The environmental group says improved dam management is needed to better support long-term ecological and recreational values on the river.
“We recognize there has been some recent local action to improve conditions below the dam, but there is room for improvement,” said Kristin Green, a water advocate for Conservation Colorado.
The Dolores was graded on flow, water quality, water diverted out of basin and major dams.
“Based on flow data from the last 10 years, McPhee Dam has reduced the rivers flows by 50 percent,” resulting in an F, the report said.
Water quality received a D because the reduced flows have resulted in dramatic increases in water temperature and increases in silt and sediment, both of which threaten native fish.
According to the report, the river received a low grade because nearly two-thirds of its water has been diverted every year, “which is incredibly unsustainable if we aim to conserve this river for the future.”
Among major dams, the river got a C because river flow has been “severely impaired” and “management of McPhee Dam is a critical component to the viability of the lower Dolores River.”
The report concludes that “overall, the Dolores River is in poor condition below McPhee Dam, but it is in no way a lost cause.”
Green said the wide-ranging solutions to improve conditions include conservation by water users, voluntary leasing of water for downstream benefits and adjusting water law’s “use it or lose it” so water-right holders are not penalized for conserving water.
“The grade is not meant to suggest nothing positive has happened, but it shows how much the river has been altered from its historic natural state due to the dam,” Green said.
In response to the low grade, Mike Preston, general manager for the Dolores Water Conservation District, which manages the dam, explained that in the past 10 years, there has been a sustained effort by a diverse group of stakeholders to improve ecological and recreational aspects of the lower Dolores.
“There has been considerable work and collaboration on this,” he said.
For example, a monitoring team studied ideal flow rates for the river and implemented them whenever a dam release was possible.
This year, there was a large and extended release below the dam that peaked at 4,000 cubic feet per second and flushed sediments, scoured channels and distributed seeds. This month, pulse releases from a reserved fish pool were triggered to flush non-native and predatory smallmouth bass off their nests to reduce populations in favor of native fish.
Preston said dam managers have worked more closely with boaters to accommodate their needs and preferred flow levels. To further fine-tune downstream management, teams descended on the river this year to study the effects of the high flows.
“There were more ecological and recreational studies done on the lower Dolores this year than ever before,” Preston said.
Water conservation by all water users is one solution that helps improve flows below the dam. Preston said that when farmers use less water to produce the same amount of crops, more water stays in the reservoir contributing to carryover storage the next year.
“Carryover storage year to year benefits everyone, including agricultural users, the downstream fishery and boaters,” he said.
To increase conservation, the district promotes cost-sharing programs for farmers to switch from side roll sprinklers to the more efficient center-pivot sprinklers.
“In the past, we did not have set objectives for when there is a spill, but now we have an adaptive management strategy ready to go that benefits boaters and ecological values,” he said.
More collaboration with groups with differing opinions on best use of water has improved the outlook and possibilities for the lower Dolores, Preston and Green said.
McPhee managers also have worked more closely with Colorado Parks and Wildlife, the Dolores River Boating Advocates, American Whitewater and The Nature Conservancy.
“There has been better cooperation, and that is a huge step in the right direction,” Green said. “Taking action on conservation solutions is important because if we don’t do anything, we risk a remarkable river that is already threatened by increasing demands and climate change.”
In response to the report, Sam Carter, of the Dolores River Boating Advocates, said there is no question that the Dolores River is challenged, but it is not due to poor reservoir operations.
“The problem is not dam management, there is simply not enough water for today’s competing interests,” he said. “It is extremely important to acknowledge that a lot of great collaborative work has been done at the local level.”
He said boating groups are dedicated to respecting water-right holders and are working with a diversity of stakeholders to find solutions for the lower Dolores.
“This year is a great example of the progress that has been made. We worked to together to ensure McPhee allocations were met, while providing a great boating season and accomplishing important ecological goals. Local conversations about a possible National Conservation Area for the Lower Dolores are still underway.”
The other Colorado rivers that were graded were the Arkansas (C), the Colorado River (D), the North Fork of the Gunnison River (B-), North Platte River (B+), Rio Grande River (B), South Platte River (C), and Yampa River (A). To see the report, go to conservationco.org