Iowa BMP Mapping Project

The goal of the Iowa BMP (Best Management Practices) Mapping Project is to provide a complete baseline set of BMPs dating from the 2007-2010 timeframe for use in watershed modeling, historic occurrence, and future practice tracking.  The BMPs mapped are: Terraces, Water and Sediment Control Basins (WASCOB), Grassed Waterways, Pond Dams, Contour Strip Cropping and Contour Buffer Strips.  We can't guarantee that mapped practices meet NRCS standards or that they are actually the indicated practice since no ground reference analysis is being performed. Data being utilized to digitize the BMPs include LiDAR derived products such as DEM, Hillshade and Slope grids; CIR aerial photography from the 2007-2010 timeframe, NAIP aerial photography and historic aerial photography.  BMPs are being collected by 12-digit HUC and finished products can be downloaded from below.

This project has been funded by the Iowa Department of Natural Resources, Iowa Department of Agriculture and Land Stewardship, Iowa Nutrient Research Center at ISU, National Laboratory for Agriculture and the Environment, the Iowa Nutrient Research and Education Council and AmericaView.

To supplement this project, the ISU GISF has created a tool to download the BMPs by HUC12 and HUC 8 watershed as an Esri file geodatabase for the state of Iowa.  In order to download data, you will be asked for some identifying information. The HUC 12 datasets have a column indicating presence in 2010, which is the named year of the inventory, even though data was collected from 2007-2010. For the 20% evaluated for historic and current practices, see project description below, those 325 HUC 12 datasets have an additional two columns indicating presence in the 1980s and presence in 2016 as that was the first year of current imagery.

The GIS Facility, in cooperation with the Iowa DNR, has edgematched all practice features with their neighboring HUC12s within their HUC8. This has also been done across HUC 8 boundaries. The edgematching process entailed clipping the features at the HUC12 boundary and then a staff person adjusted edge features so they line up with an adjacent watershed feature, if one exists. The state dataset has been completed and watersheds are ready to download. The edgematching process was completed during October, 2020; data was compressed and ready for download November 9, 2020. There is also one statewide fgdb of all six practices with a size of 138 mb. 

A companion project to the 2010 baseline inventory data tracks whether or not a particular conservation practice was evident in the 1980s or in 2016-2018 imagery. The goal of this project was to assess a representative sample of HUC12 watersheds across the state in order to determine the trends in overall changes in practice levels from the 1980s to 2010 and on to 2018. For the 1980s review, practices that are identified as partially existing were split at the relevant location and each piece was identified with the necessary status. No new practices were digitized from the 1980s imagery, only practices existing in the baseline inventory were evaluated. With the 2016-2018 imagery, practices existing in the inventory were evaluated like the 1980s; additionally, new practices were digitized and added to the dataset. The evaluation procedure was done on 20% of the entire state’s HUC 12 collection; random sampling was done by HUC 8 to choose which HUCs were processed. After a HUC 12 had QA/QC performed, it was then evaluated for 1980s and recent imagery presence or absence and the Historic Occurrence map, shown below, was updated. This companion project was completed in May 2019.