20231220 14332500 1.0 TRUE TMDL Watersheds This layer represents watershed boundaries for all approved Total Maximum Daily Load (TMDL) in Iowa. A TMDL, also called a Watershed Improvement Plan, identifies water quality problems, possible causes of those problems and proposes solutions. Full Metadata: ftp://ftp.igsb.uiowa.edu/gis_library/ia_state/watersheds/TMDL_watersheds/TMDL_watersheds.html