It is implied in the passage that Minnesota farmers ----.

Formerly, potatoes were grown on unirrigated land,
which often meant they were small and probably
misshapen. Now, however, farmers routinely irrigate
their lands to produce products acceptable to the
fast-food industry for its French fries. But in
Minnesota the groundwater that farmers pump for
potatoes has turned out to be the same water that
helps to sustain the Straight River, a major trout
fishery. Even modest pumping for potatoes, a federal
study eventually concluded, had the potential to
reduce the river's flow by one third during the
irrigation season, with adverse impact on the brown
trout. For now, the trout are not in danger, but that
could change if Minnesota were to approve
applications from farmers still eager to see potato
planting and irrigation widen.