McPhee Reservoir has strong carryover supply going into the 2020 irrigation season, and even below-average winter snowfall will refill it, officials say.
This winter’s above-average snowpack lingered into July and easily filled the 380,000 acre-foot capacity reservoir on the Dolores River. Farmers, including the Ute Mountain Ute Farm and Ranch, received full allocations.
The water supply, 140% of average, exceeded capacity by 134,683 acre-feet, allowing for a 51-day whitewater boating release on the Dolores River below McPhee from May into July.
By the end of October, the reservoir’s active supply will be at 140,000 acre-feet, said Ken Curtis, general manager for the Dolores Water Conservancy District.
That’s just 90,000 acre-feet below full active supply of 230,000 acre-feet.
An average winter brings in 300,000 acre-feet of inflow from the Dolores River, so there might be a full supply next year, Curtis said, and even a whitewater boating spill.
“Anything near average this winter will fill the reservoir and have some to spill,” he said. “We are in good shape.”
The 32,500 acre-foot fish pool stored in the reservoir also benefited from the above-average winter snowpack. The reserve is managed by Colorado Parks and Wildlife throughout the year for minimum downstream releases to benefit native fish and sport trout habitat.
When there is a managed whitewater boating spill, the fish pool reserve in the reservoir stays constant, allowing biologists to save water and increase minimum flows later.
As a result, flows below the dam are 50 cubic feet per second, when they are usually at 40 cfs. After October and through the winter, flows below the dam will drop to 40 cfs, at a time when they are usually 25 to 30 cfs.
The higher minimum flows will help fish over the winter by keeping water temperatures constant, reducing ice buildup and creating deeper pools.
McPhee recreationClosing day for the McPhee boat ramp and inspection stations is Oct. 31. The House Creek boat ramp closed last week. To prevent invasive mussels, motorized and trailered boats are allowed on the lake only when the boat ramps and inspection stations are open.
Access to the lake after Oct. 31 is limited to non-motorized, hand-launched boats, such as kayaks, paddleboards, rafts and canoes. Boat users should always drain, dry and clean boats before and after use in any waterway to prevent potential mussel contamination.
This season, McPhee had 7,893 boat inspections, according to Colorado Parks and Wildlife. Of those, 306 boats were decontaminated.
Most decontaminations are a result of standing water in the boat that comes from positive or unknown locations. This standing water has potential to transport invasive microscopic aquatic organisms.
At McPhee, two boats with mussels were intercepted; statewide, 82 were intercepted.
McPhee concerns CPW because of its proximity to Lake Powell, which is infested with the invasive zebra mussel, which causes extensive damage to irrigation infrastructure.
Concerned boat owners may contact CPW for an inspection.
In this area, the best place to call would be Navajo State Park, which can do an inspection and decontamination. The phone number is (970) 883-2208.