Officials predict poor water runoff
March 1, 2013
With mountain snowpack around Park City 29 percent lower than average, and no indication the current precipitation trends will drastically improve, officials are expecting a low spring runoff.
"I think what’s going to happen is we’ll limp along and have somewhat of an inefficient runoff," National Weather Service Hydrologist Brian McInerney said. "If it gets warm and stays dry and we start melting early in March, the efficiency of the runoff drops dramatically."
Early melting causes early-season evaporation; sublimation, when the snow on top of the snowpack turns into gas, bypassing evaporation; and water that seeps only into the top layer of the soil.
"And then as the water makes its way to the streams, it tends to evaporate, and the plants tend to suck the moisture from the top of the soil and transplant it out of their leaves," he said. "So the question is, how much water do we have in the reservoirs?"
Last year’s dry winter led to heavy depletion of the Weber Basin Water Conservancy District reservoirs, with 65 percent of the two-year supply used by late fall.
According to McInerney, 120 inches of snow would need to fall this winter for Summit County’s snowpack to get back on track.
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"There’s always a chance, but we would need so much," he said.
The five to seven day weather forecast predicts Summit County will soon have small storms interspersed with periods of warming, McInerney said
"That’s OK, but what we need are storm cycles that are three to four days long with a lot of snow and cold weather," he said.
"During the dry years between 2000 to 2004, only 50 percent of the water from the snowpack made it to the reservoirs due to inefficient runoff processes," he said. "But if you look at 2005, which was a really good year for late season storms with a cold spring and a very wet atmosphere, basically all of the mountain snow made it into the reservoirs."
Summit County Fire Warden Bryce Boyer said he monitors precipitation levels beginning in early March.
"A lot of the early indications are that we could have another dry summer," he said. "There just isn’t a lot of snowpack above, and there isn’t quite as much moisture in the snowpack that is there. But that would go with the typical cycle that is normally seen."
Boyer said wet cycles typically last for a few years, followed by a dry cycle for the next few years.
McInerney agreed that precipitation is cyclical, but said that climate change is also a factor.
"Throw climate change on top of the cycles, and the old models don’t work because we have a different atmosphere," he said. "Rain is increasing as our atmosphere warms," he said. "The average person in Park City probably won’t know the difference, but people who don’t have very good water rights, such as farmers, will be affected."
McInerney said that for the time being, he thinks the county is fine, but that too many dry years together will be problematic.
"It’s difficult for the economy, the ski industry and the farmers," he said.
The Snyderville Water Reclamation District, which operates two water treatment plants in Summit County, has also seen the negative affects of low snowpack.
"We like to see water flowing down the stream, and when the snow melts slowly, it helps maintain stream flow in East Canyon Creek and Silver Creek," Reclamation District General Manager Mike Luers said. "When the snow is lacking like it is this year, it presents the possibility of those streams drying up during the critical summer months, August and September."
The low water levels can be fatal for the fish who may not have enough water to survive, he said.
More problems arise when there isn’t enough fresh water mixing with the treated water.
"We’ve been studying the impacts of very low levels of pharmaceuticals," he said. "When we have some dilution from the stream above us, it becomes less of a problem. Tertiary treatments plants like ours are not designed to remove these very low levels of pharmaceuticals and natural hormones. Those can have a negative impact on the fish population when the stream flow becomes very low."