Ranked by surface area computed from USGS National Hydrography Dataset (NHD) lake polygons — consistent federal geometry, not state-documented acreage; figures can differ modestly from traditionally cited ones.
Reservoirs count — most of Indiana's biggest water is impounded (Monroe, Patoka, Brookville).
Lake Michigan is excluded — this list ranks inland lakes.
Lakes whose mapped polygon could not be confidently matched are excluded rather than guessed.
Lakes under 50 acres are excluded from rankings.
Public access inventories are not yet tracked for Indiana here, so access is never shown or ranked.
FAQ
Franklin County lake records
What is the biggest lake in Franklin County?
Brookville Lake — Brookville Lake in Franklin County is the biggest inland lake in Franklin County by USGS NHD surface area, at 4,364 acres.
Source data: USGS National Hydrography Dataset lake polygons as aggregated by LakeList. NHD-computed area can differ modestly from traditionally cited acreages.Lake outlines are shoreline shapes from LakeList and the USGS National Hydrography Dataset; they illustrate a lake's form and are not depth or navigation charts.