Shallow Water Management

This was compiled to aid others when seeking information on the principles that govern water quality of shallow lakes, ponds or water gardens. The emphasis is on recognizing, relating, and assimilating water conditions, along with strategies and solutions to maintain this valuable resource, for no lake was ever just water!

After establishing a goal for the water, I then review the “What” and “Why” for each water factor, along with the methods of maintenance or restoration. I hope that this information is adequate to evaluate issues and their impact on the aquatic ecosystems, with remedial alternatives needed before taking a course of action, and not relying on emotion or half-truths for guidance.

I look upon working with aquatic ecosystems as the most satisfying and enjoyable of pursuits, hobby… classify if you will. For me it is recreation, exercise, relaxation, and tranquility, all rolled into one.

I dedicate this to all the people whose work gave me some understanding of water chemistry and fisheries biology. It is their work that forms the basis for protecting, renovating and enhancing all water resources.


When I’m tired of the hustle-bustle of every day life, I go to the water’s edge and leave the day’s pressures behind. Life moves slower here. This is my cherished sanctuary, a place beyond time. Here I can reserve my choice of dreams and exit rejuvenated.

In my mind’s eye I seek an “unaltered natural environment”, but what is that? I’m not old enough to have seen what a natural environment was really like! I do know that lakes typically progress to an environment that favors plant life over animal life. So I look for that point in the aging process of a water body, where it has a great diversity of aquatic life. However reaching and maintaining this goal, I need to assistance mature.

What quality cannot be controlled without considering the use of the surrounding land. Everything I do on my street, in my driveway , and yard impacts the watershed. Human adoption and stewardship of the watershed leads to a more comprehensive, responsible, and cooperative means to limit water contaminants.

From the watershed come the inorganic materials (minerals from the soil) and the organic materials (decomposing plants and animals) providing essential elements for the living organisms. Inorganic and organic material along with photosynthesis (energy from the sun), are the building blocks of the natural cycle of growth, decay, and re-growth of the aquatic ecosystems.

The health of the food chain mirrors the health of the entire aquatic ecosystem. Each succeeding level of the food chain is dependent on the health of the level below it. Observing these aquatic biological communities gives a good indication of the long-term health of the water body. This is more fun for use than physical-chemical analysis however, only chemical analysis of constituents in the water can confirm the potential problems, such as loss of buffering capacity, low oxygen level, etc., and the presence of specific pollutants.

“Water bodies are a waste of precious water in this arid environment, with our recurring drought conditions.”

The annual difference in water usage between a body of water and a lawn area is about 35%. The use of water lilies and other aquatic plants will reduce evaporation by another 10%. By using good construction techniques, evaporation can be help to a minimum. Some of these techniques include 18-24 inches straight sides, wind breaks, and use of timers for fountains or waterfalls for when you’re outside to enjoy them.

Not only is this an erroneous assumption for good water use, but it fails to recognize the psychological benefits.

“Algae is often thought to be the greatest nuisance in water management.”

The real problem is excess nutrients in the water/ sediment. Algae is just an indicator of this condition. The use of aquatic vegetation to remove the nutrients from the water is more satisfying than looking at large populations of algae. The Herbicide Industries Marketing people have done an excellent job in convincing me that all aquatic vegetation were weeds. In their ads, everything is an aquatic weed, not an aquatic plant, and I believed it! I destroyed the aquatic vegetation, only to find that the natural law of succession decrees that when one species does or is destroyed, another will immediately rise to take its place, with no guarantee that the new life form will not be equally or more troublesome than the first!

“If it’s not broken, don’t fix it.”  

This may be true for some things, but not water management. When I waited till the problem starts to hamper my enjoyment of the water, it was too late! I must know my water and plan ahead.

“Water lilies and water hyacinths are prolific, and are a notorious nuisance.”

The problem associated with water lilies and/ or water hyacinth have been greatly exaggerated. When used correctly, these plans are of great worth, controlling nutrients and providing visual enjoyment.



It is difficult to establish goals that will be supported by all who will come in contact with a water body. Every individual has his own personalized idea of what each water body should be.

But first ask some questions. Is the water body located in a urban, suburban, or rural community? Is it cold water, temperate water, or a warm body of water? Does the water have a soil-covered liner, clay, or concrete bottom? Does the water have a vegetated, or a concrete shore line? Does the water body have a watershed? If not, is its fill water from a private well? From a water district? Or is it reclaimed water? Do I want fish in the water? If so, what kind- sport, ornamental, or other? Will I want plants in the water? If so, what kind- marginal, submerged, or floating? Would I like a complete food chain ecosystem? Will swimming be allowed? All are possible!

With those questions answered, plans can be made that appeal to your aesthetic senses.

Federal and state laws have been enacted which establish the requirements for adequate planning, implementation, management, and enforcement for control of water quality. It is known as the “The Clean Water Act,” – 1972 Federal Water Pollution Control Act. The fundamental purpose of Federal and State laws is to protect the beneficial use of water. The Beneficial Use Definition, “(WARM) Warm Freshwater Habitat- Water, supports warm water ecosystems” is the area that this book addresses.



The availability or lack of these elements is essential for aquatic life!




  • A measurement of the buffering capacity of water which prevents sudden changes in pHAlkalinity levels of 25-120 ppm with pH values between 7.3 and 8 are recognized as the best for the support of diversified aquatic life.
  • Composed primarily of carbonate (CO3) and bicarbonate (HCO3). AlkalinitypH, and Hardness affect the toxicity of many substances in the water.


  • NH3
  • Ammonia decreases the ability of fish to take oxygen into the blood and can cause suffocation. Ammonia levels as low as 0.2 ppm can damage gills and central nervous system, reduce feeding, and lowers resistance to disease.
  • Present as ammonia the unionized (NH3) form which is extremely toxic to fish, and ammonium, the ionized (NH4) form.
  • Ammonia is produced by a bacteria (Heterotrophic) which consumes complex hydrocarbons (organic waste) derived from the breakdown of plant and protein cells. Ammonia levels are pHoxygen, and temperature dependent. (See Nutrient Cycle).

Carbon Dioxide:

  • CO2
  • Excess carbon dioxide can be stressful to fish at very high levels, as it hinders oxygen uptake and has a narcotic effect on fish behavior. Toxicity to carbon dioxide varies by fish type, water temperature and dissolved oxygencontent.
  •  CO2 is produced during respiration and consumed during photosynthesis. Carbon Dioxide levels fluctuate throughout the day, just opposite the oxygen level. Aquatic plants and algae absorb carbon dioxide when they give off oxygen, and give off carbon dioxide when they absorb oxygen.
  • Carbon dioxide has a beneficial effect by changing the pH needed for the Nitrogen Cycle. (See pH Time Line).


  • HCL2
  • -Toxic- A poison gas, that is 2½ times heavier than air, or as a poison liquid 1½ times heavier than water. As thepH increases, the toxicity of chlorine is reduced; i.e., pH 7.0 the CL2 is 75% effective; at pH 7.5 it is 48% effective; and at pH 8.0 it is only 22% effective.


  • NH2CL
  • -Toxic- A poison liquid, which contains 11.5-13% chlorine and ammonia.


  • A slight green color is an indicator of planktonic life. This indicates that there is a food source for the animals of the lower food chain.
  • For aesthetic reasons it is possible to use aquatic dye, formulated to add a aqua-blue-green shade to the color of the water. Psychologically, this makes it look cooler and more inviting. Caution: Don’t overdo it. Water needs some color/ turbidity to camouflage objects you don’t want to see.


  •  CU
  • Cupper exists in waters as a soluble salt. A small amount is essential for plants’ and animals’ growth. Coppershould not exceed tolerable limits, or use when alkalinity is less than 500 ppm.
  • Copper in the form of copper sulfate (CuCO4), has been used in acquiculture systems as an algaecide and a bactericide; however, even low levels can be toxic. (Use with caution.)
  • High pH and alkalinity levels will make complex forms of copper, reducing its toxicity. It is suggested that you usechelated copper compounds due to their larger band of tolerance

Tolerance for fish life only

Copper sulfate 8.88 ppm

Chelated copper 1.20 ppm

Dissolved Oxygen:

  • O2
  • Fish, invertebrates, plants, and aerobic bacteria all require oxygen for respiration. Oxygen requirements of fish vary with the species and age of the fish, prior acclimatization temperature, and concentrations of other substances in the water. The rule of thumb is 5.0 ppm. Dissolved oxygen levels affect ammonia and nitritetoxicity.
  • Oxygen dissolves readily into water from the atmosphere at the water surface interface, so surface area is more important than depth. Oxygen diffuses very slowly, and distribution depends on the circulation/ mixing of the water. Oxygen is also produced by aquatic plants and algae, as a by-product of photosynthesis.
  • The temperature effect on oxygen is compounded by the fact that living organisms increase their activity in warm water, thus requiring more oxygen to support their metabolism. Summer nights with decreased capacity and increased oxygen demand is the most critical time.
  • Dissolved oxygen capacity of water is limited by temperature, salinity, and atmospheric pressure/ altitude. These factors determine the potential level possible for 100% saturation. Actual dissolved oxygen divided by potential dissolved oxygen = % saturation.
  • Excess oxygen leaves water slowly. Sometimes oxygen levels exceed 100% saturation (supersaturation). This can be detrimental to fish production which is usually caused by rapid drop in temperature or high density algae growth (photosynthesis). Supersaturated daytime concentrations may suggest that nighttime concentrations ofoxygen may be unacceptable.
  • Aquatic plants and algae start to put oxygen into the water after sunrise, stopping at sundown. The aquatic plants and algae remove oxygen from the water, starting after sunset, and continuing till the next day’s sun. The best time to check oxygen and carbon dioxide levels is at daybreak. This is when the oxygen and pH are the lowest.
  • It is more cost effective to operate circulators, starting after the aquatic plants and algae start to take in oxygen. This will keep the water cooler in the summer as you are running circulators at the coolest time of the day and at the same time adding oxygen from the surface interface as it is being removed by respiration.


  • Soft water increases the sensitivity of fish to toxic materials, so some hardness is beneficial. However, excessive hardness in water can limit the Nutrient Cycle and other aquatic functions. Total hardness is defined as the concentration of calcium (CA2) and magnesium (MG2) in the water. Calcium is necessary for proper egg, bone, and tissue development of young fish. Hardness is closely related to alkalinity and pH.
  • Soft: 0-50
  • Moderately soft: 50-100
  • Slightly soft: 100-150
  • Moderately hard: 150-200
  • Hard: 200-350
  • Very hard: 350-up

Hydrogen Sulfide:

  • H2S
  • The source of hydrogen sulfide is sulfur compounds from decomposing organic matter in an oxygen-less environment. Hydrogen sulfide is soluble in water and is highly toxic.


  • Fe
  • Iron typically forms as a result of low oxygen and can be removed by circulation. Fish have a low tolerance to even low concentrations of iron.


  • NO2
  • Nitrite is toxic to fish. It reduces the red blood cells’ ability to carry oxygen. Brown blood disease, a problem with catfish, is caused by toxic levels of nitrites, which can occur when salinity and oxygen levels are too low.

Sodium chloride – Nitrate Ratio:

  • A minimum of 6ppm sodium chloride for each ppm of nitrite should be present in water.
  • NO2 x 6 – salinity present = ppm salt needed
  • Acre feet x ppm salt needed x 4.55 = pounds salt required
  • Note: do not use iodized salt.

Nitrogen: See Nitrite

  • N
  • Nitrogen gas does not combine easily with other elements and cannot be used by most living things directly from the atmosphere. Nitrogen has from the atmosphere is fixed by bacteria (Azotobacter agilis) in the soil and water to form nitriteNitrite is changed by another bacteria into nitrateNitrate is used by plants and other animals. It goes through their system and is reduced into ammonia. The ammonia is changed by another bacteria into nitrite to go through the cycle over and over again. Nitrogen is essential to manufacture proteins that are vital for formation of new protoplasm in the cells. The bacterium that converts nitrogen through its cycle functions poorly below 60°F or with low oxygen levels.
  • Nitrogen itself must be above 100% saturation to be toxic. The atmosphere is 79% nitrogen which is 14.9ppm @ 68°F/29.9 at atmospheric pressure = 100% saturation.


  • The smell of rotten eggs indicates decaying organic material, hydrogen sulfide. A marsh odor is characteristic ofmethane. A fishy smell is associated with dead algae. The pigpen is an indication of blue greens.


  •  pH is a measurement of activity of hydrogen ions. pH controls the degree of dissociation of many substances. The greatest concern with pH is how it affects the toxicity of many other substances, and its effect on the NitrogenCycle. The test for pH should be at daybreak, for this is the time when the pH is the lowest. The optimum range for good water quality is 7.3 at daybreak – 8.0 at sundown.

Phosphorus: See Orthophosphate

  • P
  • Phosphorus is essential for bone formation and aquatic plant growth.


  • Pollution is a way of life, and must be faced squarely and dealt with on a continuing basis; you cannot just look the other way! Silt is one of the most serious problems in water management; even a small amount can smother fish eggs and other bottom life forms.
  • Like many others, I was faced with the “catch 22″ situation of using fertilizer on turf near water, with the fear that I was polluting the water, due to nitrogen leaching. Recent research has shown that very little nitrogen moves past the root-zone and the risk of pollution is much lower than originally though. Researchers have concluded that established landscapes’ own biological activity is able to use up to 99% of the applied nitrogen fertilizer. Less than 0.01ppm nitrogen moves past the root-zone.


  • PO4
  • Orthophosphate enters water bodies from industrial operations and sewage. Other sources are the decay of plants/ animals, with some deposition occurring from the atmosphere (100-300mg/square meter per year) as soil run-off. To reduce levels of Orthophosphate, focus on surface inputs. The largest source of Orthophosphate is detergent use in driveways. Excessive Orthophosphate can cause unwanted growth of algae, and will lead to a point where the water ceases to be enjoyable.
  • Orthophosphate, unlike nitrogen, will not percolate through soil; Orthophosphate binds to particles such as clay, so that its concentration in ground water is very low.  A favorite long term method to reduce Orthophosphate is to grow aquatic plants and later remove the plants, taking the excess nutrients with them (dry weight = 2.36% N, 1.75% P, 4.01% P2O5, 1.10% K, 1.33% K2O, 0.60% S, 0.19% Mg, 1.82% Ca, 0.27% Na). For a quick fix, the use of 100-160lbs. of aluminum sulfate or 40-120lbs. of ferric sulfate per acre will deposit the phosphates in the bottom sediment.
  • The upward movement of Orthophosphate from the lake sediment to the overlying water is usually due to lack ofoxygen at the lake bottom. Circulation of oxygen-rich water over the bottom will keep Orthophosphate locked in the sediments, unavailable for aquatic plants or algae.
  • Phosphoric anhydride (P2O5) is sometimes reported, which is the same as Orthophosphate, but in a dry state.


  • Salinity affects the ability of fish to absorb oxygen. In water bodies with existing high nitrite levels, sodium chloridewill often be added to prevent the fish from succumbing to nitrite toxicity. Salinity is usually reported as SodiumNa. Freshwater fish cannot tolerate fast changes in salinity.


  • Many biological processes are triggered by the water temperature, feeding, reproduction, immunity, and metabolism of most aquatic life. Not only is there a maximum temperature to aquatic life can live, but the solubility of oxygen in water, along with its availability to aquatic life, diminishes at higher temperatures. Furthermore, theoxygen demand by aquatic life increases as temperature rises.
  • Fish larvae and eggs usually have narrower temperature requirements than adult fish. Temperature preference among species varies widely. All species can tolerate some slow, seasonal changes, but not rapid change. Thermal stress and shock can occur when water temperature changes more than 34 degrees F in 24 hours; even less when transporting or moving fish.
  • Note: A large amount of heat is required to raise the temperature of one gram of water by one degree F. This physical property of water moderates daily and seasonal climatic changes in water temperature.

Total Dissolved Solids:

  • TDS
  • Total Dissolved solids is defined as the material left behind after a water sample is filtered and evaporated. Each body of water contains a unique mixture of dissolved materials. A convenient alternative to measuring, drying, and weighing a sample is to test the conductivity of the water. The amount of material dissolved in a sample determines its ability to conduct electricity. Conductivity meters check the flow of electricity in the water. Conductivity (µmhos/cm) x 0.67 = total dissolved solids as ppm. Rainwater is almost pure with less than 10ppm. Drinking water is usually less than 500ppm, and lakes are between 100-2000ppm. Seawater is 35,000 ppm (3.5%).


  • Turbidity is caused by suspended solid matter, which scatters light passing through water. Turbidity, cloudiness in water, blocks out the light needed by submerged aquatic vegetation, eggs, and bottom dwelling creatures. There are two major forms of turbidity.
  • Living microscopic organism plankton contributes to high turbidity when populations are large. Plankton turbidity also result in large swings of high oxygen during the day and low oxygen at night. Moderately low levels of plankton turbidity indicate a healthy, well-functioning ecosystem in which plankton flourish at a reasonable level to support the foundation of the food chain.
  • Nonliving microscopic particles, sand, clay, etc., cause turbidity which damages fish gills, interferes with the ability of fish to food and smothers eggs. This type of turbidity consistently has low levels of dissolved oxygen (low photosynthesis action is due to low light penetration) and elevated concentrations of ammonia. Suspended particles near the water surface absorb additional heat from sunlight, raising the water temperature; and with reduced oxygen, both increases the toxicity of the ammonia. This condition will also smother the aerobic bacteria needed for bioremediation.
  • Heavy rains can also cause brown turbidity conditions. The cause is negatively charged particles. These particles repel each other and are slow to settle out of the water column. The addition of positivity charged particles causes coagulation and precipitation of nonliving microscopic articles, reducing turbidity.



Planktonic Life’s profound importance is not honored, but the truth be known they are basic to life! This is the start of the food chain; nutrients and sunlight (photosynthesis) are used by the phytoplankton to grow and multiply in water, same as other plants do on the land. Phytoplankton are eaten by small fish, which are eaten by larger fish, moving the trapped energy from plant protein to a higher energy level, to animal protein.

Planktonic Life includes microscopic plants and animals; others can be seen without magnification. Visible Planktonic Life is one millimeter, 1/25 inch in size or larger, and include protozoa, amoebas, and paramecium. Next are 1/200 mm which include algae and fungi, then 1/1000 mm, the most primitive of living forms; bacteria and blue-greens.

Planktonic plants are called phytoplankton; the best known are the algae. Planktonic animals are called zooplankton; one of the most abundant is the water flea. Plants and animals that drift on the current are called plankton. Animals that swim are called nekton. Animals that are attached to and crawling on the surface of the bottom of a water body are called benthos.

The protoplasm of Planktonic Life is rich in nitrogen and phosphorus. Small amounts of chlorinechloramines,iodineozonepotassium permanganate, and copper can inhibit planktonic life.




  • The algae are primitive plants closely related to the fungi. They have no true leaves, stems, or root system. They reproduce by means of spores, cell division, or fragmentation.
  • Carbohydrate and sugar energy can be stored by algae for later use, and is the basic food for all living things.Algae are sometimes called “the green miracle”; it transmutes sun energy, carbon dioxide and hydrogen from water into carbohydrate or sugar energy. It also replenishes the atmosphere with oxygen. This is only half truth, for in fresh water, when the algae population is growing, it takes in more oxygen at night than it gives off during the day, requiring additional oxygen transfer from the water interface to support aquatic life. In addition, the presence of large populations of algae reduces oxygen transfer from the atmosphere as it reduces the wind and wave action at the surface interface.
  • Algae spores can be carried by the wind, and naturally occurs wherever water and light exist. Don’t be alarmed; learn to recognize and use algae as an indicator of nutrient loading. When the nutrient level is so high that the aquatic vegetation cannot consume it fast enough, filamentous algae occur. If the nutrient loading is still too high; the next indicator is free floating phytoplankton (green water) algae.
  •  Attached – erectfilamentous, and phytoplankton are the three most common forms dealt with in water management. When aquatic vegetation is not available, attached – erect algae is the second choice for locking up excess nutrients. A slight green color of the water is an indicator of phytoplankton growth. Changing from green to brown indicates it is dying.


  • Zooplankton are primitive animals of the lower food chain; i.e., invertebrates, crustaceans, etc.
  • Water fleas are tiny crustaceans. An adult female Water Flea in good health may produce up to 20 broods of young in a two-three day period when the water is right. Water fleas’ blood is colorless or pale pink when oxygenis high, and bright red when low.


  • Bacteria forms are based on what are termed saprophytes. These are organisms that can only utilize non-living organic carbon matter. Nature’s way of nutrient recycling is largely dependent upon bacteria. One group ofbacteria starts a process, which is then continued by another team. Bacteria recycle the raw elements, lifting them to a higher level of energy.
  • This energy is used for vitamins and enzymes for itself and higher life forms. Bacteria have been on the earth for 4.6 billion years, but in some waters, their population are too small. The maximum growth temperature is 77-86 degrees (F). At 64 degrees (F) the growth rate is cut to 50%
  • Copper Levels must be below 0.05ppm!
  • With the correct environment, bacteria can grow more rapidly, and out-compete the algae for available nutrients. Under ideal conditions nitrifying bacteria will double in population every 15 hours. The by-products of this process are carbon dioxide, water, and bacterial biomass, which is rich in protein. Bacteria are the key to keep the cycles of life flowing.

Saprophytic Non-pathogenic Bacteria:

  • Azotobacter: A rapidly motile form of bacteria which fixes nitrogen from the atmosphere into nitrite.
  • Nitrosomonas: One of the nitrite-forming bacteria having to do with oxidizing ammonia to nitrite (pH 7.8-8.0)
  • NitrocaberNitrate-producing bacteria which oxidizes nitrites to nitrates, (pH 7.3-7.5). This bacteria is not tolerant to low temperature or low oxygen.


  • Blue-Greens are often described with terms “nuisance” or “noxious” because they discolor the water, form floating scums, are foul-smelling, and occasionally cause the death of fish and other animals. But only three deserve this reputation; they are known as:
  • AnnieFannie, and MikeBlue-Greens are not true algae, and probably were the first living cells on earth. In fact, they have a closer relationship with bacteriaCyanobacteria means blue-green. While they are called Blue-Greens, their pigmentation varies widely and includes yellow-green, green-gray-green, gray-black, and even red.Blue-Greens have a better growth rate over true algae by having positive buoyancy; they shade out the true algae. Low carbon dioxide may be a sign of Blue-Greens, as only life forms at the water surface can make use of the new carbon dioxide moving into the water from the atmosphere. Also low nitrogen may be a sign of Blue-Greens.  It nitrate (NO3) is depleted, true algae cease to grow, whereas Blue-Greens can mobilize nitrogen they have stored or convert nitrogen like other nitrogen fixing bacteria.
  • Blue Greens have the tendency to rise to the surface in early morning and sink in the mid-late afternoon.


  • Produced by living organisms and function as a biochemical catalysts for bacteria to carry on their life functions. (Enzymes do not grow and reproduce as do bacteria.) Bacteria are very versatile in producing the appropriateenzymes for the material present, and with existing conditions.
  • Commercial enzymes are extracted bacteria grown under specific conditions, which a specific food source. The match between commercially-supplied enzymes and the enzyme needs for your bacteria are seldom accomplished. The formulations of enzymes do not have the versatility of bacteria formulations. In some cases, commercial enzymes can cause the bacteria to convert organic matter that is in a form unavailable  as a nutrient to a form that is available, thereby aggravating the algae problem.

Hydralytic Enzymes:

  • Amylase: digestion of starch.
  • Beta-Glucanose: digestion of vegetable gums.
  • Cellulose: digestion of cellulosic particles (plants).
  • Nemicellulase: digestion of plant polysaccharides and gums.
  • Lipase: digestion of fats and oils.
  • Pectinase: digestion of fruit containing waste.
  • Proteinase: digestion of protein.
Posted on April 16, 2014 and filed under Aquatic Maintenance, Pond Maintenance, Water Feature.