For four days in a row last week, the Big Wood River north of Ketchum hit its lowest-ever recorded flow for those dates, indicating the potential for future water shortages, regional experts say.
On Thursday, the river’s daily mean discharge at the Ketchum U.S. Geological Survey gauge site—situated near the Sawtooth National Recreation Area headquarters—dipped to 200 cubic feet per second. The previous minimum-flow record for that day at the Ketchum station was 204 cubic feet per second in 1959, USGS data shows. Measurements taken at the Ketchum site on Friday, Saturday and Sunday also broke minimum-flow records set over 60 years ago, with the river averaging a daily mean flow of 177 cfs for those days.
According to USGS spokesman Tim Merrick, the main culprit for the river’s low discharge is this year’s modest snowpack and spring runoff.
“Today’s [USDA Natural Resources Conservation Service] snow water equivalent observations show the Big Wood basin at 52 percent of normal for this time of year,” he said in a Tuesday interview. “The below-normal snowpack, of course, means less water available for runoff to the basin’s rivers and streams.”
Daily streamflow measurements taken at Hailey’s USGS gauge station near Lions Park have also been below the river’s typical flow this month. The site, which has provided researchers with over 100 years of data, recorded a median flow of 548 cfs from May 1 to Memorial Day this year, significantly less than the river’s regular median flow of 998 cfs.
Hydrologist Danny Tappa of the NRCS-Idaho Snow Survey said the water supply outlook for Wood River Valley residents is not looking great.
“The biggest concern is for users on the Magic Reservoir, as water shortages are nearly a certainty at this point,” he said. “We had a dismal fall precipitation in 2019, which didn’t help.”
Tappa said the Big Wood Basin could get a boost with this coming weekend’s 80-degree temperatures.
“It’s possible we get a quick rise in streamflow with the very warm temperatures headed our way, but any rise will be short-lived because there isn’t enough remaining snowpack to result in any significant runoff,” he said.
On its website, the city of Hailey offers several tips residents can use to conserve water this summer, outlined below:
- An old washing machine can use 40-50 gallons per load. If you are planning to replace your machine, a new front-loading or horizontal axis model uses as little as 10 gallons per load.
- Most toilets are stamped with a gallon-per-flush rate on their bowl rims. Newer toilets tend to be much more efficient than old ones, using as little as 0.8 gallons per flush.
- Repair any leaks—a leaky faucet that produces one cup of water in 15 minutes can mean a loss of 300 gallons of water per month.
- Replace old showerheads with high-efficiency models; some showerheads on the market today use as little as 1.5 gallons per minute.
- Water-thirsty grasses can be replaced with hardscape (stone or patio) areas and/or drought-tolerant plants and grasses, such as Idaho fescue, Big bluegrass and Little bluestem.