Findings and Recommendations
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FINDINGS AND 2 RECOMMENDATIONS A. Current Site A. CURRENT SITE CONDITIONS Conditions B. Goals and Objectives he study area is the last remnant of the former Great Swamp that once C. Proposed Site T Improvements stretched from Fresh Pond to the Mystic River. However, this relict eco- and Amenities system has been highly altered by the use and re-use of the area over the D. Area Specific past 350 years. Even the briefest review of historical descriptions and il- Recommendations lustrations makes clear that the appearance of the area and its vegetation, topography, soils, and geomorphology differ greatly from conditions at the time of European colonial settlement. Despite these radical changes, the area still provides ecological functions that are effectively irreplaceable. Fundamentally, water still drains through the subwatershed to the Alewife Brook. This flow of water — however altered the inputs and flow, and however contaminated the water — persists and continues to define the ecological value of the area. Little River and Alewife Brook remain the lifeblood of the area. A1. PHYSICAL RESOURCES Most of the study area is the floodplain of the Little River and Alewife Brook and is flat and low-lying. The overall elevation gradient along the length of the study area is less than half a foot, and the average elevation of the study area is less than several feet above sea level. The area is so low in elevation that at times the Mystic River flows upstream into Alewife Brook in a reverse flow. ALEWIFE MASTER PLAN 11 Following the retreat of the last glaciers 15,000 its confluence with the Little River was straight- years ago, kettle ponds such as Fresh Pond and ened and made to flow in a concrete channel to Spy Pond formed, and sands and gravels were speed drainage of water from upstream. Ur- deposited in the glacial outwash. An ancient banization in the surrounding areas decreased riverbed that once ran through the area depos- groundwater recharge, resulting in lower base ited the clays that were later mined for brick- flow. The increased stormwater runoff from making. Generally bedrock lies more than five the contributing watershed also causes in- feet below the surface. Most of the surface creased peak flows. These sudden, high inputs soils of the Alewife area were subsequently of large amounts of stormwater into the pond highly disturbed by cut and fill activities dur- and stream system contribute to bank erosion. ing development of the area. Most of the soils Despite these modifications to the hydrological now lack characteristics of naturally developed, system, all the original hydrological connec- undisturbed soils, such as defined layers and tions remain in one form or another, except for horizons, and their poor quality may serve as a the connection to Fresh Pond. constraint to restoration. Water quality in Little River and Alewife Brook is poor because of stormwater and sanitary sewer discharges. The degraded condition of Alewife wetlands also means they are less ef- fective at their natural function of buffering and improving water quality. More than 60 stormwater and combined sewer outfalls (CSO) discharge directly to the study area, while Spy Pond, Wellington Brook, and Winn’s Pond bring significant quantities of contaminated stormwater from Belmont and Arlington. Re- FIGURE 13. View of Yates Pond from the top of the Alewife cent projects by Somerville and Cambridge to subway station. separate storm and sanitary sewer systems have In addition to the soils, the hydrology of the significantly improved water quality, and con- Alewife area is also radically altered from its tinuing projects will yield yet more improve- original condition. The major tributaries to ments in the future. Little River, Wellington Brook and Winn’s Brook, and the original hydrological connec- tion with Spy Pond all enter the system now via underground pipes. Flow from Fresh Pond, the original source of water in Alewife Brook, was blocked in the 1870s, and most of Alewife Brook, upstream of its confluence with Little River, was buried in a pipe in the 1940s. The construction of Craddock Dam (since removed) and Amelia Earhart Dam on the Mystic River blocked tidal flow from Bos- ton Harbor, converting the Great Swamp from a tidal marsh to a freshwater wetland. Finally, FIGURE 14. The Alewife Reservation, shown during a major the meandering Alewife Brook downstream of storm event, serves as the fl oodplain for the Little River. 12 FINDINGS AND RECOMMENDATIONS ALEWIFE MASTER PLAN Alewife’s altered hydrology combined with ex- Reservation and Greenway are elevated, typi- tensive development in its floodplain results in cally because of fill activities, and lie outside severe flooding problems for some residents. of the floodplain. This lack of upland habi- There is simply too little flood storage capacity tat, combined with naturally high groundwater to accommodate very large storm events. In elevations, limit the opportunities to create addition, hydraulic constrictions, most notably additional flood storage capacity in the area. at the Massachusetts Avenue and Broadway The most significant areas that lie outside the bridges over Alewife Brook, impede river flow floodplain occur on abutting properties such as during high flow events. Given the sanitary the Belmont Uplands, portions of the Acorn sewer inputs to the system, local flooding may Office Park (former ADL campus), and the be a health hazard as well. Martignetti property. Because most of the Alewife area is a low-ly- A2. BIOLOGICAL RESOURCES ing network of wet places, most of the habitat Although the various places within the Alewife is either aquatic or wetland of various types. Reservation and the Alewife Brook corridor Although both the aquatic and wetland habitat seem distinct or different, they are all connect- are degraded, the aquatic habitat is relatively ed by the water that runs through them. Water worse off. Poor water quality, the long stretch unifies the Alewife area. Given how difficult it of concrete channel, and the extensive siltation is to see any water when passing through the that has occurred in the ponds and non-con- area on its two major thoroughfares, Route 2 crete channel beds dramatically reduce the and Alewife Brook Parkway, most people are habitat value of the ponds and streams for fish surprised to learn just how wet the Alewife and aquatic plants. area is under normal conditions. Most of the native fish species that once would Five ponds lie within the Reservation, and five have lived and bred in the Alewife waters are more ponds lie on adjacent properties. Some no longer found in the system. Fish such as ponds are natural, such as Little Pond and brook trout, brown bullhead, and white perch Blair Pond, whereas others were made when have been replaced by nonnative species such clay was excavated for brick-making, such as as largemouth bass and common carp, the Yates Pond. Three streams, namely, Wellington dominant fish at Alewife (refer to Appen- Brook, Winn’s Brook, and Little River contrib- dix A for a list of existing flora and fauna). ute to Alewife Brook before it joins the Mystic Anadromous fish species, namely, alewife and River. In addition, numerous drainage channels blueback herring, were once so abundant that maintain the hydrological connections among sometimes 50,000 fish were caught in one the ponds, streams, and wetlands. The wetlands catch. The Amelia Earhart Dam at Boston include shallow marshes, wooded swamps, wet Harbor continues to be an obstruction for fish meadows, and two human-made wetland types, passage but small numbers of alewife and blue- namely, stormwater detention basins and cre- back herring still manage to migrate up Alewife ated mitigation wetlands. Brook and Little River to spawn in Little Pond and Wellington Brook. Upland areas, that is, areas that lie outside the 100 year floodplain, are very limited. The only Where siltation has reduced stream depth to major upland within the Reservation is the site less than 12 inches, water temperature tends of the former MDC skating rink, northeast to be too high for many native fish species. of Little Pond. A few other locations in the Common carp, which tend to fare better un- ALEWIFE MASTER PLAN FINDINGS AND RECOMMENDATIONS 13 FIGURE 15. A series of comprehensive maps was produced to illustrate the resources at the Alewife Reservation and the Alewife Brook Greenway. This excerpt from the habitat inventory map shows habitat types and species of importance in the Alewife Reservation. der these warm, shallow, and low-water-quality The Reservation has plentiful food for preda- conditions, appear to consume most of the tors that feed on rabbits, feral cats, moles, and aquatic vegetation that does manage to grow in other small mammals. the stream channels. In contrast to the streams, the Alewife ponds have some aquatic plants Extensive stands of Phragmites (common(common reed)reed) such as pondweed, bladderwort and water and areas of thick understory shrubs and vines milfoil. Three years ago Blair Pond and Little provide extensive cover to small mammals. Pond were badly infested with the invasive Common species in the understory include water chestnut, but a concerned citizen has sumac, dogwood, speckled alder, and various controlled the problem by hand-removing the Viburnum. Bald eagles have been sighted at the plants at precisely the correct time before they Reservation, while other birds of prey appear release their seeds. Infestation is under control, to be resident. For example, a Peregrine falcon but continuing effort is needed to prevent re- has lived in the area for a number of years and infestation. at times is sighted almost daily perched on the top of the Rindge Apartment Towers during The land on the north and south banks of morning rush hour.