. Alewife Reservation & Alewife Brook master plan. Wetlands; Wetland conservation. Following the retreat of the last glaciers 15,000 years ago, kettle ponds such as Fresh Pond and Spy Pond formed, and sands and gravels were deposited in the glacial outwash. An ancient riverbed that once ran through the area depos- ited the clays that were later mined for brick- making. Generally bedrock lies more than five feet below the surface. Most of the surface soils of the Alewife area were subsequently highly disturbed by cut and fill activities dur- ing development of the area. Most of the soils no
. Alewife Reservation & Alewife Brook master plan. Wetlands; Wetland conservation. Following the retreat of the last glaciers 15,000 years ago, kettle ponds such as Fresh Pond and Spy Pond formed, and sands and gravels were deposited in the glacial outwash. An ancient riverbed that once ran through the area depos- ited the clays that were later mined for brick- making. Generally bedrock lies more than five feet below the surface. Most of the surface soils of the Alewife area were subsequently highly disturbed by cut and fill activities dur- ing development of the area. Most of the soils now lack characteristics of naturally developed, undisturbed soils, such as defined layers and horizons, and their poor quality may serve as a constraint to FIGURE 13. View of Yates Pond from the top of the Alewife subway station. In addition to the soils, the hydrology of the Alewife area is also radically altered from its original condition. The major tributaries to 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, the meandering Alewife Brook downstream of its confluence with the Little River was straight- ened and made to flow in a concrete channel to speed drainage of water from upstream. Ur- banization in the surrounding areas decreased groundwater recharge, resulting in lower base flow. The increased stormwater runoff from the contributing watershed also causes in- creased peak flows. These sudden, high inputs of large amounts of stormwater into the
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