When I think of half a century of time, it feels like a very long period that is packed with many changes. As the Highland Lake Watershed Association (HLWA) continues to celebrate its 50th year as an organization, it occurs to me it has “matured” in fulfilling its primary purpose of preserving and protecting Highland Lake. The HLWA has a larger membership, more complete understanding of lake management practices, and has brought about some significant changes in the Town of Winchester. One change occurred in 1989 when the Planning and Zoning Commission responded to HLWA’s concerns about growth and development on the watershed. The Winchester Planning and Zoning Commission passed a new regulation forming the Highland Lake District. Today this district has more stringent regulations for side and front/backyard setbacks and lot coverage that is consistent with Best Management Practices for watershed land use.

In 1996, the HLWA Water Quality Committee was begun and assumed the responsibility of developing a Water Quality Testing and Monitoring Program that would help us chart the health of the lake. Since 1996, the committee has continued an uninterrupted collection of data on the lake water oxygen content, temperature, phosphorous, total nitrogen, conductivity, salinity and pH. This information has been charted and saved for continual reference and analysis. This past year I asked the HLWA Board of Directors to approve the hiring of Dr. George Knoecklein, a professional limnologist (lake scientist), to collect further data from the streams that flow into Highland Lake and analyze the information so we can set goals and tasks for maintaining and improving our lake water quality.

Those of you who attended the annual meeting heard Dr. Knoecklein explain two important conditions he believes are significant changes in the water quality of our lake. First, water testing results indicate a trend of less oxygen in the water, particularly as the summer progresses into late August and September. Less than 1 milligram of oxygen per liter of water is scientifically termed “oxygen depletion”; most aquatic plants and animals cannot live in water with this little oxygen. The oxygen in lake water is consumed by dying and decaying plants, leaves and animal life. Over the past 70+ years, Highland Lake’s oxygen content has gone from having oxygen depletion at 62 feet deep (1937) to 25 feet deep in 2009. In other words, by late summer our lake water has zero or almost zero oxygen from the lake bottom up 25 feet from the bottom. This area is termed the “anoxic boundary.” Fish such as the brown trout that the State Department of Environmental Protection (DEP) stocks in Highland Lake cannot survive in water with less than 4 milligrams of oxygen per liter. Trout also need cold water, and the water temperature from the surface down to 25 feet is too warm by late summer. The fish are being squeezed into a very narrow band of water that will support their survival. We are monitoring this condition very carefully and have notified the DEP Fisheries Department. This is a clear indicator our lake has “aged” significantly in the past 70 years.

What can we do? Watershed property owners must be very careful not to put fertilizers with phosphates on their yards! The more phosphate on your yard, the more it leaches into the lake and feeds the weeds. The weeds die in the fall, drop to the bottom of the lake, decay and consume our precious oxygen. You can also rake leaves frequently to keep them from blowing into the lake since they too decay and consume oxygen. Please do not throw any vegetation (weeds, plants, grass clippings) into the lake. Remove fallen trees or branches.

If you believe you must use fertilizer to maintain your lawn, please have your soil tested so you know what kind and quantity you need. Use no phosphate fertilizer only!! Organic fertilizer is preferable as it is more readily absorbed by grass, plants and trees before draining down through your soil and into the lake (even under retaining walls). When you mow your grass, leave the clippings to decay on your yard; they make a wonderful natural fertilizer.

Cut down the size of your lawn; use ground covers that don’t need fertilizer or cutting. They are a win-win alternative! Plant a buffer garden along your retaining wall; plants will absorb some nutrient runoff before the phosphates and nitrates can enter the lake. Native shrubs such as laurel don’t need fertilizer or pesticides; they grow here naturally.

This fall we will have a deep winter drawdown (8 feet down) starting October 15. Please plan to remove your boat or dock so it doesn’t get stuck in the mud! The drawdown serves two purposes. First, we hope nature will cooperate to allow drying and freezing of the invasive milfoil, so we will have less to treat with Diquat next spring. Second, the drawdown will provide an opportunity for you to repair retaining walls and piers. If doing any significant activity, a permit from Inland Wetlands is required. During the drawdown, you can also pull out weeds in front of your property. Please bag them and take them to the landfill so the decayed weeds will not leach phosphates back into the lake.

I wish oxygen was the only thing we have to monitor to maintain good water quality. However, phosphorous is another very important ingredient in maintaining good water quality. The complex part is phosphates are trapped in soil in the bottom of the lake. If the land is not properly protected, during storms a lot of soil erodes into the lake from the many streams that flow off our hillsides and off your property - through the 88+ storm drains around the lake. Phosphorous is also released from soil during construction or digging in the soil even during minor projects. Although hay bales and silt fences, as required by the Inland Wetlands and Watercourses Commission, help contain soil and phosphates, the phosphates are still released with that disturbance, percolate down through the earth, and are carried into the lake by underground water.

Finally, there is a relationship between “oxygen depletion” and phosphorous. As the oxygen in the lake water gets depleted, phosphorous in the soil at the bottom of the lake gets released. This sets up a cycle of what is scientifically called “phosphorous loading.” Having little or no oxygen in the bottom of our lake is adding a significant amount of phosphorous that is released into the water through this process. As the phosphorous loading continues, relatively undetected, it can reach a threshold that can support an algae bloom and our lake will turn green! When Dr. Knoecklein was asked if an event at Highland Lake that increased phosphorous could bring us to that threshold, he replied the lake “could very easily be pushed over the edge.” Algae-laden lakes are very undesirable; algae can be toxic and unsafe to recreate in, and it can have a pungent odor. When that happens, property values drop dramatically and everyone suffers.