Does Alconox decontaminate stainless steel from radioactive contamination?
In sufficient quantity, Alconox, like just about anything, will impact the environment. If you discharge 5,000 lbs of Alconox at once, you would be discharging an EPA reportable quantity under CERCLA regulations. I presume you have no intentions of discharging anything like this quantity.
Alconox does contain phosphates which are essential nutrients and can promote algae growth in phosphorous limited ecosystems. The algae can deplete oxygen and then die causing silting up of surface waters - this is eutrophication. You would need large quantities of Alconox to cause significant eutrophication.
Alconox contains surfactants, which in high enough concentration are hazardous to fish - typically you would have to reach 100s of mg/L in concentration to be harmful to fish.
Alconox has been widely used for field cleaning of environmental sampling equipment for decades and we have never had any reported incident of environmental impact. Alconox is biodegradable.
If you spill enough Alconox directly in to a lake, I imagine it could form a stable detergent foam that might take a few hours to dissipate. Although this foam would not be particularly harmful, it would be unsightly. I suspect that a bucket full of Alconox dumped briskly in to a lake might make enough foam to be unsightly.