TCID Sets 100% Water Season, Water Orders Begin March 16

The Truckee Carson Irrigation District Board met on Mar. 10 to receive updates on current water levels as well as projected inflows into the Carson and Truckee rivers and Lahontan Reservoir over the coming months. The board also discussed and set water allocations for the upcoming irrigation season.

Despite relatively dry conditions, the board set a 100% water allocation year, with water orders to begin on Mar. 16.

TCID Watermaster Kelly Herwick reported that as of March 10, Lahontan Reservoir measured at 211,823 acre-feet (af), with target storage at 237,000 af by month’s end. He also indicated that the Carson River at Fort Churchill is flowing at 571 cubic feet per second (cfs), and the Truckee Canal at 891 cfs.

Bureau of Reclamation (BOR) Special Studies Hydrologist Maggi Kaft gave an extensive update on current and projected water conditions for April through July. A dry January that brought some snow followed by rain caused snowmelt and runoff to begin early, which could mean reduced inflows later in the season. “The current snow-water equivalent is not good,” Kaft said, noting the level is currently between 53% and 66%.

One benefit of the early snowmelt is that soil moisture and saturation are good. Kaft reported two record-high soil moisture readings around Jan. 1 and again at the end of February. While soil moisture may not seem important, it can improve snow runoff as the ground is already saturated. “This high soil moisture will hopefully mean a lot of the snowmelt will end up in the river,” Kaft stated. “So we'll have an efficient runoff.”

With the warm early-season temperatures, much of the snow in the Sierra is “ripe and ready to melt,” according to Kaft. As of Feb. 23, the mountains still retained a moderate amount of cold snow, which melts slowly through spring and into summer. The snow that was ready to melt represented about 21% of the total snow-water equivalent. However, within two days and under very warm conditions, the ready-to-melt snow level spiked to 97%. “We went through a quick and drastic change in a matter of a few days,” Kaft explained.

As the early snowmelt continues, the amount of runoff expected later in the season is declining. Kaft explained that more snow will melt in March rather than April, when runoff typically begins, and the BOR now anticipates river flows dropping to near zero by late spring and remaining low through summer and fall.

Currently, the forecast for Carson River runoff for April through July is 106% of the median, but inflows are expected to drop to zero by June 18. Due to the early runoff, inflows and water levels will appear above normal early in the season but below normal as the season continues, which will reduce storage targets.

Overall, water for the season appears within long-range median water and storage levels, with peak flows occurring early this year. There has been a continuous increase in flow into Lahontan since early January, with levels rising from 100,000 af to more than 200,000 af by the end of February. However, Kaft projected a drop in inflows from the Carson River at Fort Churchill and from the Truckee River at Wadsworth this month. “Flows recede through spring and hit zero in June,” said Kaft. “And as Fort Churchill drops off, storage declines.”

Robert Martinez with the BOR Lahontan Basin Area Office said that water diversions into Lahontan will begin in June. “We will be under storage targets.” He also said the BOR will determine Newlands water release credits as the year continues. Additionally, the Truckee and Carson divisions of the Newlands Project are not anticipating a water supply shortage at this time. The Truckee Division, supplied by Lake Tahoe and Stampede Reservoir and regulated through Derby Dam, serves Wadsworth and Fernley and diverts water about 32 miles into Lahontan Reservoir. The Carson Division is supplied by the Carson River system and delivers water along the river and into Lahontan Reservoir.

Water orders will begin March 16, with irrigation deliveries expected to follow typical seasonal operations as runoff conditions continue to evolve. TCID and the BOR will continue to monitor conditions throughout the water seasons as conditions change.