The disappearing #DoloresRiver — The #Durango Telegraph #ColoradoRiver #COriver #aridification

From The Durango Telegraph (Jonathan Romeo):

Where once a river ran, the Dolores River has all but disappeared in its lower reaches below McPhee Dam this summer, another causality of an intense drought that has gripped Southwest Colorado.

Striking images of dried up streambeds, tepid pools filled with suffocating algae and vegetation encroaching into the historic channel of the Dolores River has incited deep concerns over the ecological collapse of an entire waterway.

“It’s pretty devastating,” Jim White, an aquatic biologist for Colorado Parks and Wildlife, said. “It’s going to be a tough year for fish.”

Farmers and ranchers that rely on water from the reservoir, too, are also coming up on the losing end. This year, most irrigators are receiving just 5% to 10% of usual water shares, with valves expected to be shut off by the end of the month, an incredibly early end to the growing season sure to have economic fallouts.

“Absolutely, it’s the worst in the project history,” Ken Curtis, general manager of the Dolores Water Conservancy District, the agency that manages the dam, said of the situation on the Dolores River this year.

Completed in 1985, McPhee Dam bottlenecks the Dolores River in Southwest Colorado, just west of the town that bears its name. At the time, the project was sold as an insurance bank of water for both irrigators and the downstream fishery.

But in the years since, a crippling, 20-year drought has exposed intrinsic flaws within the management system put in place. And it all seems to have come to a head this summer after back-to-back poor water years, which has forced a reckoning among water users who rely on the strapped river…

Montezuma Tunnel entrance.

Montezuma Tunnel steel arches.

Montezuma Tunnel

Dam it

The Dolores River tumbles south out of the high country of the San Juan Mountains, and takes a sharp turn west near the town of Dolores before it heads more than 170 miles north to the Colorado River near Moab.

Near Dolores, the river skirts the edge of the Montezuma Valley, a different drainage basin where water is incredibly scarce. In the 1880s, Western settlers, looking to irrigate these arid fields, constructed a series of tunnels and large diversions to bring water over from the Dolores River.

This system, known as a transmountain diversion, brought a whole host of its own issues. Some years, flows were so erratic, that after spring runoff, agricultural needs reduced the Dolores River to a trickle. On top of concerns for the fishery below the dam, farmers and ranchers further out near Dove Creek also started to eye shares from the river. 4

So, by the mid-1900s, as was custom at the time, a dam was proposed. Much has been written and said about the concept of McPhee; even top-ranking Bureau of Reclamation officials have expressed on record the ill-advised nature of the water project in such an arid environment. Ranchers and farmers, however, came to hold water reserves in McPhee as an economic lifeline.

But, even a few years after completion, the dam started showing proverbially cracks in its plan after low-water years in the late 1980s…

“Deal with the devil”

McPhee’s first and foremost priority is to serve agriculture in the Montezuma Valley. Today, water out of the reservoir irrigates the fields of an estimated 1,500 farms, which range in size from small, three acre tracts to 1,000 acre operations.

Early on in the project’s management, however, low snowpack years in the mountains, which resulted in less available water supply coming into the dam, created tension among the competing interests for agricultural and the health of the river…

Ultimately, a “pool” of water was dedicated for releases out of the dam to support the fishery. But as the region increasingly dried out, shares have had to be reduced, and in some years the water sent down river has not provided enough habitat to sustain fish populations.

This summer, the fishery will receive just 5,000 acre feet of water, far below its 32,000 acre feet allotment. As a result, releases out of McPhee are expected to drop as low as 5 cubic feet per second, the lowest amount ever recorded (for reference, summer flows tend to be between 70 and 90 cfs).

Further downstream, the picture is even bleaker as water is lost to evaporation, sucked up by the soil and even in some cases used for irrigation. As of Wednesday, the stream gauge on the Dolores River at Bedrock, about 100 miles downstream of McPhee, was reading an inconceivable 0.45 cfs, virtually a nonexistent flow…

Short end of the stick

Thousands of fish are expected to die this year on the Dolores River.

For the first 10 miles or so downstream of McPhee Dam, the river boasts a robust trout fishery. Further on, as the river cuts toward the towns of Bedrock and Gateway, the waterway is home to many native fish, like the bluehead sucker and roundtail chub. Survival rates, as expected, are grim.

CPW’s White said that before the construction of the dam, spring runoff would replenish pools for fish to find refuge in. But that’s not the case in the post-dam world, and many fish will likely succumb to high water temperatures and the evaporation of pools in the hot summer months. And, conditions have set up perfectly for the invasive smallmouth bass to take over…

The Dolores River has been so changed and altered by the construction of McPhee Dam, and compounded by the effects of climate change, that it’s also prompted a multi-year study to understand the ecosystem’s new normal. Gigi Richard, director of the Four Corners Water Center at Fort Lewis College, said vegetation is now growing in the river bed, and the channel is losing the diversification of flow that support so many species…

Cutting off the tap

Explaining water rights is never an easy task for reporters with a word count.

But here we go: the Montezuma Valley Irrigation Co., formed in 1920 to consolidate the earliest water users, hold the most senior water rights. The next tiers in the pecking order are those served explicitly because of the construction of McPhee: farmers out near Dove Creek, the downstream fishery and the Ute Mountain Ute Tribe.

With McPhee receiving just a quarter of normal inflows from the Dolores this year, MVIC irrigators had their allocations slashed 50%, Curtis said. But that’s not the worst: all other users had their water supply cut to 5% to 10% from normal years, the worst project allocation in its history.

(The water supply for the towns of Cortez and Towaoc, which serves about 20,000 people, also comes from McPhee Reservoir and is expected to receive a sufficient amount this year.)…

Because of shortages, the Ute Mountain Ute Farm & Ranching Enterprise was forced to abandon most of its alfalfa, a profitable yet water-intensive crop, and focus on corn, less water dependent but also less valued…

Drying out

All predictions show no signs of the drought in the Southwest reversing course, so what’s to become of a reservoir like McPhee that increasingly doesn’t have enough water to meet its own demands? It’s a question managers at Lake Powell and Lake Mead, which also face record low levels, also are grappling with.

Curtis, for his part, said the water district is consumed with the emergency-response nature of this year’s drought. Montezuma County earlier this month declared a disaster emergency because of the lack of water, and funds are being sought to offset losses for farmers.

This fall, Curtis expects more serious, long-term conversations about the future of McPhee. Even further on the horizon, the dam’s Operating Agreement plan between DWCD and the Bureau of Rec expires in 2025, expected to reinvigorate the conversation. Still, Curtis doesn’t foresee any fundamental changes in the way the reservoir provides water to its customers.

“It’s not going to be fun, I can tell you that,” he said. “Fundamentally, the project didn’t anticipate this amount of shortages, so we’re having to think about what the longer-term implications are. I’m not authorized to make those decisions, no single party really is.”

By the end of the year, McPhee Reservoir is expected to drop to its lowest level since construction, at about 40% capacity. Most of that remaining water, Curtis said, is inaccessible because of topography issues.