Lake Stevens
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Forum Post Guidelines: This Forum is rated “Family Friendly”. Civil discussions are encouraged and welcomed. Name calling, negative, harassing, or threatening comments will be removed and may result in suspension or IP Ban without notice. Please refer to the Terms of Service and Forum Guidelines post for more information. Thank you
Lake Stevens
I have notice they have been spraying this stuff called Alum in Lake Stevens to kill off the Algae bloom. I know they did this last year and I was told last year that they were just spraying 15 ft out from the shore line. This year I was sure to seem them in the middle area by the aerator. So the way I have read it Algae feeds zoo-plankton which feeds Kokanee and that would mean there killing off the food source for kokanee. Im not biologist but this doesn't sound so smart to me.
Re: Lake Stevens
I have some more info on this subject and will share soon it sounds like a good thing than what I was told. Good luck to all at the Kokanee derby!
Re: Lake Stevens
(ME)I have seen that your spraying Lake Stevens again with Alum. I was wondering if it kills off all algae bloom or just specific target of the blue green? Im an avid Kokanee fisherman and know that the algae bloom feeds the zoo plankton which in turn feeds the kokanee. Has there been any research on what this does to the kokanee and there natural habitat? Thank you for your time.#########
(RESPONSE)(Boy I love questions like this! They make me go look up a few things and confirm them in my mind again. And a as a fisherman myself and growing up on lakes I like to see people concerned about what is going on. So here are a few points to answer your questions:
1. Alum does not kill algae. Alum (Aluminum Sulfate) has a lot of uses like for water clarification in the treatment of drinking water, but for our purpose in Lake Stevens and other lakes it is used to remove available phosphorus from the water column and sediments. When it hits the water it reacts with water and Phos to form Aluminum Phosphate and Sulfuric acid. The Aluminum phosphate forms a floc in the water and sinks down – if you were up close to the treated areas at all you may have noticed the water taking on a blueish-white color.
a. No, the acid isn’t an issue. Lake Stevens has a natural “buffering capacity” which helps maintain a safe pH (acidity) in the water. This isn’t the case in every lake and sometimes a buffering agent has to be applied at the same time (like Lake Ketchum which will have an Alum application next week).
2. The reason we target Phos in lakes is because this is the “limiting nutrient” in freshwater lakes. Algae need many nutirients – Phos and Nitrogen being the two main ones – and by reducing the levels of one (phos) it doesn’t matter how much of the others may be present in the lake because if they run out of phosphorus they are done. Its like grilling steaks with charcoal – run out of charcoal (phos) and it doesn’t matter how many steaks are sitting on the counter. Because blue greens make their own nitrogen in most cases removing N from the water wouldn’t help.
3. I love looking up stuff and here is a blurb from the Wisconsin DNR:
How do blue-green algae differ from true algae?
Blue-green algae, like true algae, make up a portion of the phytoplankton in many water bodies. However, blue-green algae are generally not eaten by other aquatic organisms, and thus are not an important part of the food chain. True algae (e.g., green algae) are very important to the food chain. They are known as "primary producers", a name given to living organisms that can convert sunlight and inorganic chemicals into usable energy for other living organisms. Most algae are microscopic and serve as the main supply of "high energy" food for larger organisms like zooplankton, which in turn are eaten by small fish. Small fish are then eaten by larger fish, and both small and large fish are eaten by mammals, raptors, and people.
4. So the process of applying Alum will help create a more beneficial food web within the lake by favoring the green algae species preferred by zooplankton – which are the base feeding the smaller fish, which are eaten by bigger fish and so on until the Kokanee get them.
5. There generally isn’t any direct impact to the fish during an Alum application. The main concern is the pH issue mentioned above and even as the temporarily acidic water is buffered out most fish will avoid the water – sensing it is not good to be there. Which is why when we do these applications close to shore we start near shore and work out towards the middle so we do not trap fish against the shoreline where they cannot avoid the chemical. Habitat isn’t directly affected by this treatment beyond the pH.
I hope this answers your questions, but if you have more feel free to ask.
Adam.
Adam Kleven
Aquatic Biologist
360.508.1276
AquaTechnex, LLC.
(2nd response)
(Terry McNabb <tmcnabb@aquatechnex.com>
May 15 (3 days ago)
Alum precipitates the phosphorus out of the lake water. When phosphorus goes down, the phosphorus to nitrogen ratio in the water becomes more advantageous for green algae. We are using a low dose not designed to take everything out)
This is the information I got when I asked about what it does to the kokanee.
(RESPONSE)(Boy I love questions like this! They make me go look up a few things and confirm them in my mind again. And a as a fisherman myself and growing up on lakes I like to see people concerned about what is going on. So here are a few points to answer your questions:
1. Alum does not kill algae. Alum (Aluminum Sulfate) has a lot of uses like for water clarification in the treatment of drinking water, but for our purpose in Lake Stevens and other lakes it is used to remove available phosphorus from the water column and sediments. When it hits the water it reacts with water and Phos to form Aluminum Phosphate and Sulfuric acid. The Aluminum phosphate forms a floc in the water and sinks down – if you were up close to the treated areas at all you may have noticed the water taking on a blueish-white color.
a. No, the acid isn’t an issue. Lake Stevens has a natural “buffering capacity” which helps maintain a safe pH (acidity) in the water. This isn’t the case in every lake and sometimes a buffering agent has to be applied at the same time (like Lake Ketchum which will have an Alum application next week).
2. The reason we target Phos in lakes is because this is the “limiting nutrient” in freshwater lakes. Algae need many nutirients – Phos and Nitrogen being the two main ones – and by reducing the levels of one (phos) it doesn’t matter how much of the others may be present in the lake because if they run out of phosphorus they are done. Its like grilling steaks with charcoal – run out of charcoal (phos) and it doesn’t matter how many steaks are sitting on the counter. Because blue greens make their own nitrogen in most cases removing N from the water wouldn’t help.
3. I love looking up stuff and here is a blurb from the Wisconsin DNR:
How do blue-green algae differ from true algae?
Blue-green algae, like true algae, make up a portion of the phytoplankton in many water bodies. However, blue-green algae are generally not eaten by other aquatic organisms, and thus are not an important part of the food chain. True algae (e.g., green algae) are very important to the food chain. They are known as "primary producers", a name given to living organisms that can convert sunlight and inorganic chemicals into usable energy for other living organisms. Most algae are microscopic and serve as the main supply of "high energy" food for larger organisms like zooplankton, which in turn are eaten by small fish. Small fish are then eaten by larger fish, and both small and large fish are eaten by mammals, raptors, and people.
4. So the process of applying Alum will help create a more beneficial food web within the lake by favoring the green algae species preferred by zooplankton – which are the base feeding the smaller fish, which are eaten by bigger fish and so on until the Kokanee get them.
5. There generally isn’t any direct impact to the fish during an Alum application. The main concern is the pH issue mentioned above and even as the temporarily acidic water is buffered out most fish will avoid the water – sensing it is not good to be there. Which is why when we do these applications close to shore we start near shore and work out towards the middle so we do not trap fish against the shoreline where they cannot avoid the chemical. Habitat isn’t directly affected by this treatment beyond the pH.
I hope this answers your questions, but if you have more feel free to ask.
Adam.
Adam Kleven
Aquatic Biologist
360.508.1276
AquaTechnex, LLC.
(2nd response)
(Terry McNabb <tmcnabb@aquatechnex.com>
May 15 (3 days ago)
Alum precipitates the phosphorus out of the lake water. When phosphorus goes down, the phosphorus to nitrogen ratio in the water becomes more advantageous for green algae. We are using a low dose not designed to take everything out)
This is the information I got when I asked about what it does to the kokanee.
Re: Lake Stevens
I found out that they are spraying the Lake because the aerator is broken and they think its cheaper than fixing the pump.