Uncertain future for water supply
Report’s author calls for increased storage and drought planning effort.
By Judie Steeves N
otwithstanding this year’s flooding, the current supply of water for the Okanagan Valley is not sufficient for future agricultural needs, according to climate change scientist Denise Neilsen.
A researcher at the Summerland Research and Development Centre, Neilsen was reporting to the Okanagan Water Stewardship Council on a study conducted in the past year of the Mission Creek watershed in the Central Okanagan, but she noted the situation is likely more drastic elsewhere in the valley, since the Mission Creek watershed is one of the most stable and the largest in the Okanagan Basin. She advised that more storage and drought planning is required to address the current situation.
Although all the major water licences on Mission Creek are supported by storage licences, she said both climate change and the expansion of agriculture will lead to additional water needs in future.
Climate change alone could account for a 40 per cent increase in water requirements between 2040 and 2100, she said.
At present existing agricultural water licenses are not being fully used, so adequate supply is not an issue, but Nielsen is not confident there is enough available for future agricultural needs. Those needs are the reason there is a move toward an Agricultural Water Reserve to back up the Agricultural Land Reserve, she noted.
Such a water reserve would have a number of conditions, such as: completion of a water sustainability plan; a restriction that water cannot be removed; no appurtenance for changes to non-agricultural use; a drought plan
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would be required for water-short years and the use of reclaimed water would not negate existing water licences.
At present, most of the ALR is not irrigated in B.C. but more
agricultural land may need water in future years.
While Nielsen’s study indicates surface water irrigation licences are sufficient to meet demands, waterworks
licences might not be. In future, water supply might not be sufficient to meet demand for full licence use, she adds.
Using the Water Demand Model for the Okanagan created in 2010, which calculates daily water use for each land use parcel, she said both the Black Mountain Irrigation District and South East Kelowna Irrigation District will drain their water storage 40 per cent of the time between the years 2040 and 2100. Both get water from the Mission Creek watershed. It showed SEKID is the more
vulnerable of the two, she adds. With Mission Creek as the source, the average water use between 1996 and 2006 was 50 per cent for agriculture, 23 per cent for domestic outdoor, 19 per cent for indoor and eight per cent recreation, she reported.
Neilsen pointed to this spring and summer’s floods in the Okanagan as examples of the erratic nature of precipitation events under today’s climate scenario, and the impossibility of predicting accurately.
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