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Summer 2001 Currents

Sediments Reveal Environmental History of Lake Quannapowitt

Contributed by Doug Heath, Vice President of the Friends of Lake Quannapowitt. (Edited for this newsletter)

Lake Quannapowitt in Wakefield (headwaters of the Saugus River) was formed in a shallow depression left by melting blocks of glacial ice over 13,000 years ago. The 250-acre lake has seen many changes in its long history. Many of those changes are recorded in the black ooze on its bottom that slowly accumulated over the eons. These sediments formed from leaves, dust, pollen, sand, silt and clay.

Recent tests of the upper three feet of the 11-foot deep sediments between Beebe Cove and the Quannapowitt Yacht Club show that for hundreds of years before Wakefield was settled, concentrations of metals and nutrients such as copper, arsenic and phosphorus in deeper (older) sediments averaged eight times less than in the 0.4 feet deposited since about 1750. Another metal, lead is now more than 35 times higher than in the past. Although all four elements occur naturally in the environment, these increases are the result of our industrial, highly-mobile society. The fuel we burn, the cars we drive and the lawns we fertilize have all contributed to these changes.

Fortunately, sediments effectively hold on to many metals and organic compounds (except for phosphorus contributing to the lake’s perennial overabundance of algae), so that concentrations in water tested appear to remain below health guidelines.

Historical documents show that Lake Quannapowitt’s excessive weeds were first noted in the late 19th century. In 1883, the Wakefield Fish Committee stated in its Annual Report that “a constantly increasing growth of water weeds seems to be filling the lake in a manner previously unobserved, interfering with both rowing and sailing... and there is no remedy known to the Committee to obviate this state of affairs.”

In 1920, the Wakefield Daily Item ran a story describing the lake as one of the two most weed-infested lakes in the northeast. The problem was further exacerbated by 20th century construction of paved surfaces and the storm drainage systems in the watershed which allow phosphorous to rapidly flow into the lake rather than remaining in the soil.

During January 2001, members of the Friends of Lake Quannapowitt bored holes in the ice and collected the first sediment cores ever taken in Lake Quannapowitt. Sediments in the cores were evaluated by a certified laboratory for phosphorus, lead, arsenic and copper levels.

Copper proved to be an effective time-marker. In an effort to control weed and algae growth, town records and newspaper articles show that thousands of pounds of copper sulfate were applied each year from 1927 through 1935, and during 1952 and 1961. As a result, copper levels rise dramatically in the upper 0.4 feet compared to deeper sediments. The impacts of leaded gasoline (which was phased out in the mid-1970s) also increase in the same interval.

Laboratory results for Lake Quannapowitt suggest a low sedimentation rate of approximately 0.3 mm/year or one inch in 85 years. This rate may have changed as a result of dam construction. For thousands of years, the lake was openly drained by the Saugus River, which flowed unimpeded to the Atlantic. Every year, millions of alewife and salmon swam upstream into the lake to spawn. However, beginning in 1646 mill dams constructed at the Saugus Iron Works began to alter the natural flow of the lake and river. In 1928, the Town of Wakefield constructed a dam at Lowell Street to further control lake levels for recreation, greatly reducing outflow into the Saugus River.

Results of sediment tests indicate that a relatively thin layer of Lake Quannapowitt’s abundant sediments has elevated levels of undesirable contaminants. High phosphorus content promotes dense algae growth year after year from internal recycling, irrespective of that contributed from stormwater runoff or ground water infiltration. Skimming off this shallow layer, if possible at some time in the future, would return the sediment to pre-industrial conditions and improve the health of the lake. It would also be far less expensive than wholesale removal, which is impracticable and costly.

Editor’s Note: In August, the Town of Wakefield issued an advisory against swimming and boating in the Hartshorne Cove area due to potential public health risks associated with contaminated sediments in Lake Quannapowitt. The studies leading up to this action were initially requested by the Friends of Lake Quannapowitt.

 

Bird Watching in the Watershed
Saugus River and the Whaling Industry
SRWC Comments
Editorial: Pollution at Henkel Site
Patrick’s Place (Wiley Street, Wakefield)
Volunteers Clean Town Line Brook
CoastSweep 2001Team SRWC
Around the Watershed
Sediments Reveal Environmental
History of Lake Quannapowitt


 

The Saugus River Watershed Council

P.O. Box 1092, Saugus Massachusetts 01906


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