HOUSTON >> Officials in Houston today sought to safeguard parts of their devastated city by keeping others flooded in the wake of Harvey, which retained enough rain-making power to raise the risk of flooding in the middle of the country a week after it slammed into Texas.

The mayor announced that ongoing releases of water from two reservoirs could keep thousands of homes flooded for up to 15 days and told residents that if they stayed and later needed help, first responders’ resources could be further strained.

In another Texas city with no drinking water, people waited in a line that stretched for more than a mile to get bottled water. And a new fire erupted this evening at a crippled Houston-area chemical plant that was the scene of an earlier explosion and fire.

Residents of the still-flooded western part of Houston were asked to evacuate due to the releases from two reservoirs protecting downtown. The ongoing releases were expected to keep flooded homes that had been filled with water earlier in the week. Homes that are not currently flooded probably will not be affected, officials said.

It could take three months for the Addicks and Barker reservoirs, which are normally dry, to drain. The Harris County Flood Control District said the water releases had to continue to protect the reservoirs’ structural integrity and in case more heavy rain falls.

Some of the affected houses have several feet (meters) of water in them, and the water reaches to the rooftops of others, district meteorologist Jeff Lindner said.

Mayor Sylvester Turner pleaded for more high-water vehicles and more search-and-rescue equipment as the nation’s fourth-largest city continued looking for any survivors or corpses that might have somehow escaped notice in flood-ravaged neighborhoods.

Search teams quickly worked their way down streets, sometimes not even knocking on doors if there were obvious signs that all was well — organized debris piles or full cans of trash on the curb, for instance, or neighbors confirming that the residents had evacuated.

Authorities considered it an initial search, though they did not say what subsequent searches would entail or when they would commence.

Authorities raised the death toll from the storm to 42 late today, while rescue workers conducted a block-by-block search of tens of thousands of Houston homes.

Turner also asked the Federal Emergency Management Agency to provide more workers to process applications from thousands of people seeking government help. The mayor said he will request a preliminary aid package of $75 million for debris removal alone.

The storm had lost most of its tropical characteristics but remained a source of heavy rain that threatened to cause flooding as far north as Indiana.

By this evening, Harvey had dumped more than 9 inches (23 centimeters) of rain in parts of Arkansas and Tennessee and more than 8 inches (20 centimeters) in spots in Alabama and Kentucky. Its remnants were expected to generate another 1 to 3 inches (2.5 to 8 centimeters) over parts of Kentucky, Indiana, Ohio and West Virginia.

National Weather Service meteorologists expect Harvey to break up and merge with other weather systems over the Ohio Valley late Saturday or Sunday.

More than 1,500 people were staying at shelters in Louisiana, and that number included people from communities in Texas. The state opened a seventh shelter Friday in Shreveport for up to 2,400 people, said Shauna Sanford, a spokeswoman for Louisiana Gov. John Bel Edwards.

The Texas city of Beaumont, home to almost 120,000 people near the Louisiana state line, was trying to bring in enough bottled water for people who stayed behind after a water pumping station was overwhelmed by the swollen Neches River.

The latest statewide damage surveys showed the extent of destruction. An estimated 156,000 dwellings in Harris County, or more than 10 percent of all structures in the county database, were damaged by flooding, according to the flood control district for the county, which includes Houston.

Lindner called that a conservative estimate.

Figures from the Texas Department of Public Safety indicated that nearly 87,000 homes had major or minor damage and at least 6,800 were destroyed.

Gov. Greg Abbott warned today in an interview with ABC’s “Good Morning America” that it could take years for Texas to “dig out from this catastrophe.” President Donald Trump tweeted that there’s still “so much to do” in Texas’ recovery.

At the Arkema chemical plant in Crosby, thick black smoke and towering orange flames shot up once again. The company has blamed the blasts and fires on floodwaters that engulfed the plant’s backup generators and knocked out the refrigeration necessary to keep unstable compounds from degrading and catching fire.

In Beaumont, people waited today in a line of cars that stretched more than a mile at a water-distribution center at a high school football field. Each vehicle received one case. Earlier, people stood in line at a Kroger grocery store that was giving away gallon jugs of water, which were gone in two hours.

While city officials said little about plans to restore water service, a spokeswoman for ExxonMobil, which has a refinery and chemical plants in Beaumont, said today that the company helped install a temporary intake pipe to the city’s treatment plant.

The water began pumping late Thursday and a little was flowing into some homes, but the water will not return to full pressure until the city refills reservoirs, spokeswoman Ashley Alemayehu said.

The water supply for the Bolivar Peninsula southeast of Houston was expected to run out within days, and could be out for weeks, after a pumping station 30 miles away was submerged by floodwater, officials said.

About 2,000 people live year-round on the 27-mile (43.45-kilometer) long peninsula, a narrow strip of land in the Gulf of Mexico.

People fleeing the flooding were being bused to the Beaumont airport where airplanes and helicopters waited to fly them to Dallas and elsewhere. Air ambulances were on standby for those with critical medical needs.

About 1,800 people were staying in shelters in Dallas, including about 1,000 who were flown late Thursday from Beaumont, officials said.

Harvey initially came ashore Aug. 25 as a Category 4 hurricane, then went back out to sea and lingered off the coast as a tropical storm for days. The storm brought five straight days of rain totaling close to 52 inches (1.3 meters), the heaviest tropical downpour ever recorded in the continental U.S.

Far out over the Atlantic, Hurricane Irma was following a course that could bring it near the eastern Caribbean Sea by early next week. The Category 2 storm was moving northwest at nearly 13 mph (20 kph). No coastal watches or warnings were in effect.