Legal Summary of Safe Yield and the Court Decisions

Safe Yield Under the Water Management Act

Safe yield definition, G.L. c. 21G, § 2:
“the maximum dependable withdrawals that can be made continuously from a water source, including ground or surface water, during a period of years in which the probable driest period or periods of greatest water deficiency is likely to occur, provided, however, that such dependability is relative and is a function of storage and drought probability.

Hamilton v. DEP et al, Dkt. Nos. 2006-745 and 1080 (consolidated) (Fahey, J.) Decision on Motions for Judgment on the Pleadings (July 13, 2007):

Concept of “safe yield” in the Water Management Act is fundamental to management of water source;

-safe yield takes into account natural variability of streamflow; and
-safe yield is the principal regulatory basis for determining water withdrawals in a basin;

Permits must be conditioned so that the safe yield is not exceeded;
DEP no longer believes its safe yield determination of the Ipswich River done 15 years ago is accurate; and
DEP must re-determine the safe yield of the Ipswich River “as soon as reasonably possible.”

MassDEP on Safe Yield:

“MassDEP clarifies and explains that its interpretation of the term safe yield under the Water Management Act includes environmental protection factors, including ecological health of river systems, as well as hydrologic factors.”
MassDEP Statement of Clarification of Safe Yield, November 3, 2009

“The statute establishes safe yield as the maximum amount of water that may be withdrawn under registrations and permits, which assumes some reserved amount to ensure the security of the withdrawal volumes and to preserve the resource itself. A safe yield determination normally precedes the permit proceedings; the ‘balancing’ of factors taken into account in the issuance of permits is not part of determining safe yield.”
(DEP Commissioner Robert Golledge, Final Decision in WMA appeals by the Towns of Wenham, Topsfield and Hamilton, March 31, 2006)(emphasis added).

[T]he original regulatory definition of ‘safe yield,’ which is more narrow than the definition of this term in the Act, no longer sufficiently comports with the most current and protective technical basis for determining safe yield. The concept of safe yield is fundamental to the proper management of a water source, taking into account the natural variability of streamflow, and serves as the principal regulatory basis for determining the scope of the permitted water withdrawals in a water source . . . (Preface to 2005 Revisions to 310 CMR 36.00)(emphasis added).

The concept of safe yield is the principal basis for controlling withdrawals permitted under the WMA. Safe yield is “the volume of water that can be removed from surface and groundwater without unreasonable damage to the water resource.” (MassDEP 2004 WMA policy)

“We will use the information and studies that have recently been developed in re-determining the safe yield of the Ipswich River Basin and to ensure that the purposes of the Water Management Act, including protection of the water resource itself, are being met.” (DEP Commissioner Liss letter dated December, 2002)

U.S. Geological Survey on sustainable yield:
USGS is developing a Sustainable Yield Estimator for DEP and defines Sustainable Yield as “the maximum withdrawal amount that does not result in less than a specified minimum streamflow over a period of time at a particular location in a basin.”

IRWA on safe yield:
“Safe yield is the limit on the amount of water that DEP has the authority to allocate to ensure that the individual and cumulative withdrawals from a water source are ‘dependable’ or ‘sustainable’ even during an extreme drought. This is determined based on the amount of streamflow that is available during a severe drought, minus the amount that must remain in the river to support instream interests.” (Ipswich River Watershed Association, Hamilton v. DEP et al, Memorandum in Support of Motion for Judgment on the Pleadings” at p. 23).

Updated July 2011