Reflecting on a 35-year career at the Flathead Lake Biological Station, Director Jack Stanford gave his last annual State of the Lake address to the Flathead Lakers last week.

“The thing that stunned me when I drove up the east shore all those years ago was the clarity of the water in the lake,” he said. “And it still stuns me.”

Since that drive, Flathead Lake has undergone some major changes, with Stanford and dozens of scientists and students documenting them.

Arguably the biggest change came in 1986 and 1987, when mysis shrimp, introduced decades before in upstream water bodies, found their way down to the lake and forever altered the food chain.

The shrimp population exploded as the tiny crustaceans feasted on the abundance of zooplankton in Flathead Lake. But with the resultant decrease in zooplankton came an increase in their primary source of food: algae.

Water scientists at the station estimated the lake became about 30 percent greener during that time. And while the lake is still renowned for its world-class water quality, Stanford repeatedly pointed to phosporus as the major threat to further increases in the lake’s algae presence.

Algae requires a fixed ratio of nitrogen and phosphorus for production. While outside sources such as wildfire smoke have helped to raise nitrogen levels (called “nutrient loading”) in Flathead Lake over the years, the lion’s share of that trend aligns with development in the watershed, with more fertilizer runoff and nitrogen compounds from auto traffic.

Despite that increase in nitrogen, though, the amount of phosphorus entering the water has remained relatively stable over the years and even decreased slightly, Stanford said. That makes phosphorus — which can come from fertilizers, manure, sewage and industrial sources — a limiting factor for the greening of Flathead Lake, since the algae won’t be able to take advantage of the increased nitrogen without a corresponding increase in phosphorus.

“If you give them phosphorus, it’s going to get green out there,” he said. “The story in Flathead Lake is very much about phosphorus, because nitrogen is very much increasing.”

Stanford also reiterated his concerns about the BNSF rail line that operates along the Middle Fork of Flathead River — transporting an estimated 40 million gallons of oil from the Bakken each week, along with other potential contaminants.

“If five or ten of these [rail cars] went off and spilled into the Middle Fork, the disaster would be of such a magnitude that they would probably have to close the Bakken field down, if that’s the only way to transport this stuff,” Stanford warned. “It’s going to go into solution, into the water, into the groundwater, and it isn’t going to come out for years.”

Despite his concerns, Stanford noted that the railroad has been starting the process of emergency planning for such a derailment and has been receptive to some of his concerns. He said testing needs to determine how a spill would move through the river and underlying groundwater, and the company needs to identify where the most vulnerable stretches of train line are, such as the banks most prone to flooding and erosion.

Stanford closed his final address by thanking the Flathead Lakers and others who have advocated for water quality protection over the years.

“It’s largely because of proactive intervention on things that could have changed that ... and also because people before had enough foresight to set aside Glacier National Park, the Bob Marshall Wilderness and additional wild protection,” he said. “Advocacy is critical here, and the Lakers have been at the forefront that that throughout my career.”

Stanford, who won’t officially leave his post until next summer, has worked at the biological station since 1981.

His successor Jim Elser starts work on Dec. 1.

Reporter Samuel Wilson can be reached at 758-4407 or by email at swilson@dailyinterlake.com.