A bucket of dead fish collected from a massive die off at St. Vrain State Park near Longmont. According to Colorado Parks and Wildlife, the fish died from a lack of oxygen in the water. This story was first published at KUNC news. DENVER | Rangers at St. Vrain State Park estimate 30,000 fish perished in a die-off earlier this month at Sandpiper Pond. About a quarter of the fish were cleaned up and the rest were left for wildlife. The number of d…