Over the years, the Dana Hall pond has been dealing with a case of seasonal algae during the warmer months, causing students at Dana Hall to give it the name “Matcha Pond.” The more scientific term for this phenomenon is ‘algal bloom’.

Ms. Mary Frances Hanover, biology teacher and head of the science department at Dana Hall School, explained  that algae is a “small, single-celled organism that is able to exist in all bodies of water” and the pond at Dana Hall provides the “right set of circumstances” for algal blooms to occur: warm temperatures and a high amount of nutrients, specifically nitrogen and phosphorus. 

Mr. Tom DiGiandomenico, the Facilities Director of Dana Hall School, explained that “there are drains all over campus” that connect to the Dana Hall pond, which results in all the rainwater from all over campus ending up in the pond. The pond then drains into the creek behind Dana Hall’s Music School. 

Ms. Hanover’s likely explanation for this is that because all of the rainwater is getting carried into the pond, all of the nitrogen and phosphorus from the residue is gathering within it. This, in combination with the warm weather, “provides a set of conditions for the algae to reproduce over and over again,” ultimately leading to the algae bloom during the warmer seasons. 

Mr. DiGiandomenico said that the school made the decision to treat the pond algae this year, and attempted to limit it for the first time. However, due to the drought this summer, “the treatment for algae that they put in wasn’t doing anything” as the water levels weren’t high enough to reach the drain. Mr. DiGiandomenico explained that the school is planning to restart this treatment when the “water levels are higher during the spring,” so Dana Hall may be able to experience a clear pond all year long.

Once the weather gets cold enough, the algae seems to magically disappear. Ms. Hanover explained that the algae that forms during the warmer months “sinks down to the bottom of the pond and decomposes,” which is why the algae is only visible during the warmer months. 

However, with the death of all this algae also comes decomposing bacteria, which “pulls oxygen out of the water.” This can potentially be a problem as aquatic life usually survives off of oxygen that they pull out of water. At Dana Hall, the process of algal decomposition doesn’t create an issue, as there isn’t a large population of aquatic life that is sustained by the pond. 

But outside of Dana Hall, excessive algal blooms pose a huge problem to major bodies of water. When levels of dissolved oxygen become so low that fish and other aquatic organisms are unable to thrive, it impacts fishing grounds and therefore the livelihood of people who depend on this aquatic ecosystem.