Tim's right. If the developer is still in control, he owns it. Usually ownership of the stormwater management system (retention ponds or detention ponds, swales, culverts, etc.) stays with the developer until turnover.
Go to the website of your Water Management District and search for your community's permits. Today they're known as "Environmental Resource Permits" but at one time they were known as "Surface Water Management System Permits". You should be able to find yours without too much trouble. You'll find more than you ever wanted to know about the design, planning and ownership history of your system.
Also check
and look at "Legal Operation and Maintenance Entity Requirements". The developer has to turn over the operation of the system to an entity that meets certain requirements and the permit will not be transferred out of the developer's name unless and until a maintenance and operation entity is approved by the water management district.
If you've got any chronic problems with your system and turnover is imminent, I suggest making the local WMD very aware of the situation before turnover in order that the developer is identifed as the responsible party to fix the problems before he's out of the picture.