie Pothole Region is 10, 820 ha/year”, which results in an estimated release of 2.1 million metric tonnes of carbon dioxide equivalents, and equates to an extra 5% in annual agricultural emissions throughout the region[13].

References:

[1] Rahmani, J., Creed, I.F., Badiou, P. et al. (2026) Wetlands set the pace of annual runoff in the northern Great Plains. Commun Earth Environ 7, 368 (2026).

[2] Ross, C.D., & McKenna, O.P. (2022) The Potential of Prairie Pothole Wetlands as an Agricultural Conservation Practice: A Synthesis of Empirical Data, Wetlands, 43:5.

[3] Hinson, A.L., et al. (2024) Native bee Pollination Ecosystem Services in Agricultural Wetlands and Riparian Protected Lands. Wetlands, 44:116.

[4] Cohen, A.L., Devries, J.H., & Galpern, P. (2023) Wetland cover in agricultural landscapes is positively associated with bumblebee abundance. Insect Conservation and Diversity, 17:1.

[5] Vickruck, J.L., et al. (2019) Pothole wetlands provide reservoir habitat for native bees in prairie croplands, Biological Conservation, 232.

[6] Pattison-Williams, J.K., et al. (2018) Wetlands, Flood Control and Ecosystem Services in the Smith Creek Drainage Basin: A Case Study in Saskatchewan, Canada. Ecological Economics. 147.

[7] Clare, S., et al. (2021) Does drainage pay? Quantifying agricultural profitability associated with wetland drainage practices and canola production in Alberta. Wetlands Ecology and Management. 29.

[8] Adelsperger, S.R., et al. (2024) Agricultural tile drains increase the susceptibility of streams to longer and more intense streamflow droughts. Environmental Restoration Letters. 104071.

[9] Zhou, S., & Margenot, A.J. (2025) The double-edged sword of agricultural tile drainage effects on stream flashiness: A meta-analysis. Journal of Hydrology. 651.

[10] Henry, B.L., Wesner, J.S., and Kerby, J.L. (2020) Cross-Ecosystem Effects of Agricultural Tile Drainage Surface Runoff and Selenium in the Prairie Pothole Region. General Wetland Science. 40.

[11] Ficklin, D.L., & Adelsperger, S.R. (2024) The influence of tile drains on stream temperatures throughout the agricultural Midwestern United States. GU Fall Meeting 2024, held in Washington, D.C., 9-13 December 2024, Session: Hydrology / River Temperature in a Changing World.

[12] Werner, B., et al. (2016) MODELING THE EFFECTS OF TILE DRAIN PLACEMENT ON THE HYDROLOGIC FUNCTION OF FARMED PRAIRIE WETLANDS. USGS Staff – Published Research. 1202.

[13] Whitfield, C., et al. (2025). Wetland drainage produces substantial greenhouse gas emissions in the Canadian Prairie Pothole Region. FACETS, 10.

September 9, 2022

A wetland is the general term we use to describe parts of the landscape where water and land meet and intermingle.

Ecological Services

Wetland Types

Peatlands

Non-peatlands

Wetland Loss

Nature’s Filters

Wetlands in the Prairie Pothole Region

Wetlands play important roles in agricultural fields

Tile drainage impacts wetland ecosystems and the watershed

Draining wetlands reduces resiliency to natural disasters and climate change

References:

AER Letter of Authorization re: Suncor’s McClelland Lake Wetland Complex Operational Plan

Alberta Peatlands: A Valued Resource Under Stress

Upcoming AWA Talks

Suncor’s Fort Hills Oil Sands Project – Integrated Plan Amendment Application

Letter to AER regarding the Fort Hills Oil Sands Project at the McClelland Lake Wetland Complex

Fort Hills Oil Sands Project – McClelland Lake Wetland Complex Operational Plan 2021

No money, no answers

December WLA Water Update

“Optimizing” Parks? Many questions, no answers… so far

Alberta’s Wetland Policy in the White Area: Shortcomings and Future Directions

AWA Welcomes New Northeast Alberta Protected Areas

Wood Buffalo National Park Needs Stronger Cumulative Impacts Assessment from Parks Canada