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N.C. Lake Management Society

  • October 30, 2020 1:40 PM | Johnny Foster

    An Annotated Atlas of the Freshwater Fishes of North Carolina

    Bryn Tracy, former NCLMS President, founding member, and now retired, and colleagues from NOAA and the North Carolina Museum of Natural Sciences, just published: “An Annotated Atlas of the Freshwater Fishes of North Carolina”. Their abstract from this 200 page peer-reviewed journal article reads:

    North Carolina’s first state-specific checklist of freshwater fish species was published in 1709 by John Lawson. Subsequent species lists with descriptions included: Brickell (1737), Cope (1870a), Jordan (1889a), Jordan and Evermann (1896-1900), Smith (1907), Jordan et al. (1930), Fowler (1945), Louder (1962), Ratledge et al. (1966), Menhinick et al. (1974). In 1991, Menhinick published “The Freshwater Fishes of North Carolina”, which is still widely in use because a comprehensive update has not been produced since its publication. The increase in the availability of historical records in globally accessible databases and the surge of collections post-1991 made by federal and state resource agencies, and academic and museum researchers, allowed for the creation of an update of North Carolina’s freshwater fish species in an annotated atlas. Herein we discuss the distribution of the 257 currently described and undescribed freshwater fish species within North Carolina. Annotations for each species include a distributional map with type locality noted where appropriate, remarks concerning questionable records and misidentifications, extirpations, introductions and interbasin transfers, and imperilment status.

    It may be downloaded for free at: The authors encourage you to share this link co-workers and students who might be interested in North Carolina’s fishes. As a companion to this publication, please check-out their web site — which covers all of the state’s freshwater and marine fish species, along with a blog that will feature identification keys to the freshwater species.

  • March 05, 2020 2:30 PM | Johnny Foster

    I’ve never seen a lake or pond that did not benefit enormously from aeration. In fact, aeration is the one expense that can make the most improvement in the appearance and productivity of a lake or pond. However, property owners are confused about which type of aeration is most suitable and cost-effective for their situation. This summary provides some basics to help you decide which system you prefer. More detailed information will be provided in additional articles about specific systems.

    Dissolved oxygen is critical for plant and animal respiration and problems develop when it is limited. Oxygen gets into lakes and ponds through diffusion of air at the water surface and from green plants, through photosynthesis. Diffusion at the water/air interface is greatly increased by moving water, ripples and splashing. Most oxygen supplied by plants comes from microscopic plankton, filamentous algae and submerged rooted plants growing in shallow water.

    Lakes and ponds are depleted of oxygen in several ways. No oxygen is produced in water too deep for light penetration. Aquatic plants, including plankton, consume oxygen for respiration at night. Fish and all other aquatic animals are constantly “breathing” oxygen. Multitudes of bacteria probably consume the most oxygen as they digest organic matter such as dead leaves and tree litter, aquatic animal waste, chemicals and even other bacteria.

    Another complicating factor is thermal stratification in lakes. Warm water is less dense than cold water and actually “floats” on top of cold water. Very little mixing occurs between layers and deep lake water is often very low in dissolved oxygen. Aquatic life is restricted to the upper few feet of water or it dies. Without oxygen at the bottom, toxic gases and excess nutrients are released that contribute to nuisance algae, odors and surface films. The entire lake is unattractive, unproductive and problems can be expensive to correct.

    Aeration Methods

    Many methods are being used to aerate lakes and ponds. A few of the most popular and most effective methods are described below. Most of our customers prefer: surface aerators, fountain aerators and compressed air supplied through diffusers. Aquaculture applications include: paddlewheel aerators, direct oxygen diffusers, surface aspirators and venturi air injectors. Other special applications include: pumped waterfalls, underwater circulators, air injected into deep “U” tubes, ozone injection, nano bubbles and many other developing technologies. 

    Surface aerators: These relatively efficient units use an electric motor suspended beneath a plastic float to push high volumes of lake water a short distance into the air where the water can absorb oxygen. Since the water is pushed only a foot or two into the air, the spray is not as attractive as a fountain. However, much greater volumes of water are circulated improving aeration. In addition to exposing large volumes of water to the air, surface aerators increase circulation (increasing oxygen diffusing from the air) and break down surface films. Ugly surface films caused by pollen, dust, algae, cyanobacteria, tree litter and insects are pushed to the shoreline by ripples and quickly sink. The splashing water muffles noise from traffic, neighbors or equipment. However, the spray pattern is not dramatic and “showy” and lights are not appropriate. These units are most often used in shallow lakes and ponds. Some units can be placed in water only 18 inches deep, but they are often used in lakes up to 8 feet deep. Some systems offer optional intake collars that pull deep water to the surface to reduce stratification. A basic one horsepower, double propeller unit that sprays roughly 1,000 gallons per minute 1 – 2 feet high will cost in the neighborhood of $1,800.00.

    Fountain aerators: These are “hybrid” devices that provide much of the attractiveness of high-pressure fountains while still circulating large volumes of water through the air where oxygen is absorbed. Recent design improvements provide many spray patterns with high volumes of water being pushed by energy efficient motors with up to 5-year warranties. Lights add significantly to the cost, but are incredibly attractive. Some LED light sets are programmable for many different light colors and patterns. Fountain aerators are used when dramatic attractiveness is desired in addition to surface aeration. Like surface aerators, the splashing water sound, surface film reduction and optional deep-water intake collars add to their popularity. The general cost of a one-horsepower unit with crown & geyser spray pattern (9 feet high and 24 feet diameter pumping about 500 gallons per minute) without lights is somewhere around $4,500.00. Adding lights would cost at least $1,700.00 or more. A power control panel containing all GFCI breakers, timers and controllers is included. Solar units are becoming available for certain situations.   

    Compressed air diffusers:These systems are incredible. They can provide up to 3 to 5 times more dissolved oxygen than other methods. A one horsepower motor can circulate 8,000 gallons of water per minute. A properly designed system can eliminate thermal stratification, reduce “muck” accumulation on the bottom, improve water clarity, improve fish production and reduce surface film. Recent developments of probiotic bacteria/enzyme products actually provide “biological dredging”. Under the right conditions a one horsepower unit can aerate and destratify a 10-acre lake! The important factor is lake depth. Special “synergistic airlift diffusers” create rising columns of bubbles that expand as they rise through the water column. Each bubble gets larger and the column of bubbles spreads out pulling vast quantities of “dead” deep water up with them. Oxygen diffuses from the bubbles into the water and more air enters as the surface water is circulated. The surface boil of bubbles (only evidence of aeration in operation) may spread out as much as 100 feet. An on-shore compressor (in a fan-cooled cabinet) provides air to the diffusers via special plastic tubing. Although more efficient in deep water, smaller multiple diffuser units can be used in shallow water. Most systems installed cost $1,200.00 – 5,500.00.

    Until recently, electricity must be provided for each of these aeration systems. Usually, a meter base or junction box needs to be provided near the shore of the lake or pond. Often motors up to one horsepower can use 120-volt supply. Larger units must have (and smaller units can use) 240-volt power supply. The cable must be sized according to the amperage of the motor and length of the cable. Ground fault protection must be provided because of the proximity of water. Solar powered units avoid the need for an electricity supply.

    These cost estimates are very rough. Desired options, motor size, cable length, choice of lights and the shape and depth of your lake or pond will determine your cost. Here is what interested people should do:

     1.     Prioritize your objectives. Rank the following in importance to you: a.) aeration efficiency, b.) dramatic (showy) appearance, c.) initial cost, d.) destratification, e.) algae control, f.) water quality improvement, g.) muffling extraneous sounds, h.) lights, i.) operating cost, j.) odor reduction, k.) natural (discrete) appearance and l.) muck reduction.

    2.     Determine your power supply needs. Unless you choose the solar option, electricity needs to be supplied as close to the shoreline as possible. Do you have (or can you get) 120-volt supply or 240-volt supply or both? 

    3.     If you choose a fountain aerator, do you want lights? How many? What color?

    4.     How much electrical cable will you need? What is the distance from your existing, or anticipated, power supply to the location of the aeration unit motor?

    5.     With some depth information you provide, Google Earth can be used to design your system and provide you with cost estimates. 

    Although somewhat complex, choosing an aeration system is by far the best thing you can do for your lake or pond. After installation water conditions will continue to improve each year. Your lake will be much more attractive, more fish will grow faster and the life of the lake will be extended. You can easily pay for the aeration system with lowered maintenance costs year after year. 

    Foster Lake & Pond Management provides the full range of lake, pond and stormwater management services and products. These include: construction, repairs, maintenance, certified inspections, fish stocking, fisheries management, lake mapping, vegetation management, docks, fountains and aeration.

    We have provided aquatic and stormwater solutions to our North Carolina customers for over 38 years. Call us at: 919-772-8548 or visit:

  • March 05, 2020 11:40 AM | Johnny Foster

    Until recently, this surface film was considered a form of “blue-green algae”. We now know that there is no such thing as “blue-green algae”. Blue-green algae are now classified as bacteria and are correctly called cyanobacteria. As bacteria, they are mobile and can rise and sink through the water column. They have chlorophyll and can produce food for themselves through photosynthesis. Possible colors range from yellow to red to violet to green to deep blue, blue-green, gray and black.

    Probably the oldest living forms of life, cyanobacteria are not very well understood. They exist everywhere. Nevertheless, nuisance blooms are increasingly troublesome throughout the Southeast. Cyanobacteria blooms are nuisances because they can be ugly, smell bad and can produce toxins. Sometimes the toxins have been associated with deaths of fish living in infested water or livestock and pets drinking the water. The toxins are increasingly linked to some chronic diseases. The blooms are usually not very stable and often crash in a relatively short period of time.

    Unlike desirable plankton, cyanobacteria do not contribute significant amounts of dissolved oxygen. Cyanobacteria reproduce relatively slowly, usually about 1 time per day. Dead decomposing cells consume available dissolved oxygen. They are also not good oxygen producers like green plankton algae. The slow recovery of low oxygen levels contributes to occasional fish kills. Excessive blooms are not likely in lake and ponds that are routinely managed. We usually see short-lived thin surface films that are simply unattractive.

    Because of potential toxicities, cyanobacteria are very important to aquatic resource managers. Currently being diligently researched are the physical/chemical and biological factors that encourage blooms and may potentially provide control. The factors include:

    Physical factors:

               Agitation – 

    Flushing, mixing and turbulence all may reduce cyanobacteria growth and reproduction. If water flushes through the lake faster than the nuisance can bloom, problems are reduced. If mixing can overcome the ability of the cyanobacteria to maintain its position in relation to light and available nutrients, growth is reduced. Shear turbulence can disrupt colonies and break up filaments. Aeration with fountains, and even diffused bubbles, can significantly reduce surface film formation.

                Shading – With limited light available, photosynthesis is inhibited. The concentration of the bloom and the composition of the species present are affected by the amount of light available and the depth of light penetration through the water. Shading can be effective for reducing numbers. However, the organisms ability to rise to the water surface may reduce the effectiveness of shading. 

                Temperature – Warm water temperatures, above 80oF., are associated with cyanobacteria blooms. Warm water is less dense than cooler water. Therefore, the warm water actually “floats” on top of denser cooler waters down deep causing stratification allowing surface water to warm dramatically. Through contact with the air at the surface of the water, nitrogen and carbon dioxide can be used by cyanobacteria as nutrient sources.

    Chemical factors:

                Excess nutrients - High levels of nitrogen and particularly phosphorus are associated with cyanobacteria blooms. If the nutrients are reduced for months and years, blooms have been shown to diminish. Reducing nutrient inputs is one of the most effective control techniques. 

               pH – Low pH (acidic water) tends to inhibit growth of cyanobacteria. When the pH is above 8.0 problems increase. Regular additions of lime can buffer the pH and reduce high pH conditions.

                Salinity (or salt content) – Although cyanobacteria occur in salt water, research shows some species causing problems in fresh water may be controlled by 1 – 5 parts per thousand of salt. Therefore, each acre-foot of water would require 270 – 1,350 pounds of salt. Adding salt may only be practical in small ponds without much flow through. 

               Iron – Apparently, cyanobacteria are capable of out-competing some algae for limited levels of iron. When high nitrogen and phosphorus levels exist in the lake, adding iron may encourage the growth of desirable green algae. Research is continuing but adding iron is not a widespread control technique.  

    Aquatic algaecides - Algaecides are chemicals that kill algae. Several formulations are available. Peroxide based algaecides may provide somewhat selective cyanobacteria control. Selection of the appropriate product, method of application, licensing requirements, existing weather and water conditions as well as many other factors complicate algaecide use. 


              Fish – Tilapia are fish that eat algae and will grow while eating cyanobacteria. However, the fish are tropical and will die when water temperatures drop below about 50oF. Therefore, in North Carolina they have to be stocked each spring. We have found that if we stock 50 – 100 fish per acre in the Spring, they can effectively control nuisance growth of some algae and appear to have reduced cyanobacteria issues in some ponds we manage. Recently the North Carolina Division of Inland Fisheries has restricted stocking tilapia in this state since they are not a native species. They are worried the fish will adapt to living in cooler water and may survive a warm winter. Sterile triploid grass carp eat may types of aquatic vegetation including some species of algae, but cannot filter out most types of cyanobacteria. Sterile grass carp are allowed in North Carolina but stocking may require a permit.  

                Beneficial bacteria concentrates: Beneficial bacteria/enzyme concentrates may compete with cyanobacteria for available nutrients. Probiotic and catalyst products are becoming popular for improving water quality in smaller ponds and stormwater devices. Although enormous numbers of bacteria occur naturally in lakes and ponds, these intentionally high concentrations of specific bacteria are showing beneficial results. An important factor is bottom "muck" organic sludge may be digested reducing nutrient cycling. "Bubbler" aeration and circulation appears to significantly improve effectiveness.   

                Barley straw: This has been used for “clarifying” ponds in Europe for generations and its use spread to the 

    United States. It isn't widely used but there is evidence that as the straw decomposes in water substances are released that inhibit some algae growth.   

    All of these factors and tools are considered cyanobacteria control activities. The most apparent surface film types of cyanobacteria usually represent a very small volume of material in lakes/ponds. If you could strain it out, it would only be a “handful”. It is simply very noticeable. Noxious blooms of very high volumes of cyanobacteria make the news and certainly cause important problems. However, smaller populations of these persistent species are often present without causing significant problems. We believe many times routinely treating cyanobacteria with chemicals simply makes it persist longer. Often we find that if the property owner is willing to live with it for a week or two, it will go away.   

    Foster Lake & Pond Management provides the full range of lake, pond and stormwater management services and products. These include: construction, repairs, maintenance, certified inspections, fish stocking, fisheries management, lake mapping, vegetation management, docks, fountains and aeration.

    We have provided aquatic and stormwater solutions to our North Carolina customers for over 38 years. Call us at: 919-772-8548 or visit:

  • March 05, 2020 11:24 AM | Johnny Foster

    Gone are the days when property owners expect a lake, pond or stormwater device to have absolutely no plants. Aquatic plants can be very beneficial environmentally. They remove excess nutrients from the water, provide habitat for all kinds of aquatic organisms and can actually look very attractive. For the purpose of this article I will limit my comments to emergent aquatic plants that are attractive and native to North Carolina. Submersed plants and floating plants are often more difficult for the property owner to manage and may not be attractive.

    There are many shrubs, trees and ground covers that are suitable for planting in very wet shoreline situations. They also provide all the benefits. However, this list includes plants that are easy to obtain from nurseries, have a reasonable chance of surviving when planted and are relatively diverse. You should expect to have reasonable success planting these plants.  

    1.      Blue Flag Iris: These are very attractive plants that are resistant to being eaten by muskrats, waterfowl and other animals. They form dense clumps of rhizomes (enlarged underground roots) that can be separated and spread out over time. They grow to about 3 feet high and rarely grow in water deeper than about a foot. Therefore, they rarely interfere with recreation, but provide effective shoreline erosion protection. 

    2.      Pickerel Weed: This plant is also attractive, hardy and grows rhizomes that can be split and propagated. They grow three to four feet tall and can grow in water up to about 2 feet deep. The large spikes of clusters of violet-blue flowers are very ornamental. They also attract bees and butterflies.

    3.      Duck Potato: This versatile rapidly reproducing plant can grow in water 6 – 12 inches deep. It’s rhizomes, seeds and foliage can be good wildlife food. When established the dense clumps of plants reduce shoreline erosion, provide cover for aquatic animals and remove large quantities of nutrients from the water and shoreline soil. The plants can grow to 4 feet tall.

    4.      Lizard Tail: Grows in small colonies through underground runners. The white flowers look like drooping bottle brushes 4 - 6 inches long. The plants typically grow 1 to 3 feet tall and do well in partial shade. Maximum water depth for growth is about 18 inches.

    5.      Water Willow: Will grow up to 3 feet tall in water up to about 4 feet deep. The plants don’t grow as dense as most of the others, but provide excellent fish habitat. The leaves look much like weeping willow leaves. The small but attractive white or pale lavender flowers bloom from May through October. Although it is very effective for protecting shorelines the plants may grow out further from shore than many property owners prefer.

    6.      Native sedges and rushes: There are many grass-like aquatic sedges and rushes native to North Carolina. Some examples are bulrushes, soft rushes and White-top sedge. Sedges grow in shallow water and usually have triangular stems. Rushes often grow in clumps and usually have cylindrical stems. Their shallow spreading surface roots hold shoreline soil and reduce erosion. White-top sedge is a showy 2 foot tall spreading sedge bearing attractive white flowers throughout the summer.

    These plants can be expected to spread, but are not aggressive. You can dig up plants, separate tubers and spread them where you want them. If they are expanding past where you want them, they can be controlled by hand pulling or using approved aquatic herbicides on the plants that are not where you want them. You will find that they only need controlling once per year or less. You will also probably find that these plants will reduce problems with more invasive and aggressive aquatic plants. Your shoreline will look more natural and attractive, too.

    Foster Lake & Pond Management provides the full range of lake, pond and stormwater management services and products. These include: construction, repairs, maintenance, certified inspections, fish stocking, fisheries management, lake mapping, vegetation management, docks, fountains and aeration.

    We have provided aquatic and stormwater solutions to our North Carolina customers for over 38 years. Call us at: 919-772-8548 or visit:

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