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The alum treatment on Upper Prior is progressing well and may be completed by as soon as Wednesday. The HAB crew has had some curious onlookers asking about the application technology they use on the barge and why we are so careful with the placement of alum. These are great questions and we have some excerpts of answers from the Upper Prior alum treatment website below.
Precise Alum Application
The key to a successful alum application is the formation of the floc and the precise placement of the floc on the lakebed. The floc is formed when the liquid alum mixes with lake water immediately after application. It is a whitish-green precipitant, is more dense than water and sinks through the water column at a rate of 1 foot every 2.5 minutes. Once it reaches the bottom, the floc’s active binding sites are in place to intercept phosphorus as it leaches from the lakebed.
The alum is injected a little ways under the surface of the lake. This setup effectively injects a stream of alum that flash mixes with lake water below the surface. Floc immediately forms at a depth of 2-3 feet. Forming the floc below the lake surface bypasses any interference in settling by avoiding the surface tension of the water and algal scums on the surface. It also forms the floc at a depth where it is less susceptible to wave action.
The application of alum from the barge is synced with an onboard computer and GPS system which ensures that there are no gaps in alum application. For more details check out the “Precise Alum Application” article on the Upper Prior Lake Alum Treatment website.
Lake Testing Ongoing During Treatment
District staff and HAB (our alum applicators) continue to test the lake every day during treatment to ensure the application is going to plan and nothing has gone awry. Testing ensures that the lake maintains proper pH levels and so far everything has been going smoothly and no problems have been detected.View Full Article Lake, Upper Prior, Upper Prior Lake, alum, alum treatment
A special Board meeting will be held Wednesday, May 27 from 1:30-2:00 p.m. to discuss the District’s Covid-19 policy.
To attend you can join the meeting from your computer, tablet or smartphone at https://global.gotomeeting.com/join/769200077 or dial in using your phone: +1 (646) 749-3131 (Access Code: 769-200-077).View Full Article
The first ever alum treatment on Upper Prior Lake will start Tuesday, May 26. The treatment should take 8-11 days to complete, depending on weather conditions. The contractor cannot apply the alum if it is too windy. The Upper Prior Lake alum treatment is largely funded by grant from the Minnesota Board of Water & Soil Resources (BWSR).
There are no restrictions on recreation on and in the lake during treatment. However, please give the alum barge room to work. The barge applies the alum following computerized tracks across the lake to precisely apply the correct amount of alum to each area of the lake. You can help by moving out of the barge’s way during alum application. The project will be staged out of the lot just north of Charlie’s.
Aluminum sulfate (alum) is used to improve water clarity and reduce algae blooms by reducing phosphorus levels in the lake. Phosphorus is a nutrient naturally found in lakes, however due to development and runoff, excess amounts of phosphorus feed algae blooms. Alum treatments bind phosphorus making it unavailable for algae growth.
Landowners can also do their part to improve water quality: reduce the amount of turf grass and add native plants to your yard which minimizes your use of fertilizer and improves infiltration. Visit the ‘Get Involved’ section of our website for more information and ideas. We look forward to enjoying a cleaner lake!
For more information and project updates visit the alum treatment project page on our website and the Upper Prior alum treatment website. Contact Jaime Rockney with project questions at email@example.com.View Full Article Upper Prior, Upper Prior Lake, alum, alum treatment, phosphorus
Boat inspections are now underway for the 2020 boating season. The District has engaged WaterGuards, a company based in St. Joseph, Minnesota, to conduct inspections at the three public boat launches on Prior and Spring Lake.
Inspectors inspect boats for aquatic invasive species (AIS) prior to entering and after leaving the lake. The goals of inspections are to prevent the introduction of new AIS into local lakes, stop AIS already present from spreading to new lakes and educate boaters on AIS.
The District’s AIS boat inspections are meant to supplement the Minnesota DNR’s boat inspection hours at the three launches. However, due to the Covid-19 pandemic the DNR has not yet started boat inspections this year. At this time, WaterGuards is currently covering the hours (primarily Friday-Sunday) the DNR would normally be inspecting. Inspection times are focused around predicted higher traffic times. The DNR has not yet announced their plans for 2020 AIS boat inspections.
Once an invasive species is introduced into a lake, it is impossible to eradicate and reducing or managing the growth of established aquatic invasive species is often very expensive. Prevention or early detection is an important component to effectively managing AIS.
Currently known AIS present in Prior Lake are zebra mussels, curlyleaf pondweed and Eurasian watermilfoil and curlyleaf pondweed in Spring Lake.View Full Article AIS, AIS inspections, boat inspections