The estimated cost of the Delta tunnels project, Gov. Jerry Brown’s controversial plan to re-engineer the troubled hub of California’s water network, has jumped to nearly $20 billion when accounting for inflation.

Tunnels backers say the higher cost reflects the impact from inflation over 16 years, not cost over-runs or design changes, and isn’t expected to hurt the project’s ability to move ahead.

The latest $19.9 billion price tag represents a 22 percent increase from the estimate of $16.3 billion, released by state officials last year. That $16.3 billion figure was provided in 2017 dollars.