There is extensive law regarding drainage and interconnection obligations between landowners, Iowa is pretty flat, there just has to be a path between your fields and a local river. All of the roads are edged with drainage ditches, there are bigger much deeper ditches where necessary to direct water.
Here's some drainage basics:
https://fyi.extension.wisc.edu/drainage/files/2015/09/Basic_...
There is extensive law regarding drainage and interconnection obligations between landowners, Iowa is pretty flat, there just has to be a path between your fields and a local river. All of the roads are edged with drainage ditches, there are bigger much deeper ditches where necessary to direct water.
http://publications.iowa.gov/19966/1/IADOT_tr_497_Iowa_Drain...