Flathead Lake modeling effort intensifying

Primary productivity in Flathead Lake has climbed above its target level, according to Flathead Lake Biological Station Director Jack Stanford.

Stanford delivered his annual State of the Lake report to a gathering of the Flathead Lakers on July 15. 

Primary productivity, or the lake’s ability to grow algae, climbed back above 100 grams of carbon per square meter per year in 2012, exceeding the water quality target of 80.  That was the bad news, Stanford said.

“The good news is that the decline in dissolved oxygen at the bottom of the lake isn’t getting any worse,” Stanford said.

Nitrogen, a nutrient that contributes to algae growth, is increasing. The increased nitrogen makes the amount of phosphorus lower on a relative basis, which results in algae growth being limited by the amount of phosphorus coming into the lake.

“This is just one indication of how complex this lake is,” Stanford said.

The information the Biological Station has gathered from decades of monitoring and research on the lake is being used to build a model unlike anywhere else, Stanford said. The model will demonstrate nutrient dynamics in the lake.  

Researchers have already learned from modeling that one of the most fundamental things affecting the lake is wind. Two fundamental facts, Stanford said, are that the lake is getting warmer and the wind is blowing more intensely than it used to.

Stanford showed a video of results for the change in lake temperature throughout the water column as wind direction and speed change. The wind pushes the less dense water at the surface, allowing colder water to take its place. A strong wind can pile up warm water on one side of the lake, causing dramatic temperature changes that can affect the organisms living in the water.

Now, Stanford said, with the station’s long-term database and sophisticated computer power, it is possible to use a model to understand the lake. The model will provide information to help answer questions such as what happens if you remove lake trout or what happens if water temperature increases.

“The biostation is poised to really do some great things over the year,” he said.

Stanford also discussed the threat of oil spills from railroad tank cars along the Middle Fork Flathead River.

Invasive species are also an issue for Flathead Lake.

Changing the behavior of boaters is the single most effective strategy for preventing introductions of zebra and quagga mussels and other aquatic invasive species, according to Kate Wilson of the Alberta Aquatic Invasive Species Coordinator Kate Wilson, who gave the keynote presentation to the Lakers.

Preventing transport of aquatic invasive species from areas where they have established to new areas is critical. Boats are the primary way zebra and quagga mussels are moved. That means boaters can play a big role in preventing new introductions by remembering to clean, drain and dry their boats every time they take it out of the water.

Zebra and quagga mussels aren’t the only aquatic invasive species that threaten both Alberta and Montana. Fish such as the Asian carp and round gobi, plants such as Eurasian watermilfoil and hydrilla and crustaceans such as the rusty crayfish could all wreak havoc on local waters if introduced, Wilson said.

 The biological station is sponsoring a free open house on Tuesday, Aug. 5, from 1 to 5 p.m.

Stanford will give a presentation on “Threats to the Integrity of the Crown of the Continent Ecosystem” at 3:15 p.m.

Research boat tours will depart at 1:05, 1:50, 2:35, and 4:05 p.m. Guided nature walks will take place at 2:40 and 4:10 p.m.