00:49 Tropical Storm Beta Floods Houston, Southeast Texas The storm is bringing flooding from Galveston to Houston.

At a Glance Runs on food, water, gas and other supplies have already begun as residents along the Texas coast prepare for Harvey.

Texas Gov. Greg Abbott has declared a disaster for 30 Texas counties.

At least one college campus will close and evacuate Thursday and workers are being evacuated off oil rigs in the Gulf.

Widespread evacuations have been ordered along Texas' Gulf Coast ahead of Hurricane Harvey.

Officials in Calhoun, Victoria, Jackson, San Patricio and Refugio counties north of Corpus Christi issued orders on Thursday, along with the cities of Portland, Rockport, Port Aransas, Aransas Pass, Ingleside and Robstown. All residents of Brazoria County who live on the Gulf side of the Intracoastal Canal have been ordered to evacuate , as well.

Harvey became a hurricane around 1 p.m. Eastern Thursday and is still gaining strength as it churns through the Gulf of Mexico. Harvey is forecast to make landfall as a major Category 3 hurricane sometime early Saturday morning. The last storm of that category to hit the U.S. was Hurricane Wilma in October 2005 in Florida.

The Texas Department of Transportation has released an evacuation guide with highlighted routes and important tips.

Nueces County and the City of Corpus Christi have also issued a mandatory evacuation for high profile vehicles , KZTV reports, but no full evacuation has been ordered yet.

(MORE: Hurricane Harvey Could Impact Gas Prices Nationwide; Oil Rig Workers Evacuated )

Corpus Christi Mayor Joe McComb said in a Thursday afternoon press conference that the city is strongly encouraging evacuations, and officials are "almost at the threshold for mandatory evacuation, but we are not going to cross that line right now."

"We could mandate it, but people need to make a decision of their own. I'm not going to risk our police and fire people going to try and drag somebody out of the house if they don't want to go," McComb said. "Because our fire and police, they're fathers and mothers, brothers, sisters, uncles. They've got relatives and they've got family, and we don't want to put them in harm's way because someone just wanted to stay."

The US Navy has closed Naval Air Station Corpus Christi until further notice and has ordered the evacuation of all non-essential active-duty military personnel.

Texas A&M University-Corpus Christi announced its campus would close and everyone would be required to evacuate by noon Thursday, according to a release.

Oil rigs in the Gulf of Mexico had already begun to evacuate workers earlier in the day, and residents along the Texas coast have been stocking up on food water and other supplies in the face of Hurricane Harvey.

"We got all of our food supplies yesterday ," Corpus Christi resident Robert Cavanaugh told the Corpus Christi Caller-Times. "The closer it (the storm) gets, the more crazy the stores will be."

(MORE: The Latest Harvey Forecast )

Texas Gov. Greg Abbott declared a state of disaster for at least 30 counties and urged residents to prepare for the powerful storm.

"Texans believe in taking action and always being prepared in the event of an emergency," Abbott said in a release. "That is why I am taking every precaution prior to Tropical (Storm) Harvey making landfall. Preemptively declaring a state of disaster will allow Texas to quickly deploy resources for the emergency response effort in anticipation of the storm's hazardous conditions."

On Thursday, Abbott activated about 700 members of the state National Guard. Military helicopters were also on standby in Austin and San Antonio in preparation for search and rescues and emergency evacuations.

White House spokeswoman Sarah Huckabee Sanders said President Donald Trump was "briefed and will continue to be updated as the storm progresses."

The Padre Island National Seashore in Corpus Christi, Texas, closed its North and South beaches at noon Thursday due to the storm, according to a local tourism agency.

Texas Senator Ted Cruz issued a statement Thursday asking Texans in the path of the storm to remain vigilant.

“As Texas prepares for the potential impact in the Gulf Coast region from [Hurricane] Harvey, I urge all Texans in the path of the storm to heed warnings from local officials, know your evacuation route, and avoid all high water areas," the statement reads .

Houston Area Impacts

The Houston Independent School District announced Thursday that all district schools and administrative offices will be closed on Monday, August 28 due to the threat of inclement weather.

The closure will affect more than 200,000 students — Houston ISD is the largest in Texas and the eighth-largest in the U.S. Classes are scheduled to resume on Tuesday.

"And while we wanted to start the school year with a whirlwind, this isn't the whirlwind we were thinking of," Houston ISD Superintendent Richard Carranza told reporters.

Officials on Galveston Island are planning for possible major flooding by clearing storm drains and other infrastructure, KHOU.com reported.

"We are looking at this as a rain event at this point," Galveston Office of Emergency Management Coordinator Niki Bender told KHOU. "We are watching, like everyone else, what the National Weather Service and the hurricane center are putting out."

Runs on Food, Water, Gasoline Have Already Begun

Residents along the Texas coast flocked to grocery and hardware stores and gas stations to stock up on last-minute supplies. In the Houston area, ABC 13 reported long lines at Wal-Mart and local grocery stores . Social media photos showed bare shelves, especially in the bottled water aisle.

According to WFAA, Kroger is sending nearly 80 truckloads of water and other supplies from warehouses in the Dallas-Fort Worth area to Southeast Texas as Harvey approaches.

Local farmers are anticipating the storm as well. Rice farmers in coastal Matagorda County are moving quickly to harvest their crops before the storm hits, the AP reported. Cotton farmers are doing the same in Victoria County, Matt Bochat, a county agent for Texas A&M's AgriLife Extension Service program , told the Victoria Advocate.

"We've been seeing some really good yields this year in cotton," he said. "That would be sad to see them not be able to get anything out of it."

Airports to Remain Open

Officials at Houston airports say they expect to remain open after Hurricane Harvey hits South Texas, but airlines are encouraging customers to change travel plans, according to the Associated Press.

United, Southwest and American are offering waivers for customers scheduled to fly to, from or through Houston and several other Texas cities from Friday through Sunday. Delta will waive charges for changes to flight plans through Saturday.