It's half way through the grueling ice road season. Six hundred truckers have ferried more than 4,000 loads to the northern mines. They still have 6,000 left to go, but everyday roadblocks threaten their progress. Going a few miles over the speed limit is one thing on a regular road, but on ice it's a different story. Blowouts are appearing in the ice as a result of reckless speeding. Other trucks come to a standstill when a fuel tanker overturns on the Ingraham Trail. The wreck not only blocks traffic, but it's a potential environmental disaster. Rescue crews race to prevent a diesel spill from contaminating the Yellowknife River, the only water supply for this entire outpost.