water quality program manager
Iowa State University Extension and Outreach
As outdoor temperatures warm and ice begins to thaw, ponds can provide an outdoor retreat for many Iowans. In this article, Iowa State University Extension and Outreach water quality program manager Catherine DeLong discusses best practices when treating or preventing common pond problems.
One of the most common issues that Iowa pond owners face is algae overgrowth or excessive pond vegetation due to nitrate and phosphorus loss from the surrounding agricultural landscape. According to DeLong, while some pond vegetation is essential to the health of aquatic ecosystems that support fish and other aquatic creatures, an overgrowth of pond vegetation can lead to pond odor and fish death, among other management concerns.
DeLong recommends that ponds have between 15 to 25% vegetation coverage. If vegetation levels exceed this, pond owners should consider taking action. Some options discussed in a previous publication include mechanical raking, nontoxic dyes and as a last resort, herbicides.
However, the best way to address elevated nutrient levels in ponds is through preventative pond management, since other methods may kill fish or otherwise disrupt aquatic ecosystems and can be expensive. As DeLong explained, planting a buffer zone of deep-rooted native plants around the pond is an excellent way to reduce excessive nutrient levels, prevent erosion and build a strong ecosystem around the pond.
DeLong says there are many benefits to buffers including increasing streambank stability, providing habitat for wildlife and pollinators, and increasing the beauty of the area with flowering native plants. Buffers that support streambank stability can also limit erosion, which can create additional issues for landowners such as dredging or digging sediment out of the pond.
Other preventative measures include fencing off the pond from livestock to prevent streambank erosion, discouraging geese around the pond, limiting fertilizer use near the pond or aerating the pond. For more information regarding preventing or treating excessive pond vegetation, visit the article Ponds: Managing Algae and “Weeds.”
Another common issue for pond owners in Iowa is cloudy or muddy water, referred to as turbidity. Turbidity is often related to microorganisms living within the pond, weather or animal disturbance or suspended clay particles within the water.
To determine the specific source of the turbidity, collect a water sample and hold it up to the light. If microorganisms moving erratically are visible in the water sample, the source of the turbidity is likely due to planktonic algae, which are an important part of the pond’s ecosystem. Unless there is an increase in fish kills or an undesirable odor or scum, no additional management is needed.
If the turbidity is not a result of microorganism activity, check the water sample after an additional 24 hours. If the particles have settled, the cloudiness is likely related to weather or animal disturbance and should clear in a few days. However, if the particles have not settled, there may be a chemical imbalance in the pond. For more information on managing pond turbidity, visit Ponds: Managing Cloudy or Muddy Water.
While good pond management practices can make a pond healthier and more enjoyable for landowners, it is important to remember that good pond management can also have a positive impact on Iowa’s watershed, improving water quality for all Iowans.
For more information on pond management, visit Farm Ponds – Managing Iowa Fisheries.