Nch'i-Wana*, the Great River * name given the Columbia by the native American people of the river
Nch'i-Wana*, the Great River
* name given the Columbia by the native American people of the river
Our basic scientific interest in the lower Columbia River and its estuary is prompted by the potent interaction of the river's flow and the ocean's tides to trap particles in ETM and divert detrital organic matter into higher organisms of the estuary's food web. But, we are also drawn to the Columbia because of its great power as an environmental, cultural and economic influence across the entire Pacific Northwest region of North America. And, because over the last century man has so totally abrogated the river's integrity as a free-flowing ecosystem (pre-dam history), we seek to understand the long-term consequences to estuarine ecosystem processes and valuable resources such as Pacific salmon that have been important to this region since the retreat of the Pleistocene glaciers.
The River and its Watershed
The Columbia River is the fourth largest river in the North American continent, after only the Mississippi, Mackenzie and St. Lawrence. Over its 1,955-km (1,214 mile) length, it drains an area over 660,500 km2 (255,019 miles2) that embraces portions of seven USA states and two Canadian provinces. The watershed is physiographically separated into two subbasins by the Cascade Mountains: a coastal subbasin that constitutes 8% of the watershed area is in a moist climatic regime (runoff of 2.39 m) and as a result accounts for about 24% of the total runoff, while the semiarid (runoff of 0.71 m) eastern subbasin accounts for 73% of the total runoff, which mostly occurs as snowmelt "freshet" between April and July. Since 1878, when the river's flow was first measured regularly, the mean annual discharge to the North Pacific Ocean has been approximately 5,900 m3s-1 (210,715 cfs). This input to the northeastern Pacific Ocean is responsible for a major oceanographic feature. The river contributes between 60% (winter) to 90% (summer) of the freshwater input to the North Pacific Ocean between San Francisco and the Strait of Juan de Fuca, and its surface freshwater plume may be detected for as much as 645 km (400 mi) from the mouth.
Positioned at the coastal border between the states of Washington and Oregon, the estuary is a drowned river valley that covers 412 km2 (159 mi2), 38.6% of which is intertidal habitat, including 35 km2 (13.5 mi2) of emergent brackish and salt marshes. Although not a major commercial or industrial center (local population, 25-30,000), the estuary and its surroundings still support healthy, diverse marine industry, logging, fishing, agriculture and tourism economies. It is the portal for major shipping traffic between the North Pacific Ocean and the cities of Portland (Oregon) and Longview (Washington), accommodating over 2,000 vessels annually. This commerce requires extensive dredging, filling and channelization of the estuary's geomorphology, which has resulted in the elimination of over 14,500 hectares of estuarine habitat, primarily marshes and swamps. Estuarine sediments are dominated by fine and medium sand, which are accumulating in the estuary at a rate of ~0.5 cm yr-1 because development of the river and estuary, despite the decrease in sediment supplied from upriver.
River and Estuary Modifications
Throughout the economic history and more recent reflections (see Columbia River bibliography) upon its modification for industry, agriculture and commerce, the Columbia has often been referred to as a "machine." Indeed, there can be no issue about the anthropogenic mechanics of a river controlled by eleven major hydroelectric power control dams on the mainstem Columbia, and hundreds of smaller power, flood control and irrigation dams on its tributaries; four additional major hydroelectric dams are on the Columbia's major tributary, the Snake River. Only ~4% of once-natural river above Bonneville still flows freely in the Hanford Reach, just upriver from the Columbia's confluence with the Snake and Yakima rivers. The more than 100 cataracts or rapids of the Snake and lower Columbia are now under water, and surface flow through the reservoirs averages less than 2 km hr-1. What once took a juvenile salmon only a few weeks to migrate downstream through the lower Columbia now may require two to three months. As one of the recent authors on the Columbia has observed, " The Columbia does not flow, it is operated. If reservations are made early, the river can be customized for community events." (Harden 1996). No longer a river, it is a series of slackwater impoundments designed and manipulated for the benefit of commerce and markets, and a few comparatively isolated pockets of recreation. The river now courses to the turns of the Bonneville Power Authority (BPA) power schedulers' dials in Vancouver instead of the natural cycles of snow and glacier melt and North Pacific storms.
Before extensive regulation by the dams, average annual discharge approached 17,500 m3s-1 (625,000 cfs). It is now only 12,000 m3s-1 (428,575 cfs). Regulation of river flow has redistributed this residual maximum river flow during the spring freshet to the drier summer and fall months; minimum monthly flows have been increased from a pre-regulation maximum of about 1,840 m3s-1 (~65,715 cfs) to about 2,970 m3s-1 (~106,000 cfs). Various sources suggest that, to irrigate more than 32,000 km2 of semiarid steppe, between 3.58 and 241.9 billion m3 (945.4 billion-63.9 trillion gallons) of water is presently removed from the river for irrigation, although it is not known exactly what quantity of water, along with nutrients, herbicides, and pesticides, ultimately returns to the river. Without taking into account this return flow, the present level of irrigation removal likely further decreases annual mean river flow another 5%-10%. We are now discovering that climatic variability can have a much larger effect (~20%) on long-term trends in annual flow, however. One of the more consequential secondary effects of decreased flow has been an estimated 50% decrease in the sediment delivery to the estuary between the period 1868-1934 and 1958-1981 because sediment transport is linked directly to peak river flows. This change in sediment delivery to the estuary does not take into account differences in sediment supply to the river due to changes in land use or sediments trapped behind the dams, where are relatively unknown.
Economic Benefits of the Columbia River System Today
It is impossible to discount the historic and present-day economic benefits to the region. It has been suggested that with the advent of World War II, in one fell swoop, Grand Coulee and Bonneville dams essentially extricated the United States from economic depression, the loss of World War II, communist domination, and the collapse of the country's agricultural enterprise. Blaine Harden aptly describes the construction of Grand Coulee as "...an eye-popping metaphor for Manifest Destiny. It was a vaccine for the Great Depression and a club to whip Hitler, a dynamo to power the dawn of the atomic age and a fist to smash the monopolistic greed of private utilities, a magnet for industry and a fountainhead for irrigated agriculture." The Columbia River Alliance estimates that the current economic value of hydroelectric generation, navigation, irrigation and flood control exceeds $30 billion annually. Today, Columbia River dams supply electricity to almost 50 million people on a western power grid that covers half of the United States, but two fifths of the energy end up supporting the region's industries (especially aluminum production) and agriculture. Grand Coulee alone generates $400 million each year for the United States government. Up to 25-35% of the nation's grain products are transported down the Columbia, along with a multitude of other farm and consumer products.
Impacts of Columbia River Development
But, the expense to the native indigenous peoples and Pacific salmon for development of the Pacific Northwest may have reached its nadir along Nch'i-Wana. The fifty to seventy thousand Native American Indians that once congregated along the river sustained both their populations and economies with the harvest of up to 42 million pounds (5-7 million fish) of salmon per year. Both Indians and salmon have diminished to near extinction, perhaps only partially attributable and coincident to the sedating of the river, but certainly not unrelated. Between contact with early explorers and immigrants and 1855, the Native populations of the Columbia Plateau had declined by 50%, and by 66% by 1875. The few remaining Indian peoples of the river were systematically removed from their traditional living and fishing sites and forced onto reservations. Despite treaty rights, until relatively recently aboriginal fishing access to the river and fish was denied or arrested. Over the same period, many historic salmon populations became extinct, almost every remaining population declined precipitously from historic levels, and several stocks are now severely threatened with extinction. Compared to annual runs of 10 to 16 million fish in the early 19th Century, often less than one non-hatchery million salmon now return annually to the Columbia River. More than a third of the historic spawning grounds of the Columbia River salmon have been blocked by dams which were not equipped with fish ladders. Overharvest of salmon, habitat degradation due to logging and other adverse land uses, as well as water withdrawl for irrigation have contributed extensively to this decline. However, it has been estimated that development and maintenance of the Columbia River for hydropower and transportation accounts for 80% of the salmon's decline. Hatchery-reared salmon now constitute approximately two-thirds of the remaining salmon runs, but have compensated for the decline by only about 10%. There also are increasing questions as to whether hatchery fish are contributing to the decline of wild salmon or are merely benigh physiologically and genetically inferior substitutes. While many salmon populations throughout the Pacific Northwest are depressed, the conflicts over salmon and Native American salmon fisheries on the Columbia present perhaps one of the more extreme dissentions in values and resource management in the region.
More details on the structure and ecology the Columbia River estuary, and the historic changes influencing it, can be found in a dedicated issue of Progress in Oceanography edited by L. F. Small (1990, Vol. 25, No. 1-4) as well as other technical literature.
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