Grant Park had a serious hangover from Lollapalooza -- but it's been worse.

Rain pounded music fans who danced in the muddy pits of Grant Park on Sunday, leaving the fields in worse shape than last year, organizers said.

"Due to heavy rains on Sunday, we’re seeing more damage to portions of the park than in 2013," Lindsay Hoffman, of Lollapalooza promoter C3 Presents, said in an emailed statement.

Just less than half an inch of rainfall was reported Sunday in the South Loop, according to National Weather Service meteorologist Casey Sullivan.

Parts of the park will reopen this week to the public once equipment from the three-day festival has been removed, said Bob O'Neill, president of the Grant Park Conservancy. Areas that need to be repaired will be roped off, he said.

The Chicago Park District said it usually takes three to four days for C3 staff to load out its equipment, staging and trucks. After that removal happens, a damage assessment can be made, park district spokeswoman Jessica Maxey-Faulkner said.

On Sunday night, the slick mud of the softball fields, home to Perry's stage -- west of Columbus Drive and south of Balbo Drive -- became an obstacle course for revelers as they exited Chance The Rapper's set. Potholes and puddles at the street curbs became makeshift foot baths, leaving a trail of wet earth that extended past Grant Park's exits and into the Loop.

So how bad is the damage from this year’s fest?

"The damage isn't as bad as the year it stormed and a lot of rain came down," O'Neill said.

That was in 2011, when three inches of rain soaked festgoers and the price tag skyrocketed to at least $800,000 to fix up the park. The following year, the festival was briefly evacuated because of severe weather.

This year, the damage was contained to the turf mainly at Butler and Hutchinson fields in Grant Park, where big acts and headliners performed on large stages, O'Neill said.

The park grounds get trampled every year when it hosts 300,000 concertgoers for the three-day fest, but the damage gets exacerbated by wet weather.

“When it rained, it got a little more damaged because the soil is more vulnerable to getting tossed,” he said.

The landscaping, bushes and gardens were fenced off so those areas weren’t damaged as much, he said. The turf will be the easiest and least costly to repair, he said, as some of it grows back and the improvements include aeration and seeding of the park and new sod.

Last year, the Chicago Park District estimated the cost to repair the fields at Grant Park at $210,000 to $220,000. C3 Presents was responsible for picking up the bill.

The work, which started last year a couple of days after the fest, included mulch removal and soil replacement.

"We will not know the full extent of the damage until all stages and activations are loaded out, at which point we will do a thorough walk through with the Chicago Park District to assess the damage and create a remediation plan that will leave Grant Park at or better than its pre-festival condition," C3's Hoffman said.

Not only does C3 Presents pick up the restoration tab, but the fest promoter also pays for additional improvements to Grant Park, such as new trees, bushes and gardens, leaving Grant Park in better condition, O'Neill said.

Meanwhile, a few street closures remain. Jackson Boulevard from Columbus Avenue to Lake Shore Drive will remain closed through Wednesday. Balbo Avenue from Columbus to Lake Shore Drive will remain closed through Thursday.

RedEye reporter Mick Swasko contributed.