Predicting aquatic plant growth in the St. Louis River Estuary

By June Kallestad

There’s a place in the Duluth-Superior St. Louis River Estuary some call “Coffee Ground Flats” because the bottom of this aquatic ecosystem is covered with a deep layer of century old dark brown wood chips. In the 1800s, thriving sawmill owners used the estuary as a convenient place to dispose of wood waste.

Today’s effort is to reverse the damage from that and other past industrial practices that have made some areas of the estuary unsuitable for marine life. NRRI is putting their computer modeling talents to work to help the cause. Funded by the U.S. Fish and Wildlife Service, NRRI scientists are generating simulation models to predict where aquatic vegetation will regrow if certain restoration practices – like islands or artificial reefs – are applied.

If the plants come back, so will the bugs and the fish and the birds… the goal is to develop an ‘ecological design’ for restoration after the sediments have been cleaned up.

NRRI researchers have collected data at former industrial sites at 21st and 40th Avenues West in Duluth. Their survey includes plants, bugs and birds currently living there, as well as the area’s underwater topography and wave energy. A variety of computer simulated islands will be modeled to predict if large scale engineering in the so-called “area of concern” will help break up the wave action and allow more wetland and other aquatic plants to grow.

“This will give the planners an idea of what to expect under different restoration scenarios,” George Host, NRRI GIS Lab Director, explained. “It adds solid science to the decision making process.”

St. Louis EstuaryWood and sawdust debris at the bottom of 
the bay create unfavorable habitat for fish 
and other wildlife.