Ponds and water features, in healthy balance, require little interference other than protection and their value to a golf course and its community cannot be overstated. Sparkling lake vistas, lush riparian borders, the occasional splash of a silvery fish leaping for an insect, and the elegant statue-like patience of a heron on the hunt: these are the scenes and the spaces that drive membership.
To create and maintain this kind of bucolic mood, it’s critical to understand that ponds are complete living systems, consisting of a complex, interdependent web of bacteria, algae, plants, insects, amphibians, crustaceans, fish, birds, and mammals. In healthy balance, they require little more than careful protection and regular checkups. If trouble is detected, however, it needs to be immediately addressed to prevent a cascade of failures that can wreak havoc on the health and function of the entire course.
The water in a healthy pond or waterway is clear. There are no offensive smells, the shoreline is free of trash, weeds and excessive mud, and there are signs of thriving wildlife - insects, fish, frogs, turtles, and maybe even the creatures that feed on them in turn: herons, raccoons, bigger fish.
Cloudy water can indicate a few issues, so it’s a good idea to figure out what you’re dealing with. Sediment carried in with rainwater that drains through a few eroded areas will generally add a brownish cast to the water. On the other hand, water that is brown in color but still clear may indicate an overabundance of tannins. Tannins are generally introduced by trees; whose leaves and needles fall into the water and sink to the bottom as they become waterlogged. As they decay at the bottom of the pond, the tannins are released and stain the water brown; much like a cup of tea.
It’s relatively easy to determine which situation you’re dealing with. Fill a jar with water drawn from the pond and allow it to sit for a day. If you then find clear water above a shallow layer of silt and sand, erosion is the likely source of the problem. If the water is still brown, it’s time to clear out those leaves. Whichever you identify as the source, they both point to imbalances that need to be addressed, since both problems are likely to get worse over time.
If your water is green, whether clear or cloudy, you can be fairly sure that algae is the problem. Algae is a catch-all phrase referring to single celled diatoms that float suspended in the water, or multicellular versions like slimy filamentous algae and even seaweed. While all forms of algae depend on photosynthesis to make their food, algae are neither plants, nor animals. (Protist is the term for this in-between state.) Algae issues are complex since they are intricately involved in all the biological and chemical processes in the pond.
When offensive smells appear, they are generally found around ponds or in stagnant areas of slow-moving streams. Oily or petroleum smells are typically brought in by runoff and should be immediately addressed at their source. Sewage, decay or rotting egg smells may come from the water itself, so fill a jar with pond water and carry it some distance away so you can isolate the smell. If the water in the jar has the same offensive odor, it’s time to start looking at the oxygen levels in your pond.
Ponds and waterways are unique ecosystems, consisting of an interdependent web of living elements. These components include bacteria to fish, plus chemical elements like oxygen and nitrogen. The ecosystem will naturally seek to keep all the elements in balance, so small variations rarely spell trouble. Alternately, large disturbances, particularly when outside influences are involved, can throw the ecosystem into turmoil and even destroy it. It’s our job to understand the system and support its recovery.
Nitrogen and oxygen are two of the critical elements that sustain the life cycle of a pond. They are the nutrients used by plants and algae to live and grow, and they’re supplied to a healthy pond through death and decomposition of living things within the pond. These elements must be present in adequate amounts to allow the life cycle to continue - plants must grow and waste must decay - but if they’re overly abundant, rapidly growing organisms like algae will quickly take advantage and throw the whole process into disarray. Below, is an incredibly over-simplified description, but it should give you an idea of the circular nature of the nutrient cycle in ponds and waterways.
Nitrates (a form of nitrogen) are used by plants and algae to support photosynthesis and create food for themselves. Over time, those plants and algae are either consumed by fish and other organisms, or they die and begin to decay. The portions that are consumed are eventually excreted as waste, which also begins to decay. As a product of the process of decay, ammonia is released. The ammonia is, in turn, consumed by bacteria and transformed into nitrites. Then the nitrites are themselves transformed, this time into nitrates, which are available once again as nutrients for plants and algae.
The nutrient cycle has a certain inertia all its own. Barring any catastrophe or serious outside influence, it will persist and keep the ecology in balance. But of course, there are catastrophes, and even more frequently there is outside interference. When that interference pushes the cycle far out of whack, the results for the ecosystem can be self-reinforcing and disastrous.
Our nutrient cycle discussion focused on the transformation of nitrogen through its various stages, but for simplicity’s sake we didn’t go into the role of oxygen. Let’s take then, as a given, that oxygen is a necessary component of most of these processes. Fish require oxygen constantly, and even plants use oxygen at night to break down the carbohydrates they’ve produced with photosynthesis during the daytime. Most bacteria use oxygen as they fulfill their little bacterial roles as well.
Sometimes, if the cycle gets out of whack, there may be times or places where no oxygen is available. There are several possible causes for the absence of oxygen. Any organic matter that is built up in these locations cannot decay, except through the aid of anaerobic bacteria, which specifically survives in the absence of oxygen. A colony of anaerobic bacteria will work in oxygen-starved areas to break down fish waste, dead insects, and piles of waterlogged leaves. They work very slowly, compared to their oxygen loving cousins, but they do return nutrients to the water in usable forms; especially phosphorus. So, anaerobic bacteria do have their own valuable role in a pond ecosystem. The problem is that an over-abundance of anaerobic bacteria produces certain toxins that can not only harm aquatic life but can release methane and sulfur-containing compounds that really smell quite awful. Noxious bubbles, rising to the surface of your pond, is an obvious sign that you’re dealing with some far-reaching oxygen issues.
To support a healthy ecosystem, you’ll want to consider these important factors and to help keep them in balance:
- Nutrients. With too much, you’re likely to get algae blooms, which are not appealing to the eye and can create chaos in the nutrient cycle. With too little, your plants and aquatic life will suffer and die. Nutrient imbalances tend to be self-reinforcing, so while it’s important to identify and defuse the original trigger, it’s generally best to jump right in and cut it short before things get too far out of hand.
- Oxygen. It’s hard to get too much oxygen in water, since at some point it will reach saturation and simply bubble up and into the air. Too much turbidity, from extreme efforts at oxygenating the water, could stir up debris and silt from the lake bottom causing a different set of problems. Too little oxygen, however, is an entirely different thing, since nearly every process in an aquatic ecosystem depends on it. Check out the section on aeration for a more detailed discussion.
- Temperature. There’s not much you can do about heat waves or extended cold snaps, but if extremes of temperature are becoming a concern in your area, you can make sure that your ponds are deep enough to allow your fish to keep cool during the dog days of summer and to go safely dormant (or semi-dormant) in cold winters, even when the ponds are mostly covered with ice. Eight feet is a good starting depth for small ponds on your average golf course, but larger lakes and those in the northern latitudes should reach for ten to fifteen feet.
- Sunlight. Sunlight is another factor where you’re more at the mercy of nature than not. The best you can do is consider exposure when you’re designing your course and choosing sites for water features. You can help mitigate overexposure by providing shade in the way of trees, bushes, and aquatic plants. Too much direct sun encourages algae blooms; especially after rainy or stormy weather. It also allows the water temperatures to rise, sometimes to the point where water is unable to hold sufficient oxygen, which puts aquatic wildlife at risk. Too little sunlight, on the other hand, can prevent plants and algae from photosynthesizing, which leads to rapid die-off and a whole new host of problems. Water that doesn’t get warm enough from daytime sun exposure also may not trigger reproductive signals in resident fish and other aquatic wildlife.
Algae is the great bogeyman for most pond managers. It looks unattractive, can be accompanied by unpleasant smells, can damage both pumping and irrigation equipment, and it can be frustrating to manage. Since algae spores travel by air, it is inevitable that algae will soon take up residence in even the most remote pond on your course. While it’s true that struggles with algae can rage on for years, with a thorough understanding of your pond’s life cycle and a creative ability to adapt, you can address almost any algae incident you encounter.
The first thing to remember is that algae is critical to the life cycle of every pond. A complete absence of algae would spell complete collapse of the ecosystem, as one of the foundational stones would be missing. Planktonic algae are one of the most basic forms of food and even if you’re not planning to support recreational fishing, small fish, tiny crustaceans and other aquatic creatures flourish on it. It’s not possible to have a complete, self-sustaining ecosystem without all the elements represented. Other types of algae also have roles to play, but as in all things, a healthy balance is necessary.
If you’re dealing with high levels of algae or a sudden algae bloom, there could be any of several triggering events, but the root problem is always going to be an overabundance of nutrients in the water. Algae can’t reproduce without nutrients, and when those nutrients are gone, the algae will die off. (We’ll discuss the issue of sudden die-offs later.)
Algae is not the only organism ready to consume all that food, but it is the fastest. Since algae’s habit is to overeat and then overproduce, it helps to arrange for other plants to get their chance to consume the nutrients first. These more advanced plants will grow fast and full, but they can’t explode like algae can. Plants that thrive on the banks of the riparian zone are perfect candidates here. As water flows through the fairways toward the pond, a border of ornamental grasses, rushes and cattails can absorb many of the available nutrients before they even reach the waters of the pond itself. The filtering action of the riparian zone also collects sediment and other chemicals carried by runoff before they enter the water.
If your golf course has turned toward more sustainable practices of golf course management, it’s possible that directly applied fertilizers aren’t the issue. For example, runoff from other sources, like nearby farm or ranch land could be reaching your ponds. If that’s the case, you can extend your filtering vegetation area to manage the heavier load, or you can work with your neighbors to develop a mutually beneficial solution.
It’s important to continuously monitor other possible sources of nutrients to your pond. Are grass clippings allowed to fall in the pond or is mulch or compost spread close to the banks where it can wash down during rain? Any kind of organic matter, when it decomposes, will release nutrients into the water, and neither plants nor algae particularly care where it came from. You can manage normal ebbs and flows of nutrients by planting and maintaining a healthy population of aquatic plants. These submerged plants not only take up nutrients, but they help maintain healthy oxygen levels in the water, provide hiding places for small aquatic creatures, and provide tasty food for ducks, grass carp, and other wildlife.
Algae can contribute to oxygen depletion in a pond through several mechanisms, but the result is pretty much the same: serious trouble for the pond. If you notice signs that indicate dead zones, fish deaths, or overwhelming amounts of algae that are shading out significant areas, you’ll want to immediately start increasing the oxygenation of the pond. Once that is going, it’s time to talk about what’s happening.
In an algae bloom, the biomass increases so much that it can cover the surface of the pond and shade out everything below. We already know we don’t like the appearance of the algae, but there’s more insidious stuff going on below. With sunlight blocked out, the plants (and algae) under the surface are unable to photosynthesize, so they shift into their “nighttime mode”. In this mode, they use oxygen in the water to access stored carbohydrates until the sun comes out again. Trouble is, the sun doesn’t come out again and the plants and algae that are in darkness continue to use up oxygen. The fish use the oxygen as well. If the top layer of algae continues to get sunlight, all is not lost since they’re producing oxygen all the while. Once nighttime comes, though, they too will switch to oxygen use. Over the length of a single night, the oxygen level can become so depleted that larger organisms, like mature fish, suffer.
Unfortunately, that’s not the end of it. As the bloom continues, the population explosion will eventually consume all the available nutrients in the water. Since algae grows and reproduces very rapidly, it will compete with existing aquatic plants and it will always win. If the bloom cycle continues too long, existing plants will eventually die, stuck between inadequate nutrients and inability to photosynthesize. The algae, too, will quickly die as the available nutrients are used up, and this is where the real trouble starts. This creates a large amount of dead organic matter, which settles to the bottom of the pond. When it settles, it will be broken down by bacteria. This process is essential to the health of the pond, as it eventually returns nutrients and prevents huge amounts of detritus and dead organics from filling up the pond. The problem comes in here, because the process of decomposition uses oxygen. A pond that is already low in oxygen now has a massively increased demand for it. Subsequently, if the post-bloom die-off is serious enough, you’ll see fish and other aquatic life begin to die from suffocation.
This launches a vicious circle. With even more biomass, the decomposition processes ramp up further, depleting even more oxygen but also adding more nutrients into the pond. Algae will happily take up the fresh nutrients and multiply, shading out the pond again until peak nutrition is reached, then dying off and decomposing. I’m sure you can see the pattern here, and it’s not pretty. But wait. There’s more.
At the lowest levels of the pond, the oxygen is now gone and the decomposing bacteria which use oxygen, cannot survive here anymore. So anaerobic bacteria begin to set up shop. They can only survive in the absence of oxygen, but they work much more slowly than the oxygen users, so as the biomass sinks to the bottom, the anaerobic bacteria multiply to work on the mess. While they work, they produce sulfur and methane gasses, which is the source of problems with foul smelling ponds. Nonetheless, even anaerobic bacteria have a valuable role to play in the pond’s life cycle. When the population increases, because of an enormous load of decaying matter and is coupled with less and less oxygen trouble is inevitable.
If left alone, this series of events leads inevitably to the death of the pond or lake through a process called eutrophication. Fortunately, the process can be interrupted and even reversed with proper management and maintenance. If you’ve inherited a pond or series of them that are far along in the eutrophication process, it is possible to rehabilitate them.
The ultimate source of most algae problems is an overabundance of nutrients. So, your first line of defense is to limit the amount of nutrients entering your pond. In golf courses, excess nutrients almost always come from highly fertilized greens and fairways that drain into the pond during nightly irrigation or rainy periods. Once it’s pre-loaded with an abundance of food, the algae are set to bloom on the first warm, sunny day. Other sources of excess nutrients can include manure or other animal waste, urban runoff, or nearby septic systems. If your pond’s nutrient load is at a toxic level, it’s time to talk to a pond professional about the use of chemical compounds, like alum, that can bind up specific kinds of nutrients (phosphorus in this case) and render them permanently unavailable. These binding agents can literally save your pond when the nutrient load has spun out of control.
If your golf course is still using intensive turf management practices, with lots of chemical support in the way of fertilizers, pesticides and weed killers, you’ll need to either divert these chemical-laden waters away from the pond or significantly beef up your pond’s support system. The support system, in this case, is the addition of a vegetative buffer between your managed fairways and the waterway. This buffer filters incoming runoff, taking up most of the available nutrients and excess chemicals and trapping sediment as the water flows through to the basin. With most nutrients already removed from the incoming water, the pond won’t be overwhelmed, and existing plant and algae populations can continue undisturbed. Additional support can come with the inclusion of aquatic plants, which grow submerged, typically in the toe region. They’re excellent at taking up nutrients and increasing dissolved oxygen, but it’s important not to add plants with weedy tendencies.
One major bonus, with the vegetative buffer, is that it also functions as erosion control by reinforcing the soil in the riparian zone along the borders of a lake or stream. Establishing a riparian border can be as easy or as difficult as you choose to make it. Some inexpensive methods, like live staking and live fascines, are discussed in the section on managing erosion with plants.
If your problems with algae have been ongoing and you’re experiencing noxious odors, you’re smelling the results of anaerobic bacterial decomposition. Adding oxygen to the pond, and providing good circulation throughout the pond’s area and depth, will get rid of the anaerobic bacteria & smells while permitting aerobic bacteria to move in and finish breaking down the biomass. Aeration can be accomplished using fountains, waterfalls, bubblers, and other tools, but in cases where the oxygen depletion is severe, consider using nanobubble aeration. This is a relatively new technology that emits bubbles about a million times smaller than ordinary bubbles. In normal aeration, bubbles rise to the surface and burst within seconds. This helps carry water to the surface and allows it to absorb oxygen, but there’s minimal direct transfer of oxygen at the bottom, where the need is greatest. Nanobubbles are so tiny that they have no natural buoyancy, which means they remain suspended within the water column anywhere from hours to months, saturating it with oxygen at all depths. In fact, most nanobubbles tend to burst within the water column, and transfer 79,000 times more oxygen to the water than normal bubbles that burst at the surface.
Whichever method of aeration you choose, take into consideration that oxygenated water must move throughout the pond area to be effective. Most lakes and ponds are characterized by stratified layers of water with different temperatures and oxygen levels. Typically, cooler water settles to the bottom, where it gradually loses oxygen since it remains there and is not exposed to surface air. To avoid those potential dead zones, the cooler layers must be induced to move and circulate through the entire water column, equalizing temperature and oxygen levels. Unless your aeration mechanisms are spread across the entire lake or pond, some sort of circulation mechanics should be introduced as well. In fact, in most circumstances normal aeration techniques will suffice if there is adequate circulation.
Aeration and circulation do have a potentially negative side-effect, particularly when the solution is first introduced. Once oxygen is available across the water column, aerobic bacteria is free to work on decomposing the biomass at the bottom of the pond. This has the effect of reclaiming depth in eutrophic lakes and ponds, but it also will quickly return large amounts of nutrients into the water, which could potentially trigger another algae bloom. This is an instance where simultaneous action on multiple fronts may be necessary. Since the key to preventing algae blooms ultimately rests with limiting available nutrients, you’ll need to consider removing the bulk of the organic debris and sediment. With less mass to decompose, fewer nutrients will be released.
Methods for removing sediment and detritus are discussed in the section on aging ponds.
Once your waterways and lakes have been stabilized with rocks, vegetation and other solutions, there are steps you can take to further minimize the risk of future problems. The first is to protect your buffer. Never mow the natural grasses at the edge of your stream that help stabilize the bank. Next, don’t allow your channels to get clogged up by dumping grass clippings, branches, leaves, or even rocks into the stream. Clogged, narrow channels cause the water to flow faster, with increased eroding power.
Whenever possible, avoid shoring up banks with rocks or attempting to change the course of a stream. Without the supportive matrix of plant roots, a pile of rocks is likely only to shift the force of flowing water elsewhere and eventually carry the rocks with it downstream.
Even with reinforced banks and a healthy riparian border, try to keep heavy equipment and structures away from your banks. When the ground is exceptionally wet, the additional weight could damage even normally stable banks.
Your maintenance routine should include regular inspections of your ponds and waterways. Check for signs of erosion, including muddy banks, brownish cloudy water, and areas bare of vegetation. Make sure your riparian zones are vigorous and there’s no sign of damage from human activities. Deepening channels with bare, overhanging banks, and dugouts along the bottom of streams, spell trouble.
Intentional introduction of carefully chosen native plants to the riparian zone shouldn’t produce problems with invasive species, but lakes and ponds can still be overrun with aquatic weeds such as water lettuce, hydrilla and curly-leaf pondweed. These plants spread rapidly and can quickly overrun a small pond, choking out more beneficial plants. When the plants become too thick, other wildlife are unable to find food or reproduce. Eventually you have a pond that is composed entirely of hydrilla; a thoroughly unattractive prospect.
There are several ways to deal with nuisance plants, just like in a regular garden. You can identify and pull by hand any weeds you see beginning to peek out. This can be labor intensive, but if it’s done on a regular basis during the growing season, it can keep things well under control. Maybe you can find a troop of willing volunteers from the local community who are eager to help support and maintain local wildlife habitats.
Alternatively, you can introduce a few grass carp to your pond or stream. Grass carp feed happily on most aquatic plants as well as encroaching grassy weeds. A few dozen fingerlings from a local fishery aren’t expensive and can quickly get your weed problem under control. Be sure to check with your county extension agent to verify the best number and size for your pond.
Chemical herbicides should be the last resort, and probably shouldn’t be used for those operating on the sustainable management philosophy. With a solid understanding of your pond’s life and nutrient cycle, and the helpful input of experts and other golf course managers, there should be plenty of options to successfully manage the challenge without resorting to chemicals. Remember that chemicals don’t stay right where you put them, and herbicides spreading throughout a body of water can have unintended consequences.
The word eutrophication refers to bodies of water becoming enriched with nutrients, which sounds like a good thing when a pond is brand new and essentially sterile. Yet, as we have seen, it can become a very bad thing when a natural balance cannot be maintained. Oddly enough then, eutrophic ponds and lakes that have copious amounts of available nutrients are considered old and dying. These lakes typically have an abundance of aquatic growth, which again, sounds like a good thing. Unfortunately, it’s what happens down in the depths that’s the issue.
Remember those anaerobic bacteria that work diligently, but oh-so-slowly, on the ever-increasing biomass at the bottom of ponds? That biomass will never be completely decomposed because the bacteria work too slowly. No other bacteria can step in to assist because there’s no oxygen down there, and anytime something dies, it sinks to the bottom...where there’s no oxygen.
As the bottom of the pond gradually fills up with semi-decayed organic sediment and mud, it becomes shallower and cloudier. As it continues to fill in, aquatic weeds begin to spread out from the shore across the lake where it has become shallow enough for them to survive. The surface area with clear water shrinks and eventually disappears, completely overcome by weeds and sedimentation. The process of filling in continues until the pond has finally transformed into a swamp, or perhaps a wetland. It’s a sobering thought, especially when you consider that most farm ponds qualify as eutrophic.
Since you’re dealing with artificial ponds, and even lakes in artificial circumstances, the normal process of eutrophication is significantly abridged. Where a pristine lake might undergo a maturation and aging process that covers a geological age, the bodies of water near human activity age with lightning speed. That’s not ideal for those of us concerned with maintaining a healthy and vibrant ecology over the next 50 years or more.
We’ve talked about preventive techniques to slow or even reverse the aging process in your ponds. (Keep in mind that erosion, while potentially a significant problem, isn’t causally related to the eutrophication process.) As always, the root of the problem is excessive nutrients. The next phase of the problem is thermal layering and the development of oxygen free zones with the associated slowdown in decomposition.
This leads to the next phase, which is the gradual buildup of sediment and other materials that fill up the basin and make the lake shallower and smaller until plants take it over and it gradually disappears. You’re not going to let a pond age out on your golf course, of course, but what can you do when it’s getting visibly shallower?
The first line of defense is to set the pond up with a strong aeration schedule, running 24 hours a day, accompanied by a steady recirculation pump. You can add doses of supplemental bacteria to the pond so that you immediately have a full workforce of decomposers focused on that stuff at the bottom. Consider having some brave souls in waders, or even a diver, venture in to remove tree branches or other large items. Then be prepared for a new wave of nutrient overload. Once that storm has been weathered, though, a significant amount of the accumulated organic debris should be gone, and your pond may be enjoying a few extra feet of living space. If your irrigation reservoir has experienced significant loss of volume, though, you’ll probably need to take more drastic measures.
Dredging is an intensive and potentially expensive project, but it may be the only way to rehabilitate a highly eutrophic lake. It may even be considered earlier in the process if you’ve got significant dead zones and anoxic layers full of organic debris. Sometimes excising the debris is faster than treating it and allows the healing process to begin.
At whatever stage you are when you find yourself contemplating dredging, there are helpful points to keep in mind.
- Dredging deepens the lake and increases its storage capacity.
- Dredging removes layers of nutrient-laden sediments, which helps address the perennial problem of nutrient overload.
- Dredging helps reduce the occurrence of algae blooms.
- Sediment removed from the lake, if not contaminated, can be composted, and used as a rich fertilizer elsewhere on the golf course.
- Dredging can be an expensive project
- Disposal of contaminated sediment costs extra
- The act of dredging temporarily stirs up sediment, which can be unattractive and hard on aquatic wildlife
- The process of dredging inevitably affects the biology of the lake and associated habitats.
- Equipment access to the lake disturbs the shore and access route.
There are several methods available for removing sediment from the lake bottom, and your choice will depend on your budget, the sensitivity of the local environment, how much needs to be removed, and how you intend to dispose of the extracted material. Keep in mind that a regular schedule of lower-impact dredging could eliminate the need for a large-scale dredging project altogether, and spot dredging at just a few critical locations in the short term could provide immediate, budget-friendly relief.