How can HABs be prevented & controlled?
How KDHE Works to Prevent Future HABs
Current studies show that excess nutrients (both phosphorus and nitrogen) are the main cause of algae blooms in water bodies. KDHE works to improve water quality in several ways. The NPDES permitting program ensures that industrial and municipal dischargers limit their nutrient output, while WRAPS programs support local efforts to implement and manage practices that reduce nutrient loading to streams and lakes from non-point sources.
Additionally, KDHE works to track the water quality of our state's streams, lakes, and wetlands through the development of Total Maximum Daily Load (TMDL) limits. Total maximum daily loads constitute established limits for NPDES facilities on the release of pollutants to the waters of the state, including nutrients such as phosphorus and nitrogen.
Measures to Take to Prevent Harmful Algae Bloom in the Future
Excess nutrients entering a waterbody can create conditions favorable for HABs. Runoff that includes turf and crop fertilizers or livestock waste is a major source of excess nitrogen and phosphorous input to water bodies. Pet waste, waterfowl droppings, and leaking septic systems can also contribute. Anything done to reduce these inputs will ultimately improve water quality.
There are several proactive measures that may help uptake excess nutrients in a pond or lake. One measure is to increase the aquatic plant diversity in the pond, as each type of plant will require different nutrients for growth. Appropriate shoreline plantings can also absorb nutrients at the water's edge and provide a buffer to help reduce runoff from entering the water body after heavy rains. Note that some aquatic or riparian plants are not appropriate for Kansas water bodies. Water hyacinths, although pleasing to the eye, can spread quickly and completely cover a pond or lake and are not recommended for this reason. Hydrilla and Eurasian milfoil are highly invasive plants that are illegal within the state of Kansas. Curly pondweed can also become highly invasive and can require a considerable amount of maintenance to control growth. Consult literature, garden shops, or experts in the field of native plants in Kansas to determine what would suit your region, climate, and specific needs.
If the primary purpose of a pond is for aesthetic value rather than for livestock watering, a floating garden may be an option. Floating gardens, wetlands, or islands (the names are all interchangeable) are planted floating platforms that have roots dangling into the water column. These roots can take up excess nutrients, allowing the plants above the surface to grow and use the nutrients that the algae would use otherwise. You may even grow some hydroponic vegetables on the islands by securing them alongside a dock or structure with enough depth to allow the island to float. Along with the uptake of nutrients that these floating gardens provide, the roots serve as a habitat for many beneficial organisms that also improve water quality. There are several websites that provide information about floating gardens and companies that specialize in their construction or how to construct one yourself. For more information about floating gardens or wetlands, see KDHE's presentation, Floating Wetlands - Old and New (PDF).
How to Remove Blue-Green Algae or Toxins from a Lake
There are a variety of products and techniques marketed through lake and pond management companies that can mitigate HABs. Keep in mind that excess nutrients within the system are the primary cause of HABs. The best long-term approach to address HABs is to implement practices to prevent excess nutrients (phosphorus and nitrogen) from entering the waterbody during wet weather and runoff conditions.
In-lake treatment or mitigation options are best regarded as short-term solutions. Their effects are usually temporary, and not all are effective. However, they are often used as part of a larger lake management strategy. Options may include algaecides, phosphorus binding products, or mechanical devices that destroy cyanobacteria or inhibit their growth.
KDHE continues to support research on in-lake mitigation options and is evaluating the effectiveness of some of the technologies through limited pilot projects. At this time, KDHE does not endorse or recommend any particular in-lake mitigation option, but the use of products containing copper or ingredients that are harmful to aquatic life is discouraged. Note, too, that many algae release toxins from their cells when they die, so the application of some types of algaecides, especially during an active bloom, could actually release toxins. Because lake and pond systems are extremely dynamic, it is recommended that landowners consult a professional to determine an effective course of action. It is also recommended that any treatments should be accompanied by baseline and follow-up monitoring.