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Northwest Iowa Dairy Outlooks

A local discussion of current science and issues concerning dairying in northwest iowa

Brown slim is a common condition on the downwind side of many farm ponds this summer.

Brown slim is a common condition on the downwind side of many farm ponds this summer.

This is a common condition on the downwind side of many farm ponds this summer says Extension Wildlife and Fisheries Specialist Billy Higginbotham. Despite the recent rains, plankton blooms no doubt continued to die due to the heavy cloud deck over the past two weeks. Higginbotham took this photo to give pond owners a good idea of what the” oily, brown, foamy residue” some are finding in their ponds right now. Many fear that something ran into or was dumped into the pond. This condition may persist until water temps begin to drop in a few weeks. There is really no need to try and treat it.

This filmy residue is usually brown or reddish in color and is often accompanied by bubbles.  With our high water temperatures and lack of rain, we are seeing ponds change color—often daily. This is the result of bloom die-offs of phytoplankton and/or zooplankton with residue collecting on the downwind side of the pond.

 

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