On September 28, 1994, the SWRCB issued the landmark Decision 1631 (D-1631) amending LADWP's water diversion licenses in the Mono Basin. The purpose of the Water Board's decision was twofold: to comply with Fish and Game Codes 5937 & 5946, and to protect public trust values at Mono Lake as ordered by the California Supreme Court in 1983. D-1631 calls for a lake level of 6,392 feet, which will take about 20 years to achieve. During this period, some diversions will be allowed to Los Angeles. Once the lake reaches 6,392 feet, LADWP will be able to divert an average of 31,000 acre-feet of water, or about 1/3 of Los Angeles' historical diversion from the Mono Basin. The difference will be more than made up for by replacement water supplies. D-1631 orders LADWP to develop plans to restore waterfowl and stream habitat damaged as a result of diversions, and to pay implementation costs associated with the restoration.