When drought and the accompanying heat hits, attention tends to focus on withering crops, explosive wildfires and subsoil moisture.
While those drought-caused problems are obvious, creatures that spend their lives underwater and out of sight can suffer as well.
If a stream bed dries up, of course, fish don’t do well. But even before that final step, higher temperatures and reduced stream flow hurt. The Smith River south of Great Falls is a good example.
“This has been a particularly tough year on the Smith,” said Grant Grisak, Fish, Wildlife and Parks regional fish manager. “But in reality over the past 20 years we’ve had five years of similar low flow conditions.”
Low flows on Aug. 17 also occurred in 2000, 2001, 2003, 2007 and 2016.
Some of the current water problems can be traced back to last winter.
Most of Montana had snowpack at or above 100 percent of average by late last winter. The Smith River was the exception, with a snowpack that peaked in May at 86 percent of average.
The river’s peak flow reached 652 cubic feet per second on June 14, and that was only 88 percent of average.
Usually June is when the Smith can reach its highest flows, but this year, the June daily flow was 47 percent of average.
The Smith is known by floaters and anglers for its semi-wilderness experience and good trout fishing. A typical Smith River float runs 59 miles from Camp Baker, near White Sulphur Springs, to Eden Bridge, south of Great Falls. The best time to float and fish is usually early May to early July.
But below average flows the last five years have reduced both the float season and the rivers’ rainbow trout population.
“The Smith has been on a steady decline of rainbow trout for several years,” Grisak said. “And a slight increase of brown trout. We’re trying to find out why.”
Low water and higher air temperatures contribute to higher water temperatures, which
can have deadly consequences for rainbow trout that have trouble surviving when water temperatures are above 70 degrees.
The average daily peak water temp for July on the Smith was 75.8 degrees, with a maximum water temperature of 81 on July 14.
“That’s a harsh environment for a fish to live in,” Grisak said.
To help, FWP instituted daytime angling restrictions on July 9.
While that may help reducing fishing pressure on vulnerable trout, it doesn’t address stream flow.
This summer, FWP asked several junior water users to stop diverting water for irrigation, allowing more water for the Smith’s instream flow.
Another result of this year’s low water flow and higher water temperatures is the appearance of algae throughout the river.
FWP is working with the Department of Environmental Quality to get a water sampling plan established for algae growth investigation. DEQ has agreed to begin data collection this month.
Perhaps all of these steps combined will help the Smith and its rainbow trout population in the long run.
