Beaverhead River Suffers Pollution Event for Second Consecutive Summer
For the second summer in a row the Beaverhead River became markedly cloudy and its banks and back eddies were covered in intense algal blooms, including toxic blue-green algae above and below the dam. The Beaverhead remained off-color and unfishable into September and a Dillon resident reported culturing algae from his tap water. Fish, Wildlife and Parks (FWP) partnered with the Dept. of Environmental Quality (DEQ) to take a series of samples in Clark Canyon Reservoir, the headwaters of the Beaverhead, to determine what might be causing these conditions. 
On October 27, these agencies along with the Bureau of Reclamation (BOR) held a public meeting in Dillon to discuss their findings. Upper Missouri Waterkeeper attended, as we’re very interested in learning more about (a) what’s causing these blowouts and algal blooms, and (b) what can stakeholders do proactively to stop these pollution events in years to come.
FWP, DEQ, and BOR all concluded that suspended sediment and algae caused the clarity issue, but they do not yet fully understand what is going on in the reservoir to cause these blowouts and algal blooms two years in a row. Nor could they explain why the worst turbidity was observed only as far down as the Barrett’s bulkhead diversion dam above the city of Dillon.
Nutrient pollution
DEQ knows that there are unhealthy levels of nutrients like nitrogen, phosphorus, and sediment entering the reservoir from both Red Rocks Creek and Horse Prairie Creek, but cited funding constraints and difficulty prioritizing Montana’s impaired waterways that’s resulted in limited data collection. DEQ hopes to ramp up water quality monitoring in these feeder streams in the coming years.
The lake “turned over”
FWP biologists determined the bottom layer of the lake reached levels of zero oxygen (anoxic zones) for at least a few weeks this summer, causing internal loading of phosphorous (a chemical reaction on the reservoir’s bottom). They also know that the reservoir’s temperature layers inverted, or destratisfied two years in a row. Without oxygen a lake’s self-purification capability is not only reduced, it is reversed. The zooplankton which help keep a lake clean cannot live, and the lake’s nutrients are then recycled from the sediment. This forms a layer of muck at the bottom, which serves as a fertilizer for weed and excessive algae growth. When this stuff is flushed out downstream, it causes the algal blooms and blowouts that made a section of the Beaverhead un-usable for about two months. This “turnover” event hadn’t occurred in the Clark Canyon Reservoir until 2014, though it has happened much more frequently in the Ruby Reservoir. 
The dam has reached its shelf-life
An engineer hired by DEQ to look into sedimentation issues on the upstream side of the dam concluded the dam has reached its lifespan after nineteen years of collecting sediment against the dam and beneath the outflow pipe. The dam was constructed with a “dead pool” immediately in front of the dam and several feet below the outflow pipe, but over time it has filled with muck and currently, sediment levels are at or near the outflow pipe into the Beaverhead River.
As a result of these conditions, the Bureau of Reclamation has rescheduled a planned survey of Canyon Ferry Dam on the Missouri River and will survey the Clark Canyon Dam in 2016.
What does this mean for the fishery?
FWP will not have any data on what this y
ear’s pollution event means for the fishery until they are able to conduct counts next spring. Anecdotally, guides and outfitters have contacted Upper Missouri Waterkeeper complaining that insect hatches were noticeably scarce and algae levels were higher than normal this season, even below Barrett’s Diversion.
Clark Canyon Hydroelectric Facility?
Though it was not discussed or mentioned in the meeting, a bit of digging back at the Upper Missouri Waterkeeper office turned up a pending permit submitted by Clark Canyon Hydro, LLC to change the use of Clark Canyon Dam to a hydroelectric facility. This proposed dramatic change in operation of the dam involves the installation of two new turbines to the existing dam. This change in use raises several concerns for downstream fisheries health given the risks associated with operation of hydroelectric facilities (e.g., high temperature discharges, high nutrient and sediment loading, low DO levels, etc). These types of potential issues can dramatically affect downstream water quality and fisheries health.
We will continue to watchdog the proposed hydroelectric permit and intend to intervene in the Federal Energy Regulatory Commission (FERC) licensing process to ensure any final permit contains necessary terms that protect your rights to clean, fishable, swimmable, boatable water. Stay tuned for more info here as we keep track of this proposal.
Get involved
DEQ and FWP are asking for public comment regarding project & sample planning development for the Clark Canyon Reservoir. If you have comments, contact us and we’ll help get you in touch with the agencies. Likewise, the agencies will have another meeting in Dillon next spring; meantime, if you’ve seen impacts on the Beaverhead around Clark Canyon dam, or have other concerns about these algal blooms, blowouts, or the proposed hydroelectric facility, please contact us at Wade@UpperMissouriWaterkeeper.org !
Click here to view FWP’s powerpoint presentation on water quality impairment in the Beaverhead.
Click here to view DEQ’s powerpoint presentation on nutrient loading in Clark Canyon reservoir and downstream effects.