Modeling in future for Flathead Lake

The bad news about Flathead Lake is that 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.

“The good news is that the decline in dissolved oxygen at the bottom of the lake isn’t getting any worse,” Flathead Lake Biological Station director Jack Stanford reported in his annual State of the Lake report at the Flathead Lakers’ annual meeting.

Nitrogen, a nutrient that contributes to algae growth, is increasing, Stanford said, but the increased nitrogen means that algae growth is now being limited by the amount of phosphorus coming into the lake.

Data on Flathead Lake that the Biological Station has gathered over decades of monitoring and research is being used to build a model “unlike anywhere else,” Stanford said. The model will demonstrate nutrient dynamics in the lake.

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

Wind pushes less dense water at the surface, allowing colder water to take its place, Stanford explained. A strong wind can pile up warm water on one side of the lake, causing dramatic temperature changes that can affect organisms living in the water.

With the Biological Station’s long-term database and sophisticated computer power, it is now possible to develop and use a model to really understand the story of the lake, Stanford said. Testing so far shows an excellent correlation between hydrologic and temperature modeling results and actual data.

The model will provide good information to help answer questions such as “What happens if you remove lake trout?” or “What happens if water temperature increases?”

Stanford said he hopes to have the full model in use by next year. He encourages the public to attend the 2015 Flathead Lakers meeting to see the model results and learn what it says about Flathead Lake and its future.

Stanford also discussed the threat of oil spills from railroad tank cars along the Middle Fork Flathead River. He said there are more tank cars of oil traveling through the watershed than ever before, and local emergency responders are not prepared for a derailment and spill.

Highly explosive Bakken oil is not the only oil product being transported —dilbit, or diluted bitumen, is also aboard the trains. Benzene and other chemicals are added to lower the viscosity of the thick bitumen mined from the Canadian tar sands.

If a train derailment led to a spill, Stanford said, part of the dilbit would volatilize into the atmosphere and part of it would end up in the water, including the groundwater aquifer system.

He called for a dye test to be conducted to see how fast oil or dilbit could travel downstream and where it would accumulate to help local personnel prepare for an accident that seems inevitable.

“If one of those big trains goes into the Middle Fork, we will regret it for a long time,” he said. “Our well-being is closely tied to Flathead Lake’s clean, clear water. Thanks to people concerned about the lake, like all of you, we can keep it that way for future generations.”