Assays exceeding 1 ounce of gold per ton have been obtained from three of these areas, and selected quartz-arsenopyrite vein material from one prospect assayed about of gold per ton. A bucketline dredge was constructed in Cache Creek in the 1920s, and used locally-abundant coal to fire the boilers. Later, a hydroelectric plant was used to run the dredge. The dredge mined the entire valley of Cache Creek as far as the mouth of Nugget Creek, then bulldozers mined what remained. Hydraulic mining was also widely used before 1942, and many ditches can be found all over the Dutch Hills today. About 115,000 ounces of placer gold was reported to have been produced from Cache Creek. An active placer mine operated in 1998-1999. The first reported mining in what was to become The Blue Ribbon Mine took place in 1906. Except for some stretches when no mining took place, some gold has probably been recovered every year since. The total amount recovered is unknown, but at least have been reported recovered, mostly by small-scale hand or mechanized methods. The placer mine continues operating today, and the company is actively exploring lode deposits. Harry Frost  Henry Frost (August 17, 1914 – March 28, 1973) was a Canadian professional ice hockey forward who played three games in the National Hockey League for the Boston Bruins, including one in playoffs for Stanley Cup winning Boston Bruins in 1939. Boston honoured him by putting his name on the Stanley Cup. He was born in Kerr Lake, Ontario. Challenge–dechallenge–rechallenge  Challenge–dechallenge–rechallenge (CDR) is a medical testing protocol in which a medicine or drug is administered, withdrawn, then re-administered, while being monitored for adverse effects at each stage. The protocol is used when statistical testing is inappropriate due to an idiosyncratic reaction by a specific individual, or a lack of sufficient test subjects and unit of analysis is the individual. During the dechallenge (withdrawal) phase, the medication is allowed to wash out of the system in order to determine what effect the medication is having on an individual. CDR is one means of establishing the validity and benefits of medication in treating specific conditions as well as any adverse drug reactions. The Food and Drug Administration of the United States lists positive dechallenge reactions (an adverse event which disappears on withdrawal of the medication) as well as negative (an adverse event which continues after withdrawal), as well as positive rechallenge (symptoms re-occurring on re-administration) and negative rechallenge (failure of a symptom to re-occur after re-administration).