"So far we have been extremely lucky and our ATMs are up and running. We had them filled in preparation for the storm," she said. "Additionally, we are part of the Allpoint network, so members can have other surcharge-free options if they had to evacuate." 

ATM operator Dolphin Debit temporarily closed its Houston office and is operating according to its business continuity plan, according to EVP and co-founder Gary Walston. Employees there are all accounted for and the company is still servicing ATMs throughout the country, he said. 

Walston wasn't sure how many of the company's ATMs were out of service in Houston on Monday but expected to know in the next 24 to 48 hours. 

"I think the most frustrating part right now is just knowing that you physically can't get to some locations," he said. "And so there's nothing you can do to even assess the situation on some of these, except for the remote management capabilities that we have." 

Most ATMs are surprisingly weather-resistant, he noted. 

"The machines themselves are very durable in the sense that they can withstand massive downpours and that's not an issue. It's really just flooding coming up that becomes an issue," Walston explained. "Once the water rises up to a certain level at the ATM, most of them have a circuit breaker that will trip and shut the machine off."

Many credit union members can also use branches and ATMs belonging to other credit unions.

"Naturally there are a few areas where CO-OP ATMs are inaccessible due to Tropical Strom Harvey," CO-OP Financial Services SVP Kathy Herziger-Snider told CU Times. "However, we have been reminding both our client credit unions and their members that both CO-OP ATM and CO-OP Shared Branch networks are available to them any time severe weather or other emergency causes closure of local branches or ATMs and forces members to relocate." CO-OP Financial Services operates a network of 30,000 ATMs and 5,600 branches for members of participating credit unions. 

If their ATMs get caught in the flood, credit unions should not spend too much time worrying about the security of the cash inside, Walston noted. 

"If you think about an ATM and the security of an ATM and the difficulty involved with trying to steal one or break into one, even in the best of conditions, it's extraordinarily difficult," he said. Even if criminals have the tools or equipment to attempt theft, they can't physically go very far, he noted. 

When the water recedes, the rebuilding will begin. For operators like Dolpin Debit, that will likely mean replacing several ATMs.

"This is what we do on a regular basis is really just relieve the credit union and the staff of the burden of operating an ATM," Walston said. "And so when you get into a crisis situation like this, it makes it even better because it's one less thing that they have to worry about. So it's all on our shoulders."