Great Lakes water levels expected to stay low

WASHINGTON — Water levels in the Great Lakes likely will rise over the next six months but will still remain critically low, scientists predict.

The lakes have experienced low levels for a record 14 years, disrupting shipping and recreational boating and possibly altering the biology of the entire Great Lakes watershed.

Keith Kompoltowicz, watershed hydrology branch chief for the U.S. Army Corps of Engineers in Detroit, said in a call with reporters that the Great Lakes will need “several years of very wet weather” combined with lower evaporation rates to return the region to normal.

The question, however, is what now constitutes normal. The fact that record low water levels have persisted for a longer period than ever before in recorded history has raised the question of whether these low levels represent a new norm for the Great Lakes.

“We simply don’t know,” said Drew Gronewold, a hydrologist at NOAA’s Great Lakes Environmental Research Laboratory. “We are going to continue to monitor and watch the system to try and understand it better.”

Gronewold pointed to unique changes in precipitation and evaporation as the main causes of the steep drop in water levels. Before a 1998 el Nino, water levels largely responded to long-term changes in precipitation because they were greater than changes in evaporation, he explained.

Scientists, however, began seeing gradual and persistent long-term increases in both evaporation and precipitation in the 1990s. Then suddenly in 1998 and 1999 evaporation accelerated well beyond precipitation and since then lake levels have dropped like a stone.