Possible bad news for Lake Stevens kokanee

[kelson]

It appears a done deal that the City of Lake Stevens plans to remove the aerator and treat the lake with alum (aluminum sulfate) to suppress high phosphate levels. Evidently the alum bonds to the phosphate and falls to the lake bottom forming a thin crust. Seems like this could have some impact on the benthic organisms which are a sognificantfood source in the aquatic food chain. Can anyone shed any further information on this? Below is a link to the article regarding the plan.

Thanks,
K

http://www.lakestevensjournal.com/news/ ... ludes_alum

[red]

http://www.lakestevenswa.gov/DocumentCenter/View/1122

[redadams]

http://www.lakestevenswa.gov/DocumentCenter/View/1122

Aluminum sulfate and the compound it turns into once immersed in water, aluminum hydroxide, are not toxic to plant life, fish or any other wildlife that might be present in the pond when the chemical is applied correctly. It is usually applied with another compound, sodium aluminate, that keeps the composition of the water at a consistent level to prevent any fluctuation in water chemistry. Copper sulfate, however, can be highly toxic to fish. Application of this chemical can result in fish kills throughout the entire body of water, especially when the total alkalinity of the water is too low. When the copper sulfate becomes copper carbonate, this chemical does not break down any further and instead collects on the bottom of the pond. If this builds up too much, it can kill the plant life growing in the pond and create more problems within the ecosystem.

Read more: Aluminum Sulfate Vs. Copper Sulfate Algae Control | eHow http://www.ehow.com/info_8783617_alu...#ixzz2VmR57DkK

[Smalma]

Red -
Thanks for the link; I had seen it. Of concern is that no where is there any discussion on the fish resource found in Stevens or the potential impact on that resource from this treatment.

Also found it interesting that there was no mention of the chemical treatment of herbicides to rid Stevens of Eurasian milfoil in 2011 and 2012. Could it be that the blue-green alga blooms last year were related to that treatment (release of nutrients from the decomposing weeds and the weed community no longer taking up the nutrients for weed growth rather than blue-green blooms).

Redadams -
Understand that the alum (aluminum sulfate) itself is not toxic to the fish and does not represent a direct threat to them. However the potential issue is that the treatment is aimed at removing the phosphates from the water column ; in effect changing the lake's ecosystem. While I fully understand why the treatment is desirable the fact remains it is only addressing the symptoms of the lakes nutrient loading problems and not the source of those problems. By treating the symptoms there continues to be delays in address the larger problem. First the aerator and now the alum treatment are allowing the decision makers to avoid making difficult decisions.

There is ample documentation of alum treatments resulting in short impacts on the zooplankton community (specifically daphnia which is the driver for kokanee production in Stevens) from alum treatment. The stripping the water column of phosphates at this time of year will not likely have much affect the larger adult fish the are the backbone of this year's fishing my question or concern is how will that affect the "blooms" this time of year and more specifically the food sources that the small fry (kokanee and other species) that are dependent on those food resources for their survival (they have little fat reserves to carry them through lean periods at their small size - typically the small kokanee fry are planted this time of year.

While those short term impacts may not be much of a concern the fact that the plan calls for annual treatments for the next 6 to 12 years means those impacts may well have long term impacts.

While I and others may be alarmists the fact that none of these issues were not discussed or even considered to be concerns is indeed alarming.

The Stevens kokanee fishery is unique for the Puget Sound region providing significant recreational use and anything reducing that fishery has to be concerning.

Curt

[redadams]

Curt i think the lake stevens kokanee fishing will soon be a thing of the past. the town took the cheep way out. they didn't want to pay $4,000,000 to fix the pump have been fishing the lake for 40 years. it's sad to see what is going on it's more about water sports then fishing the way i see it

[kelson]

Thank you Smalma, Red and redadams for your insightful comments. The treatment for this year was conducted last Tuesday. I was on the lake as it happened. Fishing was OK that day as long as you could stay away from the plume trail from the application vessels. I have fished once since the application and fishing remains OK. My concern, like Smalma, is beyond this year. I queried the WDFW about the plan to treat the lake and they knew nothing about it. Obviously permits to chemically alter public waters come easy. I would think that all governing state and county agencies would be in the loop to maximize the positives and reduce any potential detrimental impacts.
Many have weighed in on this topic on forums and I thank all for their insight and expertise. I'm one of Smalma's alarmists for sure, as I love this fishery and don't want to see it damaged. Time will tell.
Fish on,
K