If you want to find Nutria in the Dallas/Fort Worth area start by finding a place with water and reeds. After that it should be easy, these little guys are thriving all across the metroplex.
Wikipedia has this to say about the Nutria:
Coypus can live up to six years in captivity, but individuals uncommonly live past three years old; according to one study, 80% of coypus die within the first year, and less than 15% of a wild population is over three years old. Male coypus reach sexual maturity as early as four months, and females as early as three months; however, both can have a prolonged adolescence, up to the age of 9 months. Once a female is pregnant, gestation lasts 130 days, and she may give birth to as few as one or as many as 13 offspring. Baby coypus are born fully furred and with open eyes; they can eat vegetation with their parents within hours of birth. A female coypu can become pregnant again the day after she gives birth to her young. If timed properly, a female can become pregnant three times within a year. Newborn coypus nurse for seven to eight weeks, after which they leave their mothers.
Besides breeding quickly, each coypu consumes large amounts of vegetation. An individual consumes about 25% of its body weight daily, and feeds year-round. Being one of the world’s larger extant rodents, a mature, healthy coypu averages 5.4 kg (12 lb) in weight, but they can reach as much as 10 kg (22 lb). They eat the base of the above-ground stems of plants, and often will dig through the organic soil for roots and rhizomes to eat. Their creation of “eat-outs”, areas where a majority of the above- and below-ground biomass has been removed, produces patches in the environment, which in turn disrupts the habitat for other animals and humans dependent on marshes.
Coypus are found most commonly in freshwater marshes, but also inhabit brackish marshes and rarely salt marshes.