A request to create additional space in Don Pedro Reservoir during what officials are calling the Tuolumne River Watershed’s wettest year in recorded history was denied Friday, according to the Turlock Irrigation District.
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. Based on current weather forecasts and inflows, TID said Thursday that this process would have taken anywhere from eight to 10 days.
“TID would rather continue flows at this current level and lower the reservoir as much as possible as opposed to having to close spillway gates immediately and then risk a higher chance of opening them repeatedly over the next few weeks and months,” said TID Incident Commander Jason Hicks on Tuesday.
A decision to open one of three controlled spillway gates at Don Pedro Reservoir was made in conjunction with USACE on Monday before the reservoir reached its maximum capacity of 830 feet. As of 4 p.m. Friday, the reservoir was at 829 feet.
TID must now determine when it will need to close the controlled spillway gate according to USACE regulations. Based on the current inflow of approximately 14,500 cfs into Don Pedro, the gate will close in the next two to three days.
TID said that the deviation that was requested 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.
TID said that it gathered support regarding the deviation from stakeholders along the Tuolumne River, citing that more than 15 affected local public agencies, governing bodies, elected officials and businesses backed up the request.
“Many downstream stakeholders would rather maintain the Tuolumne River and San Joaquin River at their current inflow rates and elevations for an acceptable period of time, rather than see flows and elevation drop significantly only to watch them rise to historic levels later this year due to historic rainfall and snowpack runoff,” said TID in a released statement.