2013-06-05 P & R Packet - Laserfiche WebLink

Home Browse Search

An earlier evaluation of the TMDL set a target phosphorus level of 80, but the Minnesota Center for Environmental Advocacy said the TMDL must use the state standard of 60, causing a delay. The TMDL is still in the approval process. Algae blooms of Peltier Lake are a function of the high phosphorus levels. One pound of phosphorus can create up to 500 pounds of algae. Much of the bloom is in the form of undesirable blue green algae. The lake has had Aphanizomenon algae (the small sliver like green flakes) for long periods over the summer. Other algae also occurs. Not only are these blooms disgusting in appearance, their component algae can release toxins that can harm or kill animals, and it is not clearly understood how or when these toxins occur. Algal blooms are not only ugly, but are a public health concern. I would personally rather have large numbers of beneficial aquatic plants that absorb nutrients than have algae blooms with possible toxins. Have you ever noticed how clear and clean the lake looks in spring? The lake is clearest when the aquatic plants are all growing healthy. A lake needs healthy aquatic plants, especially a lake like Peltier. These plants absorb nutrients, provide oxygen, stabilize the sediments and provide shelter for smaller beneficial creatures among other things. Even the Curlyleaf Pondweed helps the lake in spring. The unfortunate habit of Curlyleaf is that it dies in midsummer and makes a mess. For years, we tried harvesting the Curlyleaf in various ways but it is expensive, time consuming and the harvesting cuts out the good aquatic plants too. The good aquatic plants never seem to get established. Harvesting might even tend to tip the environment to favor the invasive species. (Here's a side note on Eurasian Watermilfoil whose presence is feared in many other lakes: this invasive species does not seem to be causing a problem in Peltier Lake at this time. It does not grow thick and nasty in Peltier Lake. Ironically, it might be a good thing if Eurasian Watermilfoil replaced the Curlyleaf because it does not die in midsummer. It might absorb nutrients and stabilize sediments all summer reducing phosphorus in the lake.) A curious evolution occurred at Rice Lake, just downstream from Peltier Lake. A few years ago, Rice Lake suddenly became totally infested with the invasive Curlyleaf Pondweed. It covered the entire lake and was extremely thick. There's a seaplane base on Rice Lake and seaplanes were having trouble with the Curlyleaf. There were plans to try to do something. As I understand it, a year or two later, native aquatic plants like Coontail and Elodea totally took over virtually eliminating the Curlyleaf. Native plants took over the invasive plant! Nature at least partly solved a problem. Why did that lake evolve from an invasive to a native aquatic plant? I'm not sure anyone knows the answer to that. Here's another example closer to home. Before 1998, the north part of Peltier Lake was filled with beneficial native aquatic plants, mostly Coontail. The north part of Peltier Lake is very shallow with fine silt sediments (filled with phosphorus). The native aquatic plants in north Peltier Lake absorbed nutrients coming from upstream and stabilized the sediments, holding the phosphorus in place among other things. With intense high speed boat activity north of the island, hundreds of thousands of square feet of that native vegetation was destroyed allowing invasive Curlyleaf Pondweed and a sprinkling of Eurasian Watermilfoil to invade. Later, much of the surrounding native plants were replaced by Curlyleaf Pondweed. In midsummer, that whole area turned to nasty algae blooms. Peltier Lake nearly lost a major aquatic plant buffer and filter. A DNR aquatic plant survey expert thought that whole area would be lost to the invasive species. However, with the no -wake zone established, native plants communities began to return. It has taken 14 years for that area to get close to recovery and we are very lucky the native plant community is successfully eliminating the exotics. That area is now mostly Coontail and some Elodea. A small insignificant amount of the invasive Curlyleaf remains. It is imperative that the whole north part of the lake be protected by a no -wake zone to prevent damage to o the sensitive native aquatic community. The Lino Lakes Environmental Board also identified rare plants in the north part of the lake adding to the need for protection. Another positive change in the plant community is occurring on the south side of the lake and perhaps elsewhere. I have noticed (others have noticed too) in our own area on the south side of the lake that the aquatic plants are staying all year. It looks like the invasive Curlyleaf Pondweed is being displaced by native aquatic plants like Coontail and Elodea (perhaps the same process as happened in the north end of the lake). The south side of the lake has only had 10 years or so of undisturbed growth. Perhaps after 14 years, the Curlyleaf Pondweed will be displaced as it has in the north part of the lake. Thought has been given to harvest plants.