Mekong River Commission

Hydropower in the Fraser and Columbia Rivers:
a contrast in approaches to fisheries protection

By John W. Ferguson and Michael Healey*

The previous edition of Catch and Culture (Vol 14, No 3) carried two articles that described the possible impact on fisheries of proposed hydropower dams on the mainstream of the Mekong. As further background on dams and their impacts on fisheries, in this paper we examine what has happened to wild fish stocks in two river basins on the Pacific seaboard of North America that have had contrasting development histories. The Fraser River has dams on its tributaries but not on the mainstream, while the Columbia River has dams on both tributaries and the mainstream. We discuss the implications this has had for stocks of salmon in the two rivers, and what we might learn from the different development approaches in managing water resource development in the Mekong.

Fraser River Basin
The Fraser River is the largest river that drains the Pacific seaboard of Canada, and the fifth largest in the country. The catchment has an area of 234,00 km², covering about one-quarter of the area of the province of British Columbia. The mean annual discharge is 3,600 m³/sec. However, the discharge is seasonal, being dominated by the annual snowmelt in the summer months. As a result the peak discharge, which occurs in May/June (~ 8,000 m³/sec), can be ten times larger than the flow in the winter months of February and March (~ 800 m³/sec).

The basin is the home to almost three million people (about two-thirds of the population of British Columbia) including more than 100 indigenous tribes (Native Americans (US) and First Nations (Canada)). It is the 'economic engine' of the province, producing about 80% of British Columbia's GDP. Much of this is derived from natural resources. Fisheries, both commercial and recreational, make an important contribution to the economy of the basin.

According to Northcote and Larkin (1989), the Fraser River is the greatest salmonid producing system in the world. It contains seven species of salmon (genus Oncorhynchus), which form the core of the lucrative commercial and recreational fisheries of British Columbia and are critically important to the cultures of First Nation societies in the basin. Harvesting salmon contributes more than US$1 billion annually to the economies of British Columbia and the adjacent state of Washington in the USA.

There are five commercially important species of Pacific salmon, namely sockeye salmon (O. nerka), pink salmon (O. gorbuscha), chum salmon (O. keta) coho salmon (O. kisutch) and Chinook salmon (O. tschawytscha). These species are anadromous, spawning in freshwater but migrating to the sea as juveniles where they grow to adulthood. They are harvested mainly in the ocean but also to some extent in freshwater. The two remaining species, rainbow/ steelhead trout (O. mykiss) and cutthroat trout (O. clarkii), also have anadromous populations but most complete their lifecycles in freshwater. They are harvested mainly in recreational fisheries (the five Pacific salmon species are also harvested in recreational fisheries).

Columbia River Basin
The Columbia River has a catchment of 567,000 km² and a mean annual discharge of 7,800 m³/sec. It is the largest river in the Pacific Northwest. The headwaters of the river are in the Canadian province of British Columbia, but 85% of its drainage basin is in the USA. Here the basin covers nearly all of Idaho, large portions of Oregon, and Washington and small portions of Montana, Wyoming, Utah, and Nevada. The natural flow rates of the Columbia River are also highly seasonal, peaking at 13,592 m³/sec in the summer months and 3,898 m³/sec in the winter months (see box on page 7). However, discharge is regulated by many large water storage reservoirs located in the upper watershed, and flows are released for multiple purposes, including flood control, hydropower production, and irrigation.

Based on recent run sizes and harvest levels, salmon and steelhead production in the Columbia River Basin contributed $142 million in personal income annually to communities on the West Coast in 2005 (IEAB, 2005).

Like the Fraser River, the fish community is comprised primarily of anadromous species including the seven salmonid species living in the Canadian river. Other important species include the native Pacific lamprey (Lampetra tridentate) and the introduced American shad (Alosa sapidissima).

Fraser and Columbia basins

Early Development
Salmon have been an important source of food for the Native American peoples living in the Pacific Northwest for at least 10,000 years (Butler and O'Connor, 2004). Before the intervention of European settlers, an estimated 8-10 million adult salmon returned each year to the Columbia River (National Research Council, 1996). The extent of their harvest is unkown, but Schalk (1986) estimates that in the early 1800s Native Americans caught 19,000 tonnes of salmon from the river annually.

European colonists first arrived in the region in the late 1700s. By the mid 1800s, the settlers had begun to exploit the natural resources of both basins with dramatic effect on the habitat and stocks of wild salmonids.

In 1858, gold was discovered in the Fraser River and placer mining caused significant degradation of salmon spawning and nursery areas. Exploiting the timber resources of the basin added further stress to the wild population as a forestry practice at the time involved the construction of temporary 'splash dams' behind which logs were stored. These blocked salmon migrations and release of the impounded water scoured riverbed gravels, destroying eggs and young fish.

Perhaps the gravest damage to wild stocks in the Fraser Basin was caused during the construction of the Canadian Northern Railway in 1914 when blasting in the Fraser Canyon caused a rockslide in the narrow channel at Hell's Gate. This constriction was already a difficult passage for salmon during their spawning migration and the slide further narrowed the river, increasing water velocity and altering flow patterns. Stocks of sockeye and pink salmon, in particular, were hit by this catastrophe, and pressure on these species, which was exacerbated by heavy fishing, caused populations to plummet. Prior to 1916, the catch of Fraser River sockeye averaged 8.5 million fish; from 1917 to 1932 the catch averaged only 1.7 million fish (see chart at below).

The declines in sockeye and pink salmon ultimately led to the creation of a joint Canada/US management agency in 1937, the International Pacific Salmon Fisheries Commission (IPSFC). This agency played a central role in managing and rebuilding sockeye and pink salmon runs in the Fraser River. With the backing of the IPSFC, fishways were built around the blockage at Hell's Gate and fisheries were managed to ensure adequate migrations. Gradually, Fraser sockeye and pink salmon began to increase in abundance and reached historic levels in the 1990s. Despite a slight recent decline in some species (sockeye and coho salmon), today the Fraser River salmonid fishery is one of the most productive fisheries in the world.

Fraser sockeye salmon runs (1901-2006)

In the Columbia Basin, early colonial settlers and fur trappers traded salmon from Native Americans. However, the volume of salmon traded was small because the fish spoiled quickly if left untreated. This changed in the 1860s when procedures for canning salmon were developed and extensive harvesting began following the installation of the first cannery in 1866 (see chart below). Further development of the basin through hydropower, flood control, transport of commerce, and irrigation began in the early 1900s. The sharp decline in the abundance of salmon from historic levels can be attributed to the overfishing, habitat degradation, and impaired access to spawning grounds resulting from these developments (Lichatowich, 1999).

Hydropower Development
Development of the hydropower potential of both basins began in the early 1900s but has taken very differing routes from then to the present day. Hydropower projects in the Fraser Basin are limited to the tributary system and the mainstream remains undeveloped. In contrast, both the mainstream and the tributary network of the Columbia River have been heavily developed. As a result, in the Columbia River salmon must pass from one to nine dams on their migrations to spawning and nursery grounds.

There were plans for dams on the mainstream of the Fraser River, but none of these were approved. The most ambitious proposed scheme, at Moran Canyon, involved a 261 m high dam and a 260 km long reservoir with a power generation capacity equal to the combined output of the Grand Coulee and two Hoover dams.

If this dam had been constructed, it may well have been the first of many dams on the mainstream and could have lead to the development of the full hydropower potential of the basin. Why this did not occur is not entirely clear. Certainly public opinion was divided over the Moran dam, but the proposal had influential supporters and the government of British Columbia was promoting power development in the province. However, a variety of factors seem to have contributed to keeping the Fraser River free flowing:

• The salmon runs were important to the economies of both British Columbia and Washington, and were administered under an international agreement. This would have made it difficult for British Columbia to initiate the project unilaterally;
• Careful review and analysis of the impacts of the dams revealed the inadequacy of possible mitigation schemes, such as fish ladders and artificial propagation;
• Opposition to the dam was well organised whereas the proponents were fragmented and competitive;
• There were numerous alternative sites available for hydropower development in the province other than the Fraser River, and also in the Columbia River basin;
• In Canada, the responsibility for fisheries management lies with the federal government. The federal government opposed the dam because of its likely impact the salmon stocks and the importance of these to the First Nations people;
• The free flowing Fraser River remains very productive and, although some salmon runs are enhanced through artificial propagation and stocking, the majority of salmon production from the river is from wild stock. Had the mainstream been dammed, it is very likely that many sockeye and Chinook salmon populations would have been lost.

Columbia River commercial salmon harvests (1866-2006)

In stark contrast, the hydropower potential of the Columbia River has been developed vigorously since the early 1900s. Fish passage at the lowest mainstream dam, at Bonneville, has been monitored since the dam was constructed in 1938. The records show that the overall abundance of adult salmon entering the river is now relatively stable, albeit at lower levels than before European colonisation. The average salmon count over the last decade was just over 1 million fish, whereas the population of returning adults in pre-colonial times is estimated at around 8 - 10 million fish.

However, these levels have been achieved through stocking of hatchery-reared juvenile fish, while the abundance and diversity of wild salmonid populations have decreased significantly since the late 1800s. The first hatchery in the Columbia Basin began production in 1877—well before the first hydropower development. The product from these hatcheries was used to supplement losses from harvest and habitat degradation, and since 1888 there has not been a year in which production in the Columbia Basin was entirely natural.

In 2008, 147 million juvenile salmon arrived that the river's estuary prior to entering the Pacific Ocean. The proportion of this population that are from wild stock varies greatly with species, but, as an example, 75% of the yearling juvenile Chinook salmon arriving at McNary Dam were estimated to have been of hatchery stock. Gustafson et al. (2007) estimated that 30% of the historic salmon populations have been lost, and that many of the remaining wild stocks have been significantly reduced due to the impacts of dams and a period of poor ocean productivity. As a result, 13 of the 16 'population units' used to define structure of salmon populations in the basin are now classed as 'threatened' or 'endangered'.

It is clear that artificial propagation on its own does not preserve the natural salmon fisheries of the Columbia Basin. Additional measures, primarily fish ladders, to help the upstream migration of adult salmon have been installed at each of the 13 hydropower dams on the mainstream. While these passages have performed quite well, mortality of fish migrating upstream through the hydropower system remained a significant problem during the 1960s and early 1970s. This was due in part due to high levels of gas supersaturation in the tailrace at the base of the dams. Furthermore, few mainstream dams were designed to take account of the downstream migration of juvenile salmon.

These issues came to a head during the extreme low flow years of 1973 and 1977 when survival rates of juvenile salmon migrating downstream through the hydropower systems dropped to less than 5% (Raymond, 1988). It was then clear that additional protection measures were needed to sustain salmon stocks and provided the impetus for the long process of improving passage conditions for juvenile salmon that continues today. Major milestones were:

• Installation of systems to guide fish away from turbine intakes and bypass fish around dams (1975);
• Collection of migrating juvenile salmon at upstream dams and transporting them in barges to below downstream dams (1980);
• Storage of water in flood control reservoirs during the winter to provide increased flows through mainstream dams during the following spring and summer to assist downstream migration (1982); l Spill water at dams to provide non-turbine passage routes (1982);
• Abatement of total dissolved gas and management of gas supersaturation (1996):
• Development of surface-orientated routes of passage at many dam sites (1990s):
• Development of new turbine designs that improve survival of fish passing through turbines (1990s).

The message for the Mekong
The contrasting approaches to hydroelectric development in the Fraser and Columbia basins provides some clear messages regarding the potential impact mainstream dams may have on the fisheries resources of the Mekong.

Firstly, the location of dams in reaches of large rivers can have profound impacts on fish populations and fisheries. The absence of dams on the mainstream of the Fraser River has helped to preserve this worldclass fishery. In contrast, dams on the mainstream of the Columbia River contributed to the severe depletion of wild fish stocks.

Secondly, overcoming the impacts of large dams on migratory fishes in the Fraser and Columbia has required the integration of a number of mitigation measures. Most prominent are fish passages (fish ladders) for upstream migration and a range of methods for getting juvenile fish downstream past the barriers. At the same time, water flows need to be managed to provide favourable conditions for fish passage (which is often contrary to hydropower generation requirements). Stocking of hatchery produced juvenile fish, while contributing to the numbers of fish in the system, does not assist in preserving wild fish stocks.

Finally, mitigation solutions are very costly and take time to develop and implement. In the Columbia River, over the last 30 years over US$ 7 billion has been spent on mitigating the effects of dams on salmon (Williams, 2008). In fact, these costs are currently approaching US$1 billion a year. However, these technological fixes do not fully restore migratory conditions to levels under which salmon evolved prior to dams being installed. Thus, they may keep salmon stocks from going extinct, but are not likely to provide complete mitigation for freshwater ecosystems that have been altered by water resource development (Williams, 2008).

Beyond these general lessons, the mitigation methods developed in the Columbia Basin raises more specific issues that are pertinent to the Mekong. Perhaps the most important is that the measures in the Columbia River target a small number of species (five) of the same salmonid group. Populations of other commercially and culturally important fish, such as the Pacific lamprey and sturgeon, remain under severe stress. In addition, introduced species, such as the American shad, have been quick to adapt to the changing riverine ecosystems, possibly adding additional stress to the populations native fish.

The Mekong has a much greater fish biodiversity than the Columbia or Fraser Rivers (approximately 900 compared with 30-40 species). The Mekong has at least 58 highly migratory species threatened by mainstream dam development (Halls and Kshatriya, in press), while the Columbia and Fraser Rivers have 9 and 8 migratory species respectively. Therefore, devising solutions to mitigate the impact of mainstream dams on the Mekong's fisheries appears far more challenging than the task that faced the efforts to preserve the salmonids of the Pacific Northwest. 

*Dr Ferguson is Director of the Fish Ecology Division of the Northwest Fisheries Science Center in Seattle and Dr Healey is Professor Emeritus at the Institute for Resources, Environment and Sustainability at the University of British Columbia in Vancouver

References
Butler, V. and J. O'Connor. 2004. 9,000 years of salmon fishing on the Columbia River, North America. Quaternary Research 62: 1-8.

Gustafson, R., R. Waples, J. Myers, L. Weitkamp, G. Bryant, O. Johnson and J. Hard. 2007. Pacific salmon extinctions: quantifying lost and remaining diversity. Conservation Biology 21(4): 1009-1020.

Halls, A. and Kshatriya, M. in press. Modelling the cumulative effects of mainstream hydropower dams on migratory fish populations in the lower Mekong basin. MRC Technical Paper No. 25. Mekong River Commission, Vientiane.

Independent Economic Advisory Board (IEAB). 2005. Economic effects from Columbia River Basin anadromous salmonid fish production: IEAB Report 2005-1. Report to Northwest Power Planning Council, Portland Oregon. 46 p. plus Appendices.

Lichatowich, J. 1999. Salmon without rivers, a history of the Pacific Salmon crisis. Island Press, Washington D.C

National Research Council (NRC). 1996. Upstream: Salmon and society in the Pacific Northwest. National Academy Press, Washington D.C

Northcote, T., and P. Larkin. 1989. The Fraser River: A major salmonine productive system. Pp. 174-204 in D. Dodge, (ed.) Proceedings of the International Large River Symposium. Canadian Special Publications Fisheries Aquatic Science 106.

Raymond, H. 1988. Effects of hydroelectric development and fisheries enhancement on spring and summer Chinook salmon and steelhead in the Columbia River Basin. North American Journal of Fisheries Management 8: 1-24.

Schalk, R. 1986. Estimating salmon and steelhead usage in the Columbia Basin before 1850: The anthropological perspective. Northwest Environmental Journal 2(2): 1-29.

Williams, J.G. 2008. Mitigating the effects of high-head dams on the Columbia River, USA: experience from the trenches. Hydrobiologia 609: 241-251.