Ipswich River Fisheries Current Status and Restoration Approach June 2002 Figure 1: Ipswich River Watershed with USGS Streamflow Gage Locations

Transcription

1 Ipswich River Fisheries Current Status and Restoration Approach June 2002 Figure 1: Ipswich River Watershed with USGS Streamflow Gage Locations The following report was prepared by the Ipswich River Fisheries Restoration Task Group ( Task Group ). The Task Group includes representatives of the Ipswich River Watershed Association (IRWA), Essex County Greenbelt Association, Massachusetts Audubon Society, Massachusetts Department of Environmental Protection (DEP), Massachusetts Division of Marine Fisheries (DMF), Massachusetts Division of Fisheries and Wildlife (DFW), United States Environmental Protection Agency and Fish and Wildlife Service (FWS). The United States Geological Survey, National Marine Fisheries Service and Massachusetts Executive Office of Environmental Affairs (Massachusetts Watershed Initiative) contributed information used in the development of this report and provided comments on information presented. 1

2 Impairment of the Ipswich River: The Ipswich River s native fisheries are seriously degraded as a result of flow alterations caused by water withdrawals and diversions, dams and changes in land use. The historic fishery has been greatly impacted, resulting in the loss of fluvial specialist and river dependent species, and domination by macrohabitat generalists, which tolerate warm temperatures and ponded conditions. i Even the generalist species have been affected by frequent dewatering of the riverbed. Passage of diadromous species, as well as movement of freshwater species, has been impaired or blocked by dams. The Ipswich River has been named one of the most threatened rivers in the nation (American Rivers, 1997), and is considered a stressed basin under the hydrological criteria developed by the Massachusetts Water Resources Commission. ii The Ipswich River was listed on the 1998 S. 303(d) list of waters impaired under the Federal Clean Water Act (CWA), noting the need for confirmation of flow alteration and low dissolved oxygen. iii The objective of the CWA is the protection and restoration of the physical, chemical and biological integrity of the nation s waters. iv Loss of physical integrity: Lack of water results in the loss of physical integrity of the Ipswich River. A recent study of the Ipswich River Watershed by the United States Geological Survey (USGS) found that the severity and duration of low-flows has increased as a result of water withdrawals and other alterations to the watershed. Groundwater withdrawals, wastewater transfers and land use alterations which increase impervious areas combine to result in flow reductions of more than 90% in the upper Ipswich River during low-flow periods. v A companion USGS study investigating the relationship of flow to aquatic habitat found that critical habitats are lost due to reduced flows, including riffles and stream margin habitats. vi Riffles are essential areas of rivers because they provide turbulence that aerates the water, adding oxygen; and they provide habitat for key macroinvertebrates and fish. Reduced flows cause the river to dry up first at the riffles, thus segmenting the river into a series of isolated pools, rather than providing a continuum of flowing water. This in turn reduces diversity and abundance of habitat, subsequently affecting aquatic biota. Reduced flows also result in water retreating from streambanks and river margins, which normally provide the most diverse habitat structure in pools and runs. As a result, cover and potential food sources for biota are lost. Dams also adversely affect the physical integrity of the river. Dams and the associated impoundments reduce the amount of riverine habitat, especially riffles which are scarce in this low-gradient system. The loss of riffles diminishes habitat for fish and macroinvertebrates important in the aquatic food web, and decreases the zone in which oxygenation of river water can occur. While water going over a dam is re-aerated, periods of no flow over the dam can result in stagnant conditions in the impoundment, where the water is prone to reduced oxygen levels and increases in temperature. Dams also block fish movement, affecting both resident and diadromous species. As dams impound water and trap sediments, they may leave downstream river reaches starved for both water and sediments. The Ipswich River Watershed experiences disruption of groundwater hydrology, caused by water withdrawals, infiltration into sewers, and runoff from impervious areas, which prevents replenishment of groundwater. These hydrological alterations result in loss of baseflow, the discharge of groundwater into the river that supports flow between precipitation events. The physical effects of diminished baseflow are not limited to loss of water. Groundwater temperature is typically F, a cool-water source for the river in summer and a warming 2

3 source in winter. Diminished baseflow in summer may result in warmer water temperatures, because when cool inflow is reduced, the reduced volume of water in the river heats more rapidly. Stormwater runoff from pavement and other surface features is typically much warmer in summer, affecting the suitability of the river for organisms such as brook trout, which cannot tolerate warm temperatures. Warmer water has less capacity to hold dissolved oxygen. In winter, the groundwater inflow helps keep the river flowing even in freezing conditions. Investigations of the Ipswich River s low-flow problems and the impacts on fisheries have focused on the extreme low-flow conditions of the Ipswich River in summer and early fall. Surface water diversions, which are restricted to the December May, have negligible effects on summer low flows. vii However, streamflows during the diversion pumping season are diminished by water withdrawals. Because the diversion thresholds that regulate large volume water withdrawals from the Ipswich River are very low, the total volume diverted sometimes approaches or exceeds the amount of water remaining in the river during droughts that occur in late fall, winter or spring. The loss of water during these periods may affect the availability of habitat, susceptibility to freezing, geomorphological processes and other ecological values. Loss of chemical integrity: Portions of the Ipswich River Watershed experience low dissolved oxygen, at times far below the 5 ppm water quality standard for Class B waters. During the summer low-flow season in the Upper Ipswich Watershed, dissolved oxygen of 0-1 ppm is not uncommon, and levels below 3 ppm are typical. During storm events, pollution, including the higher summer temperature of runoff, affects the river. Reduced flow results in less assimilative capacity for oxygen-demanding substances and less dilution for conservative substances such as heavy metals. Research by the Marine Biological Laboratory at Woods Hole indicates that reduced freshwater flow into Plum Island Sound estuary causes estuarine salinity to increase and to penetrate further upstream into normally oligohaline regions of the estuary. Moderate salinity increases in the oligohaline region during summer have been found to greatly increase inorganic nitrogen flux from sediments into overlying water, thus increasing the potential for algal blooms. Altered salinity regimes are also likely to affect the distribution of optimal habitats for larval and juvenile fish and shellfish. viii Loss of biological integrity: Fish surveys conducted by the Massachusetts Division of Fisheries and Wildlife, in collaboration with USGS, found that the population of fluvial specialists and fluvial-dependent species of fish is significantly depressed in the Ipswich River system. The current fish assemblage in the river system is dominated by three warm-water species that can tolerate low-flow and ponded conditions. ix Diadromous or pulse fishes, those that migrate in or out of the river system for spawning, are greatly affected by changes to the river system. The herring run, which was highly productive historically, was extirpated in the nineteenth century due to dams and other alterations of the river. For more information regarding factors affecting the fish community, see Armstrong and others (2001). Macroinvertebrate sampling by the Ipswich River Watershed Association indicates a loss of diversity at flow-impaired sites as compared to control sites. x Other impacts on biological integrity, such as impacts on wetlands, floodplains, birds, reptiles, amphibians, mammals etc., are not the subject of this report, but are areas of concern. 3

4 Impacts on designated uses: The purpose of the Massachusetts Surface Water Quality Standards is to take all actions necessary or appropriate to secure to the Commonwealth the quality benefits of the CWA. The objective of the CWA is the restoration and maintenance of the physical, chemical and biological integrity of the Nation s waters (314 CMR 4.01(4)). The Massachusetts Surface Water Quality Standards (WQS, 314 CMR 4.00 et. seq.) specify designated uses, criteria to protect those uses, and an antidegradation policy. xi In the WQS, the Ipswich River and tributaries are Class B waters above the tidallyinfluenced section, with the exception of public water supply reservoirs and tributaries thereto, which are Class A; these are classified as High Quality Waters under the antidegradation provision (314 CMR 4.04(2), 4.06 Table 27). Class B waters are designated as a habitat for fish, other aquatic life 1 and wildlife, and for primary and secondary contact recreation (314 CMR 4.05 (3)b). The tidal portion is Class SA, excellent habitat for fish, aquatic life and wildlife, primary and secondary recreation, and suitable for shellfish harvest without depuration (314 CMR 4.05 (4)a). The impact on freshwater and diadromous fisheries has been described above, and is the primary focus of this report. The Ipswich River s suitability for canoeing and kayaking is greatly diminished during the summer and early fall, a popular time for these activities, due to extreme low-flows and even no-flow episodes, which occur chronically. Swimming and passive recreation adjacent to the Ipswich River are frequently impaired or eliminated due to low-flow, no-flow, algal blooms and other pollution. Water withdrawals are a major factor in causing or exacerbating low-flows. The use of the Ipswich River and its surrounding aquifers for water supply must be modified if flows and habitat are to be restored. Private water supplies and fire ponds have been vulnerable during dry periods in the past. Restoration Goals Recommended by Task Group: Restore the physical, chemical and biological integrity of the Ipswich River, so that it can sustain its designated uses under the Massachusetts Surface Water Quality Standards. o Protect and restore a healthy and productive ecosystem, including critical aquatic and riparian habitats. o Restore the target fish community and other aquatic life that would be expected to occur in this river, in the absence of hydrological alterations. o Achieve sustainable use of the Ipswich River Watershed for water supply. o Restore flows sufficient to support recreation. Recommended Restoration Objectives: 1) Target Fish Community: The Task Group developed a target fish community for the Ipswich River, defining those species that would be expected to exist in the Ipswich River, in the absence of hydrological modifications. xii The target fish community sets forth the expected native fluvial-dominated fish community of the Ipswich River, and defines a clear restoration objective. The task group evaluated recent studies of the Ipswich River watershed, including the hydrological model and aquatic habitat study of the United States Geological Survey, as well as fish survey data collected by USGS and the Massachusetts Division of Fisheries and Wildlife CMR 4.02: Aquatic life means a native, naturally diverse, community of aquatic flora and fauna. 4

5 The task group also reviewed historical fisheries data for the Ipswich River; recent target fish communities developed for the Quinebaug River Watershed in Massachusetts and Connecticut xiii and the Lamprey River Watershed in New Hampshire; and fish survey data for other rivers in Maine, New Hampshire and Massachusetts. The existing fish community was evaluated and categorized according to whether species present are fluvial specialists (requiring flowing water throughout their life cycles); fluvialdependent (requiring flowing water for part of their life cycle); or macrohabitat generalists (tolerant of ponded as well as flowing conditions). The evaluation found that the existing fish community is dominated by typical pond or generalist species such as pickerels, eels and sunfishes. Typical stream or fluvial fishes, which would be expected to dominate the Ipswich River system, make up a small percentage of the total fish community; and several fluvial species were absent from the recent survey data. For further information about the target fish assemblage investigation developed for the Ipswich River, see Target Fish Assemblage for the Ipswich River, Ipswich River Fisheries Restoration Task Group, 2001 [appended]. 2) Recommended Flow Regime for Fisheries Protection: The United States Geological Survey, in collaboration with the Massachusetts Division of Fish and Wildlife, recently completed a study of the relationship of hydrology to aquatic habitat in the Ipswich River. The study ( Aquatic Habitat Study ) evaluated a number of instream flow protection approaches, including two standard-setting methods (Median August calculated using FWS method, and Tennant calculated using the fair habitat index 2 ) and two standard-setting-plus methods (R2Cross and Wetted Perimeter, which are methods that provide a single flow recommendation or standard, based on hydraulic measurements of the subject stream) xiv. The August median and Tennant methods were applied to streamflows without water withdrawals, as simulated by the Ipswich HSPF model (Zarriello and Ries, 2000). The USGS study concluded that restoration of the aquatic ecosystem of the Ipswich River could be achieved by maintenance of a minimum streamflow requirement of about cfsm 3 for the summer period, together with higher streamflow requirements for other seasons. These flow restorations, combined with removal of dams and other barriers to fish passage, would allow fish communities to recover toward the goal of maintaining target communities consisting of more fluvial species in higher numbers. xv Using information from the Aquatic Habitat Study, the Task Group identified the following broad management objectives to restore the Ipswich River s aquatic habitat and fisheries: a. Maintain flow over the riffles b. Maintain water to the channel margins c. Maintain seasonal variation in flow which closely approximates the natural hydrograph Based on the results obtained using the 4 standard-setting methods and evaluation of other factors, the task group developed the following recommendations for streamflows needed to protect and restore the Ipswich River fisheries: 2 The Aquatic Habitat Study evaluated Tennant s indices for good, fair and poor habitat. The fair habitat index of 30% of mean annual flow was used for the calculations described in this paragraph. See also endnote xiii. 3 cfsm=cubic feet per second per square mile 5

6 Flow recommendations ( recommended fisheries streamflows ): June-October 0.49 cfsm November February 1.0 cfsm (provisional recommendation) March May 2.5 cfsm (provisional recommendation) June to October recommendation: The recent study by USGS, in collaboration with Massachusetts environmental agencies, focused on the low-flow period. Methods evaluated included Tennant, Median August, Wetted Perimeter and R2Cross. The study found that streamflow values needed to preserve habitat sufficient to support a healthy fish population (using an average of the four methods at four sites) ranged from 0.44 cfsm to 0.65 cfsm, with an overall average of 0.49 cfsm. When the standard-setting-plus methods were evaluated at the study sites by applying R2Cross at the single natural riffle site and Wetted Perimeter at the 3 altered sites, and again using the same values for Median August and Tennant as above for the 4 sites, the average was 0.42 cfsm. The Task Group recommends a streamflow of 0.49 cfsm for the June to October period, based on the average of the 4 methods at the 4 sites in the USGS study (0.49 cfsm), and the close agreement between the average of the methods (0.49 cfsm) and the FWS Aquatic Base Flow (ABF) default value (0.50 cfsm) for the summer period. xvi Streamflows lower than those recommended result in segmentation of the river, loss of critical habitats, and adverse impacts on the fish community. The Task Group noted that significant damage has occurred to the Ipswich River fisheries, and there is need for effective management measures to achieve restoration objectives. Consideration of management issues and approaches to eliminate additional water losses during low-flow periods, are addressed below in the section titled Management and Implementation Recommendations. November to May provisional recommendations: While recent investigations in the Ipswich River Watershed have focused on the effects of extreme low-flow conditions, a growing body of research and observation indicates that hydrological modifications throughout the year have a range of effects on ecosystem functions. xvii As noted above, the Aquatic Habitat Study focused primarily on the summer low-flow period, and recommended higher streamflow thresholds for other seasons. USGS also evaluated the Range of Variability Approach, discussed below, and developed an annual hydrograph indicating a range of flow values throughout the year that would approximate the natural hydrograph. The ABF provides guidance regarding flows needed for fisheries protection during the November to May period, based on a study of unregulated streams throughout New England. The ABF default value for November to March is 1.0 cfsm and the default for April through May is 4.0 cfsm. The Task Group s recommendations for November May seek to maintain seasonal variations in flow that mimic the natural hydrograph. The monthly medians as measured at the South Middleton and Ipswich gages are shown in Table 3. 6

7 Table 3 Monthly Medians (based on recorded streamflow data) South Middleton gage Ipswich gage cfs cfsm cfs cfsm November December January February March April May Pending further study to evaluate the fisheries streamflow requirements for the November to May period, the Task Group recommends the ABF default value of 1.0 cfsm for November through February, and the value of 2.5 cfsm for March through May. The spring threshold is adjusted to reflect the lack of snowmelt during this period, resulting in somewhat lower flows than occur typically in New England during the spring. The average of the monthly medians for the March-May period is 2.5 cfsm. The Task Group s recommendations for the November to May period are provisional, recognizing that further research is needed pertaining to the hydrologic regime needed to support ecosystem function year-round. The Task Group noted a range of specific considerations and concerns regarding streamflows from November through May, detailed below. November February The Task Group s provisional streamflow recommendation for fisheries protection for November through February is 1.0 cfsm, based on the ABF default. An evaluation of the actual monthly medians for those months indicates that streamflows in the Ipswich River tend to be higher than the ABF during December through February. The difference is especially marked in February typically the most flow-stressed winter month for many New England rivers. Whereas precipitation is bound in snowpack during these months for many of the rivers studied in developing the ABF, the Ipswich River s winter hydrograph reflects a greater proportion of runoff and snowmelt than snowpack. The Task Group concurred that all available information supports the conclusion that streamflow thresholds should not be lower than 1.0 cfsm for this period, and that the 1.0 cfsm recommended threshold may require reexamination based on future research. Additional measures to better mimic the natural hydrograph are addressed in the sections below on the Range of Variability Approach, and Management and Implementation. The Task Group identified November as a period of particular concern. Water withdrawals during early-mid November could coincide with the latter period of outmigration of juvenile anadromous fishes. The artificial current created by pumping during this period may cause outmigrating juvenile fishes to become entrained or impinged by pumps, resulting in high mortality and distribution to other waters. The modification of river current near the pumping station could also attract juveniles and delay their outmigration. Screening or other protection against entrainment may be required, in addition to protective flow thresholds and the percent diminishment approach mentioned as a management alternative below. 7

8 Reduced water volume during the winter months may result in more rapid freezing, resulting in production of frazil ice on the stream margins and anchor ice on the stream bottom, which may have significant effects on dissolved oxygen and aquatic habitat. Reduced discharge may have long-term effects on ecosystem function, potentially impacting the denitrification potential of wetlands and affecting other nutrient dynamics. Allowing pumping during November may restrict groundwater recharge and other recovery of the river system. The ABF default during November is recommended to allow groundwater recharge and recovery at the end of the growing season. March through May The recommended fisheries threshold for March-May is 2.5 cfsm. This is the average of the monthly medians for those months. The ABF default for the spring period is 4.0 cfsm, reflecting average conditions across New England, where many streams experience high runoff from snowmelt during the spring months. As this situation occurs less frequently in the Ipswich due to lower snowpack, the average of the monthly medians was used. Maintaining adequate streamflows in spring is important to preserving ecological functions. High flows scour the river bottom, maintain floodplain ecosystems, trigger spawning runs, provide spawning habitat in the floodplains, and recharge aquifers. Diminishment of spring flows may contribute to changes in wetland types or conversion of wetlands to upland, diminishing the beneficial functions of wetlands for which they are protected by law. Range of Variability Approach Poff, Richter and others have studied the natural pattern of flow variability of a river system and its role in creating and sustaining biodiversity and environmental integrity. Richter and others developed the Range of Variability Approach (RVA), which identifies a target flow regime that resembles a river s natural flow variability. xviii The RVA composite hydrograph synthesizes 33 hydrologic indices, defines a range of variability that the natural ecosystem may tolerate, and provides an indicator of streamflow levels that are likely to result in adverse environmental impacts. The RVA may provide further guidance regarding regulation of water withdrawals and other anthropogenic changes to streamflows, as it may indicate a hydrological regime needed to support wetlands, floodplain and other ecosystem values and functions. When streamflow values fall in the lowest quartile of the composite RVA hydrograph, limiting anthropogenic changes to streamflow to the maximum extent possible is indicated. Additional management considerations regarding fisheries streamflow recommendations: The recommended fisheries streamflows represent the amount of water needed in the river to support a healthy fish community, based on the best information currently available. However, additional factors warrant further examination in evaluating the adequacy of these streamflow recommendations to protect the fisheries resource, including the following: There is a lag time in the recovery of streamflow after groundwater pumping is reduced or stopped. This lag time suggests that management actions should be taken earlier, at higher streamflows than the recommended fisheries thresholds, to prevent flows from going below the recommendations and damaging the resource. 8

9 Water losses caused by unregulated water withdrawals, dewatering by sewers, loss of groundwater recharge due to imperviousness, and capture of water by dams, will result in further diminishment of streamflows during low-flow periods, regardless of the regulation of large water withdrawals. The effects of these water losses must be factored into management decisions to effectively prevent extreme low-flows. During winter-spring drought periods, water withdrawals and diversions may result in significant changes to the natural flow regime. Current management measures allow a high percentage of total flow to be removed, without a clear understanding of the impacts of these withdrawals. The thresholds that currently regulate surface water diversions from the Ipswich River are less than or equal to the recommended summer fisheries thresholds, despite the fact that these withdrawals take place from December through May. Improved regulation of these withdrawals, to incorporate fisheries protection needs, is needed. Standard-setting methods do not provide the detailed, site-specific information that incremental methods can provide. Where necessary, additional information on the relationship between flow and habitat could be obtained by the application of technically sophisticated methods such as Instream Flow Incremental Method (IFIM). Management and Implementation Recommendations: Above, the Task Group focused on what streamflows are needed to support fisheries and ecosystem function. The question remains how to restore the Ipswich River s hydrological balance to achieve these streamflows. Many alterations of the watershed have occurred, some of which cannot be readily managed on a day-to-day basis in response to low-flow events. A comprehensive approach is needed to restore the Ipswich River s hydrology and mimic the natural hydrograph. Recent hydrological modeling of management scenarios by USGS suggests that the flow problems of the Ipswich River can be solved by employing a combination of management alternatives. This modeling found that reducing groundwater withdrawals, while concurrently reducing out-of-basin wastewater transfers, could restore streamflows in the most critically impaired section of the Ipswich River. Seasonal (May-October) water imports to upper watershed communities, in combination with groundwater discharge of highly treated wastewater, were found to achieve flows even higher than the simulated baseline flows. xix The Task Group recommends implementation of a number of management approaches to ensure the sustainability of the region s water supply, while restoring flows needed to support fisheries. The Task Group s expectation is that the combined effect of a range of management measures, implemented over the next decade, will result in significantly improved streamflows. As streamflows recover, there will be fewer occasions when flows are below the fisheries thresholds, resulting in less stress on both the natural resource and the region s water supply. In the interim period, more effective management of water withdrawals and transfers is necessary to prevent further damage and make steady progress toward restoration. A range of management alternatives can be employed to solve the streamflow problems. The Task Group recommends that those local, state and federal officials with the responsibility of managing the water resources of the Ipswich River employ management approaches which promise improved protection of the environment, including the following (without limitation, and unranked): 9

10 a. Stringent implementation of no net loss of water in all water resource management decisions, and net gain of water as a primary goal of comprehensive water resource management plans at the local and regional levels; b. Mitigation for existing and proposed water losses; c. Aggressive implementation of water conservation as a source of water in lieu of existing or proposed sources; d. Implementation of mandatory water use restrictions and other adaptive/ demand management measures, based on flow triggers, to protect both water supply capacity and natural resources during low-flow periods; e. Use of alternative, less damaging water sources during low-flow events, including out-of-basin sources, provided that the use doesn t impair aquatic uses in the donor basin; f. Optimization of water withdrawals to prevent environmental damage; g. Reduction in the amount of water exported from the Ipswich River Watershed for water supply and/or wastewater transfers, by implementing in-basin treatment and discharge; h. Increased infiltration of stormwater through use of Best Management Practices, adoption of higher than 1:1 recharge ratios for new development and retrofitting of existing development to improve groundwater recharge while protecting water quality; i. Use of a percent diminishment approach (such as is used in Vermont) to regulate water withdrawals; this approach sets a limit on the percentage of flow, above a specified fisheries threshold, that may be withdrawn at a given point in time. j. Implementation of measures to reduce fish mortality (screens on pumps, mechanisms to prevent entrainment or impingement, especially of juvenile anadromous species); k. Implementation of additional regulatory measures based on recent scientific findings, such as the Range of Variability Approach. Regulation of Water Withdrawals The Ipswich River Watershed is currently overallocated for water supply, to the detriment of other interests protected under the Massachusetts Water Management Act and other laws. Water Management Act permits should include more effective provisions to limit water withdrawals, especially during low-flow and peak demand periods, and to address local and cumulative impacts. The Task Group recommends that DEP exercise regulatory authority over all water withdrawals used for irrigation purposes, to address the problem of private irrigation sources being used during periods when municipal supplies are under water use restrictions or bans. Local regulation should consistently employ the most effective demand management practices. Groundwater withdrawals must be regulated more effectively. Regular monitoring of water levels and streamflows near large wells is necessary to identify impacts in timely fashion, and take appropriate action. Management of groundwater withdrawals must take into account the lag times that occur between taking an action and achieving an effect. When groundwater pumping is reduced or stopped, depletion of ground- and surface waters continues for a period of time. Similarly, reduction in water demand is typically delayed for days, weeks or longer after a demand management measure is employed. Due to these delayed responses, the Task Group recommends that stringent demand management measures be employed sooner, at higher flows 10

11 than the fisheries protection thresholds. The purpose of this recommendation is to begin action early enough to avoid reaching the action flow thresholds. If, despite these measures, flows decline below the recommended fisheries thresholds, the Task Group recommends restricting groundwater withdrawals by implementing flow-triggered cutoffs in the near-term (1-3 years) of those groundwater withdrawals which exhibit the strongest impact on surface flow. For water supplies with less severe impacts, stringent demand management measures should be required in the near term, with implementation of a flowtriggered cutoff threshold to be phased in over a period of 5-10 years. This requirement should be phased in during Water Management Act permit and registration renewal processes, allowing a reasonable amount of time for suppliers to seek and implement alternative sources. Staff gages or other streamflow monitoring devices should be installed in proximity to wellfields so that flow-triggered regulation can be based on local effects as well as cumulative impacts to the river system. Surface water diversions, which are authorized between December 1 and May 31, are currently governed by flow thresholds that are significantly lower than the fisheries thresholds: Water supply Current regulatory threshold conversion to cfsm Lynn 10 mgd at S.Middleton 0.35 Peabody 15 mgd at S.Middleton 0.50 Salem-Beverly WSB 28 mgd at Ipswich gage 0.35 The Task Group notes that these thresholds are applied from December to May, yet they are approximately at, or below, the recommended summer thresholds. Fisheries interests are not protected by these low thresholds. In addition, the total amount of water that may be withdrawn from the river during these periods may exceed the amount left in the river by % or more. Improved regulation of these diversions is recommended, including higher diversion thresholds, a percent diminishment approach and special measures for drought periods. In recognition that drought periods may occur during the diversion pumping period, resulting in streamflows that are insufficient to support water withdrawals at the recommended fisheries streamflows, the Task Force recommends implementation of adaptive or flexible management measures to balance water supply and fisheries protection needs during such periods. These measures should include water conservation requirements and water use restrictions. Communities relying on diversions during such periods should identify emergency/alternative water sources and system modifications to reduce their vulnerability to drought impacts on the Ipswich River. Diversions that result in the segmentation of the river and loss of critical habitats should not be permitted. If proposals to construct or expand reservoirs or increase diversions should be made in the future, the hydrological capacity of the Ipswich River should be evaluated to ensure that such a proposal will not further burden the limited resources of the river system or result in dewatering downstream reaches. The evaluation should require verification that recommended instream flows for fisheries protection could be maintained during a drought of record. Future investigation: The Task Group s recommendations recognize limitations in current knowledge of the impacts of flow alteration on aquatic systems of the Ipswich River. This report focuses on restoration of the riverine fisheries. Further investigation would be appropriate regarding the 11

12 impacts of flow alterations on other measures of biological integrity, including other freshwater faunal and floral communities and estuarine resources in the Class SA tidal portion of the Ipswich River. Additional investigations about the impacts of flow alterations during the November-May period are recommended. The Task Group s provisional recommendations for November through May are based on fish migration periods, as well as the restoration objective of maintaining seasonal variation in flow which mimics the natural hydrograph, as a means of supporting natural ecological functions. Further study of the effects of water withdrawals on the anadromous and resident fish, floodplains and wetlands, mortality of juvenile anadromous fishes due to entrainment, and greater susceptibility to freezing (DO loss, freezing to the bottom) were identified as matters of interest. Linking additional studies to the Plum Island Ecosystems Long-Term Ecological Research program led by the Marine Biological Laboratory at Woods Hole may assist in gaining greater insight into the effects of hydrological modification on river and wetland ecosystem function from the micro to the macro scale. The impacts of dams on river flows were not evaluated during the recent hydrological modeling and aquatic habitat studies. Evaluation of the effects of dams on streamflows, dissolved oxygen, fish movement and available habitat would provide information useful in prioritizing habitat restoration activities related to dams. Other Habitat Improvements and Restoration Objectives: Beyond flow restoration, the task group identified other habitat improvements and restoration objectives. These include: a) Fish community restoration b) Dam removals and improved fish passage c) Stream restoration The Massachusetts Division of Marine Fisheries, in collaboration with IRWA and other non-profit organizations, is engaged in a long-term project to restore river herring to the Ipswich River. Restoration activities, which have been underway for a decade, include conducting habitat assessments, improving fish passage at the Ipswich dam, stocking the river with blueback herring each spring, and counting returning herring. A Dam Study Group is investigating dams, to consider whether specific dams may be appropriate candidates for removal to improve streamflows, habitat and fish passage. The Task Group noted that dam removals and stream restoration are not dependent on flow restoration, and work in these areas may proceed prior to achieving flow restoration objectives. Monitoring: As stated above, monitoring of localized impacts of water withdrawals on streamflow is a key recommendation for improved management. Other monitoring activities that would be useful in achieving the restoration goals include additional monitoring of macroinvertebrates; fishes; dissolved oxygen; continued monitoring of water quality and water quantity; and linkage to ongoing long-term ecosystem studies in the Ipswich River Watershed. Additional data on streamflows at ungaged locations would be useful, particularly in headwater tributaries and upper reaches of the mainstem of the river. 12

13 References: i Armstrong, D.S., Richards, T.A., and Parker, G.W., 2001, Assessment of habitat, fish communities, and streamflow requirements for habitat protection, Ipswich River, Massachusetts: U.S. Geological Survey, Water-Resources Investigations Report ii Report on Stressed Basins in Massachusetts, 2001, Interim Definition, Massachusetts Water Resources Commission. iii Massachusetts Department of Environmental Protection, 1998, 303(d) List of Impaired Waters. Two major segments of the Ipswich River; from the confluence of Maple Meadow and Lubbers Brooks to the Salem Beverly Waterway Canal, and, from the Salem Beverly Waterway Canal to the Sylvania Dam (essentially the entire river), are listed on DEP's (d) List as " (d) Segments Needing Confirmation". Flow alteration is listed as one of the "Pollutant/Stressors" in each segment. Maple Meadow Brook in its entirety is also listed within the same category due to flow alteration. iv Clean Water Act and Regulations: Federal Water Pollution Control Act, 33 U.S.C. ss 1251 et seq., Pub. L Federal Clean Water Act Regulations, 40 CFR v Zarriello, Phillip J., Ries, Kernell G., III, 2000, A precipitation-runoff model for analysis of the effects of water withdrawal on streamflow, Ipswich River basin, Massachusetts, United States Geological Survey Water Resources Investigation Report , 99 p. vi Armstrong, Richards and Parker, vii Zarriello and Ries, viii Dr. Charles Hopkinson, Ecosystem Center, Marine Biological Laboratory at Woods Hole, personal communication ix Armstrong, Richards and Parker, 2001, pp x Ipswich River Watershed Association, Macroinvertebrate Data Report, 1999, pp xi Massachusetts Clean Water Act Regulations, 314 CMR 4.0, and Massachusetts Clean Water Act, MGL Ch. 21 ss Water quality standards are provisions of State or Federal law which consist of a designated use or uses for the waters of the United States and water quality criteria for such waters based on such uses. Water quality standards are to protect the public health or welfare, enhance the quality or water and serve the purposes of the Act. xii Lang, Vernon et al, 2001, Target Fish Assemblage for the Ipswich River Watershed, Ipswich River Fisheries Restoration Task Force. xiii Bain, Mark B. and M.S. Meixler, 2000, Defining a target fish community for planning and evaluating enhancements of the Quinebaug River in Massachusetts and Connecticut, New York Cooperative Fish and Wildlife Research Unit, Cornell University. xiv Armstrong, Richards and Parker, References cited for the standard-setting methods are: Tennant Method: Tennant, D.L., 1976, Instream flow regimens for fish, wildlife, recreation, and related environmental resources, in Instream flow needs, Vol II: Boise, Idaho, Proceedings of the symposium and specialty conference on instream flow needs, May 3-6, American Fisheries Society, p Median August: U.S. Fish and Wildlife Service, 1981, Interim regional policy for New England stream flow recommendations: Newton Corner, Mass. 13

14 Wetted Perimeter Method: Nelson, F.A. 1984, Guidelines for using the wetted perimeter (WETP) computer program of the Montana Department of Fish, Wildlife and Parks: Bozeman, Mont., Montana Dept. of Fish, Wildlife and Parks. Leathe, S.A., and Nelson, F.A., 1986, A literature evaluation of Montana s wetted perimeter inflection point method for deriving instream flow recommendations: Helena, Mont., Department of Fish, Wildlife and Parks, 70 p. R2Cross Method: Espegren, G.D., 1996, Development of instream flow recommendations in Colorado using R2Cross: Denver, Colo., Water Conservation Board, 34 p. Espegren, 1998, Evaluation of the standards and methods used for quantifying instream flows in Colorado: Denver, Colo., Water Conservation Board, 18 p. xv Armstrong, Richards and Parker, 2001, p. 67. xvi U.S. Fish and Wildlife Service, 1981, Interim regional policy for New England stream flow recommendations: Newton Corner, Mass. xvii Poff, N.L., Allan, J.D., Bain, M.B., Karr, J.R., Prestegaard, K.L., Richter, B.D., Sparks, R.E. and Stromberg J.C., 1997, The natural flow regime: A paradigm for river conservation and restoration, BioScience v. 47:11. p xviii Richter, B.D., Baumgartner, J.V., Wigington, Robert and Braun, D.P., 1997, How much water does a river need?: Freshwater Biology, v. 37, p xix Zarriello, Philip J., 2002, Effects of water-management alternatives on streamflow in the Ipswich River Basin, Massachusetts, United States Geological Survey, Open File Report xx Zarriello,