Lake Fertilization

Pond management and lake fertilization

There are times in the life of a pond or lake when clearing the water may be necessary. At those times, there are flocking agents that will do the job well. You should be aware however, that a completely clear pond or lake is not the optimum circumstance for a healthy body of water. Unfortunately, there are many who suffer from the illusion of healthy happy fish in a beautiful crystal clear pond, but it is just that, an illusion! For healthy fish, and for a healthy pond ecosystem, there must be something growing in the water, and that something is phytoplankton. The way to get it is through fertilization.

Nowhere in the world of living things can the effects of fertilization be seen more clearly than in a pond or lake. The effect can be almost immediate, and often drastic. The results, if properly implemented, will be a near incredible increase in fish size and numbers. Properly timed and implemented fertilizer applications will also reduce the population of unwanted submersed and emergent weeds.

An analogy: Cattle pastures and fish ponds

Think of it in terms of a cattle pasture. If you fertilize the grass, the cattle will grow more quickly, and the pasture may be able to support more cows. Reproduction will increase, and pounds of milk or beef per acre will increase. Lake fertilization works the same way. Increased pond fertility will increase the food source for your fish, which will increase their size and numbers. If done properly, you will also cause the grasses to outgrow the weeds.

What kind of fertilizer and how much

Fertilization will produce algae bloom, or phytoplankton in your pond. The right fertilizer is a fertilizer high in phosphorous and low in the other 2 elements. Phosphorous is the middle number in the 3 numbers listed on a bag of fertilizer. You need to add 40 lbs of 20% phosphorous, or 20 lbs of 40% phosphorous, or something similar in ratio per acre to initiate algae bloom. It takes about 4 to 8 pounds of pure phosphorous to produce or maintain algae bloom in an acre of water. If you had a product with 80% active ingredient, you would need about 10 pounds. However you get there, you need about 8 pounds of the second number in the fertilizer label, and as little of the other ingredients as possible.

There are some great pond and lake fertilizers available, but if you can’t find them, regular old high phosphorous agricultural fertilizer granules can be used. There are also liquids available, but when using liquids in a pond or lake, always remember that the fertilizer is heavier than the pond water, and will sink to the bottom unless you add water before releasing it into the pond water.

An alternative to phosphorous for pond fertilization

With phosphorous being closely monitored today, and restrictions on the horizon, it may be a good idea to look into alternatives such as the ones mentioned in this post by Mr. Bhaskar on our Lake Advice Blog: Diatom Algae. For the details on various methods fertilize your pond see Pond Fertilization Methods . Find more information about the effects of lake fertilization throughout this site.

Pond Management Cost


We are often asked about pond management cost. To give you some idea of the cost, think about it in relation to what you spend on your lawn. If you hire someone to do it for you, the cost will be higher than if you do the work yourself. Of course, either way, you will have expenses, like equipment costs and maintenance, fertilizers and other amendments, and pest control products. The same is true of your lake or pond, and the similarities in cost may amaze you!

The right pond for you

It would be great if you had the perfect lake. You know, that perfect pond, just right for your needs, with just the right size, and just the right depth to produce your favorite game fish, or operate your favorite water craft, or for family recreational swimming. That would be great, but it is not likely to happen unless you build your own pond on your own property. Even if you built your own, you would still have problems, and you would still have to practice pond management to keep it the way you want it. More and more home buyers are purchasing property with farm or ranch ponds or lakes on them, and like many other parts of property ownership, the cost of maintaining such amenities can be an unexpected expense. The fact is, that you probably inherited your lake by buying the property on which it exists, and there is a huge possibility that it came to you in pretty sad condition, and that it is not exactly what you would have chosen if you had the option. Your pond may have been a farm pond or ranch stock tank, or an irrigation reservoir never intended to be used for the purposes you have in mind. It has likely not been used for any human purposes in some time, and was probably not maintained in any human sense of the word for some time.

Ponds need management

Contrary to popular belief, a man made pond or lake will not take care of itself in any manner remotely related to the needs of human beings. It will silt in, become overgrown, become home to undesirable wildlife, and may even become a health hazard. For human purposes, a pond or lake needs human maintenance. That is where you have to begin. In short, the perfect pond or lake for you is the one you own! To get it into the condition you want, and to develop it into what you want it to be, will require some sound pond management practices.

Property management costs

There are many hidden costs that come with home and property ownership. There are home owner association fees, taxes, home owners insurance, lawn maintenance, and home repairs that can make home ownership a little more expensive than it seems on the surface. Most new property owners have some idea of the costs of lawn care, and taxes and insurance, but may not realize that ponds and lakes require maintenance as well, and that the cost of pond management can be equal to, or greater than the cost of maintaining a similar sized lawn.

Pond management cost

Intensive pond management

The average lawn size in the United States is about 10,000 square feet. That is a little less than 1/4 of an acre. The average cost of maintaining that amount of lawn is about $50.00 per week, or $200.00 per month, or $2,400.00 per year. That would translate into about $9,600.00 per acre for intensive lake or pond maintenance. If a property owner has a 1 acre pond, he can reasonably expect to spend almost $10,000.00 per year on intensive professional pond management or lake care per year. This may be a little unsettling for the property owner, but it is something that should be considered before purchasing property with a pond or lake, and budgeted for if the property owner already has such a property.

Average pond management

In reality, most ponds and lakes are maintained fairly well with management equal to the cost of a similar area in pasture land. Mowing an acre of pastureland in our area of operation usually costs around $40.00 to $50.00 per acre, per mowing. This can be multiplied by the number of acres, and the number of times it is mowed for a year. So, if we have a one acre area, which needs to be mowed 6 times per year, we come up with an average figure of $270.00 per year of basic care. Ponds, like lawns and pastures benefit from some mineral and chemical applications to keep the beneficial plants alive and growing, and to keep the weeds away. A rough average of such costs would lead to a figure approximating the cost of mowing, so the total cost would be something around $500.00 to $600.00 per acre, per year to maintain an acre of land, or an acre of water at a reasonable level. Of course the property owner has options for pond management, and much of it can be accomplished "in house" for much less money with the right information, and that is why we are here. See also: Lake Restoration