July 6, 2018
Q.: Bob from the East Shore asks: We have noticed an abundance of weeds and algae on the lake this year. What’s the cause and is there a recommended approach for controlling them?
A.: Bridget: I’ve received several reports of abundant plant growth and the presence of a “green mat” in the water. I’ll respond in two parts 1) Why the increase in plant and algae life? 2) What can be done to control them?
Why the increase: I reached out to local water quality expert and retired Trine professor, Pete Hippensteel, to understand why we may be seeing more plant growth and algae this year. May is an active time for land activities. Spring applications of fertilizers are being applied by homeowners on lawns and farmers are readying the fields for planting. He explains that May water quality data for most lakes around the county are showing higher phosphate levels than typical which is nourishment for both plants and algae. He attributes the higher phosphate levels to the amount of rainfall received this spring resulting in runoff from lawns and farm fields entering the lake.
In talking to a few area farmers, they reported increased rates of erosion this spring. Bruce Moody explains that the increase in phosphorus may be a function of erosion caused by the higher intensity rain events. The phosphorus is bound to the soil particles that may be flowing into the lake.
Aquatic plants and algae occur naturally in a healthy lake. Excessive plants or algae negatively affect wildlife, recreational opportunities, and water quality. Hippensteel also notes that the heavy rain in May followed by three or four hot and sunny days created the perfect condition for an algae bloom. Wind and storm events drive algae from open lake areas along a shoreline, making the ‘bloom’ or “green mat” more noticeable and concerning.
What can be done: The amount of rain, the intensity, and the number of storm events this spring played a key role in the higher levels of algae and aquatic plants. While we have no control over the weather, we can help to minimize its effects by mindful application of fertilizers and implementation of effective erosion control practices. Some simple recommendations to implement are: test soil, including lawns, for chemical need, follow the recommended application rate, and avoid applications and soil preparations when risk of significant rain events are forecasted. Keeping our fertilizers and top soil where they belong will save money and preserve the balance in our lakes.
When balance is disrupted and an overabundance of plants affect the recreational use of our lakes the Indiana Department of Natural Restoration (IDNR) has provided direction on approved methods to control aquatic plants. The IDNR recommendations can be found in Managing Aquatic Plants In Indiana Lakes and range from physical, chemical and biological control methods along with timing, collection and permitting stipulations to prevent the spread of noxious plants and an imbalance of our lakes eco-system.
Make plans to join us for an informative Plant Identification Workshop on August 5th at 1:30 pm. Meet at Clear Lake Town Hall. We will learn how to identify aquatic plants and ways to control them.
Clear, clean water is one of the Conservancy’s ultimate goals, but it’s a complex effort. Thanks for your interest in improving water quality because it is a community-wide effort.
This periodic short column allows Conservancy Executive Director Bridget Harrison to give all of us the same answer at the same time. If you have or hear such questions or concerns, let Bridget know by email firstname.lastname@example.org or phone call, (260) 316-1397. Also, help us by spreading the word about this new source of reliable and timely information about community and environmental questions in the Clear Lake Watershed.