Lakes and Wetlands in Pelican Landing | 02/14/2013
Pelican Landing residents enjoy 91 lakes and 40 wetland areas that provide habitat for birds, ducks, fish, turtles, otters, alligators and other wildlife, floodwater management, and a source of water for irrigation.
Lakes or Ponds - Most of the "lakes" in Pelican Landing are actually storm water wet detention ponds. The system of ponds or storm water management system was designed by the developer of the Pelican Landing and permitted by Southwest Florida Water Management District (SWFWMD) and Lee County.
Storm water detention ponds reduce flooding during high water periods and they play an important role by trapping sediments and other large solids carried by run-off from roads, parking lots and lawns. In addition to sediments, storm water ponds also collect a number of other pollutants such as bacteria, oils, fertilizers, heavy metals and organic contaminants such as animal wastes, pesticides and herbicides. Stagnant water allows heavier contaminants, such as solids or metals, to sink to the bottom of the pond and eventually become bottom layer sediment. The retained water or clean water is passed on to nearby streams or wetlands.
Nutrients from storm water runoff can seep into the water and provide food for unwanted plants, like algae. Excessive algal growth can lead to decreased oxygen in the water needed by fish to breathe, resulting in fish kills. Bacteria and other pathogens from pet waste can create health hazards in ponds.
Littoral Shelves - By design and regulation, newer ponds contain littoral shelves, which are shallow areas within the pond. Littoral shelves provide emergent aquatic vegetation appropriate water depth necessary to thrive and compete with algae for space, light and nutrients as well as filter out pollutants such as heavy metals, oils and fertilizers. The littoral shelf also prevents lake bank erosion and provides a rich habitat for wildlife. Littoral shelves are usually 1-2 feet in depth and occupy up to 30% of the entire surface area of the pond.
An unplanted littoral shelf or one that is sparsely covered by vegetation will regularly make algae blooms worse. In the deeper areas of a pond, water depths deprive algae the benefit of full sunlight needed to grow algae; but in an area that is just a few feet deep such as a littoral shelf, the algae have the benefit of full, consistent sunlight. In these shallow areas, algae can grow rapidly. The thicker and denser the littoral vegetation, the less sunlight, living space and nutrients will be available for algae growth. If managed properly, ponds and littoral shelves can provide an aesthetically pleasing and healthy habitat for a wide variety of wildlife; including insects, fish, birds and turtles.
The older lakes that are mostly near the original Pelican Landing golf course, and lakes in more mature communities, do not have littoral shelves or vegetation near the lake bank and are unable to absorb excessive nutrients from fertilizer and pollutants in the water.
Littoral Plants - Lee County requires that:
- Plants growing on the littoral shelf must be selected based upon expected water level fluctuations and maximum water depths;
- The shelf must be planted with at least 4 native species;
- 85% of these plants must survive and they must cover a minimum of 85% of the surface area of the littoral shelf;
- Exotic or nuisance species must stay below 15%; and
- Regular maintenance be provided to control native nuisance plants, which can overpopulate and crowd out native species.
The following is a limited list of commercially available native trees and shrubs acceptable to meet Lee County's requirement for Littoral Plants. It is by no means a complete listing of acceptable species.
3" below normal water leve 1
2" - 24" below normal water level
3" - 12" below normal water level
24" - 36" below normal water level
Fragrant Water Lily
Algae - Excess nutrients in the water combined with warm, sunny weather, will cause algae to grow rapidly and produce an algae bloom. Algae are primitive plants with no true leaves, stems or root systems. Many creatures in the pond use algae as food. Algae is natural and does help break down the nutrients in the pond, however, too much algae may cause problems. Plants need sunlight to grow. When algae cover the surface of the pond, it reduces the amount of light to other plants that live in the water or on the bottom of the pond. This can prevent many native plants from growing and reduce the viability of the pond ecosystem. Algae can also lead to a variety of problems such as:
- Blue-green algae can cause illness and some fatalities in pets, livestock and wildlife,
- Exposure to or ingestion of blue-green algae can also lead to a variety of human discomforts,
- Algae contamination can discolor drinking water and create unpleasant odors and tastes,
- Excessive algae growth can also impart distasteful flavor to fish,
- Algae decomposition can deplete oxygen in bodies of water and kill fish,
- Excessive algae growth can quickly change lakes, ponds, lagoons and shorelines from scenic to unsightly.
Once littoral shelves become successful and sufficient plant coverage is reached, algae growth is greatly decreased. Installed plants cover the surface of the water and block sunlight, which prevents algae growth. Some communities stock their lakes with Tilapia, an algae eating fish.
The CDD's use several different options to help control algae blooms and submerged vegetation. Sometimes to treat algae blooms and aquatic weeds, the CDD's use a certified lake maintenance contractor who is certified to apply approved chemicals. In some ponds without littoral selves the CDD's can use biological solutions such as Triploid Carp. The CDD's also use other methods such as rakes, various aeration devices, and beneficial bacteria/microbes to control algae and aquatic weeds. However, the best method is educating the community to help prevent nutrients, such as fertilizers from ever entering the ponds.
The most effective form of biological control is use of the herbivorous fish, the Triploid Grass Carp. These carp are sterile, so they will not reproduce but they do grow rapidly and can live for at least 10 years. Their diet consists almost entirely of aquatic plants including many types of submerged vegetation. However, they are not effective for the control of bulrush, filamentous algae, water lilies or cattails. Grass carp usually take six months to one year to be effective in reducing problem vegetation and will go dormant during the winter when water temperatures dip below 70 degrees. The Southwest Florida Water Management District (SWFWMD), the agency responsible for managing the area's storm water system, only permit grass carp in ponds without a littoral shelf. The downside to carp is that they eat both the undesirable plants and beneficial plants.
The CDD has a permit that was issued some years ago to stock 12 lakes with grass carp. Seven of the 12 could benefit from grass carp so 150 carp were purchased in 2011 to stock the 7 lakes. The fish barriers were checked to prevent any migration from one lake to another. The carp were released on April 14th, 2011, and are in lakes A-1, A-2, A-6, A-7, A-8, A-10 and A-13.
Weeds - By definition, a weed is "a plant growing out of place." Plants can benefit a pond, but they become "weeds" by growing out of control or in areas where they interfere with pond use. An excess "bad vs. good" plant growth can create a variety of problems including stunted fish populations, mosquito growth, foul odor, and clogged irrigation pipes. Many aquatic weeds are of little value as a food source or habitat structure so ridding ponds of invasive species allows nature to restore native plants to support the fish and wildlife.
Many of what some consider to be weeds are actually beneficial plants. This is often the case with Spikerush. It is the policy of the CDD's not to remove any beneficial shoreline plants. The proper plants will prevent shoreline soil erosion and help to prevent flooding by slowing down the flow of storm water run-off during major rain events. Aquatic plants pump oxygen into the water and create habitats by providing cover and nurseries for fish and other organisms. More importantly, vegetated shorelines improve the water quality by filtering polluted runoff and trapping sediments.
The Irrigation System - Single family, multi-family, and most tower buildings in Pelican Landing receive potable water from Bonita Springs Utilities, and nonpotable or irrigation water from either the Bay Creek or Bayside Improvement Community Development Districts (the CDD's). Almost all properties have two water meters and receive two water bills.
Irrigation water is pumped into the irrigation system from the big lake just South of the Central Gate and from a smaller lake with the big fountain just South of the South Gate. These "irrigation" lakes receive water from lakes and wetlands throughout Pelican Landing if the water level is high enough to flow from one lake to another. When the lake levels are lower and there is no flow between lakes, the "irrigation" lakes receive well water from a series of "permitted" water wells along Walden Center Drive and North Commons Drive, and a series of water wells along Greenview Avenue. Water is pumped from the irrigation lakes throughout the community to irrigate lawns, common landscaped areas, and sections of the golf courses.
While the "irrigation" ponds may be replenished with well water, it is not permitted to fill storm water wet detention ponds. While everyone wants their pond to look aesthetically pleasing, these ponds were designed as part of a storm water system by managing the runoff from rainfall. A storm water pond is specifically designed to help prevent flooding and remove pollutants from the water. Adding water to a pond can cause flooding by interfering with the pond's design and ability to hold storm water runoff.
Aeration Devices and Fountains - Aeration exposes water to air, where it absorbs oxygen. In a healthy pond, when plants and fish die off, their remains fall to the bottom, and beneficial bacteria break down the waste. But algae forms when oxygen levels decline, coating the water's surface and denying plants and fish the oxygen and sunlight needed for survival. Aeration uses the power of water, air or machinery to force both oxygen-depleted water and waste to the pond's surface, where gases are released and oxygen is absorbed, thus allowing beneficial bacteria to thrive, and depleting algae's food source. When algae disappear, fish and plant life can flourish. Surprisingly, fountains are not considered to be effective aeration devices and fountains disrupt wildlife and fish.
Water Quality - Water quality varies from lake to lake and from well to well. An analysis of the water quality in 11 Pelican Landing lakes or technically called wet detention ponds "shows that all the ponds are eutropic (nutrient enriched) while some being at times hypereutropic (highly nutrient enriched, e.g. pond A2 between Bay Cedar and the golf course).
Pond water pH and hardness are very high because it is very likely buffered by calcium carbonates. Such water hardness will select algae and plants, which tend to thrive in hardwater. Such plants e.g. Utricularia sp.(common and collectively called bladderworts that are cultivated for their flowers, which are often compared with those of snapdragons and ordhids) and bottom brown algae (at times sloughing) mats have been reported. "Water dominated by bicarbonates and carbonates also tend to select blue green phytoplanktonic algae as well as, calcareous algae mats growing on the pond's shallowest portions." "Water chlorinity converted into salinity units shows that 9 of 11 ponds tested are not fresh water while only 2 of the 11 ponds are clearly fresh water ponds in the subsurface."
Eutrophication - is the natural aging process of a pond. Residents ask, we haven't had problems with our pond in the past; what has changed? A pond begins as a well-balanced ecosystem of plants, fish and invertebrates. Over time, however, watershed run-off often produces nutrient overload, which can contribute to an overabundance of vegetation, reduce invertebrates and crowd out fish populations.
Green water or "scum" on the top of your water can be any of several things: duckweed, watermeal, or algae. Frequently these are mistaken for each other. Duckweed are very small floating leaves with a small root while watermeal resembles green sand. Filamentous algae form dense mats that float on top of the water and planktonic, or blue-green algae, give water a 'pea soup' consistency.
Responsibility - The Bay Creek and Bayside Community Development Districts (CDD) are responsible for managing and maintaining the storm water wet detention ponds and wetlands in Pelican Landing. These two districts are managed by a professional CDD management company, and supervised by two Boards of Supervisors elected from and by the residents. Pond and wetland maintenance are currently contracted to two certified lake maintenance contractors.
The Future - In 2010 the CDD's began testing water quality in eight ponds, and the $1500 monthly program was increased to eleven ponds. In the fall of 2012, the CDD contracted with the Southwest Florida Aquatic Ecology Group at FGCU for a Health assessment of Pelican Landing ponds. The objective of this contract is to assess the ecology of each pond within the various watersheds identified on the property.
Subsequently, the CDD's will consider a contract with FGCU to identify and pool the ponds, which behave in a similar fashion into groups. Each group will then receive different experimental management treatments. With that information, the best treatment can be determined for each group of ponds having similar ecology.