Water Quantity

Water Quantity

Back to
Summary

Water quantity in the Peace sub-basin has undergone moderate change. Observations by Indigenous communities and scientists suggest that ice is less thick, with earlier break-ups and later freeze-up dates in many waterbodies, particularly in the lower Peace. Less snow was reported in the lower Peace (the northern and eastern regions of the sub-basin), while there is more snow accumulation in the upper Peace (the western and southern regions). Water levels in lakes, rivers, and creeks are more variable, although communities have generally observed lower levels than in the past. Late winter flows have increased in some small tributaries while freshet flows in Peace River have decreased. These changes are likely the result of a combination of flow regulation on the Peace River by the W.A.C. Bennett Dam and the effects of climate change. Changes in water quantity threaten to further disrupt the aquatic ecosystem health and the ability for Indigenous communities to practice a traditional way of life in the sub-basin.

The following table summarizes the availability of information for each Water Quantity indicator.

Signs and Signals

Indigenous Knowledge Information and Data

Indigenous Knowledge Availability 1

Science Information and Data

Science Data Availability2

Snow and Ice

Local observations and oral histories of changes in snow quality, ice thickness, presence and break up of ice jams

Limited observations from few locations.

Available modeling information / stats on snow quality, ice thickness, presence and break up of ice jams

Snow data and analyses available. Many studies on ice cover and ice jams on the Peace River.

Water Flows and Levels

Local observations and oral histories of changing flow / water levels in rivers / lakes and aquifers over time

Many observations from several locations.

Seasonal statistics including changes in flow / water levels in rivers / lakes and aquifers over time

Long-term data sets available from some Water Survey of Canada stations; data from four stations on the Peace River and four stations in major tributaries were analyzed.

Climate

Local observations and oral histories of temperature, precipitation normal and extremes over time

No information found.

Temperature, precipitation normals and extremes over time

Data available from weather stations in the basin, analyses completed. Other sources are Pacific Climate Impacts Consortium (PCIC), Climate BC and Climate WNA (Western North America).

Water Use

Not assigned a Sign or Signal

Not assessed.

Number of water licenses, purpose, volume allocated, and volume actually used vs. water flow / level; Water demand from various sectors, including dams, agriculture, oil and gas, etc., trends in water use over time

Water Licenses available but not retrieved for this report. Reports available.

1Qualifiers for the availability of local and Indigenous Knowledge observations in publicly available sources: Limited = 1-2 observations; Some = 3-4 observations; Many = 5 or more observations; Few = 1-3 locations; Several = 4 or more locations
2 Qualifiers for the availability of science data in publicly available sources: Low = Individual studies or locations; Many = Network of monitoring stations across the basin

Snow & Ice

Changes in ice quality, the presence and break-up of ice jams and reductions in snow have been observed in the lower Peace sub-basin, while snow mass increased in the south-western portion of the sub-basin.

In the Peace-Athabasca Delta region, elders from Fort Chipewyan have observed the colour of ice has changed as it no longer appears blue in the winter. They have also observed that ice is more slushy and weaker than in the past.[3] Conversely, scientific studies have measured a slight increasing trend in ice thickness on the Peace River at Peace Point from post W.A.C. Bennett Dam (1972) to 2006.[4],[5]

Mikisew Cree First Nation elders and river users have observed that ice conditions and break-ups in the Peace-Athabasca Delta are changing, reporting in one study that ice “just melts away” and that jams and break-ups in the Peace-Athabasca Delta no longer occur with the same force and intensity as in the past due to lower water levels and changing flood patterns.[2]

Freeze-up trend analysis from 1971 to 2002 indicates that freeze-up has been occurring at higher river stages since the construction the of W.A.C. Bennett Dam. This results in fewer ice-jam floods because it increases the required stage for ice breakup to occur and promotes more thermal ice-breakup events. These act to reduce the likelihood of mechanical break-up events, which promote ice-jams and related flooding.[6],[7]

Ice-jam flooding in the lower Peace only occurs when the discharge at Peace Point is > 4000 m3/s; mean monthly flows exceeded this threshold in 13 of 58 years on record. The freshet maximum monthly discharge decreased between 1972 and 2017 by 13.5 m3/s per year. However, this change is not statistically significant and may be attributed to natural variability.[8]

The Peace-Athabasca Delta has received less water from flooding since the W.A.C. Bennett Dam regulation. Both climate trends and the impacts of regulation have influenced the reduced incidence of ice-jam flooding delivering water to the Delta. Analysis of one research team indicates that regulation played a greater role in this result than climate trends (climate alone would have reduced flood frequency by 21%, while the total observed reduction is 57%).[9] Another research team, however, has presented paleolimnological evidence that drying of the Delta and ice-jam flood frequency is driven by climate variability.[10],[11]

There has been a significant decrease in snowfall at Fort Chipewyan between 1962 and 2003.[12] A corresponding trend of declining snow mass in the eastern portion of the Peace sub-basin was found in a recent analysis of satellite imagery and climate data. On the other hand, snow mass has increased markedly in the western portion of the basin, in particular at high elevations.

Change in Average March Snow Mass (as Snow Water Equivalent, in mm/decade) in the Peace sub-basin 1980 to 2015. Positive (light green, yellow, orange, red) values indicate increases in snow mass, negative (dark green) values indicate declines in snow mass.

Snow mass trends were derived using a multi-dataset approach described in Mudryk et al. 2020, and provided by Environment and Climate Change Canada.

Climate teleconnections with Pacific origins have impacts on lake break-up and freeze-up dates in Western Canada, with certain phases of these teleconnections shifting break-up earlier (and quicker) and to a lesser extent freeze-up later. A mid-1970s shift in Pacific-related climate teleconnections (e.g., El Nino Southern Oscillation, Pacific Decadal Oscillation, etc.) has resulted in a regional shift in break-up and freeze-up dates with lakes much more strongly impacted than rivers. Freeze-up has occurred later and break-up earlier as a result. While the effects of global warming on the teleconnection patterns examined in that study remain uncertain, models suggest that as climate warms, El Nino-type patterns may become more frequent and would likely result in shorter ice durations, particularly in western Canada.[13]

Documented sources of Indigenous Knowledge information regarding changes in snow quality in the Peace sub-basin were not found.

Water Flows & Levels

Declines in water levels across the basin and increased flooding in some areas have been observed by Indigenous communities in the Peace sub-basin. Streamflow records indicate earlier spring freshets and lower summer streamflows, and some lake levels have declined.

Many Indigenous communities have observed a marked decline in water levels in the Peace sub-basin in the past several decades. Trend analyses on lake level data from 1972 to 2018 indicate that lake level changes are site specific, with decreasing trends in Mamawi Lake in the Peace Athabasca Delta and no significant trends in Lake Claire in the Peace Athabasca Delta and Sturgeon Lake near Valleyview (this study, see figure). Members of Treaty 8 First Nations from BC and Alberta have reported that water levels across the sub-basin are low and affecting fish spawning habitat in tributaries of the Peace River.[14] In the lower Peace, members from Mikisew Cree First Nation and Athabasca Chipewyan First Nation have reported shallower water conditions throughout the Peace-Athabasca Delta, which poses challenges for boat access and travel.[15] Lower water levels are typically attributed to an increase in surface water diversion for industrial activity in recent years, particularly hydroelectric and hydraulic fracturing activities.[16] The “drying of the Delta” is a widely reported phenomenon and the relative importance of climate change and hydroelectric development in driving this change has been subject to much debate[17] (see Athabasca sub-basin assessment).

The Kelly Lake Métis have similarly observed lower levels in rivers and lakes in the upper Peace including Hythe River, Beaverlodge River, and Horse Lake.[18] According to Kelly Lake Métis elders, many creeks within their traditional territory are running dry in late May rather than late July or early August, much earlier than in the past.[19] Similarly, a declining trend in the lake levels from 1983 to 2008 has been recorded in Saskatoon Lake near Grande Prairie, but an updated analysis of lake level data would be required to verify recent trends.[20]

Freshet and early summer (May, June) flows on the Peace River have decreased since the W.A.C. Bennet Dam has been operational (1972). June flows decreased by 1.2 % and 0.9% annually (9 and 15 m3/s, respectively) in the Peace River at Hudson’s Hope and at Taylor, and summer (July) flows have decreased further downstream at Peace River at Peace Point by 1.0 % annually (29 m3/s). Tributaries to the Peace River have also had apparent (although not statistically significant) decreases in freshet flows, indicating that these decreasing trends may be a regional response to a shifting climate signal.

Saskatoon Lake Level Trend 1983 to 2008, reproduced with permission from Casey [20]


August Lake Level trends for a selection of lakes in the Peace subbasin, based on WSC data. Data labels are the Sen’s slope (annual change in mean monthly level in m) and annual percent change relative to long term mean monthly level. Data from the Water Survey of Canada


Trends in June streamflows at Selected Water Survey of Canada Stations in the Peace sub-basin. Data labels are the Sen’s slope (annual change in mean monthly flow in m3/s) and annual percent change relative to long term mean monthly flow. Data from the Water Survey of Canada

More fluctuations in water levels and increased flooding in some parts of the sub-basin are reported by members of Treaty 8 First Nations from BC and Alberta as “100-year” flooding events are now more common.[21] Members of Halfway River First Nation have specifically raised concerns about high water levels in Halfway River, a tributary to Peace River in northern BC, and increased flooding events in recent years.[22]

Water levels appear to fluctuate more and are more unpredictable than in the past. “100-year” floods and droughts become a regular occurrence,

Parlee et al., 2020

Local residents have reported changes in the flow regime and sediment transport in some places along the Peace River. An increase in silt is making it difficult to traverse the shoreline (as the silt is clay-like and “slippery”), and accumulating sediment is thought to be creating higher benches along the river banks, and in some cases, preventing natural overbank flooding.[23]

The Peace River south of the W.A.C. Bennett Dam. Image source: Jason Woodhead via Flickr Creative Commons (copyright-free).

Analysis of Water Survey of Canada flow data showed that late winter flow has increased in some small tributaries. For example, the Parsnip River above Misinchinka River had February flows increase by 1.02 % per year. This trend is likely linked to increased winter temperatures contributing to more winter snow melt.

Trends in February streamflows at Selected Water Survey of Canada Stations in the Mackenzie Peace sub-basin. Data labels are the Sen’s slope (annual change in mean monthly flow in m3/s) and annual percent change relative to long term mean monthly flow. Data from the Water Survey of Canada

 Mean annual flow was steady at six out of eight analyzed stations of the Peace sub-basin, while it decreased in the Smoky River by 1.7 m3/s per year (0.5 %) and in the Peace River at Peace Point by 10.7 m3/s per year (0.5 %). Previous analysis of streamflows on datasets spanning 1977 to 2001 had shown that declining trends in annual flows occur in the Notikewin River, Little Smoky River and around Peace River oil sands, where a maximum decline of 3% annually was observed.[24]

Peak instantaneous flows remain unchanged over the period of record across the sub-basin.

 

 

Climate

Air temperatures increased from 1948 to 2016, with largest increases recorded in winter. Decreases in annual winter precipitation largely outweigh precipitation increases in spring, summer and fall.

The Peace sub-basin experienced the greatest temperature increase in the winter, with the smallest increases in the fall. The greatest increase in precipitation occurred in the spring, and winter precipitation decreased significantly. Annual precipitation increased marginally as spring, summer, and fall increases were largely outweighed by winter decreases.[25]

 

Temperature and Precipitation trends in the Peace Sub-basin (1948 – 2016 for temperature, 1948 – 2012 for precipitation). From: Bonsal et al. in review

Sub-basin

Season

Temperature Change (°C)

Precipitation Change (%)

Peace

Spring

2.3

12.6

Summer

1.5

2.6

Fall

0.8

3.8

Winter

4.9

-19.6

Annual

2.2

0.7

Note: Spring: Mar-Apr-May, Summer: Jun-Jul-Aug, Fall: Sep-Oct-Nov, Winter: Dec-Jan-Feb

Water Use

Water is withdrawn from surface and groundwater sources for commercial, municipal and industrial use across the Peace sub-basin. While total annual allocation represents a small portion of annual Peace River flows and a portion of water is returned, local impacts to smaller water courses are less well understood.

In 2011, 150 million m3 of water was licensed for use in the Alberta portion of the Peace River watershed, which is 89% of the water allocations in the watershed. Surface water allocations equalled 0.3% of flows of Peace River at Peace Point.[26] In 2013, 195 million m3 was licensed for use. Sixty-six percent of the allocations are for commercial use, including pulp mills and thermal power projects, with 19% for municipal and with 7% for industry (oil and gas). Of the water allocations, only 38% (57 million m3) is licensed for consumption with the remainder being returned to the Peace after use. Data shows that only 52% of licensed surface water was used in 2011.

Next Indicator
Water Quality