Hopatcong Crescent Cove – Testing Proves Major Improvements using Aeration for HAB Reduction

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Lake Hopatcong has undergone multiple pilot projects over the summer of 2020 to help reduce HABs as funded partially by the NJDEP Grant Programs, as pledged by Gov. Murphy after the Visit to Lake Hopatcong in 2019 at the height of the HAB outbreak on the lake.

What is different about the Crescent Cove project is that this was the only project that came from one of the towns. Hopatcong Mayor Francis spent last Winter visiting Trenton, developing a strategy, reviewing possible solutions, and visiting other lakes to create the final DEP proposal. Everything was completed by the Mayor, without a cost to the taxpayers.

Background of the Crescent Cove Project:

thumbnail Cresent Before 1Hopatcong Mayor Francis purposely targeted the Crescent Cove area of Lake Hopatcong, due to water currents and other factors, it has been named as the most impaired areas of the lake, where the HAB count levels were the highest throughout 2019. As a result of the Grant Application Hopatcong received $145,000 to start the first phase of the proposed project. The Mayor is still working with the DEP to gain permission and funding for the second phase of the project.

After a long investigative process by the Mayor into EverBlue Lake Systems, visits to similar lakes under the company’s management, the Mayor and EverBlue developed a Grant Proposal in 2019 for DEP funding.

To develop the full DEP proposal and to better understand the problems within the cove, EverBlue conducted a free assessment of Crescent Cove that focused on many different areas:

  1. Understanding the Lake as an entire ecosystem
  2. Studying the Lake data for the last 10 years
  3. Gained a full understanding of the water currents within the lake
  4. Performed depth profiling mapping within the Crescent Cove area
  5. Studying the HAB and other algae information first-hand as it was occurring in 2019

grants icon 9Read the two final DEP Submissions:

Implementation of the Crescent Cove Project:

Crescent Cove MapThe model and design for Crescent Cove is a fine defused bubble aeration system that is the first step to creating an environment within the cove that would allow for the digestion and reduction of the fertilizers and nutrients that are driving the algae and weed growth in that area. As part of the plan, 38 diffusers and 31,000 feet of the airline were installed in Crescent Cove.

According to John Tucci, CEO, and Founder of EverBlue Lake Systems.

“Our design concept for Crescent Cove needed to be overly aggressive with higher than the normal points for aeration. The volume of air was greatly increased to nearly 2CFM per acre. These changes made to the standard model help with the amount of circulation that is needed to be generated to start returning positive results. The aeration system will be completely turning over the water 1.5 times a day, where it only happens twice a year in most lakes.”

At the mouth of Crescent Cove, EverBlue designed an aeration curtain that may not fully stop the inflow of unwanted material from the rest of the lake, but it will utilize the wind and current that blows toward the back of the cove to move the aeration effects further back into the cove.

Testing Results within Crescent Cove:

Testing costs were not approved by the NJDEP, so EverBlue Lakes agreed to provide sampling and analysis services on the project as an in-kind service at no cost to the Borough or the State DEP.

 Crescent Cove 2020 Testing Results Chart

See the full Testing Report

Analysis included:

  • Total Phosphorus
  • Ortho Phosphate
  • Nitrate
  • Nitrite
  • Algal Community Composition

Across the multiple locations within the cove, samples were taken at the surface, middle of the water column ~3.5 to 4’ and within 1 foot from the bottom.

Crescent Cove 2020 Testing ResultsThe data shows a decreasing trend of Total Phosphorus in both the Treatment Area and the Control Area with the Treatment Area experiencing a faster drop in the 30 days following system turn-on. While a half-season is not enough data for definitive conclusions, preliminary conclusions include:

  • There is no evidence that the aeration system is increasing Total Phosphorus through resuspending sediments and nutrients from the bottom sediments. This is a common concern often raised by Lake Scientists regarding bottom-diffused aeration.
  • There is a correlation between rapidly reduced Total Phosphorus in the Treatment Area and the start-up of Aeration. This is also occurring in the Control Area. This may be a natural pattern for parts or all of Lake Hopatcong. However, since Crescent Cove is consistently regarded as the most impaired area of Lake Hopatcong with water quality far worse than the main body of the lake, it is reasonable to draw the preliminary conclusion that the Aeration System delivered a positive treatment effect on reducing Total Phosphorus in Crescent Cove.

Recommended Changes for Crescent Cove in 2021:

The implementation of the Aeration System in Crescent Cover correlates to decreased Phosphorus levels, while blue-green algae levels largely remaining under “Watch Levels” for the majority of Crescent Cove.

Residents and Borough Officials report significantly better conditions for weed growth and algae growth in Crescent Cove as compared to prior seasons.

Now that EverBlue Lakes is aware that we are responsible for the primary data capture and analysis for the project, we are planning to make the following changes for 2021.

Testing Methodology:

  • Data capture at each of the water quality site locations at least once per month.
  • Data capture at sediment sampling sites in May of 2021 and October of 2021 will include the Control Site outside the Treatment area.
  • A switch from algal cell counts to blue-green algae in-situ fluorometer readings to resolve any issues with differing cell count standards and counting methods.
  • Inclusion of temperature, dissolved oxygen readings, and Secchi Disk readings in the Treatment Zone and Control site.

About EverBlue Lakes Systems:

EverBlue Lakes was selected for this project based on extensive due diligence on the part of the Borough of Hopatcong which researched over several months into viable in-lake solutions to HABs.

EverBlue Lakes has installed and manages more large lake aeration systems than any firm in the United States and over more than a decade has become the leader in natural, non-chemical solutions for lake restoration. EverBlue Lakes patented Lake Aeration Technology has been proven to deliver the benefits reported in the scientific literature that have confirmed that aeration/circulation, when done properly can prevent and inhibit the development of HABs. More than a decade of independent scientific assessment has confirmed the effectiveness of EverBlue Lakes aeration design model and technology.

“EverBlue Lakes maintains a fully staffed location within 90 minutes of Lake Hopatcong. We have the manpower and equipment to fully maintain and monitor the proposed Aeration System and successfully deploy the BioBlast Treatment for the duration of the project.” EverBlue acknowledges that this project was a true partnership with the Borough of Hopatcong as the DPW, Water Authority Works helped with multiple areas of the project as well as the local marinas that greatly helped launch the project.


 

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