Today HAB begins Day 9 of the 2019 Cedar application and we have now settled into an efficient routine. The weather continues to be awesome, alum deliveries have been consistent and on-time and the application barge continues to steadily apply the alum floc to the lakebed sediments in the application zone. Yesterday the barge applied about 29,000 gallons of alum to a 63-acre portion of the lake. Today’s application is well underway and are set for another productive day at Cedar Lake!
Yesterday we discussed the importance phosphorus in determining lake water quality. Today’s article (see below) address the question “Where Does This Phosphorus Come From?”
At Cedar Lake, phosphorus in the lakebed sediments has increased over the years and is released when oxygen levels decrease at the lake bottom. The water column periodically mixes during high summer winds and cool conditions, bringing phosphorus-rich water to the surface for algal uptake and growth. Samples from the bottom of the lake confirmed that phosphorus is very high in the sediments and available to be released into the overlying water column. The alum application produces a “floc” that settles to the bottom of the lake. The floc has sites where phosphorus in the sediments become chemically bound as it leaches from the bottom. The floc effectively intercepts and binds the phosphorus, which makes it unavailable for the algae to use for growth. The goals of the project are to reduce the internal loading of phosphorus from the sediments, lower the amount of phosphorus available to algae in the water, reduce the amount of algae and potential toxins and improve the recreational opportunities for lake users.