This summer we saw some unusually unpleasant lake conditions; clumps of algae, bad smells, poor swimming conditions and dead fish to name a few. There are several culprits to blame, but one of them, phosphorus, played a significant role in the creation of these large algae blooms.
Phosphorus enters our lakes through various means, some are located very near our lakes and others are deceptively far. These contamination sources can also be very specific, like a single pipe outlet (“point sources”), or more broad like farmlands (“non-point sources”). Regardless of the source, the phosphorus that gets in is a major nutrient for algae, and makes it grow out of control.
So what has been done to address the issue?
Under the Clean Water Act, steps have been made to reduce this nutrient. We currently have laws in place that limit the amount of phosphorus that point sources can let into our lakes every year. Other measures such as phosphorus reductions in fertilizers and dish soaps are parts of an “upstream” reduction approach.
The Clean Water Act however, has only affected those “point sources” of phosphorus. Meanwhile, the non-point sources that have been contributing more and more phosphorus contamination are just now becoming the target of new regulations.
For a full timeline of water quality programs in Wisconsin history, check out this DNR page.
Enter the revised strategy: Adaptive Management
The current system we use to reduce phosphorus counts on point sources of phosphorus pollution to reduce their own discharges by a set level. This level (represented in tons) is based on scientific research and surveys. In this way, we try to reduce the amount of phosphorus in the lakes by preventing an amount from ever entering it.
But ecosystems are complex creatures, and a reduction number does not always result in improved lakes. As we try to further reduce phosphorous levels in the lake, adaptive management allows the point sources to work together with non-point sources to get at the ultimate goal: improving lake water quality.
In the end, the beauty of adaptive management is that it will make it easier for polluters to meet their phosphorus reduction targets, but at the same time will measure their success on the actual health of the waterways
To learn more basics about the nuances of adaptive management, the DNR has put together a page comparing water quality trading and adaptive management goals