HUMAN USE OF NATURAL RESOURCES IN THE SOUTH OKANAGAN AND LOWER SIMILKAMEEN VALLEYS

Richard J. Cannings and Eva Durance

HISTORICAL WATER USE

TWENTIETH CENTURY

1900-1960

Agricultural irrigation was, and remains, the largest single user of water in the region. Beginning in the 1890's, the advent of large-scale orcharding was supported by the construction of open-flume irrigation systems from upland lakes and streams. The first dam, on Penticton Creek, was built in 1905. In 1919, the Provincial government bought and subdivided land along the Okanagan River for war veterans and built a permanent irrigation canal and system in the south end of the Valley. The construction of a dam below Vaseux Lake prevented most migration and spawning of the Columbia River salmon runs further north, and since 1954 there have been no sockeye spawning beyond this point. About 150 or so manage still to negotiate the downstream weirs between Oliver and Osoyoos Lake and spawn in McIntyre Creek (R. Manual, pers. comm.)

After World War II, veterans' lands were opened up in Cawston, on the West Bench near Penticton, and in the Central Okanagan. To service these small holdings, most in orchards and hobby farms, pressurized irrigation systems were built.

Irrigation Districts were set up, along with water-user communities, starting in 1914 with the passing of legislation allowing public irrigation corporations. There are now 17 Irrigation Districts in the RDOS. Annual water use for these Districts and for the three municipalities, Penticton, Osoyoos, and Princeton, now exceeds 100,000 acre feet; of this 77% goes for agriculture, 50% for tree fruits and the rest for residential and industrial uses. About 40,000 acres are irrigatedmost by sprinkler systems, although this is changing to some degree with the advent in the past six to seven years of high-density fruit-tree plantings and new vineyards which use drip-irrigation systems. (Durance and Gibson, 1991).

1950-1980

The 1950's and 1960's, however, saw the greatest damage to the natural system with the damming and channelizing of most of the River, but the destruction of wetlands and marshes continues today and the demands of an increased population put additional pressure on the waterways and on authorities to alter them further.

Other agricultural practices also altered or destroyed natural water systems. Wetlands throughout the southern part of the Valley were filled in or drained for crops and forage, and riparian vegetation was cut down, burned, or destroyed by livestock in search of water. Early clean-cultivation practices in orchards resulted in heavy fertilizer loading to waterways which, along with livestock manure, increased phosphorous levels to the point that there were serious algae blooms in the central lakes into the early 1970's when some controls were put on this source of pollution.

By 1957, the Okanagan River had been channellized from Penticton south and a dam at the north end of Penticton built to stop the periodic flooding in the expanding town. This effectively destroyed the marshlands, cottonwood thickets, and other wildlife habitat, leaving the present degraded remnants of the oxbows on either side of the channel and Parkway A 1990 estimate (Sarell) put the loss of valley bottom riparian habitats at 85% largely from direct and indirect effects of this channelling. Only about 7.45 km of the Okanagan River between Okanagan Lake and the border remain in a relatively natural state, and the report notes that as the current, straightened, channel is much shorter than the natural, meandering, river, "the above figures underestimate the amount of the original river that has been altered". (O. Dyer. notes prepared to update SOCS participants, 1994).

1980-PRESENT

Heavy use of agricultural chemicals continues to affect water in the area. The State of the Environment Report (1995?) reports that "a preliminary survey of groundwater in the Osoyoos area in 1987 found five samples out of 22 to contain detectable levels of pesticides." (p. 82). Although the pesticides were found in low concentrations, their presence indicates the possibility of groundwater contamination which would in turn pollute Osoyoos Lake. Wells in the Osoyoos area also have shown nitrate-nitrogen levels in one-third of samples taken to be equal to or greater than 10ppm, the Canadian standard for drinking water; this is likely due to orchard fertilization. Testing in other areas of the Valley has also found these types of pollution in groundwater.

Forestry practices, while not directly using water or waterways have affected water quality. Clearing trees and brush to the very edge of creeks has destabilized banks, increased sediments and decreased cover for fish and other aquatic life forms. The loss of shade over the water also increases water temperatures making them too high form some indigenous fish species. (Charting a Course...)

Recreation, housing, and tourism are all human activities that in some formor other have made, and continue to make use of water in the study area. Fishing has been primarily recreational since the mid 19th century, but is an important economic factor because of the businesses it supports. Tourism in the Valley is heavily dependent on the scenery, climate, and water-based recreation available including fishing, swimming, and boating. These two activities have certain detrimental effects on water-dependent wildlife and on wildlife habitat related to water. Some 'game' fish species have been introduced such as lake whitefish and largemouth and smallmouth bass and man-made beaches have destroyed natural riparian vegetation and lake-edge habitat; however, in many important respects, these activities are highly dependent upon healthy water systems and are largely neutral or even potentially a positive force for better water management. Unfortunately, as is noted in Charting a Course for the Okanagan (1993), "the linkage of water quantity and quality, the natural system, and human demands is rarely considered as well as the effects on recreation and tourist activities such as sport fishing and boating." (p. ?)

Housing and the growth of urban centres has put serious strains on both water quality and quantity in the South Okanagan. While agriculture remains the largest user of water, residential use has risen with the increased population along with increased potential for pollution from improperly maintained septic systems and from residential use of lawn, garden, and home-maintenance chemicals. The rapid increase in homes, both permanent and seasonal, along waterways has also led to degradation and destruction of riparian and water environments as well as general disturbance of wildlife from human presence.

In 1973, A.C. Brooks documented for the Canada-BC Okanagan Basin Water Study wildlife problems associated with the management of the water basin. In this, he notes the detrimental effects of waterfront property development, which he states had increased greatly since flood control measures had been introduced. House now could be built close to the water with the usual result that the land was cleared of trees and waterfront vegetation as well as wharfs and boathouses being built over the water. Wildlife habitat was destroyed, particularly that of creatures partly or solely dependent on water, and many wildlife species disappeared. Park authorities were also to blame; he uses as an example the development of Sunoka Point Park with the destruction of most of its huge cottonwood ecosystem.

These kinds of waterfront alienation, particularly on private lands, have accelerated since the 1970's with virtually no waterfront properties remaining 'undeveloped' along any of the lakes and rivers of the study area. On Okanagan Lake, south of Peachland, only one, small, semi-natural marsh remains, in Summerland. The marshlands of Vaseux Wildlife Preserve and those at the north end of Osoyoos Lake are the only large ones left relatively untramelled.