Report: Scum on Iowa water can harm people, environment

DES MOINES - Runoff from farm fields and urban sources is creating “pond scum” that can harm people, animals and the environment, a new report from Iowa Policy Project concludes.

“Blue-green algae - some call it ‘pond scum' - in lakes or other waterways in Iowa can signal the proliferation of cyanobacteria. In some cases, the bacteria produces toxins that can harm people, animals and the environment,” said Andrea Heffernan of Iowa City, the report's author.

Her report, co-authored with research associate Teresa Galluzzo, tells how cyanobacteria results from excess nutrients entering Iowa waterways.

High levels of cyanobacteria have been reported in recent years in several Iowa waterways, including Carter Lake near Council Bluffs, and in the Des Moines and Raccoon rivers, which are source waterways for Des Moines Water Works.

In 2008 and 2009, the report stated, the Des Moines source waters had elevated levels above the point where water treatment problems may emerge. In 2004, high levels of cyanobacteria and cyanotoxins at Carter Lake were found after swimmers complained of rashes and analysts saw other indications of a cyanobacterial “bloom.”

The report said voluntary conservation practices in agriculture are not enough to deal with the issue.

“Iowa leaders should strike at the source to address the environmental harm and health effects caused by cyanobacteria, and protect its water and citizens,” Heffernan said. “That means there should be regulatory standards for cyanobacteria levels, certainly, but there also needs to be limits on the amount of phosphorus and nitrogen from all sources.”

The authors recommend better manure management, buffer systems, precision farming to tailor nutrients to specific plots of ground, and conservation agriculture to reduce tillage and increase retention of crop residue, to foster retention of nutrients and water in soil and reduce the need for more fertilizer.

Galluzzo said another issue to watch is the effect of climate change.

“There are three things that could lead to increased cyanobacterial blooms,” Galluzzo said. “Heavy downpours are predicted to increase, and this can contribute to more runoff. Temperatures of water and air are expected to increase, and this increases the likelihood of blooms.

“Finally, with longer growing seasons that are expected, greater application of fertilizers, pesticides and herbicides can contribute to an even greater overabundance of nutrients in our waterways.”

To see a copy of the report, go to www.iowapolicyproject.org

The Iowa Policy Project is a nonpartisan research organization based in Iowa City, focusing on energy and the environment, economic opportunity and budget issues.

Iowa News Service