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Posts tagged "Upper Prior Lake"

How was lake water quality in 2020?

Posted by PLSLWD Staff - December 26, 2020 - News, Prior Lake, Spring Lake

In a bright spot of 2020, both Spring and Prior Lakes saw improved water quality this year which was a boon to everyone who swarmed to the lake this summer for swimming, fishing and boating. This year marked the first time that all three water quality standards – the goal for a healthy lake – were met on either Spring Lake or Upper Prior Lake.

In the graphs shown below you can see how the levels for each of three water quality parameters have generally improved over time for each lake. The dashed lines show the water quality standards – the goal to meet for good water quality.

Water clarity (Secchi disk depth), total phosphorus concentration and chlorophyll-a concentration are the main standards used by View Full Article →

View Full Article Prior Lake, Spring Lake, Upper Prior, Upper Prior Lake, Water quality, alum, alum treatment, phosphorus, spring

Alum Treatment Complete on Upper Prior!

Posted by PLSLWD Staff - June 5, 2020 - News, Prior Lake

The Upper Prior Lake alum treatment is now complete! The contractor finished the alum application on Wednesday, ahead of schedule. Find more details on the alum treatment website here.

Alum treatments have been identified as a way to address high levels of internal phosphorus stored in the lake bottom sediment on Spring and Upper Prior Lakes. Both lakes are listed by the State of Minnesota as impaired lakes due to the high levels of phosphorus.

While phosphorus is an essential nutrient for plants, too much phosphorus can lead to excessive algae growth in lakes. Excessive algae is not only unsightly and undesirable for recreation, it can also reduce lake oxygen levels leading to fish kills and kill beneficial aquatic plants by blocking sunlight. An alum treatment reduces internal phosphorus by applying aluminum sulfate (alum) to the lake; the alum binds to the phosphorus making it unavailable for algae growth.

Alum treatments are only one of many ways the Prior Lake-Spring Lake Watershed District is working to improve and protect water quality in your local lakes and wetlands. Reducing the incoming sources of phosphorus and nutrients to the lakes is also important.

We’re looking forward to a cleaner lake!

View Full Article Upper Prior, Upper Prior Lake, alum, alum treatment, phosphorus

Upper Prior Alum Treatment Update

Posted by PLSLWD Staff - June 1, 2020 - News, Prior Lake

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.

Cloudy floc from alum as it is being appliedThe 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

Upper Prior Lake Alum Treatment: Begins May 26

Posted by PLSLWD Staff - May 21, 2020 - News, Prior Lake

Barge applying alum on Spring Lake 2018

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 jrockney@plslwd.org.

View Full Article Upper Prior, Upper Prior Lake, alum, alum treatment, phosphorus

Spring Lake Alum Treatment Starts May 4

Posted by PLSLWD Staff - May 1, 2020 - News, Prior Lake, Spring Lake

Barge applying alum on Spring Lake 2018The third and final dose of the alum treatment on Spring Lake is set to begin Monday, May 4. The treatment should take 10-14 days to complete, depending on weather conditions as the contractor cannot apply the alum if it is too windy. The project will be staged at the Spring Lake boat launch. The launch will remain open for public use.

Updates on the treatment will be posted on the alum website as well as the District’s Facebook page.

Treatment on Upper Prior is currently scheduled to begin on May 26 and should take 8-11 days to complete. This is the first time Upper Prior Lake has been treated with alum! The treatment schedule is still dependent on some grant approvals so the start date is subject to change. The treatment is largely funded by a grant from the Minnesota Board of Soil & Water Resources (BWSR). The project will likely be staged at the Dewitt boat launch which will remain open to the public. However, we are looking into a couple other potential locations for staging.

Barge applying alum on Spring Lake 2018Why are we doing alum treatments?  In short, Spring and Upper Prior Lakes have too much phosphorus which causes algae to grow.

Aluminum sulfate (alum) binds with the phosphorus, inactivating it and making it unavailable for algae to use. Less algae is not only visually more appealing and better for recreation, it allows more sunlight to reach the lake bottom which is beneficial for aquatic plants and fish. Find out more here.

What else is there to know?  Boating, swimming, fishing, and eating the fish you catch during the treatment is fine. The water is safe for dogs to drink and play in as well.

Please avoid getting in the way of the barge. The barge follows computerized tracks and is programmed to apply specific doses of alum to the different locations in the lake. If you are on the lake and see the barge headed your way, please help us out and move out of the barge’s way. The water will appear temporarily cloudy after the alum is applied (see photo above), this is normal and the water will clear up as the alum settles to the bottom.

Alum treatments are just one of many ways the District is working to improve the water quality in our lakes. Find more information on our website here.

You can find more information on our website here and the alum treatment website here. If you have further questions, please contact Jaime Rockney at jrockney@plslwd.org or 952-440-0068.

View Full Article Spring Lake, Upper Prior, Upper Prior Lake, alum, alum treatment

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Prior Lake – Spring Lake Watershed District

The District covers about 42 square miles in Scott County, MN. Water in the PLSLWD flows mainly from the southwest to the northeast through Spring, Upper Prior and Lower Prior Lakes, and then north through the Prior Lake Outlet Channel to the Minnesota River near Valley Fair amusement park.
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Prior Lake - Spring Lake Watershed District
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