Lake Management Plan

Highland Lake Watershed Association Lake Management Plan

The Highland Lake Management Plan is based on recommendations made by Dr. George Knoecklein (Highland Lake Watershed Association’s (HLWA) consulting limnologist) in his 2008-2010 lake monitoring reports. Some of the data is based on records dating back to 1938; the preponderance of the data is from 1996 forward. Recommendations are divided into the major categories of 1. Lake Water Quality, 2. Aquatic Plants, 3. Inlet Streams and 4. Miscellaneous. Recommendations are listed on the basis of priority in each category.

1. Lake Water Quality
   1. Water Clarity
      1. Continue to monitor water clarity during April through November at predetermined stations in each bay;
      2. During the summer, measure water clarity at different times of the week to see if boat traffic may be causing turbidity due to shoreline erosion;
      3. Conduct shorefront inspection (during deep drawdown) to identify areas of active erosion. Note the areas and determine if there is any remedy.
   2. Dissolved Oxygen
      1. Continue to monitor dissolved oxygen from surface to lakebed, during April through November, to identify the degree of oxygen depletion and movement of the anoxic boundary. Take particular note of readings in April and November to verify that the lake oxygen is fully mixed from surface to bottom at the beginning and end of the season;
      2. Continue to collect oxygen data to determine if there is evidence that lake level drawdown and oxygen depletion are linked.
   3. Phosphorus
      1. Continue to monitor phosphorus to determine total annual watershed loading;
      2. Conduct regular phosphorus monitoring of inlet streams to identify average and ranges of incoming phosphorus loads. Rank streams that have phosphorus concentrations that exceed acceptable ranges. Prioritize streams that will require additional testing and analysis to choose method of remediation (see Inlet Streams below);
      3. Limit phosphorus fertilizers on waterfront properties and at least the first-tier homes. Send a letter to watershed property owners beyond the first tier explaining the need to reduce/eliminate phosphorus use, proper maintenance of septic systems and other important watershed management methods;
      4. Remove silt from Sucker Brook Detention Basin to restore its effective functioning (DEEP Permit needed).
   4. Other Parameters
      1. Continue monitoring temperature, conductivity, ammonia, Nitrate/Nitrite, Alkalinity and pH monthly from April through November.
2. Aquatic Plant Surveys
   1. Conduct periodic aquatic plant surveys of the whole lake to record native plant populations and spread/control of invasive species. These should be in addition to pre-post herbicide treatment surveys;
   2. Continue herbicide treatment annually for the invasive milfoils and minor naiad;
   3. Continue monitoring the potentially nuisance native species such as large-leaf pondweed, clasping-leaf pondweed, and southern naiad to determine where/how these plants can be controlled.
3. Stream Water Monitoring
   1. Develop a regular stream monitoring program to collect nutrient chemistry data from all inflow streams;
   2. Develop mean and acceptable ranges of phosphorus from each stream’s subbasin (area that drains into that stream);
   3. In stream basins where values exceed acceptable phosphorus ranges, investigate upstream areas to find causes of high nutrient loading;
   4. Stream monitoring in April should include analysis to identify changes as a result of using Ice-B-Gone for snow/ice control;
   5. Determine if other tributary streams to Highland Lake exist;
   6. Determine the path of Platt Hill Brook and adjacent intermittent stream to ensure accuracy of testing site.
4. Miscellaneous
   1. Confer with the Highland Lake Water Level Committee regarding the length of time between deep drawdowns. There is some evidence that eight-foot draws may contribute to oxygen depletion;
   2. Confer with the Highland Lake Water Level Committee regarding the analysis of “hard structures” (piers and retaining walls) to determine possible reduction in depth/length of drawdowns to reduce the chance of “mud islands”;
   3. HLWA continue Legacy Program (purchasing wooded watershed lots) to maintain as much forested open space on the watershed as possible;
   4. HLWA work with Planning and Zoning to create more protective zoning/regulations regarding tree cutting within 75 feet of the waterfront (Salisbury as model).