"maintained them" is a correct and usable phrase in written English.
It can be used to describe the act of keeping something or someone in good condition or functioning properly. Example: The farmer maintained his crops by regularly watering and fertilizing them.
Most of the San Lorenzans liked their stoves, and maintained them well enough.
He said, "We both had separate lives before we knew each other, and we've maintained them".
The library did not remove the murals, but maintained them erratically.
"Maybe the city doesn't think people care about the parks, but if it maintained them, then maybe people would care".
He added that it was also doubtful that they could have bought such weapons abroad and maintained them, given international sanctions.
For his part, Mr. Warsh said New Jersey Transit usually built the bus shelters, though the municipalities or private entities maintained them.
The eventual bill for repaving those roads will add much more to deficits than if we had maintained them properly in the first place.
"Ewww," complained my offspring as we negotiated the Costco checkout with a wagonload of Huggies, wipes and the same diaper rash ointment that maintained them as the "dry, happy babies" in all those TV ads.
The United States has restored relations with other Communist states, including China and former warring enemy Vietnam, and maintained them with the Kremlin, but seemed incapable of behaving maturely with its small Cuban neighbor.
"Unlike Cape Cod, which bought farms and maintained them as costly open space as conservation land, the Vineyard fathers protected their farmers by purchasing the development rights and keeping the farmers on the land, thereby providing food throughout the summer and fall season".
All this has one crucial upshot: though we got them on the cheap, paying as little as a 10th of the sum they would have cost if we built and maintained them ourselves, they fail what Plesch calls "the 1940 test": if we were at war without the say-so of the US, we probably couldn't use them.
