Defiance County Environmental Data
- Index to program areas, educational information, newsletters and events available through Ohio State University Extension.
- http://defiance.osu.edu/

Defiance Soil and Water Conservation District
- Agency responsible for protecting the natural resources within the county that assists landowners in planning and applying conservation practices on their land.
- http://www.defiance-county.com/SWCD/index.html

Defiance County Ground-Water Resources
- Factsheet providing information on ground-water resources in the county.
- http://ohioline.osu.edu/aex-fact/0490_20.html

Defiance County Water Resources
- Factsheet providing information on water resources and drinking-water quality in the county.
- http://ohioline.osu.edu/aex-fact/0480_20.html