b'Another important source of nitrogen is the atmosphere, which is polluted by auto exhaust and smokestack emissions from power plants and heavy industry.These contaminants travel from as far away as the Midwest or as nearby as the local power plant. While atmospheric deposition may contribute up to 60% of the annual nitrogen pollution in an estuary, it is difficult for us to control.Fertilizers used on lawns, gardens and golf courses are also sources of nitrogen. If too much is applied or if the ground is heavily irrigated after being fertilized, the nitrogen will dissolve in the water and travel beyond the reach of the grass roots and into the groundwater.The breakdown of nitrogen sources for Little Mill Pond is typi- cal of the proportions found in other Chatham embayments.Water quality of estuaries due to nutrient loading has been assessed by the Chatham Water Watchers in support of the Massachusetts Estuaries Project. A simple summary of the data is shown in the Figure on the opposite page.Phosphorus, Another Nutrient, Aff ects Our Freshwater PondsProtecting our ponds water quality is of prime importance to maintain these ecosystems.Development and land use can impact the water quality by introducing pollutants from septic systems, lawns and storm-water discharges into the water or onto pond edges.In freshwater bodies, phosphorus is the critical nutrient.As phosphorus from various sources enters a freshwater system, plant growth is stimulated, and if excessive, eutrophication occurs.Phosphorus sources include wastewater, street runoff , and soil erosion.Phosphorus has been removed from laundry detergents but is still found in many automatic dishwasher detergents.It is usually wastewater systems within a few hundred feet of the pond that are the primary phosphorus sources.Because phosphorus, unlike nitrogen, is actively bound up in the soil, the eff ects of phosphorus on freshwater systems can be minimized by setback requirements for septic systems. Establishment of natural vegetated buff ers around pond shorelines is an important tool in protecting the water quality of our many ponds.In 1998, the towns Water Quality Laboratory initiated a pond monitoring program.The intent of the program is to deter-mine the current status of the major ponds in Chatham, provide data to support pond management initiatives, and to provide long-term monitoring.Though there is limited information concerning the water quality in the ponds, many are showing signs of impact to varying degree, with Lovers Lake and Stillwater Pond considered highly degraded.The program is focusing on the Great Ponds and Black Pond-east due to the proximity of the golf course.Bacteria Are Harmful To Our HealthBacterial contamination poses a constant threat to swimming areas and shellfi sh beds.Cockle Cove Creek has been closed to swimming for several years due to high bacterial readings, primarily from natural sources.The form of bacteria associated with beach closing is enterrococci, commonly found in the fecal material of warm-blooded animals, including humans.Most enter-rococcibacteria is believed to enter water bodies via storm water runoffor from natural sources (wildlife/waterfowl) rather than septic systems.Increased boating activities associated with accelerated growth has also contributed to local coastal pollution through sources such as outboard motor combustion, boat sewage discharge and fueling spills.Many of these discharges contain nitrogen and most include bacterial as well.Coastal waters have been degraded to the point where some shellfi sh areas are closed to shell- fi shing on a seasonal basis every year.These seasonal closures are most commonly the result of natural conditions, including increased water temperatures that prolong bacterial survival and increased wildlife/waterfowl activity.Examples of seasonal shellfi sh closures in Chatham include Bucks Creek, Mill Creek and Oyster Pond.Recent eff orts to manage storm water runoffinto Oyster Pond have resulted in the reopening of approximately 12 acres of the Pond, on a seasonal basis, that had been closed year-round since the mid 1980s. Page 17bluepages.indd 17 8/26/2009 1:49:46 PM'