Hydrologic Modifications o Agricultural Settings

In order to support agricultural uses of land, many hydrologic modifications have been made. Many of these modifications make waterways more vulnerable to pollutants. Should the modifications have been made? Are there ways to minimize the threats given the existing modifications?

North America looks very different now than it did when the European settlers first arrived. Many of the initial changes made by settlers were made to support agriculture. Wetlands were drained, prairies were plowed, and forests were cleared to make way for farm fields. Once the fields were in place, rivers were straightened, , moved, constricted by levees, or even wiped out to avoid flooding valuable crops. Irrigation systems were installed to take water into dry areas turning them into pockets of profitable land. All of these modifications changed the natural "plumbing system", or hydrology of the land. Two of the most common modifications are tiling and agricultural drainage wells.

Draining the Land

Puddles may be good for the water and wildlife, but they are not good for crops. Many Iowa farmers have drained their land using one of two systems, tiling or agricultural drainage wells.

Tiling is an underground drainage system that uses "pipes" to collect water from low lying areas and move it to a waterway. With tiling, drainage from farm fields shoots directly into waterways, taking pollutants along with it. Tiled fields cover much of the state of Iowa, including land with large animal confinements located on or near it. When accidents happen, manure or farm chemicals have a straight shot into waterways.

Because of Iowa’s unique geology, farmers also rely on agricultural drainage wells. The wells drain water off the land and directly into underground aquifers, one of the state’s primary sources of drinking water. Any pollutant that makes its way into one of these wells has far-reaching, perhaps irreversible effects.

Agricultural modifications have made it possible to farm 90% of the land in Iowa, producing a net profit of over $2.5 million in 2000. No one is suggesting that all the land should be converted back to its natural state, but there are some things that can be done to minimize the negative effects of the hydrologic modifications.

• Expand programs that encourage farmers to restore important natural areas.
• Enact laws to regulate activities on tiled fields and around agricultural drainage wells.
• Monitor and time farm field chemical and manure applications to reduce runoff potential.