Water: a decorahnews.com special report

Runoff is the major conduit by which human activity adversely affects water quality, and the process carries many trickling effects into different aspects of the northeast Iowa community.

As Luther's professor of Biology Jodi Enos-Berlage points out, there are three distinct detriments to the quality of our surface water which primarily occur due to runoff: Bacterial infection, soil erosion and imbalances of nutrients.

"The first problem is bacteria, which is almost entirely coming from fecal matter, such as manure," Enos-Berlage says. "If farmers spread manure and it's dry for a few days, most of that bacteria will die. If you spread it and it rains, then that runoff from the field is carrying all sorts of bacteria to the water."

However, Dr. Enos-Berlage said that bacteria in the water is really only a concern to humans and can often be dealt with during the water treatment process.

According to Dr. Enos-Berlage, the ecosystem that is built around Iowa's waters is much more susceptible to nutrient imbalances and soil erosion, which are often a result of poor agricultural practices.

Nutrient pollution usually manifests as a spike in nitrate or phosphorus levels in surface water, which is introduced into the water supply as runoff carries agricultural soils treated with fertilizers and pesticide into the water, although fertilizer used in towns can also contribute.

Not only does this nutrient spike affect the ecosystem of Iowa, but it has significant effects downstream, such as in the "Dead Zone" of the Gulf in Mexico, which will be explored in a later story.

According to Dr. Enos-Berlage, and others including Tom Murray of the Driftless Chapter of Trout Unlimited, Northeast Iowa's waters are particularly susceptible to harm from soil erosion. According to Murray, due to the varied and more vertical landscape of the Driftless area, topsoil can erode more easily erode here than in other parts of the state.

"If you just look around in Decorah, you can see exposed bluffs and hills," Murray said. "When we get big rain events, which we are seeing a lot of these days, it carries that topsoil down into the rivers and streams which makes the water turbid."

Not only does this erosion lead to a loss in valuable soil for farmers, but it also has an effect on aquatic life.

"Any input into the water can be harmful," Murray said, "But inputs that reduced the amount of oxygen in the water, like soil, can really have an effect on aquatic life and fish populations."

Dr. Enos-Berlage agrees with Murray, particularly when it comes to populations of trout and other fish.

"Turbidity in the water is particularly damaging for native fish and plant populations." Enos-Berlage said. "Not only does it reduce the amount of oxygen that wildlife can access, but the clouding of the water after lots of erosion, when it looks like chocolate milk, can also make it difficult to find food."

Erosion's harm to native fish populations, is one thing directly harming the northeast Iowa angling industry, which makes up a big portion of Winneshiek County's tourism draw. This aspect of the water quality issue will also be explored in a story later this week.

Murray and Berlage both agree, however, that their are ways to combat soil erosion and nutrient displacement throughout the adoption of buffer strips and terracing; agriculture practices which are already widely in place on Northeast Iowa farms.

"Buffer strips are where you dedicate strips of land to growing native plant species," Murray said. "They trap much of the soil and nutrients flowing in runoff, and prevent it from actually making it into the surface water. Terraces also work in this way too. It's been proven to work and you can still make good money as a farmer."

Murray also notes that Conservation Reserve Program (CRP) land is another good way to manage runoff, as this land set aside from agricultural development acts as a large buffer strip from soil erosion.

Dr. Enos-Berlage agrees with Murray on CRP, but points out that the amount of CRP land in Iowa has been reduced significantly, in a trend seen all over the United States, over the last few decades.

In 2007, Iowa had at least 1,970,000 acres of land dedicated to the CRP, however in 2015, that number has been reduced by nearly 25% with CRP land now occupying 1,485,000 acres.