The proposed 49er stadium for Santa Clara seats 68,500 fans. A three part draft environmental impact report, or EIR spells out what that construction would mean and the problems that come with it.
"It speaks to every environmental issue that comes into play -- traffic parking, light, noise," said Assistant City Manager Ron Garratt.
In many cases, the draft EIR cites significant unavoidable impact. The study concludes air pollutants would exceed established thresholds on game days and for other large events.
It projects a substantial increase in ambient noise levels up to 46 times a year and a substantial increase in weekday traffic at 17 intersections, up to four times a year on game days and another four days for other events. It's the traffic impact that most concerns opponents.
Bill bailey is with the group Santa Clara Plays Fair.
"Traffic jams along great America Parkway for sure, a closure on Tasman and an inability of residents on the north side to enter their homes without showing a checkpoint or utility bill to a police officer at a checkpoint," said Bailey.
The draft EIR estimates up to 19 percent of fans would take public transit and supporters argue its designed to handle large crowds.
"Santa Clara had the foresight to build this infrastructure decades ago and allows us to to take a stadium and plunk it down in the entertainment district and only have two, maybe four days of significant traffic a year, I think that's pretty positive," said stadium supporter Lisa Gillmor.
The 49ers said the team is pleased the process is moving forward and now they will review the draft report.
Cedar Fair, the owners of Great America, told ABC7 they have significant issues with the traffic and parking situation and if the city does not address those concerns, there could be legal action.
The public has 45 days to comment on the draft EIR and then a final document will be completed. A citywide election next year will determine if the stadium is built.