Wildflower Preserve Water Quality Initiatives

Water sampling data has shown that three of the Wildflower Preserve ponds have very high levels of total phosphorous, nitrogen, and chlorophyll.  Pond 1 has by far the highest readings.  The high nutrient levels in Pond 1 are believed to be directly linked to the fact that this pond received treated sewage effluent during the time that Wildflower operated as a golf course (and for several years after the course was closed).

As the Wildflower pond system was designed, when water levels in the ponds rise, pond 1 feeds excess water to pond 2, which in turn feeds pond 3.  Excess water from pond 3 flows thru pipes and a drainage creek into Lemon Creek.  Lemon Creek connects into Lemon  Bay.

Thanks to Charlotte Harbor National Estuary Program (CHNEP) grant funding, Lemon Bay Conservancy volunteers have initiated water quality initiatives at Wildflower Preserve that focus on Pond 1, the pond with the highest nutrient loads and the pond that is “upstream” of other elements of the preserve water drainage network.  Watch a video about our water quality initiatives:

Duckweed Pond and Diaphragm Pump

Duckweed Pond and Diaphragm Pump

Duckweed Harvesting:  Pond 1 is covered by a heavy mat of duckweed.  Research at North Carolina State and at other venues has shown that duckweed plants contain very high nutrient levels.  Duckweed also grows very quickly.  By “harvesting” the duckweed on a periodic basis, removing the plants from the water body, we have the potential to significantly reduce the phosphorous and nitrogen levels in the pond as we will be removing the nutrients which have been taken up by the duckweed.

Duckweed Pond is about 100’ wide by 235’ long.  To concentrate the duckweed at one end of the pond, we start by using two volunteers in kayaks on either side of the 100’ width of the pond.  The volunteers use a custom-made net (120’ long by 1.5’ deep) to pull the duckweed to one end of the pond.

Volunteers removing Duckweed

Volunteers removing Duckweed

With the duckweed collected in a thick, floating mat at one end of the pond, we float the end of a diaphragm “trash” pump intake hose just below the water’s surface to collect the duckweed.  The outflow hose from the pump is placed into a wooden frame. Periodically, as the frame fills with duckweed, flat-end shovels are used to remove the duckweed from the frame.

In  addition to the pump, our volunteers use fine mesh nets to scoop duckweed from the pond and empty it into buckets.  Other volunteers carry the buckets to the drying area and empty them.

We place the duckweed on large sections of screening and landscape cloth near the pond to allow it to dry out.  We plan to move some of the duckweed to our butterfly habitat to use it for mulch and fertilizer.  We are also talking to local gardeners and garden clubs about experimenting with uses for the duckweed.

Volunteers planting floating islands

Volunteers planting floating islands

Floating Plant Islands:  In a second initiative, we are using floating island systems from Beemats, a company based in New Smyrna Beach, to remove additional nutrients in Pond 1.  Because the pond has high, steep sides, shoreline plantings to help reduce nutrients are not possible without significant land re-contouring.

The Beemats system uses floating mats to place native plants into the pond where they not only absorb nutrients, but also provide habitat for wildlife and fish.  Once the plants grow, they will be harvested and replaced with new plantings to remove the nutrients captured by the plants from the pond.

In February 2013, our volunteers worked with Forest Beeman, owner of Beemats, to install two 100’ square foot floating islands.  As of early June 2013, the plants on the islands are growing rapidly in the very high nutrient conditions in Pond 1 and we anticipate that we may be able to harvest them twice per year, rather than on the annual cycle that was originally planned.

Solar aerator

Solar aerator

Solar Pond Aeration:  As we reduce the duckweed cover on the pond, we anticipate increased algae growth, which can lead to very low oxygen levels in the pond.  The purpose of the aeration system is to add dissolved oxygen into the water column and help improve overall pond health.

We do not have electrical power available at Duckweed Pond, so we used grant funding to purchase a solar pond aeration system.  Our volunteers installed the solar aerator in February 2013.  The solar panels charge 12-volt batteries that allow the aerator to run 24 hours a day.

Lemon Bay Conservancy thanks the Charlotte Harbor National Estuary Program for providing the grant funding for all of these initiatives!

To learn more about our ongoing Water Sampling program, click here.