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Lower Dolores D-minus: Low flows hamper native fish, trout

Native fish on the Lower Dolores River use deep pools like this one to seek refuge during drought.

Conservation Colorado’s grade of D-minus for the Lower Dolores River must be put into context.

Conservation Colorado is an environmental organization, and the score is not based on how well the Dolores Water Conservancy District, which manages McPhee Dam, is serving the consumptive water users who are its primary constituents.

Those users are served well by the policy of storing as much water as possible in the reservoir through the winter, or at least until a fairly good assessment can be made of the snowpack that will feed the next year’s runoff.

Rafters also were served well this year by two stints of high flows. Mike Preston, general manager for the DWCD, includes rafters among the stakeholders who are working to improve the ecological and recreational aspects of the Lower Dolores.

The organization is right, though, in pointing out the low flows below the dam have been harmful to both native fish in the warm water stretches of the river that begin below Bradfield Bridge, and in the trout fishery between Bradfield and the dam. Fish benefit from conditions that mimic unrestricted streamflows: high water during the runoff season and much less the rest of the year, although “less” is a relative term.

In recent years. low flows have been too low. For both of those fish populations, a few cubic feet per second can make a difference in the temperature and oxygen content of the water and can help keep the river clean.

Native fish have few advocates, other than wildlife managers, lovers of desert ecosystems and environmental groups like Conservation Colorado.

Trout do have fans, and when the dam was first constructed, anglers had hopes that a healthy trout fishery would be sustainable below the dam. Fishing is a popular activity above Bradfield Bridge, and guides, mostly from Telluride and Durango, earn big money on that stretch of water.

How anglers’ local expenditures compares to rafters’ is a fair question for which insufficient data exists, and that might not be the right question to ask anyway.

There is not enough water for everyone to have all they want and the DWCD is always going to want to save as much water for next year as possible, because there are years when runoff is insufficient to meet water rights. Conservation will always be important even, and especially, in years when there’s no spill for rafters or fish or anything else.

Could an additional solution be a different balance of interests – maybe a slightly lower but still raftable flow for a slightly shorter time – provide enough water to improve conditions for fish when they need it, during the years when a spill is possible?

Let’s give DWCD credit for collaborating and continuing their work to broaden those efforts.

Oct 12, 2017
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