With what officials are calling the wettest year on record for the Tuolumne River Watershed, the Turlock Irrigation District Board of Directors will consider a 48-inch irrigation cap for the 2017 irrigation season, which could begin as early as the end of this month.
“We have more than enough water out there for everyone,” said Assistant General Manager of Water Resources Tou Her during TID’s grower meeting on Tuesday. “We can’t even get rid of it quickly enough.”
Her said that in addition to the 48 inches of surface water that will potentially be available for the 2017 irrigation season, growers will also get the opportunity to take advantage of supplemental replenishment water “above and beyond that.” A number of eastside growers within Turlock Subbasin are also expected to receive additional replenishment water as well.
Her added that TID is a conjunctive management district, meaning that it utilizes both surface water and groundwater. In years such as this one when the district has plentiful surface water, TID said that it promotes flood irrigation to recharge groundwater aquifers.
“We are strongly encouraging all of you who can to flood irrigate,” said Her.
Looking at the 2017 precipitation year, which began in September, February marks the fourth month so far that has surpassed its historical average of 6.09 inches with 14.75 inches in 2017. The Tuolumne River Watershed has now received 51.40 inches of precipitation, which is over 200 percent of the region’s historical average of 25.38 inches for the period between September and February.
Her said that this year marks the wettest year on record for the period between September and February with 51.40 inches of rainfall. The second wettest year was in 1983 with 48.97 inches, followed by 47.80 inches in 1969.
“2017 ranks as number one — the wettest September to February period on record,” said Her.
Her said that if the region were to have average hydrological conditions going forward, the year would conclude with 61.6 inches of precipitation, which would still be considered the wettest year on record. If that were the case, the region would still experience approximately 2.8 million acre-feet of water between now in July.
“Keep in mind, our reservoir is full,” said Her. “That is one-and-a-half times Don Pedro sitting out there in the watershed.”
If the Tuolumne River Watershed were to continue experiencing above-average hydrological conditions through July, Her said that the region could end with 71.5 inches of precipitation, which could mean another 3.6 million acre-feet of water.
“I know a few of you have signs that say ‘Pray for Rain’ in your front yard, but let me just say tonight that this is probably a good time for you to go ahead and hibernate those signs — at least for this year,” laughed Her.
Pending the Board’s approval on March 21, Her said that the 2017 irrigation season could begin as early as March 30 and conclude towards the end of October. TID will adhere to a normal year water rate schedule, which encompasses a fixed charge of $60 per acre.
During Tuesday’s meeting, Her also updated growers on Don Pedro Reservoir, where officials opened one controlled spillway gate for the first time in 20 years on Feb. 20 to make additional releases to the Tuolumne River. Just before 5 a.m. Monday, TID closed the controlled spillway gate in compliance with the U.S. Army Corps of Engineer Flood Control Manual regarding operation of the reservoir.
TID filed a request with the U.S. Army Corps of Engineers for a deviation to maintain releases of approximately 16,000 cubic feet per second until Don Pedro Reservoir is lowered to 815 feet, however, the request was denied on Friday.
This deviation would have created additional space in the reservoir to accommodate future inflows as the Tuolumne River Watershed has already accumulated 200 percent of the average precipitation for this date. Officials added that snow sensors are recording a historic snowpack that will potentially unleash a million acre-feet of additional inflow into the reservoir after the arrival of warmer storms or weather in the coming months. Without this deviation, TID said that it could be forced to open a controlled spillway gate again this year.
At the time the spillway was closed, the reservoir was at 828.7 feet. As of 5:30 p.m. Tuesday, the reservoir was at 828 feet. Current releases to the Tuolumne River are approximately 10,100 cubic feet per second, a rate that TID is expected to continue to keep the river at 9th Street in Modesto below an elevation of 55 feet.
Following the spillway closure, Don Pedro Lake was reopened for recreational use; however, certain road closures, including Bonds Flat Road beyond Fleming Meadows and Blue Oaks campgrounds, remain in effect. For more information on lake operations, visit donpedrolake.com.
Earlier this week, TID was still working to restore specific power lines along the Tuolumne River that were de-energized on Feb. 20 in the interest of electrical safety. Officials have restored more than 900 services since they began work on the morning of Feb. 21, and less than 90 services remain without power. Those who had their property affected by these outages can check if they have been restored by calling TID’s customer service line at 883-8300. More information on the safety outages and the re-energization process is available at tid.org/RiverOutage.