In the winter of 1968, a pollution-fed algal bloom on Lake Minnetonka turned the water bright red, causing consternation to people who lived nearby and giving rise to a freshwater biological institute that would have a lasting influence on environmental research in Minnesota.

The institute's co-founder, Dick Gray, died last week at 95 after five decades of environmental study, writing and activism.

Gray co-founded the Freshwater Society in Navarre by raising $4 million and building a state-of-the-art research lab that was donated to the University of Minnesota. His son, Jim Gray, said the project was inspired when his father drilled into Lake Minnetonka's ice for one of his frequent, home-laboratory water clarity checks. The gush of red water wasn't readily explained by area scientists at the time.

"He had an insatiable curiosity and was always entrepreneurial," said Tom Skramstad, a longtime friend and past chairman of the Freshwater Society. "He's created a legacy here that hopefully will last forever."

For 20 years the Gray Freshwater Biological Institute conducted research, published reports and trained more than 45 doctoral students before the U returned the laboratory to the nonprofit Freshwater Society, which continues to influence environmental policymakers. Gray was active on the society's board until shortly before his death from an aggressive brain tumor.

"Every day, all day, he was on the go," said Skramstad.

Richard G. Gray attended Dartmouth College and graduated from the U in 1940 with a degree in petroleum geology, then served as a naval officer on a troop carrier during World War II.

In the late 1940s, '50s and early '60s, Gray's family would summer in a cabin on Lake Minnetonka that he later turned into a year-round home.

Jim Gray and Skramstad said Dick Gray dedicated much of his life to various natural science interests after making millions on the sale of manufacturing companies he had built. He also was president for a time of the IDS investment company in Minneapolis before its sale to American Express.

Gray's other interests included archaeology and astronomy, and he was a longtime supporter of the Wolf Ridge Environmental Learning Center and the Science Museum of Minnesota. Friends also remember him as an avid tennis player who enjoyed the game into his 80s.

Gray's close attention to the water quality on Lake Minnetonka made him the pre-eminent authority on the lake's ice-out date — a declaration that has only recently been taken over by the Hennepin County Water Patrol.

Gray wrote regular columns for the Sun Newspapers — explaining rainbows, northern lights, fireflies and other complex natural phenomena in layman's language — that were collected for two books. He also helped to produce the popular Minnesota Weatherguide Environment Calendar.

A celebration of Gray's life is scheduled for April 19 at 1 p.m. at the Gray Freshwater Center in Navarre.

He is survived by his partner, 100-year-old Marion Downs of Wayzata, a renowned audiologist; sister Marjorie Gray Vogel, 102, of Red Wing, Minn.; sons Richard Jr. of Thailand, Jim of Lake Minnetonka and Steve of Minneapolis; six grandchildren, and five great-grandchildren. Gray was preceded in death by his wife, Kathryn Simmons Gray, and his subsequent partner, Molly Simmons.

Tony Kennedy • 612-673-4213