The Idaho Statesman ran a good piece on climate change Tuesday, “Climate change accelerating, complicating Idaho’s spring runoff.” The report:
The effects of global warming are making it more difficult for reservoir managers to control floods and manage flows for irrigation, recreation and fisheries.
Two days of record high temperatures and two days of record rainfall the same week in late April sent 26,000 cubic feet per second surging into the Boise River dam system, forcing federal river managers to increase flows to more than 8,100 cfs — the highest flow out of Lucky Peak Dam since 1998 and just the second time it has hit 8,100 in 30 years.
The water station at Twin Springs on the Middle Fork of the Boise River has been recording flow data for 100 years. Such long-term monitoring is increasingly important — and rare — as scientists try to understand long-range effects of climate change. PROVIDED BY USGS
We reported last year on a US Geological Survey study that found “Global Warming Drives Rockies Snowpack Loss Unrivaled in 800 Years, Threatens Western Water Supply.”
As many recent studies find, it is increasingly going to be feast or famine, flood or drought, because of manmade climate change (see “Study: Global warming is driving increased frequency of extreme wet or dry summer weather in southeast, so droughts and deluges are likely to get worse“).
As the Idaho Statesman piece explains:
The more variability in the climate, the harder it is for the two federal dam-managing agencies to balance their competing tasks of preventing floods while filling the reservoirs to provide water for various uses.
The evidence that the runoff timing has changed is based on streamflow gauges maintained by the U.S. Geological Survey. One of the oldest is the gauge on the Middle Fork of the Boise River, installed near Twin Springs above Arrowrock Dam in 1912.
It shows that runoff that used to begin in early April now starts in late March. That flow used to peak in late May or June, but now peaks in early May.
Droughts and wet years have come and gone over the past century on the Boise River, said USGS hydrologist Greg Clark. But the past 30 years have generally been drier. With the snowpack melting earlier, that leaves flows even lower in the late summer and fall in the tributaries above reservoirs and in rivers without dams.
And this increase in extremes has real impact for real communities:
That affects things besides farmers’ irrigation water. It affects fish, for instance, especially since the water is getting warmer, said Clark, associate director for the Idaho Water Science Center in Boise.
It also affects recreation. On the Boise River, the longer period of high flows through town through the spring to prevent flooding delays floating season. On rivers such as the Middle Fork of the Salmon, low flows late in the season limit the number of days for whitewater rafting.
Yet, just as we need to be spending more money on measurement and planning, money for the key federal agencies is being cut and “money for the 100-year-old Boise Middle Fork streamflow gauge is in doubt.”
The story ends with a warning from Ron Abramovich, “a water-supply specialist with the Natural Resources Conservation Service in Boise”:
“A lot of people think global warming is going to be a gradual increase in temperatures,” said Abramovich. “It may be a roller coaster … kind of like the stock market.”
It is noteworthy that a local paper did such a good job of reporting on a subject that has proved challenging to say the least for many in the national media (see “Silence of the Lambs 2: Media Herd’s Coverage of Climate Change Drops Sharply — Again“). Special kudos to The Idaho Statesman for not undermining the science with any false balance.