Imperial Oil's Cold Lake asset is the largest in situ oil sands recovery operation in Canada and among the country's largest sources of crude oil production. In 2001, 65,400 m(3) of water in the form of steam was injected into the ground each day, producing 20,300 m(3) of bitumen. The bulk of the water (95%) is recycled and used for steam generation. As of the end of 2001, total proved reserves before government royalties were about 147 million m(3). Through extensive research and piloting activity over a period of twenty years, Imperial developed the "cyclic steam stimulation" (CSS) process for commercial recovery of bitumen from its Cold Lake asset. Production has grown steadily from under 1,000 m(3) per day in the mid-1970s to over 20,000 m(3) per day in 2001. To date, the CSS process has been used to recover almost 100 million m(3) of bitumen from the Cold Lake asset. Cumulative capital expenditure at Cold Lake is approximately CDN$2.3 billion through year-end 2001.