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algal growth. Mr. Kretchmer also shared images of lake water before and after the addition of lawn <br /> fertilizer. <br /> Sarah MacDougall discussed field studies conducted in the pond. In 2009, AECOM conducted studies <br /> regarding in lake water quality as well as nutrient content of sediment, groundwater, stormwater and <br /> cranberry.bog flood discharge. Complementary studies had also been conducted by Mashpee <br /> Environmental Coalition, the Mashpee Wampanoag Tribe, Town of Mashpee Water Quality <br /> Monitoring Program, State Department of Environmental Protection, Department of Public Health and <br /> local residents. All study results from 2009 were assessed. <br /> Ms. MacDougall discussed the dissolved oxygen and temperature, noting that because Santuit was <br /> shallow, a strong summer thermal stratification was not created resulting in a water column that was <br /> homogenized by blowing winds. In lake summer water profiles showed no major differences between <br /> the temperature and dissolved oxygen between the surface and the bottom of the pond. A slight <br /> difference occurred in the deeper part of the pond. A Sonde probe was used at the bottom of the pond <br /> which provided dissolved oxygen saturation from May 29-June 1 and depicted the larger drops in <br /> dissolved oxygen at night due to the lack of photosynthesis. The Sonde also provided information <br /> about dissolved oxygen relative to average wind speed and a chart noted the lowest concentration of <br /> oxygen occurring during low wind events. Live organisms and fish require a minimum amount of <br /> oxygen in the water and low oxygen conditions would result in a release of phosphorus from the <br /> sediment. Ms. MacDougall also shared a chart depicting some water quality results and noted that <br /> major indicators of nutrient status were Total Phosphorus and Chlorophyll A. Data has shown that the <br /> pond was extremely eutrophic and extremely nutrient rich. AECOM also conducted sediment <br /> sampling in four locations, three of which were in the soft mucky sediment and one sampling in the <br /> sandy landing. The samples were analyzed to determine the types of phosphorus present, such as <br /> loosely absorbed phosphorus and iron bound phosphorus. It was determined that the town landing <br /> does not have a high phosphorus concentration but the mucky sediments have large concentrations of <br /> available phosphorus, with the potential of being released under low oxygen conditions. Porewater <br /> samplers and seepage meters were also utilized to check data on groundwater quality and quantity. <br /> Other than the Timberlane Drive neighborhood, inorganic nitrogen levels were within natural range. <br /> Wet weather sampling was conducted and it was noted that the Timberlane Drive stormwater <br /> improvements were effective and prevented the sheetflow from directly entering the pond. High <br /> phosphorus concentrations were present in the runoff. Regarding two rounds of cranberry bog flood <br /> discharge samplings, Ms. MacDougall stated that, overall, the bogs did not contribute a large portion to <br /> the nutrient budget, although it was a source that should be addressed. The aquatic plant survey <br /> indicated a dramatic shift from previous historical surveys. <br /> Overall, Ms. MacDougall stated that records from 1948 indicated a well oxygenated pond that began to <br /> decline in the 1980s, although the pond was still dominated by macrophytes and aquatic plant growth. <br /> The water quality declined in 2000 with higher concentrations of Chlorophyll A, sparse plant growth <br /> and extensive algal growth. The largest source of phosphorus, responsible for the increasing algal <br /> growth, was found in the bottom sediment and totaled 78% of the phosphorus load. Additional sources <br /> included water fowl(1%), direct precipitation, septic systems, cranberry bogs, surface runoff and <br /> groundwater totaling 3%-5%of the phosphorus budget. The current total average in-lake phosphorus <br /> concentration has been calculated to be 80 micrograms per liter, which presents a 97% chance of an <br /> algal bloom. <br /> In order to meet designated uses of the pond, such as swimming and recreation, an in-lake target would <br /> be needed in order to move toward the goal of infrequent algal blooms. Achievement of an in-lake <br /> phosphorus concentration of 15 micrograms per liter would offer a 1% probability of an algal bloom. <br /> 3 <br />