Heading into the warmer summer months, it’s that time of year again when homeowners with ponds start watching for algae growth that has the potential to blossom into a full-fledged algae bloom. While some algae growth can be a good thing, harmful algae blooms can be toxic – even deadly. Did you know one of the biggest contributors to pond algae growth are improperly maintained or failing septic systems? Here’s a quick look what causes algae growth, how to tell if your septic system may be adding to the problem, and some great tips for preventing algae blooms in your pond.

Ponds and Algae Growth

The presence of algae in any pond is not inherently a bad thing. In fact, these plantlike organisms actually contribute to a balanced aquatic ecology by absorbing nitrates in the water. They are also an excellent source of food for certain fish. However, when the algae growth gets out of control, it can cause the pond to become toxic, particularly if certain kinds of blue-green algae are present. Algae thrive in nitrogen-rich environments. In any healthy body of water, nitrates come from the degradation of plant and fish waste. However, when surface water runoff and groundwater contain added nitrogen and phosphorus – typically from landscaping, farming, or failing septic systems – the increase in food for the algae can contribute to a rapid bloom, especially in smaller bodies of water, like ponds.

Ponds are particularly susceptible to algae blooms. Because they are often shallow, slow-moving bodies of water, ponds provide the perfect environment for algae to thrive. Algae derives energy from the sun, like plants, through photosynthesis. When there is an abundance of sunlight, as there is in a shallow pond where the sun can penetrate to the sea floor, any excess of nutrients (nitrogen and phosphorus) will allow the algae population to explode. Ponds are also typically stagnant or slow-moving bodies of water. Because algae grow on the surface of the water, undisturbed, shallow, nutrient-rich water provides the ideal environment for an algae bloom to occur.

Algae blooms not only affect the aesthetics of your home’s pond, but they can also create a toxic, even deadly, environment for any animals (including humans) that are in contact with the pond. An overpopulation of algae can lead to the depletion of oxygen as algae die off and decompose, which can impact the water’s ability to support life. Cyanobacteria, also known as blue-green algae, are photosynthetic microorganisms that can grow into harmful algae blooms capable of producing toxins. These toxins are not only harmful to the animals living in and around the pond, but if the water from a pond contaminated with cyanotoxins gets into the groundwater, it can also impact that drinking water supply for humans.

Signs the Septic System is Contributing to Algae Growth

A properly installed and maintained septic system should not contribute in any way to algae growth in your property’s pond. When installing a septic system on a property with a pond, it is critically important to ensure the system is setback far enough to prevent effluent from being able to reach the pond. At minimum, a septic system should be setback 50 feet, but in some localities and under certain circumstances, a greater distance may be required. Local health departments regulate the standards for septic installation, including determining proper setback from any water source. If a system does not have the necessary setback, even a perfectly functioning septic system will be capable of contributing nitrates to your pond that may increase algae growth. If you are not certain your septic has the proper setback and are concerned it may be contaminating your property’s pond, you should schedule an inspection right away.

Even with proper setback, however, an improperly maintained septic system will be able to contaminate nearby water sources with nitrogen that contributes to algae blooms. If you notice signs that your septic is not functioning properly, there’s a good chance your system is at least partially to blame for algae blooms in nearby ponds. Lush grass above or around your system, unpleasant odors in and around your home, or backed up or gurgling drains are all indications that your system is malfunctioning. If you notice any of these signs of septic failure, do not hesitate to schedule a service visit so that your system can be restored to proper functioning.

Tips for Discouraging Algae Blooms in Ponds

Getting ahead of algae growth is the best way to manage algae blooms in your pond. Using a few simple techniques, you can prevent or significantly reduce algae problems.

Limit the Use of Fertilizers

Because fertilizer runoff is one of the main contributing factors to algae blooms, one great way to prevent them is to limit the use of fertilizers around your property. By adopting “green” mowing practices, you can reduce the need for fertilizers. For example, keep your mower blades set to no less than 3” to allow the grass to develop a healthier root structure. Longer grass is also able to “shade out” weeds, which reduces the need for weed-killing chemicals. Leaving grass clippings on the lawn, rather than bagging them, will allow nutrients to return to the soil.

Plant Foliage to Create a Vegetated Buffer

Vegetated buffers around your pond’s shore will not only stabilize the bank and help prevent erosion, but they also filter out nutrients and even pollutants from the surface and groundwater. In fact, a 15 ft. buffer can filter as much as 50% of the phosphorus in the water headed toward your pond. A vegetated buffer will help prevent unwanted nutrients from entering your pond, and they will also improve the aesthetic beauty surrounding your pond.

Install a Fountain or Aerator

Algae grow on the surface of water, which is why they thrive on slow-moving or stagnant water. By installing a fountain or aerator, you not only increase your pond’s aesthetics, you also interfere with algae growth on the surface of the water. Fountains and aerators also increase the oxygen levels in your pond (which your fish will appreciate) while reducing the amount of usable phosphorous through the chemical reaction of oxidation.

As always, keep up with septic system maintenance to ensure your system is not contributing to algae growth. Conserve water to prevent your system from becoming overwhelmed and have your system regularly inspected and pumped. Keep an eye out for the telltale signs that your septic system needs maintenance. As soon as you notice any signs that your septic system is overwhelmed, contact us to schedule a service visit. Cape Cod Septic Services is licensed, and insured to deliver exceptional service for your septic system maintenance, emergencies, and inspections.


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