http://www.digitaljournal.com/article/324828

Swimmers' urine blamed for 500 fish deaths in German lake

Posted May 13, 2012 by Leigh Goessl
Hundreds of fish have been found dead in a German lake. The cause of death has been purportedly linked to the urine of swimmers, and this theory is currently being examined.
An image of several dead fish along the banks of the Salton Sea taken in 2000
AnimAlu
An image of several dead fish along the banks of the Salton Sea taken in 2000
Lake Eichbaum is said to be a popular place for swimmers as the weather warms. However, the recent discovery of approximately 500 dead fish is being attributed to an excess of urine being present in the lake water.
Seemingly, there has been a "longstanding feud" between anglers and swimmers, according to media reports.
"Swimmers who urinate in the lake are introducing a lot of phosphate," Manfred Siedler, spokesman for the Hamburger Angling Association (ASV), told Bild newspaper (via The Local). "We're calculating half a litre of urine per swimmer per day."
Swimming is currently banned in the water due to high levels of algae present in the lake, and The Local reports the Urban Development and Environment Authority (BSU) is looking to get the lake reopened for swimmers.
BSU is blaming ice skaters as causing the fish deaths, not urine.
"The ice-skaters make a noise that wakes the fish out of hibernation," BSU spokeswoman Kerstin Graupner told The Local. "Then they can't breathe and freeze. That's a very common phenomenon."
BSU is purportedly arguing the fish were significantly decomposed, suggesting their deaths were not recent. Scientists at Hamburg University have been asked to test the urine theory to determine if this was the cause of death. Initial tests are said that pH levels are high at a level of 8.7, and very alkaline.
Anti-phosphate treatments have reportedly not worked in bringing some balance to the lake.
Whether this is legitimate or not was questioned by io9, citing too many details missing from the one report (The Local) that all media are sourcing. However, this report describes a way that urine could theoretically be killing off fish, and causing the excess growth of algae, lowering the overall oxygen in the lake, thus impacting the fish.
While human urine in Lake Eichbaum seemingly hasn't brought harm to people, in other areas of the globe, one has to be careful if they decide to relieve themselves in the water.