SECTION 1. Section 2 of Chapter 21G shall be amended to strike the definition of safe yield in its entirety and replace with the following: -

''Safe yield'', the maximum dependable withdrawals that can be made continuously from a water source including ground or surface water annually without depleting the source beyond its ability to be replenished naturally. Provided, however, that such dependability is a function of storage and drought probability.

SECTION 2. Chapter 21G shall be amended to add the following: -

The Department of Environmental Protection (DEP) shall re-calculate safe yield for each basin in Massachusetts, based on seasonal supply in the summer months, and taking into account the existence of reservoir storage, or lack thereof. Safe Yield shall be recalculated at a frequency as determined by DEP, but no longer than every 10 years.

SECTION 3. Chapter 21G shall be amended to add the following: -

The Department of Environmental Protection (DEP) shall calculate safe yield for each of the sub-basins in Massachusetts and take into account withdrawals on the sub basin scale when issuing permits. Stream Flow calculated by USGS shall be used in this analysis.