Recognition of Normal Variation for Existing Withdrawals

(1) At the time when initial permit applications were due to be filed for a water source, any person who had an accepted registration statement for an existing withdrawal was able to request that the registration statement be amended to include an amount of water which the Department determined to be within the normal variation of the average volume withdrawn between January 1, 1981 and December 31, 1985. (2) For registrants with groundwater withdrawals, the Department did not recognize as an existing withdrawal any volume in excess of one standard deviation of the average existing withdrawal volume for which a registration statement was accepted by the Department. (3) For registrants who withdraw surface water from more than one water source, the Department recognized as an existing withdrawal a volume not to exceed 2.5 times the standard deviation of the average existing withdrawal volume for each water source for which a registration statement was accepted by the Department, provided that no recognition of such normal variation authorized withdrawals in any year of a volume in excess of the sum of the existing withdrawal volumes from all of the registrant's water sources for which registration statements were accepted by the Department. For the purpose of 310 CMR 36.36, standard deviation of the average existing withdrawal volume is defined as the unbiased estimate derived from the sample of five annual volumes of the registered withdrawal.