LOCATED AT: 143 COUNTY ROAD, IPSWICH MA MAIL: P.O. BOX 576, IPSWICH, MA 01938 PHONE: 978-412-8200 FAX: 978-412-9100

Low Flows & Floods

Low flows are one of the most pressing issues facing the Ipswich River. Despite our location in the relatively wet northeast, the Ipswich River is one of the most flow stressed rivers in the United States, going dry roughly every other year over the past decade.

Low Flow in Reading
Normal Flow in Reading Two views of the Ipswich River from the same spot in Reading in late August 2005 (top) and July 2005 (bottom).
(Photos: E. Levin, S. Sullivan)

In 1997 the Ipswich River was designated as one of the “20 Most
Threatened Rivers in America”, as determined by American Rivers. In 2003 that designation was upgraded to one of the “10 Most Endangered Rivers in America” due to worsening flow conditions.

Low Flows

During the summers of 1995, 1997, 1999, 2001, 2002, and 2005 much of the upper half of the river ran dry or was reduced to isolated pools. In 1999, the river experienced record low flows in May, June, July, and August. Major fish kills were documented in 1997, 1999, 2002, and 2005.

Water withdrawals for public water supply are the major cause of unnaturally low and no flow conditions in the Ipswich River, according to studies by the United States Geological Survey (USGS). In recent years the communities that have water supply sources in the Ipswich watershed have used an average of about 40 million gallons of water per day. About two thirds of this water comes directly from the Ipswich River or wells within the Ipswich watershed.

While public water supply withdrawals are the most significant cause of the river drying up, they are not the only factors causing the Ipswich River’s flow problems. Twenty to 25 million gallons a day of the water supply is discharged out of the watershed, resulting in a major water deficit. Additional millions of gallons of stormwater and groundwater leak or flow into sewers, and that water is also removed from the watershed. The USGS studies found that diversions of wastewater out of the upper reaches of the Ipswich watershed also significantly contribute to low flow conditions.

The rapid pace of development in some portions of the watershed results in further disruption of the natural hydrology of the Ipswich watershed. Stormwater rushes across pavement, buildings, and other impervious surfaces, instead of soaking into the soil and recharging underground aquifers. The result is increased flooding in periods of high rainfall and snowmelt and decreased flow in dry periods. This deprives rivers and streams of the critical base flow that under natural conditions keeps them flowing and healthy in summer.

Consider these trends:

  • In the late 1800’s, before the first sewers were built in Ipswich River communities, most of the water withdrawn from the watershed was returned as wastewater to the basin. In 2002, it is estimated that about 80% of the total wastewater produced in the basin (about 8.8 billion gallons per year) is exported out of the basin.
  • The Ipswich River’s all-time low-flow record of 0.1 cubic feet per second, set in 1957, was tied or broken on 18 days in 1997, with a new low of 0.05 cubic feet per second being set in September of 1997. That record was broken in 2002, with a new extreme of 0.04 cubic feet per second.
  • On average, water use doubles (or worse) in many communities in the Ipswich River Watershed in summer. This means that the most water is used when the River’s flows are naturally lowest.
  • Primarily due to low flows, almost 50% of the native river fish species have been eliminated from the river, or greatly reduced in numbers.

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Flooding and Stormwater

Howlett Brook at Topsfield Road Flooded

During May 2006 flooding, Howlett Brook submerged portions of Ipswich Road in Topsfield, upstream of Willowdale State Forest. (Photo: L. Manzi)

Increased development across the watershed can lead to higher high flows during storm events (aka stormwater). Techniques to improve water filtering into the ground during and after storm events (rather than running off paved surfaces) are being tested in the Ipswich River and at IRWA’s new headquarters, Riverbend.

In May of 2006, the Ipswich River experienced record flooding after a week of heavy rains. Peak flows measured at USGS gaging stations on the Ipswich River were the highest recorded since data collection began in the 1930s.

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What can we do?

Positive steps are being taken to restore the Ipswich River’s flows. These steps include the completion of several studies by the United States Geological Survey that have established the links between wastewater export, water withdrawals, and the severe low and no-flow events in the Ipswich. These studies have also produced several technically sound management scenarios that have coalesced into the first ever Ipswich River Watershed Management Plan, released in 2002.

In addition, IRWA is working to ensure that state policies and water withdrawal permits are protective of ecosystem health.

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For more information:

Low flows and Instream Flow

Flooding

Stormwater

  • Visit our Water Friendly Demonstration page for information on projects built around our watershed that utilize water friendly techniques and reduce stormwater
  • Massachusetts Department of Environmental Protection: Stormwater Policies and Guidance Includes information on state regulations and guidance for communities, planners, and designers.
  • University of Washington Water Center: Stormwater Management Includes information on Best Management Practices and new technologies.

Press Releases and Recent News Features on Low Flow in the Ipswich River Watershed

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