How do we know?

Triplett and Edlund
SMM researchers Mark Edlund and Laura Triplett remove a sample from the river bottom. The mud contains a record of river conditions going back hundreds of years. (Photo courtesy Dan Engstrom, courtesy SCWRS)

A lot of people watch the river flow

Over the past 25 years, several different studies have examined conditions in the St. Croix River:

  • Researchers from the Science Museum of Minnesota took sediment samples from the bottom of Lake St. Croix. These samples, dating back to 1850, show how the river has changed over time.
  • The Minnesota Pollution Control Agency and the Metropolitan Council of the Twin Cities have regularly monitored the water since the 1960s. This data gives us a very detailed picture of river conditions and how they are changing over time.
  • Citizen volunteers have monitored water quality and interviewed recreational users. Most people still find the river in excellent condition—meaning it's not too late to save it.
  • The US Geologic Survey took water samples from major tributaries to find out which areas contributed the most phosphorus to the St. Croix.
  • The Science Museum also hit the books, compiling historical data on population, industry, technology, etc., and matching that against the other findings to understand why the river changed when it did.
  • The USGS took the info from the various surveys and plugged it into computer simulations, to see how the river might change in the future if phosphorus increased, decreased, or stayed the same.