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Lake Oscawana Civic Association Hears Plan to Manage Phosphorus in Watershed
by Edward Paul Greiff
 | | Steve Axinn, President of LOCA, along with the map showing levels of watershed runoff into Lake Oscawana. |
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"Before we all grow too old to care we will have a restoration plan in place for this lake. I was born on this lake and I grew up on it. I swam in it in the 40's. We were underwater for hours at a time and our eyes never burned. The water was so clear that you could really see five feet underwater and you did not come out of the lake with skin rashes. You can't do that anymore in our lake. That is unacceptable," said Steve Axinn, President of LOCA (Lake Oscawana Civic Association), as he concluded the LOCA public meeting held April 26, 2008 to hear a report presented by Dr. Fred S. Lubnow.
Mr. Axinn said he sent out approximately 700 invitations inviting residents to attend Dr. Lubnow's presentation, and about 100 residents packed Putnam Valley's Town Hall this past Saturday. LOCA sponsored and paid for this milestone event, it was video taped and it will appear on channel 20.
Dr. Fred Lubnow took all of the previous research done on Lake Oscawana, added his own research and analysis, ran the results through a model and developed an outline for a proposed "Lake Oscawana Management Plan." His conclusions focused on internal and external lake restoration strategies that, when done simultaneously, achieve the maximum results in reducing phosphorus in the lake and also increase the district's chances of receiving financial grants to offset restoration costs.
In-Lake strategies for restoration he says should "seriously consider reducing the internal phosphorous load through either the installation of an aeration system or the use of alum."
A "Hypolimnetic Aeration" system Dr. Lubnow says oxygenates the deeper anoxic areas of the lake without disturbing stratification of higher and lower temperature lake waters. Basically it uses an aeration compressor unit that pulls water from the bottom to the surface where it is aerated and returned to the bottom. Oxygenating the deeper water will cause sediment particles to absorb phosphorous out of the water column thereby reducing available phosphorous.
Artificial circulation aeration, Dr. Lubnow says, prevents anoxia by disrupting stratification and maintaining a constant temperature and oxygen profile. This technique prevents oxygen depletion thereby binding phosphorous to sediment particles. It increases the numbers of zooplankton which can reduce nuisance algae blooms. Because of the uniform temperature profile, a cold water fishery cannot be maintained.
Dr. Lubnow recommends that while attacking the phosphorous problem on one front you need to also attack it on another front: aquatic plants. For nuisance aquatic plants he recommended to continue to focus on weed harvesting. Other methods, such as systemic herbicides, sterile grass carp and aquatic weevil could all be considered but input from the watershed stakeholders would be required.
A chemical such as aluminum sulfate can be used, says Dr. Lubnow. It chemically binds tightly with phosphorus and can significantly reduce the release of phosphorous from the sediments on the bottom of the lake thereby making phosphorous unavailable for algae growth. An excess of aluminum can make the waters toxic, therefore if it is used the process requires careful monitoring and testing.
Watershed strategies for stormwater need to "identify locations that may be appropriate for the installation of "Structural Best Management Practices" (BMPs) - start small!" Lubnow recommends smaller filtering and catch basin devices that can be easily installed or retrofitted into the existing stormwater infrastructure.
Watershed strategies for septic management call for a public education initiative and the passing of a mandatory "pump-out and inspection ordinance." He recommends septic pump-out at least every two years. Steve Axinn said he would locate a company that will give Lake Oscawana residents a discount.
Additional Watershed strategies call for an "aggressive public education campaign on the use of non-phosphorus fertilizers and shoreline landscaping, the preservation and protection of existing forested and wetland areas, and to make sure new development adheres to State requirements (stormwater BMP manual) and the MS4 Permit."
The restoration strategies were developed after Dr. Lubnow analyzed the sources of Lake Oscawana pollutants. What he discovered was that the external sources (surface runoff 21.9% and septic leaching 21.3%) contributed 43.2% while internal loading contributed 52.3%. Atmospheric rainfall contributed a negligible 4.0%.
Dr. Lubnow is working on a model to determine the TMDL (Total Maximum Daily Load) for Lake Oscawana, the existing and targeted phosphorus loads. With this knowledge a "Management Plan" is developed that addresses the problems in the most efficient and cost effective manner. The ultimate goal is to link the Management Plan with the TMDL. This increases chances of receiving funding for projects," says Dr. Lubnow, "additional refinements of the State's TMDL for Lake Oscawana are required."
The implementation of any lake management plan requires extensive permitting from New York State Department of Environmental Conservation (DEC).
Dr. Lubnow said he would have a proposed plan in about two weeks.
Steve Axinn said that when he gets the plan they will have another meeting like this one for public input and opinions on how they feel about funding such a costly project. He is looking at this as a project for 2010.
Dr. Fred Lubnow provided cost estimates for the various restoration methodologies he talked about in his report and they ranged from $200,000 to $300,000 to provide Hypolimnetic aeration to Lake Oscawana, or $150,000 to $250,000 plus annual operating and maintenance costs for an artificial circulation system, or $200,000 for an aluminum sulfate solution. When he submits his proposed Management Plan in about two weeks he said he would have more
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