You can't just go around talking trash about the River Walk and expect to get away with it . . . at least according to San Antonio Mayor Julian Castro, who took a friendly jab at Houston Mayor Annise Parker after she called his city's celebrated tourist attraction "a cement ditch."

"Seems like Houstonians have a little river envy," Castro told KAAB Fox San Antonio. "Mayor Parker is a good mayor. We have a good relationship, but it was clear from her comments that Houstonians are more than a little jealous of the River Walk."

Parker doled out the "cement ditch" comparison during a Wednesday ceremony recognizing Buffalo Bayou Park's placement on the 2012 10 Great Public Spaces list compiled by the American Planning Association. Though the quip was meant in jest — and used to highlight efforts to preserve the bayou's natural ecosystem — our neighbors to the west aren't taking it.

"She doesn't understand nature, she doesn't understand urban planning and she's missing out on a wonderful opportunity in life," San Antonio resident Sarah Harte complained to KAAB.

"I can't believe anyone would have anything bad to say about the San Antonio River Walk," said another resident. "That's just beyond belief."

For now, the two mayors appear to be keeping their cool. Castro is hoping to smooth things over with an open invitation for Parker to join him for lunch on the River Walk the next time she's in San Antonio.