The following table identifies the weighted average useful lives by class of intangible asset:


	Weighted Average Remaining Useful Life (in years)
Water rights		13.4
Surface rights		13.4
Saltwater disposal rights		13.8
Customer contract		12.9
Customer relationship		19.9
Sourced water		24.9

Definite lived intangible assets are comprised of the following at June 30, 2026 and December 31, 2025:


	June 30, 2026			December 31, 2025
(in thousands)	Gross Carrying Amount	Accumulated Amortization	Net	Gross Carrying Amount	Accumulated Amortization	Net
Water rights	$136,166	$(14,322)	$121,844	$136,166	$(9,783)	$126,383
Surface rights	60,550	(6,546)	54,004	60,550	(4,528)	56,022
Saltwater disposal rights	9,300	(775)	8,525	9,300	(465)	8,835
Customer contract	404,457	(4,006)	400,451	—	—	—
Customer relationships	49,605	(319)	49,286	—	—	—
Sourced water	40,285	(207)	40,078
Total	$700,363	$(26,175)	$674,188	$206,016	$(14,776)	$191,240

Amortization expense for the three months ended June 30, 2026 and 2025, for intangible assets, which include permits, water rights, surface rights, customer contracts and customer relationships was approximately $8.1 million and $3.4 million, respectively. For the six months ended June 30, 2026 and 2025, amortization expense was $11.5 million and $4.6 million, respectively.

Estimated remaining amortization expense for the future periods is expected to be as follows:


(in thousands)
Year Ending December 31,
Remainder of 2026	$	23,441
2027		48,938
2028		48,938
2029		48,938
2030		48,938
Thereafter		454,995
Total future amortization	$	674,188