The suit says the agreement violates state laws against zoning by contract and that the city violated the Texas Open Meetings Act in how it handled public hearings on the agreement. The Austin-based Stratus and the city deny the suit's allegations and say they will fight the SOS suit.

Under the agreement, approved last summer, Stratus may develop 750,000 sf of office space, 250,000 sf of retail space, 830 single-family homes and 900 multifamily units on the property in the Barton Springs watershed. The land is broken up into several parcels along South MoPac Expressway, Slaughter Lane and Texas 45. Stratus also would receive $15 million in waived fees.

When they approved the agreement, several council members said it held Stratus to less development than it could do under the development regulations in effect when construction was proposed for the properties in the 1980s. The SOS suit, filed this week in Travis County District court, seeks to have the agreement declared void.