The Truckee-Carson Irrigation District Board of Directors heard a report from Watermaster Kelly Herwick this week at their regular board meeting regarding the outlook for water supply for the rest of the irrigation season. According to Herwick, he said that on-the-ground observations of the system has shown a flux in the Truckee River flows and inflows. There are currently significant variations in the forecasting done through the Truckee River Operating Agreement as opposed to what is actually coming down the river.
Herwick said Lahontan storage is currently at 82,541 acre-feet, and last month it was at 126,144 af. Inflows into the reservoir are running approximately 117 af in a 24-hour period and current releases from the reservoir are at 721 af. He said that currently, if they continue to receive inflows in this manner there will be an additional 5,841 af by October 1. This year, estimated releases are at 166,179 af.
“We are still within a couple percentages of our allocation,” said Herwick. Looking at the TROA forecasting, projections for storage in Lahontan at the end of August are 47,120 af. In comparison, he said that modeling projected 86,929 af at the end of July and the actual ending storage was 85,408. Modeling also shows 189 af for the average flows at Wadsworth, and currently the flow is 123 af. Modeling at the Fort Churchill gauge shows 0 and Herwick expects that to be correct.
“Today, based on the modeling, we are on par with 2020 going into August,” said Herwick. “If we have the same average of 750 af, we will end with 46,000 af in storage by the end of August.” He said modeling shows 39,403 at the beginning of September and the model projects lower releases during September. When comparing to 2020, the projections are similar, “which means we will have some water to start October with, minus the minimum pool, which will give us a week or two in October.”
The actual numbers will depend on demand, but Herwick says if this year stays on par with 2020, deliveries in October will be possible.
Board members originally set the allocation for this year at 70% on the Carson Division and raised that allocation on June 22 to 85%. In 2020 the allocation was 90%.
“Two years ago, we ran more water in July than this year, but we expect to see more demand in August this year,” said Herwick. He expects the demand to drop in September. “Based on current projections we’re looking at the first week in October, possibly longer, depending on demand,” he said about how long the irrigation season will last.