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Review

Ice Jam Flooding of the Drying Peace-Athabasca Delta: Hindsight on the Accuracy of the Traditional Knowledge and Historical Flood Record

by
Spyros Beltaos
Watershed Hydrology and Ecology Research Division, Environment and Climate Change Canada, Canada Centre for Inland Waters, 867 Lakeshore Rd., Burlington, ON L7S 1A1, Canada
Environments 2025, 12(10), 376; https://doi.org/10.3390/environments12100376
Submission received: 25 August 2025 / Revised: 23 September 2025 / Accepted: 9 October 2025 / Published: 13 October 2025
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Abstract

The Peace-Athabasca Delta (PAD) in northern Alberta, Canada, is one of the world’s largest inland freshwater deltas and is largely located within the Wood Buffalo National Park, a UNESCO World Heritage Site. Owing to its ecological and socioeconomic significance, the PAD has been designated a Ramsar wetland of international importance. A paucity of large-scale Peace River ice jam flooding and concurrent drying trend during the past five decades has motivated various studies on relevant processes and on possible remedial action. In turn, many of these studies are informed by a flood record that was compiled in 1995, based on Historical information and Traditional Knowledge (H-TK flood record). Later work has expressed occasional reservations regarding the accuracy of this record, while much more is now known about the physical and hydroclimatic controls of PAD ice jams. This paper examines the 20th century portion of the H-TK record in the light of recent scientific advances made since the 1990s and of a wealth of hydrometric and climatic indicators, along with eyewitness corroborations, that extend back to the early 1900s. Systematic observational data and monitoring reports that have become available since the 1990s have also provided valuable documentation of PAD flooding. It is concluded that the record of major ice-jam floods is reliable, while the possibility of “missed” events cannot be precluded. The record of minor ice jam floods, which is largely inferred from reversed tributary flows entering Lake Athabasca, may not be reliable because more than half of the reported events might not have occurred at all. The value of the H-TK record is primarily in the major events, which generate overland inundation and can amply recharge various ponds, lakes, and wetlands of the PAD. Implications of the results for pre- and post-regulation flood frequencies and for future park management are discussed.

1. Introduction

The Peace-Athabasca Delta (PAD) in northern Alberta, Canada, is one of the world’s largest inland freshwater deltas, home to large populations of waterfowl, muskrat, beaver, and free-ranging wood bison. The delta region has been designated a Ramsar wetland of international importance and is largely located within the Wood Buffalo National Park (WBNP), a UNESCO World Heritage Site [1]. Moreover, the delta is a homeland for the Indigenous Peoples of the region. During the past five decades, this complex and dynamic delta has, in-between rare overland flooding events, experienced prolonged dry periods and considerable reduction in the area covered by the myriad of lakes, ponds, and wetlands (basins) that provide habitat for aquatic life [2,3,4,5,6,7,8,9]. Ice jamming is the primary mechanism that can cause overland flooding and recharge the high-elevation (isolated) basins of the PAD [10]. Beneficial ice jams can form in the lower Peace and Athabasca Rivers, as well as in their tributaries and distributaries. Herein, the focus will be on the regulated Peace River and the Peace Sector of the delta (or Peace Delta; Figure 1). The upper panel of Figure 1 shows the lower Peace River (Boyer Rapids to the mouth of Peace) as well as the upper Slave River, along with major tributaries within the Peace Delta. Sweetgrass Landing, situated north of Lake Claire, marks the beginning of the PAD reach of Peace River.
The regulation of Peace River began with construction (1968), reservoir-filling (1968–1971), and operation (1972 onwards) of the W.A.C. Bennett hydroelectric dam in British Columbia, located some 1200 km upstream of the PAD (Figure 1, lower panel). The Peace Canyon dam, located 23 km downstream of the Bennett dam, was completed in 1980. The Site-C dam (became operational in 2025) and the proposed Dunvegan damsite are located ~105 and ~280 km downstream of the Bennett dam, respectively [11].
Beginning in the early 1970s, concern over the post-regulation drying of the PAD motivated many technical studies. One of these studies aimed at development of a record of past floods [12], based on a comprehensive review of historical sources and on interviews with Indigenous residents to draw on Traditional Knowledge. The combined record is herein termed the H-TK record and extends from the early 1800s to the early 1990s. The H-TK record, along with comprehensively monitored and recorded spring flood occurrences after 1992, suggests that major ice jam floods (IJFs) occur less frequently after 1967 than they did in the pre-regulation period of the 20th century [13]. Flooding can also be generated by ice jams forming on the lower Athabasca River and its tributaries or distributaries; the present discussion is confined to Peace River ice jams.
The authors of two hydrological studies [10,14] noted the post-regulation reduction in IJF frequency and discussed possible causes. Moreover, they discovered that the H-TK record completely “missed” a major IJF that occurred in the spring of 1972 and expressed a reservation as to the spatial extent of reported overbank flooding occurrences at a single location. However, their overall assessment of the record was positive: “Despite the disparate nature of the historical data, the early summaries by Peterson (1992, 1995) and the subsequent additional archive information reviewed by Prowse et al. (1996a) corroborated the occurrence of most of the major floods that were recorded at the Peace Point hydrometric station (Prowse and Lalonde, 1996) and validated the use of the site as an indicator of flood events that affect the northern perched-basin regime of the PAD” [14]. The accuracy of the H-TK record has been assessed much less favourably by the authors of paleolimnological studies within the PAD, who used proxy evidence to infer a very different flood history during the 20th century [15,16,17,18].
Ongoing research since 1995 and recent monitoring activities by several stakeholder agencies have resulted in improved understanding of ice-jam and flooding processes, which can now be applied to re-assess the overall accuracy of the H-TK record. The influence of such variables as total winter snowfall, total winter degree-days of frost, river discharge, and freezeup level has been clarified [19,20,21]. Moreover, the significance of flow reversals in PAD tributaries of the Peace River, often assumed to indicate an IJF in the historical record, has been elucidated via seasonal monitoring programs. Consequently, the objective of this paper is to scrutinize the H-TK record in the light of current understandings pertaining to local ice-jamming and flooding processes.

2. Background Information and Hydroclimatic Controls

Before delving into the H-TK record, it is helpful to discuss the variables that affect the occurrence or non-occurrence of Peace River IJFs in the PAD. Experience and numerical modelling studies [22,23] have indicated that large river discharge is a necessary, albeit not sufficient, condition for flood occurrence. Based on their model runs, the authors of [22] concluded that a flow of at least ~5000 m3/s is required to produce ‘macro-scale’ flooding of the PAD for ice jam toes (lodgment sites) located at Moose Island and Rocky Point. On the other hand, very long jams lodged at Scow Channel outfall could cause overbank flooding as far upstream as the Claire River mouth with flows as low as 2500 m3/s. The same authors [22] pointed out that their modelling results should be viewed with caution owing to such limitations as sparsity of bathymetric information and complete lack of model calibration/verification data.
Aided by enhanced river bathymetry and model calibration data that became available during the IJFs of 1996 and 1997, the author of [23] found that Peace Point flows more than ~4000 m3/s could produce overland flooding if a sizeable (tens of km long) jam were to form at one of the usual toe sites shown in Figure 1. Flow records of the Peace Point hydrometric station (number 07KC001, in operation since 1959) indicate that peak breakup flows in major IJF years of the instrumental record (1963, 1965, 1972, 1974, 1996, 1997, 2014) were well above 4000 and even 5000 m3/s. [Historical daily mean flow data are published by Water Survey of Canada (WSC) and can be found at Historical Hydrometric Data Search—Water Level and Flow—Environment Canada—accessed 12 August 2025]. At the same time, such large flows have also occurred in non-IJF years (1967, 1979, 1994, 2003, 2007, 2013, 2018, 2020, 2022). In turn, this suggests that additional factors influence whether a sizeable jam forms, or does not form, in the PAD reach of Peace River.
One such factor is the freezeup level (HF = peak 7-day running average water level during freezeup and early winter), which partly indexes the resistance of the winter ice cover to mobilization and transport. High resistance retards the advance of the breakup front along the river and reduces the chances of significant ice-jam formation in the PAD reach via thermal degradation of the local ice cover and melting of the incoming volume of ice rubble [21]. It has been shown empirically and via logistic regression that the probability of a major IJF occurring in anyone year increases as breakup flow increases and as HF decreases [20]. This property is illustrated in Figure 2, in which major ice jam floods plot in the “north-western” area of the graph. A major flood might have also occurred in 1967, as discussed in Section 4.1.
In general, HF values more than 214 m (CGVD28) at Peace Point are not conducive to major IJF occurrence [19,21,24]. The regulation of Peace River, which commenced in 1968, has enhanced HF elevations owing to increased hydropower demand during the fall and winter [10]. For the period 1972–2016, an average post-regulation increase in HF of 1.6 m has been estimated [25].
An additional resistance variable has been postulated to be the coldness of the winter [26]. It is expressed as accumulated degree-days of frost (DDF) at Fort Chipewyan (Figure 1) and believed to index the end-of-winter, or maximum thickness of the ice cover. However, comprehensive thickness data from the Peace Point hydrometric station exhibit no correlation between maximum ice thickness and DDF [21], possibly because of ignoring the important effect of snowfall [27].
Flow data are not available in advance of, or during, a breakup event and therefore they can offer no guidance to pre-breakup forecasts of whether an IJF may occur. An index of potential for high breakup flow is the total winter snowfall at Grande Prairie (Nov.–Mar., [10]) or total winter precipitation while DDF remains negative (Nov.–Apr., [26]). Reference [21] introduced the total Nov.-Mar. snowfall, expressed in mm of water equivalent (daily snowfall in mm = total daily precipitation in mm minus daily rainfall in mm). This quantity (herein denoted by SNw) correlates positively with breakup flow, albeit with considerable scatter (Figure 3). Going back to the early 1900s, there are occasional gaps in the Grande Prairie climate records. Such gaps have been filled using climate data from Beaverlodge, which is located ~40 km west of Grande Prairie (SNw at Grande Prairie ≈ 0.94SNw at Beaverlodge, R2 = 0.98, standard error = 18 mm; based on data from the overlapping period 1943 to 1996). Historical climate data at Canadian meteorological stations can be found at Historical Data—Climate—Environment and Climate Change Canada—(accessed 14 August 2025).

3. H-TK Data Sources and Caveats

Peterson [12] indicates that written historical records of the Hudson Bay Company posts from Fort Chipewyan (HBCFC) and Fort Vermilion (HBCFV) were collected by the Historical Services Section of Parks Canada, Prairie and Northern Regional Office [29]. A search of the Hudson Bay Archives in Winnipeg provided information about high water events, unusual weather patterns, activities which were affected by high water (haying, travel, etc.) and ice conditions. Fur sales data were also collected to test possible correlation of muskrat pelt numbers with flood or dry years. Written records from Park Warden Station reports in WBNP were obtained by searching the National Archives in Ottawa. The time period extended [21,28] from the 1920s to 1953. Few of the warden diaries or month-end reports survive in the archives. The most complete record covers the years 1947 to 1953. Written records also came from the RCM (Roman Catholic Mission) journals. This record extends from 1910 to 1950 to bridge the data gap from HBC to WBNP records, but the total available record starts at 1874. Indigenous knowledge was also explored in 1992 via interviews with long term Fort Chipewyan residents, producing vivid descriptions of major flood events that occurred during the preceding ~40-year period.
Details about data sources and associated time periods are summarized in Table 1 and Table 2. Though written records go back to the early 1800s, the present discussion will be limited to the 20th and 21st centuries. This allows comparison of pre- and post-regulation flood regimes during comparably long, consecutive, periods. Additionally, relevant hydroclimatic data such as temperature, precipitation, flow discharge, only became available after the year 1900. The instrumental record of the Peace Point hydrometric station begins in 1959 but can be partly supplemented by the record of the station located at the Town of Peace River (TPR), some 740 km upstream; this dataset begins in 1915 but contains a gap between 1931 and 1958 (WSC station number 07HA001). The flood travel time from TPR to Peace Point during breakup is ~5 days [10], while the breakup peak is typically augmented by tributaries along the way [28].
For the H-TK record, Peterson [12] cautioned that flood events might have occurred in years in which none had been reported. A good example is the spring of 1972, for which the H-TK record (oral history) indicated no event. On the other hand, archival information retrieved by [14] suggested that a major IJF “probably” occurred in that year. This aligns with the large 1972 breakup flows at Peace Point (peak = 5600 m3/s). It is also possible that the year of a flood may have been misreported in the oral history portion of the H-TK record. This was the case for the major IJF of 1963, which three local people, respectively, placed in 1961, 1962, and 1963; it was reported as a 1962 event in [12]. The correct year was determined by further inspection of archival information [14], aligning with the fact that large breakup flows occurred in 1963 (peak = 9000 m3/s) but not in 1961 (peak = 3030 m3/s) or 1962 (peak = 3350 m3/s).
Peterson [12] ranked the magnitudes of various spring breakup events as follows:
0.
Written records available but no mention of a high water event, or in living memory no high water event occurred;
1.
record of high water or current flowing into the bay at Ft. Chipewyan, limited in duration and apparent strength;
2.
record of unusually high water or flow into the bay at Ft. Chipewyan but (a) of limited duration, and/or (b) area flooded, but not extensively;
3.
record of unusually high water or flow into the bay at Ft. Chipewyan (a) over an extended time, and/or (b) flooding covering a large area.
Overland inundation from major (magnitude 3) ice-jam floods was identified in [12] as the most ecologically important high-water event. No overland flooding has been reported for lesser (magnitude 1 or 2) high-water events. A later compilation of PAD flood events [33] used the terms “small”, “moderate”, and “large” for floods of magnitude 1, 2, and 3, respectively; this terminology is adopted hereafter.

4. Review of Reported Floods and Assessment of Record Accuracy

4.1. Large Ice-Jam Floods

Detailed information on Peace River spring breakup floods was presented in [12] in a single table, where each entry was assigned a magnitude (1, 2, or 3). In the 20th and 21st centuries, large IJFs have been reported for the years 1900, 1904, 1920, 1932, 1933, 1934, 1942, 1943, 1948, 1958, 1963, 1965, 1972, 1974, 1996, 1997, and 2014. The 1948 event was assigned a magnitude of 3 (large) in [12] but was characterized as moderate (magnitude of 2) in [33]. Reference [35] argued in favour of a large event, based on evidence pertaining to the 2014 event.
With one exception (1920), the large events involved witness accounts of overland flooding at various locations along the lower Peace River (Table 3). Occurrence of overbank flooding in 1920 is suggested by the high breakup flows at TPR, indicating that peak flows at Peace Point would have exceeded ~7700 m3/s, well within the range of known peak breakup flows associated with other large IJFs (5600 to 9160 m3/s). Moreover, natural freezeup levels were considerably lower than they have been after regulation [25]. For the 1920 breakup event, freezeup flows (October–November 1919) were low, even for natural conditions, suggesting an HF value well below 214 m. Consequently, the 1920 event would plot inside the large-flood region of Figure 2.
It has been pointed out [14] that witness accounts of overland flooding often referred to single locations along the Peace River, so that there is no information about the spatial extent of flooding. However, numerical ice-jam modelling [22,23] has indicated that overland flooding is generated by ice jams that are tens of km long. Therefore, observed overland flooding at one location implies the occurrence of similar conditions over substantial segments of the Peace River. At the same time, detailed descriptions of relatively recent events leave no doubt about the extent of flooding generated by large events. For instance, Reference [5], citing earlier reports by others, listed the following:
  • 1963 Ice-Jam Flood: “Ice jam flooding from the Peace R. in early May and the Athabasca River, flood came overland from the Embarras R. for 3 d; all of Peace Delta to Athabasca and east to Rochers R. flooded”.
  • 1974 Ice-Jam Flood: “Over a period of 10–14 days, overland sheet flow from the Athabasca and Peace Rivers spread to virtually all areas of the PAD, including Lakes Claire and Mamawi, forming one big lake. The water was so high that one could travel by boat from Fort Chipewyan to Carlson’s Landing without hitting dry land. Only isolated hills (bedrock outcrop) were above water”.
Extensive overland flooding was also documented via aerial reconnaissance during the large IJFs of 1996, 1997 [31,32] and 2014 [34]. Overall, the H-TK record of large IJFs can be assessed as accurate for years in which breakup flows are known. However, relevant flow data are not available prior to 1916 and during 1932–1957. These time periods contain the reported large events of 1900, 1904, 1932, 1933, 1934, 1942, 1943, and 1948. Further scrutiny can be based on winter precipitation data, which begin in 1917. Figure 4 shows that all but one of the plotted large events are associated with SNw values in excess of ~130 mm.
The one exception is the event of 1942, for which SNw is only 66 mm. According to Table 2, the Peace River was “very high” and “many of the Indians lost houses and belongings (Peace Pt.?), water high at Rocky Pt”. According to Figure 3, a SNw value of 66 mm could only generate a peak breakup flow of 4000 m3/s or less. This flow can cause incipient riverbank overtopping [23] but is not enough to raise water levels well above bankfull stage and destroy “houses and belongings”. According to [22], a minimum of ~5000 m3/s is needed for widespread overland flooding. At the same time, it is unlikely that the year of the 1942 flood has been misreported, given the source (WBNP Warden records). A possible explanation is that the modest snowmelt runoff from the southern portions of the Peace River basin, which is indexed by SNw, was augmented by runoff from the northern portions, as happened in 2022. In that year, there was considerable winter snowfall at Grande Prairie, but the snowpack was severely depleted by mid-winter thaws. However, the resulting low breakup flows at TPR were greatly exceeded by flows experienced at Peace Point and farther downstream [21]. There are no flow or winter precipitation data for the reported large IJFs of 1900 and 1904. However, the respective witness accounts of overland flooding (Table 2) leave no doubt as to the magnitude of accompanying breakup flows.
With reference to Figure 4, the apparent “threshold” of 130 mm for a large IJF should be lowered to ~100 mm because the 2020 event generated one of the largest breakup flows on record with SNw being slightly over 100 mm (Figure 3); failure to flood in 2020 has been attributed to unusually high freezeup levels [21,28].
There are no hydrometric data for Peace Point prior to 1959, with which to examine the freezeup level guideline of HF < ~214 m for the large IJFs that occurred between 1900 and 1959. However, naturalized freezeup levels during the years 1972–2016 [25] indicate a non exceedance probability of 94% for 214 m in any one year. If the same probability distribution holds for the pre-instrumental period, chances are that most or all of the pre-1959 events were associated with HF values that did not exceed 214 m.
Favourable conditions for a large IJF occurred in the spring of 1967, i.e., maximum breakup flow = 7360 m3/s, HF = 212.83 m (see also Figure 2). A flood for that year was mentioned in [36], but without details as to the season of occurrence [33]. Numerical modelling (writer, unpublished data) suggested that a large IJF would have ensued if a Peace River jam had formed near the PAD. The end-of-winter ice thickness at Peace Point was about average (0.91 m), while air temperature data at Fort Chipewyan indicate moderate thermal exposure of the ice cover up to the onset of the breakup event (May 7 at Peace Point): the cumulative degree days above a base temperature of −5 °C [37] were 121.4, near the midpoint of the range (~70 to 156 °C-days) associated with the seven post-1959 large IJFs. It is thus unlikely that the pre-breakup ice cover would have deteriorated so much as to be unable to arrest incoming ice runs and form ice jams. Additionally, the total spring breakup reverse flow volume from Peace River towards the PAD has been estimated in [38] to have been 1.6 billion m3, comparable to reverse volumes generated by the large IJFs of 1965, 1974, and 1996 (1.4, 1.8, and 1.7 billion m3, respectively). It appears that the 1967 breakup could be another example of a “missed” large event, in addition to that of 1972.
It can be concluded that the H-TK record of large IJFs is reliable in so far as the reported events are concerned. There is one documented instance of failure to register an event (1972), and there may have been others during the period of the H-TK record (e.g., 1967). Increasing concern over drying PAD conditions motivated various technical studies and recognition of the importance of spring ice jams as agents of PAD replenishment. In turn, this led to enhanced breakup monitoring activities (Table 1). It is therefore highly unlikely that any large IJFs have been missed after 1992.
For the pre-regulation portion of the 20th century (1900 to 1967), the record contains 12 + (68 − 12)p large events, with p being the probability of missing a large event in any one year. For the regulated period up to 1992 (1968 to 1992), which has two large events (1972, 1974), the large event number is 2 + (21 − 2)p. The reservoir filling years, 1968–1971, are excluded from this calculation because they could not have produced an ice jam flood, owing to low breakup flows. The total number of large IJFs in the regulated period is therefore equal to 5 + 19p, after addition of the events of 1996, 1997, and 2014, and assigning zero probability of missing an event after 1992. The respective flood frequencies work out to be 0.18 + 0.82p and 0.09 + 0.35p, indicating that the natural frequency of large IJFs was ~ twice that of the regulation period. [The ratio (0.18 + 0.82p)/(0.09 + 0.35p) varies from 2.0 to 2.2 as p varies from 0 to an unlikely high value of 0.4]. This result aligns with findings by [25], deriving from naturalized freezeup levels and breakup flows during the period 1972–2016.

4.2. Small and Moderate Spring Floods

Table 4 and Table 5 summarize the moderate and small events of the H-TK record, as described in [12]. The record contains numerous such events, all but two of which have been inferred by the arrival of Peace River water and/or ice into Lake Athabasca.
Peace River tributaries reverse direction when the water level at their junctions is higher than that of Lake Athabasca. Such reversals may occur when ice jams have formed in the Peace River, but the presence of a jam is not a necessary condition for tributary reversal. This was first noticed by the writer during field reconnaissance in the springs of 2002 and 2003, neither of which produced a jam in the PAD reach of Peace River. A sizeable breakup flow and a continuous sheet ice cover are enough to cause tributary reversals.
The similarity of the descriptions of the lesser (small and moderate) events suggests that some events that have been designated as moderate might have been small and vice versa. Because large event descriptions typically involve eyewitness accounts of overland flooding, it is highly unlikely that a lesser event might have been large or that a large event might have been a lesser one. This assessment aligns with a personal communication (2020) from M. Peterson, the author of [12].
The two exceptions to the merely inferred lesser events involve eyewitness accounts from the spring breakups of 1979 (small event) and 1994 (moderate event). In 1979, jamming on the QF (Quatre Fourches) channel caused local flooding and replenishment of nearby basins but there is no indication of jamming in, and overland flooding from, the Peace River (see also more detailed information in [30]. In 1994, a jam did form near Rocky Point, causing flooding of Moose Island, but without overland flooding [5]. As is shown next, these are the only lesser events for which there is confidence in their actual occurrence and designation. The Fort Chipewyan oral history, which spanned the period ~1950–1992, indicates that “Minor events were apparently common but could not be recalled in detail sufficient to record date or impact” [12].
Examination of historical water level records at gauges located near the mouth of Peace River (station no. 07NA001, Riviere des Rochers above Slave River) and on Lake Athabasca at Fort Chipewyan (station no. 07MD001) provided additional insights. A reversal is assumed to occur when the daily mean water level of Riviere des Rochers (RdR) exceeds that of Lake Athabasca. Readers may note that reversal of Riviere des Rochers entails reversal of the QF channel, too, because the Peace River water level at the junction of the latter tributary is higher than the water level at the junction of RdR (Figure 1). It is of interest to examine how flow reversals indicated by the hydrometric record compare with the H-TK record of lesser events, as discussed next.
The hydrometric record begins in 1960 but contains frequent data gaps. Altogether, there are 52 years with data (including from field reconnaissance) at both stations, as of 2024. Of these, the years up to 1992 are excluded from the comparison because the oral history mentions occurrence of minor events that were not recalled clearly enough to assign dates. Therefore, the “usable” part of the hydrometric record contains 32 years (1993–2024). During this period, there were 3 large IJFs (1996, 1997, 2014) and 5 lesser events (1994, 2007, 2008, 2020, 2022). There were also 13 years with spring “exceedances” (RdR higher than Lake Athabasca), each lasting for varying numbers of days and involving elevation differences of varying magnitude (Table 6). Consequently, the chance that a reversal signifies a lesser flood event is estimated as 5/13 = 0.38. It can be concluded that the H-TK record of lesser events is often unreliable, in the sense that only a fraction of the reported events might have taken place. It follows that there is no point in computing and comparing pre- and post-regulation frequencies of lesser events. This assessment is reinforced by the fact that there is a large gap in their record between 1941 and 1979.
The RdR/Lake Athabasca hydrometric records also enable estimation of the chance that a spring reversal might signify a large event, i.e., ~3/13 = 0.23. Of course, this estimate only applies so long as there is no other evidence of flooding, such as overland inundation, damage to property, etc. Such estimates can be helpful in research that seeks to define probabilities that reported events did occur or that they were of a different than the assigned magnitude [39].

5. Discussion

Understanding of Peace River ice-jam flooding processes along the PAD reach and of associated hydroclimatic controls has advanced considerably since publication of the H-TK record [12]. The positive (for spring flooding) effects of large Grande Prairie winter snowfall and Peace Point breakup flow have been elucidated, while the negative effects of high freezeup levels have been extensively documented (e.g., [4,10,14,20,21,22,23]. Such advances, along with local hydrometric records that begin in 1959 or later, led to the conclusion that the reported large IJFs did indeed occur, with the possible exception of the 1942 event. In that year, the breakup flow is not known, while the Grande Prairie winter snowfall was too low to generate sufficient PAD flows for a large IJF. However, the 2022 breakup event demonstrated that large PAD flows can also occur from timely northern-basin runoff, despite low upper river flows. Considering that the large IJFs, which involve overland inundation, are the most beneficial to the PAD basins [12], the validation of the H-TK record of large IJFs is of particular ecological significance.
A cumulative plot of flood events helps visualize how frequency may change over time, since it can be quantified by the slope of a trendline that fits the data points. The cumulative number of large IJFs is shown in Figure 5, which evinces an abrupt reduction in flood frequency after 1967, the last pre-regulation year. This finding also applies to a comparison that does not include the 1942 event.
Hydrometric data from the PAD area have made it possible to scrutinize the H-TK assumption that mere reverse flow from the Peace River tributaries into Lake Athabasca indicates a lesser IJF. It was shown in Section 4.2 that flow reversals often occur during the spring breakup in non-event years. The chance of a lesser event having occurred given a reversal was estimated as ~40%, meaning that more than half of the reported lesser events may not have occurred at all. This finding does not greatly diminish the value of the H-TK record because lesser events are, by far, not as effective in recharging PAD basins as are large ones, which involve overland inundation. The oral history reinforces this assessment: even though it clearly marked the dates of large events, it merely noted that minor events were common, but “could not be recalled in detail”. In turn this implies that minor events were deemed by the Indigenous residents to be of secondary significance to basin replenishment.
The present findings reinforce earlier work indicating that ecologically important PAD ice-jam floods that are generated by the lower Peace River are considerably less frequent in the post-regulation period than they were under natural conditions. The reduction in frequency is likely to be severely exacerbated during this century by projected changes in hydroclimatic controls (breakup flows, ice cover thickness) resulting from climatic warming [26,39,40,41]. Because such projections rely on accurate information about the magnitude and year of occurrence of large floods, the presented validation of the H-TK record of major events enhances confidence in assessments of future flood regimes.
One of the remedial measures recommended by the WBNP Action Plan [1] is to “Establish protocols for, and identify circumstances under which, a strategic release of water from the Williston Reservoir behind the W.A.C. Bennet Dam could enhance an ice jam flood event within WBNP to encourage flooding of the PAD, including its perched basins, while minimizing unwanted upstream and downstream risks.” A Protocol for Strategic Flow Releases is presently under development and, once implemented, is expected to render ice-jam flooding more beneficial to PAD ecology via higher, and longer-lasting, local water levels during major events. Its effectiveness and application in practice will need to be evaluated and fine-tuned via extensive monitoring activities by various stakeholder agencies [18,20], including Indigenous community-based monitoring [42]. Monitoring could also contribute towards improved quantification of flood magnitude.

6. Summary and Conclusions

The H-TK record of Peace River ice jam floods near the PAD, which was published in 1995, can inform research and decision-making pertaining to actions that can help recharge the drying Peace-Athabasca Delta. Its accuracy over the years 1900–1992 has been assessed in the light of current understanding of relevant physical processes and of local hydrometric datasets for Peace River at Peace Point, Riviere des Rochers above Slave River, and Lake Athabasca at Fort Chipewyan. Reported large ice-jam floods typically involve witnessed overland flooding at one or more locations along the lower Peace River, while reported lesser events were typically inferred from observed reversals of Peace River tributaries towards Lake Athabasca.
Based on earlier numerical modelling results, it was first noted that single-location overland inundation implies more extensive flooding because ice jams need to be tens of km long before they can cause overtopping of the riverbanks. Hydroclimatic indicators of a large IJF, such as breakup flow, winter snowfall at Grande Prairie, and freezeup level have been favourable for large IJF years, with the possible exception of the 1942 event. Overall, the H-TK record of large IJFs is shown to be reliable, in the sense that all or nearly all the reported events did occur. However, the possibility that some large events were missed, e.g., the 1972 large IJF, cannot be precluded. The available evidence suggests that 1967 may have also been a large IJF year. Frequency estimates indicate that large IJFs were about twice as frequent under natural conditions (1900–1967) than under the regulation regime (1972–2025).
Unlike for the large IJFs, the record of lesser events (small, moderate), which is largely based on inference pertaining to tributary flow reversals, may not be reliable: hydrometric records and field observations have shown that the Riviere des Rochers and thence the Chenal des Quatre Fourches often reverse in non-event years. Consequently, the primary value of the H-TK record is in the set of large IJFs, which are the predominant agents of PAD basin recharge.
The present validation of the large events adds confidence in the H-TK record, which is partly based on Indigenous knowledge. In turn, this reinforces climate-related projections of severe reductions in large-flood frequency during this century and underscores the need for implementation of remedial measures like Strategic Flow Releases. The success of such measures will partially depend on comprehensive monitoring activities, including Indigenous community-based monitoring.

Funding

This research received no external funding.

Data Availability Statement

No new data were created or analyzed in this study.

Acknowledgments

The writer gratefully acknowledges the support of Environment and Climate Change Canada in preparing this manuscript, which is primarily intended to contribute to Canada’s Wood Buffalo National Park Action Plan.

Conflicts of Interest

The author declares no conflict of interest.

References

  1. WBNP (Wood Buffalo National Park). Development of a Multi-Jurisdiction Action Plan to Protect the World Heritage Values of Wood Buffalo National Park; Wood Buffalo National Park World Heritage Site Action Plan—Wood Buffalo National Park; Fort Smith, NT, Canada, 2019; ISBN R64-546/2019E-PDF. Available online: https://publications.gc.ca/collections/collection_2021/pc/R64-546-2019-eng.pdf (accessed on 8 October 2025).
  2. Peace-Athabasca Delta Project Group. The Peace-Athabasca Delta, A Canadian Resource; Summary Report; Fort Chipewyan, AB, Canada; Saskatoon, SK, Canada, 1972; 144p, Available online: http://parkscanadahistory.com/publications/woodbuffalo/pad-sum-rpt-1972.pdf (accessed on 8 October 2025).
  3. Peace-Athabasca Delta Project Group. Peace-Athabasca Delta Project; Technical Report: A report prepared for Environment Ministers of Canada, Alberta, and Saskatchewan; Queen’s Printer: Edmonton, AB, Canada, 1973; 176p. [Google Scholar]
  4. Prowse, T.D.; Conly, M.; Lalonde, V. Hydrometeorological Conditions Controlling Ice-Jam Floods, Peace River Near the Peace-Athabasca Delta; Northern River Basins Study Project Report No. 103; NRBS: Edmonton, AB, Canada, 1996; 66p, Available online: https://publications.gc.ca/collections/collection_2025/eccc/r71/R71-49-3-103-eng.pdf (accessed on 8 October 2025).
  5. Peters, D.L. Controls on the Persistence of Water in Perched Basins of the Peace-Athabasca Delta, Northern Canada. Ph.D. Thesis, Trent University, Peterborough, ON, Canada, 2003. [Google Scholar]
  6. Peters, D.L.; Prowse, T.D.; Pietroniro, A.; Leconte, R. Flood Hydrology of the Peace-Athabasca Delta, Northern Canada. Hydrol. Process. 2006, 20, 4073–4096. [Google Scholar] [CrossRef]
  7. Ward, E.M.; Gorelick, S.M. Drying drives decline in muskrat population in the Peace-Athabasca Delta, Canada. Environ. Res. Lett. 2018, 13, 124026. [Google Scholar] [CrossRef]
  8. Ward, E.M.; Wysong, K.; Gorelick, S.M. Drying landscape and interannual herbivory-driven habitat degradation control semiaquatic mammal population dynamics. Ecohydrology 2020, 13, e2169. [Google Scholar] [CrossRef]
  9. Ward, E.M.; Solari, K.A.; Varudkar, A.; Gorelick, S.M.; Hadly, E.A. Muskrats as a bellwether of a drying delta. Nat. Commun. Biol. 2021, 4, 750. [Google Scholar] [CrossRef] [PubMed]
  10. Prowse, T.D.; Conly, F.M. Effects of climatic variability and flow regulation on ice-jam flooding of a northern delta. Hydrol. Process. 1998, 12, 1589–1610. [Google Scholar] [CrossRef]
  11. Jasek, M.; Pryse-Phillips, A. Influence of the proposed site C hydroelectric project on the ice regime of the Peace River. Can. J. Civ. Eng. 2015, 42, 645–655. [Google Scholar] [CrossRef]
  12. Peterson, M. Peace–Athabasca Flood History Study. In Peace–Athabasca Delta Technical Studies, Task F.1—Flood History; Peace–Athabasca Delta Technical Studies, Communications; Parks Canada: Fort Chipewyan, AB, Canada, 1995; 32p, Available online: https://books.google.co.jp/books/about/Peace_Athabasca_Delta_flood_history_stud.html?id=yygJ0AEACAAJ&redir_esc=y (accessed on 8 October 2025).
  13. IEC (Independent Environmental Consultants). Strategic Environmental Assessment of Potential Cumulative Impacts of All Developments on the World Heritage Values of Wood Buffalo National Park; Volume 1: Final SEA Report; Markham, ON, Canada, 2018; 247p, Available online: http://parkscanadahistory.com/publications/woodbuffalo/sea-rpt-v1-e-2018.pdf (accessed on 8 October 2025).
  14. Prowse, T.D.; Conly, F.M. A review of hydroecological results of the Northern River Basins Study, Canada. Part 2. Peace–Athabasca Delta. River Res. Appl. 2002, 18, 447–460. [Google Scholar] [CrossRef]
  15. Wolfe, B.B.; Hall, R.I.; Last, W.M.; Edwards, T.W.D.; English, M.C.; Karst-Riddoch, T.L.; Paterson, A.; Palmini, R. Reconstruction of multi-century flood histories from oxbow lake sediments, Peace-Athabasca Delta, Canada. Hydrol. Process. 2006, 20, 4131–4153. [Google Scholar] [CrossRef]
  16. Wolfe, B.B.; Hall, R.I.; Wiklund, J.A.; Kay, M.L. Past variation in Lower Peace River ice-jam flood frequency. Environ. Rev. 2020, 28, 209–217. [Google Scholar] [CrossRef]
  17. Kay, M.L.; MacDonald, L.A.; Wiklund, J.A.; Girard, C.A.; Wolfe, B.B.; Hall, R.I. ‘Paleofloodscapes’: Application of sediment source fingerprinting to track flood regime change over space and time at the Peace-Athabasca Delta, Canada. Sci. Total Environ. 2024, 912, 169538. [Google Scholar] [CrossRef]
  18. Beltaos, S.; Peters, D.L. Commentary on “Past variation in Lower Peace River ice-jam flood frequency” by Wolfe et al. (2020). Environ. Rev. 2020, 28, 560–566. [Google Scholar] [CrossRef]
  19. CRM (Compass Resource Management). Strategic Flow Release Protocol Decision Sketch Project; Final report, prepared for Environment and Climate Change Canada; Compass Resource Management: Vancouver, BC, Canada, 2023; 62p. [Google Scholar]
  20. Beltaos, S. Using Logistic Regression to Identify the Key Hydrologic Controls of Ice-Jam Flooding near the Peace–Athabasca Delta: Assessment of Uncertainty and Linkage with Physical Process Understanding. Water 2023, 15, 3825. [Google Scholar] [CrossRef]
  21. Beltaos, S. Ice-Jam Flooding of the Peace–Athabasca Delta, Canada: Insights from Recent Notable Spring Breakup Events and Implications for Strategic Flow Releases from Upstream Dams. Geosciences 2024, 14, 335. [Google Scholar] [CrossRef]
  22. Demuth, M.N.; Hicks, F.E.; Prowse, T.D.; McKay, K. A numerical modelling analysis of ice jam flooding on the Peace/Slave River, Peace–Athabasca delta. Peace–Athabasca Delta Technical Studies—P-ADJAM, Sub-component of Task F.2: Ice Studies. In Peace–Athabasca Delta Technical Studies Appendices: I, Understanding the Ecosystem, Task Reports; National Hydrology Research Institute Contribution Series CS-96016; Environment Canada: Saskatoon, SK, Canada, 1996. [Google Scholar]
  23. Beltaos, S. Numerical modelling of ice-jam flooding on the Peace–Athabasca Delta. Hydrol. Process. 2003, 17, 3685–3702. [Google Scholar] [CrossRef]
  24. Timoney, K.P. The Peace-Athabasca Delta: Portrait of a Dynamic Ecosystem; The University of Alberta Press: Edmonton, AB, Canada, 2013; Available online: https://ualbertapress.ca/9780888647306/the-peace-athabasca-delta/ (accessed on 8 October 2025).
  25. Beltaos, S.; Peters, D.L. Naturalizing the freezeup regimes of regulated rivers and exploring implications to spring ice-jam flooding. Hydrol. Process. 2021, 35, e14321. [Google Scholar] [CrossRef]
  26. Lamontagne, J.R.; Jasek, M.; Smith, J.D. Coupling physical understanding and statistical modeling to estimate ice jam flood frequency in the northern Peace-Athabasca Delta under climate change. Cold Reg. Sci. Technol. 2021, 192, 103383. [Google Scholar] [CrossRef]
  27. Ashton, G.D. River and lake ice thickening, thinning, and snow ice formation. Cold Reg. Sci. Technol. 2011, 68, 3–19. [Google Scholar] [CrossRef]
  28. Beltaos, S.; Carter, T. Minor 2020 ice jamming in lower Peace River despite extreme breakup flows: Assessment of hydroclimatic controls. In Proceedings of the CGU HS Committee on River Ice Processes and the Environment 21st Workshop on the Hydraulics of Ice Covered Rivers, Saskatoon, SK, Canada, 29 August–1 September 2021. [Google Scholar]
  29. Thomson, S. Peace-Athabasca Delta Flood History. In Historical Services, Prairie & Northern Region Documentary Information; Appended to Report by Peterson and Courtorielle; Fort Chipewyan, AK, Canada, 1992; Available online: http://parkscanadahistory.com/publications/woodbuffalo/flood-history-1993.pdf (accessed on 8 October 2025).
  30. Peterson, M.; Courtorielle, W. Flood History Study, Peace/Athabasca Delta, Wood Buffalo National Park; Data Report 92-14/WB; Parks Canada: Fort Chipewyan, AK, Canada, 1992; 62p. [Google Scholar]
  31. Giroux, S. 1996 Peace–Athabasca Delta Flood Report; Wood Buffalo National Park; Parks Canada: Fort Chipewyan, AB, Canada, 1997; 31p. [Google Scholar]
  32. Giroux, S. 1997 Peace–Athabasca Delta Flood Report; Wood Buffalo National Park; Parks Canada: Fort Chipewyan, AB, Canada, 1997; 36p. [Google Scholar]
  33. Timoney, K.P. Three centuries of change in the Peace–Athabasca Delta, Canada. Clim. Change 2009, 93, 485–515. [Google Scholar] [CrossRef]
  34. Straka, J.; Gray, Q. WBNP Flood Monitoring Report: Flood Extent, May 2014; Parks Canada: Fort Smith, NWT, Canada, 2014; 17p. [Google Scholar]
  35. Jasek, M.; Lamontagne, J.; Smith, J.D. Analysis of Climatic and Riverine Factors Influencing Peace River Ice Jam Flood Frequency in the Peace-Athabasca Delta: From History to Future Climate Implications. In Proceedings of the CGU HS Committee on River Ice Processes and the Environment 21st Workshop on the Hydraulics of Ice Covered Rivers, Saskatoon, SK, Canada, 29 August–1 September 2021. [Google Scholar]
  36. Dirschl, H.J. Evaluation of Ecological Effects of Recent Low Water Levels in the Peace-Athabasca Delta; Canadian Wildlife Service, Department of the Environment, Occasional Paper No. 13; Saskatoon, SK, Canada, 1972; 28p, Available online: http://parkscanadahistory.com/wildlife/paper-13.pdf (accessed on 8 October 2025).
  37. Bilello, M.A. Maximum Thickness and Subsequent Decay of Lake, River and Fast Sea Ice in Canada and Alaska; Report 80–86; U.S. Army Cold Regions Research and Engineering Laboratory: Hanover, NH, USA, 1980; 160p. [Google Scholar]
  38. Peters, D.L.; Buttle, J.M. The effects of flow regulation and climatic variability on obstructed drainage and reverse flow contribution in a Northern river–lake–Delta complex, Mackenzie basin headwaters. River Res. Appl. 2010, 26, 1065–1089. [Google Scholar] [CrossRef]
  39. Smith, J.D.; Lamontagne, J.R.; Jasek, M. Considering uncertainty of historical ice jam flood records in a Bayesian frequency analysis for the Peace-Athabasca Delta. Water Resour. Res. 2024, 60, e2022WR034377. [Google Scholar] [CrossRef]
  40. Beltaos, S.; Prowse, T.; Bonsal, B.; MacKay, R.; Romolo, L.; Pietroniro, A.; Toth, B. Climatic effects on ice-jam flooding of the Peace-Athabasca Delta. Hydrol. Process. 2006, 20, 4031–4050. [Google Scholar] [CrossRef]
  41. Beltaos, S.; Bonsal, B. Climate change impacts on Peace River ice thickness and implications to ice-jam flooding of Peace-Athabasca Delta, Canada. Cold Reg. Sci. Technol. 2021, 186, 103279. [Google Scholar] [CrossRef]
  42. Maclean, B.; Bampfylde, C.; Lepine, M.; Tssessaze, L. Towards a Rights-Based Ice Monitoring Trigger. In Proceedings of the CGU HS Committee on River Ice Processes and the Environment 21st Workshop on the Hydraulics of Ice Covered Rivers, Saskatoon, SK, Canada, 29 August–1 September 2021. [Google Scholar]
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Figure 1. Plan view of Lower Peace River and Peace Sector of the Peace-Athabasca Delta. Common ice-jam lodgment sites (or “toes”) are shown in the upper portion of the figure. Also shown are sites of Water Survey of Canada hydrometric gauges.
Figure 1. Plan view of Lower Peace River and Peace Sector of the Peace-Athabasca Delta. Common ice-jam lodgment sites (or “toes”) are shown in the upper portion of the figure. Also shown are sites of Water Survey of Canada hydrometric gauges.
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Environments 12 00376 g002
Figure 2. Plot of the peak breakup discharge versus the freezeup level at the Peace Point hydrometric station, 1962–2023. The red circles mark major ice jam floods that have occurred in the instrumental period.
Figure 2. Plot of the peak breakup discharge versus the freezeup level at the Peace Point hydrometric station, 1962–2023. The red circles mark major ice jam floods that have occurred in the instrumental period.
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Environments 12 00376 g003
Figure 3. Peak breakup discharge generally increases with total winter snowfall at Grande Prairie, albeit with considerable scatter. Red circles mark major ice-jam floods. Failure to flood in the extreme-flow spring of 2020 was likely caused by unusually high freezeup levels along the Peace River [21,28].
Figure 3. Peak breakup discharge generally increases with total winter snowfall at Grande Prairie, albeit with considerable scatter. Red circles mark major ice-jam floods. Failure to flood in the extreme-flow spring of 2020 was likely caused by unusually high freezeup levels along the Peace River [21,28].
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Environments 12 00376 g004
Figure 4. Water equivalent of total Nov-Mar snowfall at Grande Prairie (SNw) for the period 1917–2024. Red circles mark large (magnitude 3) ice-jam floods. With a single exception, such flood events are associated with SNw values > 130 mm.
Figure 4. Water equivalent of total Nov-Mar snowfall at Grande Prairie (SNw) for the period 1917–2024. Red circles mark large (magnitude 3) ice-jam floods. With a single exception, such flood events are associated with SNw values > 130 mm.
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Environments 12 00376 g005
Figure 5. Cumulative number of known large ice-jam flood events that occurred in the PAD reach of Peace River during the period 1900 to 2025. The reservoir filling years 1968–1971 are excluded. Note the sharp decrease in trendline slope after 1967.
Figure 5. Cumulative number of known large ice-jam flood events that occurred in the PAD reach of Peace River during the period 1900 to 2025. The reservoir filling years 1968–1971 are excluded. Note the sharp decrease in trendline slope after 1967.
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Table 1. Data sources on past PAD spring flooding up to 1992 [12].
Table 1. Data sources on past PAD spring flooding up to 1992 [12].
Time PeriodSourceComments
1803–1912HBC (Hudson’s Bay Company)Records at Fort Chipewyan and at Fort Vermilion. Most of the references are to Lake Athabasca water levels (16 May 1888: “Water rising rapidly: current coming from Riviere des Rochers as well as from Quatre Fourches and running into the Lake”.), but there are entries where ice jams or floods were observed, e.g., 29 April 1900: Indians report the Peace River being awfully high and water passing over Pointe Providence and overflowing the Quatre Fourches River and Lake Mamawee
1813–1967 HBC Ft. Vermilion flood recordRecords from Ft. Vermilion were used to determine if Peace River ice jam floods had occurred but had not been noted at Ft. Chipewyan
1874–1950RCM (Roman Catholic Mission)Records from Ft. Chipewyan
1922–1953WBNP Warden RecordsThe WBNP records are fragmented due to a lack of policy in archiving
1932–1993Lake Athabasca Water LevelsMost of the historical records refer to Lake Athabasca water levels. River levels and conditions must therefore be inferred. It is not clear if there is a correlation between spring ice jam events and Lake Athabasca water levels
1950–1992Ft. Chipewyan Oral History
(Traditional Knowledge)
Data collection began with a series of interviews of local people having a long history of trapping in and around the delta [30]. A series of questions was posed to each of ten participants, and maps at 1:50,000 scale of the delta were used to identify locations of ice jams and other pertinent information. The spatial extent of flooding was recorded where information was available		Six high water events between 1958 and 1990. Recalled events that preceded construction of the Bennett Dam (pre 1967) were major IJFs. Although it was impossible to delineate what areas were flooded by each event, major floods probably covered all of the Delta. Generally, information on major flood years was corroborated by several participants. Minor events were apparently common but could not be recalled in detail sufficient to record date or impact.
Table 2. Data sources on past PAD spring flooding after 1992 and supporting hydrometric information for the PAD since 1959.
Table 2. Data sources on past PAD spring flooding after 1992 and supporting hydrometric information for the PAD since 1959.
1993–presentAerial and remote monitoring of ice breakup conditions by several agencies, including two First Nations (ACFN 1, MCFN 2) Parks Canada, Alberta Environment, Environment Canada, BC Hydro.Major IJFs in 1996, 1997, and 2014 were documented in considerable detail; all three generated overland flooding. Lesser events in 1994, 2007, 2008, 2020 and 2022 produced significant reversed flows in Peace River tributaries but no overland flooding [5,21,31,32,33,34]
1959–presentPeace Point water levels and flows 3Hydrometric station records of breakup water levels have occasional gaps
1960–presentPAD Water Levels 3Hydrometric station records of breakup water levels have frequent gaps
1 Athabasca Chipewyan First Nation; 2 Mikisew Cree First Nation; 3 from WSC records.
Table 3. Peace River spring breakup floods of magnitude 3 (large). From [12].
Table 3. Peace River spring breakup floods of magnitude 3 (large). From [12].
Date(s)SourceDescription
27–29 April 1900HBCFCPeace R. being awfully high and water passing over Point Providence and overflowing the Quatre Fourches R. and Lake Mamawi
2 May 1904HBCFCTrader and residents at Jackfish had to abandon homes due to ice jam; houses and animals have been swept away on the upper Peace R.
13 May 1920RCMWater very high, rivers free of ice, flood
2–14 May1932RCM
WBNP		Water very high not seen as high for many years; thick ice, 7–8 ft., and trees pushed into lake from Quatre Fourches R.; people were flooded out of spring camps, water more than 6 ft. above banks.
5–18 May 1933RCM
WBNP		Big flood, behind Quatre Fourches R., because of ice jams. 6–8 ft. water covered whole country around Peace Pt./Jackfish R.; people north of Rocky Pt. on stages for 3 days; flooding at the 30th baseline on Slave R.; flooding in delta lasted 1 week with only high ridges not flooded.
4–9 May 1934RCMIce jam on Quatre Fourches R. and Hay R. (Prairie R.); big floods behind jams; houses lost at Peace Pt.
1–6 May1942WBNPPeace R. very high, many of the Indians lost houses and belongings (Peace Pt.?); water high at Rocky Pt
22–30 April 1943WBNPIce is going out of Peace R. and the water has come over the lower bank; ice piled up 20 ft. on both shores.
May 1948WBNPFlooding around Egg L.; country around Rocky Pt. flooded; log jam at Embarras Portage flooded Snowbirds Settlement 3 ft. above bank
May 1958TRADPeace delta from Peace R.; all lands to Lake Claire; Athabasca R. flooded from Ess Bend
May 1962 (1)TRADAll of Peace delta to Athabasca R. and east to Riviere des Rochers
May 1965TRADAll of Peace delta to Lake Claire, east to Quatre Fourches R.
27 April 1974 (2)TRADAll of PAD, flooding from Peace R. and Athabasca R.
(1) The year was misreported; should have been 1963. (2) Delta inundation lasted for 10–14 days.
Table 4. Peace River spring breakup floods of magnitude 2 (moderate). From [12].
Table 4. Peace River spring breakup floods of magnitude 2 (moderate). From [12].
Date(s)SourceDescription
27–28 March 1919RCMHigh water; Water from the Peace R. coming in lake.
7 May 1922RCMIce and water from Peace R. coming in the lake.
3–7 May 1937RCMWater changes direction, water gets in the lake from Quatres Fourches R. and Riviere des Rocher.
21–23 April 1941RCMWater coming into the lake from the Peace R.
25–28 April 1994
28–29 April 1994		WBNPIce jam at Boyer Rapids flooded local area upstream to Jackfish R.
Ice jam at Rocky Pt. caused local flooding at Moose Island, Baril Creek some water into Claire River.
Table 5. Peace River spring breakup floods of magnitude 1 (small). From [12].
Table 5. Peace River spring breakup floods of magnitude 1 (small). From [12].
Date(s)SourceDescription
28 April.
10 May
1906		HBCFCWater rises suddenly very high.
Water rising every day; some of the rivers must be rising.
4 May 1914RCMWater coming in lake from Peace R.
27–28 April 1925RCMWater rising.
24–27 April 1926RCMWater and ice of Peace R. come in the lake, water level going up fast.
5–14 May 1930RCMPeace R. comes in the lake, pushing ice into the lake.
8 May 1935RCMWater gets into the lake from the Peace R.
11–15 May 1936RCMPeace R. pushing, water going up quickly.
6 May 1940RCMIce in front of mission starts moving, gets into lake.
13 May 1979TRADLocal flooding from ice jam at Four Forks.
Table 6. Riviere des Rochers flow reversals during the spring breakup and occasional coincidence with reported floods in Peace Delta.
Table 6. Riviere des Rochers flow reversals during the spring breakup and occasional coincidence with reported floods in Peace Delta.
YearSpring Flood Magnitude, Peace Delta Stage Exceedance (RdR Above Lake Athabasca)Exceedance Duration and Amount, as Applicable; Comments
1993No event no
1994ModeratenoIce jam located near Rocky Point caused reversal in the QF channel
1995No eventno
1996LargeyesGap in data; visual observations indicated exceedance
1997LargeyesGap in data; visual observations indicated exceedance
1998No eventno
1999No eventno
2000No eventno
2001No eventno
2002No eventyesAt least 6 days, up to 0.3 m, gap in data
2003No eventyesGap in data; visual observations indicated exceedance over several days
2004No eventno
2005No eventno
2006No eventno
2007SmallyesGap in data; visual observations indicated exceedance
2008SmallyesAt least 3 days, gap in data, 0.3 m or more; visually confirmed
2009No eventno
2010No eventno
2011No eventyes5 days, exceedance up to 0.5 m
2012No eventno
2013No eventyesAt least 3 days, exceedance up to 0.9 m
2014LargeyesGap in data; visual observations indicated exceedance
2015No eventyesAt least 2 days, up to 0.8 m, gap in data
2016No eventnogap in data
2017No eventno
2018No eventyesGap in data; visual observations indicated exceedance
2019No eventno
2020SmallyesGap in data; visual observations indicated exceedance
2021No eventno
2022Moderateyes4 days, up to 0.6 m
2023No eventnoGap in data, highly thermal event
2024No eventnoProvisional data, highly thermal event
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Beltaos, S. Ice Jam Flooding of the Drying Peace-Athabasca Delta: Hindsight on the Accuracy of the Traditional Knowledge and Historical Flood Record. Environments 2025, 12, 376. https://doi.org/10.3390/environments12100376

AMA Style

Beltaos S. Ice Jam Flooding of the Drying Peace-Athabasca Delta: Hindsight on the Accuracy of the Traditional Knowledge and Historical Flood Record. Environments. 2025; 12(10):376. https://doi.org/10.3390/environments12100376

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Beltaos, Spyros. 2025. "Ice Jam Flooding of the Drying Peace-Athabasca Delta: Hindsight on the Accuracy of the Traditional Knowledge and Historical Flood Record" Environments 12, no. 10: 376. https://doi.org/10.3390/environments12100376

APA Style

Beltaos, S. (2025). Ice Jam Flooding of the Drying Peace-Athabasca Delta: Hindsight on the Accuracy of the Traditional Knowledge and Historical Flood Record. Environments, 12(10), 376. https://doi.org/10.3390/environments12100376

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