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Publications—Water-Resources Investigations Report 02 –4278

Simulation of Reservoir Storage and Firm Yields of Three Surface-Water Supplies, Ipswich River Basin, Massachusetts

By Phillip J. Zarriello

U.S. Geological Survey Water–Resources Investigations Report 02–4278

Prepared in cooperation with the Massachusetts Department of Environmental Protection

This report is available in Portable Document Format (PDF):

WRIR 02-4278 (2.2 MB)  - 58 pages


A Hydrologic Simulation Program FORTRAN (HSPF) model previously developed for the Ipswich River Basin was modified to simulate the hydrologic response and firm yields of the water-supply systems of Lynn, Peabody, and Salem-Beverly. The updated model, expanded to include a portion of the Saugus River Basin that supplies water to Lynn, simulated reservoir system storage over a 35-year period (1961-95) under permitted withdrawals and hypothetical restrictions designed to maintain seasonally varied streamflow for aquatic habitat. A firm yield was calculated for each system and each withdrawal restriction by altering demands until the system failed. This is considered the maximum withdrawal rate that satisfies demands, but depletes reservoir storage.

Simulations indicate that, under the permitted withdrawals, Lynn and Salem-Beverly were able to meet demands and generally have their reservoir system recover to full capacity during most years; reservoir storage averaged 83 and 82 percent of capacity, respectively. The firm yields for the Lynn and Salem-Beverly systems were 11.4 and 12.2 million gallons per day (Mgal/d), respectively, or 8 and 21 percent more than average 1998-2000 demands, respectively. Under permitted withdrawals and average 1998-2000 demands, the Peabody system failed in all years; thus Peabody purchased water to meet demands. The firm yield for the Peabody system is 3.70 Mgal/d, or 37 percent less than the average 1998-2000 demand.

Simulations that limit withdrawals to levels recommended by the Ipswich River Fisheries Restoration Task Group (IRFRTG) indicate that under average 1998-2000 demands, reservoir storage was depleted in each of the three systems. Reservoir storage under average 1998-2000 demands and IRFRTG-recommended streamflow requirements averaged 15, 22, and 71 percent of capacity for the Lynn, Peabody, Salem-Beverly systems, respectively. The firm-yield estimates under the IRFRTG-recommended streamflow requirements were 6.02, 1.94, and 7.69 Mgal/d or 43, 64, and 34 percent less than the average 1998-2000 demands for the Lynn, Peabody, and Salem-Beverly systems, respectively. Simulations that limit withdrawals from the Saugus River to a less stringent set of restrictions (based on an Instream Flow Incremental Methodology study) than those previously simulated indicate that the firm yield of the Lynn system is about 31 percent less than the average 1998-2000 withdrawals (7.31 Mgal/d).




Purpose and Scope


Study Area

Lynn Water-Supply System

Peabody Water-Supply System

Salem-Beverly Water-Supply System

Water Withdrawals

Water Withdrawal Restrictions

Permitted Withdrawals

Hypotheticcal Restrictions

Model Description

Model Fit to High Flows

Modifications to the HSPF Model

Structural Modifications




Special Actions




Simulated Reservoir Storage and Firm Yield

Lynn-Permitted Withdrawals

Lynn-Hypothetical Restrictions-IRFRTG

Lynn-Hypothetical Restrictions-SRIFIM

Peabody-Permitted Withdrawals

Peabody-Hypothetical Restrictions

Salem-Beverly-Permitted Withdrawals

Salem-Beverly-Hypothetical Restrictions

Discussion of Simulation Results



This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.

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Suggested Citation: Zarriello,P.J., 2002, Simulation of Reservoir Storage and Firm Yields of Three Surface-Water Supplies, Ipswich River Basin, Massachusetts, WRI 02-4278, 56 p.

For additional information write to:

USGS Massachusetts–Rhode Island Water Science Center
10 Bearfoot Road
Northborough, MA 01532

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U.S. Department of the Interior, U.S. Geological Survey
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Last modified: Monday, 02-Apr-2007 12:15:58 EDT
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