Water Supply Update (3)

Early April showers helped, but the projected run-off is still lower than normal.

April 18, 2001

North facing slopes of Parleys Canyon.  Snowpack measurements in this watershed are about 60 percent of normal.

“March was a huge bust,” exclaimed Randy Julander, snow survey supervisor for the Natural Resource Conservation Service, to an assembled group of water managers at a meeting held at the Jordan Valley Water Conservancy District on April 11, 2001.  Julander was referring to last month's snowpack within the state’s northern watersheds -- it didn’t materialize. That’s the bad news, on the other hand soil moisture this year is much better than last year when nearly one-half the run-off disappeared into the ground before reaching the reservoirs. However, Julander said it could be worse. “Southern Oregon irrigators get zero allocation this year – what water there is will be used for instream flows and the salmon.”

Brian McInerney, National Weather Service, had the same message, “We needed a big March, but didn’t get it.” The run-off volumes during the period of April to July are projected below normal.  The Utah Lake Basin is projected at 60 percent of normal, Weber Basin 50 percent, and the Bear River Basin 35 percent. Southern Utah does much better with the southeast region of the state 100 percent of normal and the Virgin River 75 percent. He noted that the first week of April helped the situation. “We’re adding moisture to the system and that’s the way we want it to go.” said McInerney.

Of greatest concern is the water supply in Deer Creek Reservoir located in Provo Canyon. This reservoir is a major water source for most of Salt Lake County. According to McInerney, the run-off into Deer Creek Reservoir is projected to be 44 percent of normal.  Anticipated below normal run-off into Deer Creek Reservoir prompted Provo River Water Users Association (PRWUA) general manager Keith Denos last February to notify shareholders there would only be a 60 percent allotment this coming summer. The Metropolitan Water District of Salt Lake & Sandy owns 61.7 percent of the stock in the Provo River Project. The reduced allocation has a direct effect on Salt Lake City and Sandy City’s water supply.

A lot will depend on how the spring snowmelt plays out. The amount of water that can be stored in Deer Creek is tied to a complex system of water rights on the Provo, Weber and Duchesne rivers.   If it’s a slow melt with low stream flows, the water that can be stored under the PRWUA's water rights will be less than if it is a short duration extremely high runoff with large volumes. The concern is keeping enough water in the reservoir this year to protect against another poor water year.  The amount of water that can be stored in Deer Creek will not be completely known until June or July. The allocation could be adjusted upward or downward according to the spring run-off.

While March snow didn’t materialize, the first two weeks of April did provide some hope. A week of steady valley showers and snow in the higher elevations was climaxed with a heavy snowstorm on April 12. This wet period improved the percentage of normal readings at nearly all of the critical snow measurement sites. According to mid-month snow course measurements, public utilities hydrologist Dan Schenck reported that

Trial Lake SNOTEL hydrograph shows 2001 winter snowpack (red) compared to last year (green) and average (blue). Early April moisture has improved the percentage of normal.

Brighton in Big Cottonwood Canyon was 90 percent of normal and Cecret Lake in Little Cottonwood Canyon 86 percent of normal.  Trial Lake increased its water content by 3-1/2 inches and as of April 16, is 69 percent of normal. The entire Utah Lake – Jordan River Basin rose to 79 percent of normal in a two-week period.  

Despite the two-weeks of storms, water managers are still planning for a less than normal run-off and reduced supplies this summer. The Weber Basin Water Conservancy District has already notified its users that no watering will be allowed between 10 a.m. to 6 p.m. 

A wet and cooler spring and summer will help reduce demand but, “The forecast is for normal conditions,” said McInerney.