Where LakeList data comes from

Core source families

• U.S. Geological Survey hydrography for waterbody geometry and geographic context.
• Geographic Names Information System records for official and commonly used place names.
• State natural-resource agencies for lake facts, fisheries, stocking, regulations, water quality, invasive species, public access, and historical depth maps.
• Minnesota DNR lake bathymetry (Lake Bathymetric Outlines, Contours, and DEM) for measured depth contours on Minnesota lakes. Bathymetry © Minnesota DNR, used with permission; not for navigation.
• Michigan DNR Institute for Fisheries Research inland lake contours for Michigan depth maps, digitized by the DNR from historical survey sheets and labeled as historical rather than re-surveyed.
• Indiana DNR Division of Fish & Wildlife lake bathymetry for Indiana depth maps — modern echosounder surveys and older digitized contour maps, labeled per lake.
• Texas Water Development Board hydrographic surveys for measured depth contours on surveyed Texas reservoirs.
• C-MAP Genesis Social Map community sonar, used with permission, decoded into depth contours where boaters have recorded soundings. More accurate than a model but still an estimate, and never presented as a survey.
• North Temperate Lakes LTER research bathymetry for a small set of measured Wisconsin lakes.
• OpenStreetMap contributors for supplemental roads, access, parks, and nearby-place context.
• Recreation Information Database records for public recreation and campground context.
• National Weather Service APIs for forecasts and weather observations.

Source links and freshness

Lake pages retain source names, identifiers, retrieval dates, or direct official links when the upstream source provides them. Freshness varies by dataset: forecasts can change hourly, while a surveyed depth map or lake boundary may be decades old and still remain the latest official record.

Measured, historical, and modeled values

Measured observations are presented with dates when available. Historical maps keep their original source context and are labeled as not for navigation. Modeled values, including estimated water temperature or interpolated depth coverage, are labeled as estimates rather than observations.

Coverage rules

Not every lake has every feature. LakeList publishes stable pages only when a record has enough identity, location, and source evidence to be useful. Feature-specific sections stay hidden or explain their limits when qualified source data is unavailable.

For the current state-by-state counts — how many lakes have depth maps, which agency published each one, and what is still missing — see what data LakeList has.

Official sources control

LakeList is a planning aid. Regulations, access status, hazards, weather, and water conditions can change after a page is updated. Follow the official links on a lake page before making a safety, navigation, fishing, swimming, or travel decision.