v3.26.1
Note 3 - Reportable Segments - Goodwill by Segment (Details) - USD ($)
Dec. 31, 2025
Dec. 31, 2024
May 31, 1988
Goodwill $ 5,714,000 $ 5,714,000 $ 7,006,000
Water and Land Resources [Member]      
Goodwill 3,813,000 3,813,000  
Water Filtration Technology [Member]      
Goodwill $ 1,901,000 $ 1,901,000