North Lincolnshire Council has written to landowners in the Scunthorpe area about its proposed Lakes project.
The authority's Lincolnshire Lakes development is planned for an area west of the town. It will include 12,000 new homes, lakes and leisure facilities.
The council is asking landowners what land they own. It also outlines the project in the letter.
A spokesman said it was collecting the information for its database, ahead of a consultation period.
Councillor Mick Grant, cabinet member for housing and strategic planning at the council, said: "This is a huge project that will effectively create a new sustainable waterside neighbourhood.
"It is imperative that we hear from local landowners, not just to confirm what land they own, but to keep them informed and involved throughout the project."