Approximately 27,000 people reside in the Upper Iowa River Watershed with approximately 23,000 of those living in the Iowa portion of the watershed. Over half of the population is living within incorporated or unincorporated communities. The largest community in the watershed is the City of Decorah, population 8,127. Although the Upper Iowa River Watershed is still a relatively rural watershed, communities do impact flooding and water quality. A 2018 study conducted by Zhang, Villarini, Vecchi and Smith published in Nature found that an increase in impervious surfaces can increase total rainfall, shift the location of maximum rainfall, and increase the changes of extreme flooding. Find more information here.
The Upper Iowa River Hydrologic Assessment recognizes the impact that shifts in land use from agricultural uses to urban uses can have on hydrology, runoff and flood magnitude noting the following.
“The transition from agricultural to urban land uses has a profound impact on local hydrology, increasing the amount of runoff, the speed at which water moves through the landscape, and the magnitude of flood peaks. The factors that contribute to these increases (Meierdiercks et al., 2010) are the increase in the percentage of impervious areas within the drainage catchment and its location (Mejia et al., 2010), and the more efficient drainage of the landscape associated with the constructed drainage system — the surface, pipe, and roadway channels that add to the natural stream drainage system. Although traditional stormwater management practices aim to reduce increased flood peaks, urban areas have long periods of high flows that can erode stream channels and degrade aquatic habitat.”
The Table of UIR Watershed Urban Areas provides information about the urban areas in the Upper Iowa River Watershed. It details their name, county, approximate population (2010 Census) and participation/lack of participation in the Upper Iowa River WMA. Please note that only incorporated communities in Iowa were allowed and invited to participate in the Upper Iowa River WMA.