Are the river flows declining?
Many residents of the Kettle River watershed are worried that the rivers are drying up. Again and again, we have heard that the flows are declining; summers are much drier than they used to be; and global warming is taking its toll on the river.
The truth may be surprising, and more complicated than we remember.
According to the recent technical assessment of the Kettle River watershed, there was no trend in either average annual or August flows over the last 80 years at Laurier, Washington. [nbnote ]Summit Environmental. 2012. Kettle River Watershed Management Plan: Phase 1 Technical Assessment. Section 4.3.3, “Trends in River Discharge over time”. Accessible at: http://kettleriver.ca/wp-content/uploads/2012/11/summit_2012_krwmp-phase-1.pdf[/nbnote]
The last decade was particularly dry, with extreme low flows in 2003 and 2009. Residents will recall very poor sport fishing, impassable tubing conditions and the unprecedented letter from the BC government requesting that water licence holders limit their water use. However, the last two years of data reveal flows are again within historical norms due to higher precipitation and later snow melt.
This river naturally varies from year to year, with weather being the largest influence on flows. The recent data does show a very fast decline from higher than average flows to lower than average flows between July and September. We will look to see if there is any trend in the “downward slope” in flows from summer to fall, and whether it is related to water use.
The bottom line? Overall, the flows aren’t declining, but in dry years late summer and fall low flows impact our communities and ecosystems. We will all have to look closely to see how we can lessen the impact. Future columns will focus on the relationship between water use and flow, and connections between surface water bodies and groundwater.
Adapted from a column originally published January 23, 2013 in the Grand Forks Gazette.
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