Water Quality Report Review

Dave Ernes – Lake Management Committee

Understanding how our lake behaves is paramount in any effort to improve it. During the 2021 recreational season, data was collected for our lake. This data has been compiled in the 2021 Water Quality Report recently received. It is one of the most comprehensive evaluations of our lake and its tributaries in recent years. This article gives a brief overview of this report. It should be noted that most of the data involved monitoring for sources of nutrients, the main driving force behind algal blooms.
 
The Executive Summary states that our lake continues to be eutrophic, a classification that our lake has had since at least 1978. If you are unfamiliar with this term, it is based on what is known as the Trophic State Index (TSI). As lakes age, they become more “productive” regarding algae, aquatic plants, etc. and the TSI is a way to measure this. It is impacted by many factors including location, weather, and other external factors and has varied from year to year. The good news is that the application of VodaGuard C this past year reduced the chlorophyll level below the EPA criteria, with a resultant TSI at the low end of the eutrophic range.
 
Nutrients enter our lake both from internal sources (sediment) and external (watershed) sources. The first set of data was collected to evaluate the internal source. It shows that our lake continues to be stratified into an oxygen-rich top layer and an oxygen poor lower layer (think of a Black and Tan). As a consequence of this, over the course of the summer, the sediment at the bottom releases nutrients into the water. If this stratification is strong enough, it prevents the migration of the nutrients to the surface until the fall turnover. What we found was that the turbulence from the rains of July resulted in the lake becoming less stratified, allowing the nutrients to mix with the water at the surface. This may help explain why the VodaGuard treatment started to lose its effectiveness towards the later part of the summer. Luckily, the stratification was re-established in August.
 
The other source of nutrient entering the lake is from the watershed. Our watershed is large, and one of the ways it enters the lake is via the tributaries. The data collected from the five main tributaries showed that, not surprisingly, Rock Creek is the worst offender regarding nutrients. One interesting finding was that Fisherman’s Cove exhibited the second largest phosphorous concentration, and an elevated bacteria level.
 
The last section of the report details some potential mitigation strategies to further improve the lake, like aeration and nutrient inactivation. Each is correlated with the likelihood that it would be effective for our lake. Many of these will be further evaluated in our 2022 Management Plan.
 
One of those strategies is for us to do our part. It is true that no single individual can have the same effect as a storm, but collectively we certainly do. What we do on our property regarding fertilizer, mowing practices, and even landscaping design can have positive or negative effect.  Many articles have been written detailing Best Practices. So, as we move forwards with our efforts to improve the quality of our lake, each of us can do their part, so please …  

Be Lake Responsible

The Water Quality Monitoring Report can be found on the Lake Management Page of the RRA Website under Lake Surveys and Studies.