Golf courses in America’s greater Houston area, albeit the least of concerns there, nonetheless have been inundated with flooding that will contribute to the devastating economic impact the region will experience in the weeks and months ahead.

The extent of the damage caused by Hurricane Harvey won’t be understood for some time and is likely to expand in the days ahead after the storm hit the Texas gulf coast over the weekend and continues to dump rain on the region.

“This is not over yet,” Steve Timms, president and CEO of the Houston Golf Association, said. “This storm got caught between two high pressure systems. They’re usually out of here, but this one camped over south Texas. It’s now backed up, and they’re projecting that by tonight it’ll be back in Gulf of Mexico, which could have further strengthening. We could be in for a forecast of 15 to 20 inches of additional rainfall.”

The association’s offices are adjacent to the Golf Club of Houston, site of the PGA Tour event formerly known as the Shell Houston Open. The tournament course there is bisected by the Greens Bayou, which carries water from north of Houston down to Galveston Bay and into the Gulf of Mexico.

“It’s been out of its banks since probably yesterday [Sunday] at about 9am,” Timms said. “We’ve had literally massive flooding. We’ve never seen anything like it.

“If it were to stop raining now, I would say we’re probably at least another day or two before we’ll see any significant receding of water. It’s a massive amount of water. We’ve received so much rain upstream of us that it’s got to come through major bayous. The longer you keep water on turf, the more silt and turf damage you’re going to have. I just can’t even start imagining how much damage there will be. Obviously, it’ll be significant. One thing we do is that greens and tees are built up out of the 100-year floodplain to protect them. But this is not a 100-year event. It’s more like a 500-year event.”

Timms said he spoke on Monday morning with Robin Burke, wife of Champions Golf Club co-founder Jackie Burke. “Cypress Creek, which runs through their golf course, is way out of its banks. She said the 18th tee on the Cypress Creek golf course is under water, which is a pretty good distance away from Cypress Creek. It’s pretty devastating flooding for Champions.”

The Cypress Creek course has hosted the US Open and a Ryder Cup, among other prestigious events.

The Woodlands Country Club north of Houston, the site of the PGA Tour Champions’ Insperity Invitational, has sustained moderate flooding, its director of golf Darrell Fuston said.

“I expect the Woodlands Country Club to be OK for the most part. The Palmer Course tends to have high water on it, but it shouldn’t be too awful. Other courses in area are not going to be as fortunate. Kingwood, the Golf Club of Houston. There’s some others I’m hearing about.”

Fuston has been unable to inspect whatever damage there is to his courses. The flooding is such that he is trapped on the street on which he lives, he said.

“So many of these courses are built in floodplains designed to be runoffs when floods happen,” Fuston said. “I guess there’s a reason they are where they are. So much water moves over the courses, but something like this is unprecedented, really.”

The Houston area’s newest high-profile course, Bluejack National in Montgomery, Texas, largely escaped damage, despite encountering between 15 and 20 inches of rain, general manager Casey Paulson said.

“We’re about an hour north of Houston,” he said. “We’ve had a ton of rain, but it’s not quite as bad as some of the stuff you’ve seen on TV. No serious damages here. We’ve had a couple of trees go down. That’s about the extent of it. We’ve been pretty fortunate out here.”