Note 2 - Reportable Segments - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenues	$ 513	$ 809	$ 1,634	$ 939
Cost of sales	852	768	1,856	790
General and administrative	6,305	5,320	11,035	9,251
Depreciation	305	305	600	634
Total costs and expenses	7,462	6,393	13,491	10,675
Operating loss	(6,949)	(5,584)	(11,857)	(9,736)
Water and Land Resources [Member]
Revenues	350	379	986	509
Cost of sales	679	432	1,339	454
General and administrative	5,917	5,232	10,397	8,999
Depreciation	292	271	574	549
Total costs and expenses	6,888	5,935	12,310	10,002
Operating loss	(6,538)	(5,556)	(11,324)	(9,493)
Water Treatment [Member]
Revenues	163	430	648	430
Cost of sales	173	336	517	336
General and administrative	388	88	638	252
Depreciation	13	34	26	85
Total costs and expenses	574	458	1,181	673
Operating loss	$ (411)	$ (28)	$ (533)	$ (243)