News: Spring 2009 |
For past articles, see News Archives. |
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Lake-Friendly Lawn Care: Use Zero Phosphorus Fertilizer
Phosphorus does not break down well in soil thus it ends up in the groundwater that flows into the lake. Because Waramaug is already phosphorus nutrient rich (which causes excessive algae and aquatic weed growth) we strongly discourage use of lawn fertilizers near the lake.
...we strongly discourage use of lawn fertilizers... |
The Kent Greenhouse has stocked a zero phosphate fertilizer and South Farms Nursery in Goshen carries a good line of organic products (North Country Organics). Also look for Scotts Champion 13-0-44 Potassium Plus or Greenview 27-0-12. Look at Lawn to Lake for more tips.
Consider adding native plants to your lawn area. For ideas, please visit our buffer planting at 149 West Shore Road. After four years, it has become a natural looking country landscape, doing its job as a native habitat for many insect and bird species, filtering runoff and preventing erosion. A list of the plant materials used there can be found in a box at the site, or you can download a PDF of the list of plants.
Lake Saving Lawn Care Practices:
- Consider smaller lawns with shrub borders or native plantings to replace the lawn area.
- Choose grass and/or groundcover that minimizes maintenance, fertilizer and pesticide application.
- Consider allowing natural vegetation to reestablish itself.
- Water infrequently but thoroughly.
- Mow only when necessary -- the ideal height for healthy grass is 2.5 to 3 inches.
- Use non-motorized lawn mowers for small lawns.
- Leave grass clippings on the lawn.
- Avoid using fertilizers and broadleaf herbicides.
- Pull weeds by hand in small yards.
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2008 Monitoring Report Shows Positive Results
Dr. Robert Kortmann, the Task Force's lead scientist, has delivered a detailed monitoring report for 2008 which shows encouraging results in several areas including water clarity, phosphorous, oxygen and algae. In addition, the Layer Aeration Systems appeared to operate effectively in 2008 despite delayed activation due to the Washington Boat Launch construction.A summary of the Dr. Kortmann's report follows:
Lake Waramaug - Summary Report 2008
Prepared for: Lake Waramaug Task Force
Prepared by: Robert W. Kortmann, Ph.D.
Ecosystem Consulting Service, Inc. February, 2009
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Secchi disk transparency between Memorial Day and Labor Day (a measure of water clarity and light penetration) was the best recorded since management and monitoring began in the late 1970's. A modest fall algae bloom did result in reduced clarity and dying algae caused some floating algae scum. (See charts at right.)
Oxygen Levels
The annual spring Diatom maximum was very productive in April 2008, resulting in very high dissolved oxygen saturation (up to 174%). When the Diatom population crashed in late May a "clear water phase" followed, and persisted for much of the summer. Dissolved oxygen remained at 6m through the summer, which sustained mid-depth habitat. A strong thermocline established at 5m, and descended in late summer.
As has been observed in prior years, oxygen loss ascends higher in the water column in more shallow areas of the lake (primarily due to proximity to the bottom and high sediment oxygen demand).
Phosphorus Levels
Total phosphorus concentrations remained relatively low, with a spring concentration of 21 ppb and summer concentrations between 14-20 ppb in surface water, setting the stage for "mesotrophic conditions". Nitrate-N was consumed early (typical) which favors N-fixing bluegreen algae.
Algae Report
Bluegreen algae remain the dominant phytoplankton group, especially N-fixing species.
Although bluegreen algae were dominant, the species that are most likely to cause nuisance blooms (Anabaena and Aphanizomenom) were not dominant most of the summer.
Phytoplankton densities have remained relatively low since 2000, and Diatoms have become more dominant during winter and spring.
Green algae have gained a greater fraction of the total phytoplankton since 2004, suggesting they are beginning to compete with the bluegreens. During the past two years green algae have reached 30% of the phytoplankton community. Total density has decreased, % Greens has increased.
Zooplankton Levels
Large-bodied Cladocera peaked in June (due to abundant Diatoms and Greens as a food resource. Although a larger population of these herbivorous animals ("algae eaters") is desirable the population is persisting and is able to respond to availability of food resources.
Layer Aeration System Operation
The Layer Aeration System in the deep basin of Lake Waramaug was activated somewhat later than normal due to delays in completing the new boat launch facility. However, the system was quite effective in 2008 (in combination with greater light penetration and resulting deeper photosynthetic oxygen production). The two Layer Aerators are set to function at somewhat different depth ranges. In June it was noted that most airflow was to the aerator closest to the compressor at the Washington town beach. This aerator functions in the 4.5-7 m depth range. Water clarity was very good at the time and the airflow was intentionally left alone ("If it isn't broken, don't try to fix it"). That was intended to manage the mid-depth layer more intensively. The approach was successful.
Past Newsletter Articles are available from the archives.
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