WASHINGTON — Many public colleges and universities expect their lowest-income students to pay a third, half or even more of their families’ annual incomes each year for college, a new study has found.With most American students enrolling in in-state public institutions in the hope of gaining affordable degrees, the new figures show that the net price — the full cost of attending college minus scholarships — can be surprisingly high for families that make $30,000 a year or less.As of 2010-11, the average net price for in-state tuition at four-year public institutions in Texas, charged to people in families earning $30,000 or less per year, was $8,907.That compares with a low of $5,046 in Wyoming and a high of $12,442 in Maine.TCU, in Fort Worth, was one of the most expensive four-year private schools for the poor in 2010-11, according to the report. Sixteen percent of the school’s population received Pell Grants, indicating that they’re low-income. But, after scholarships, the average cost to students from families making $30,000 or less was $22,193.“That is something we’re concerned about and making progress on,” Mike Scott, director of scholarships and student financial aid at TCU, said in an interview.In the past year, the school put additional money toward the needs of lower-income students, he said. Trustees also determined that part of the revenue from tuition increases would go to need-based financial aid.“We’ve been steadily increasing the amount of money we give based on need,” he said.The numbers track with national trends: the growing student loan debt and declining college completion among low-income students.Because of the high net price, “these students are left with little choice but to take on heavy debt loads or engage in activities that lessen their likelihood of earning their degrees, such as working full time while enrolled or dropping out until they can afford to return,” Stephen Burd wrote in a recent report for the New America Foundation, a nonpartisan group that examines the effects of rising inequality and other trends.The federal government has increased its spending on Pell Grants for the neediest students. Still, the high net prices show that the grants go only so far.Burd, a senior analyst for the foundation’s education policy program, looked at data that the Education Department has required public and private colleges and universities to provide for the past few years. The latest average net prices are for the 2010-11 school year.The net price and much more information about all colleges and universities nationwide are on the department’s College Navigator website.The foundation’s report argued that many private colleges use their own scholarship money to bring in top students from more affluent families to boost their position in the U.S. News & World Report annual rankings.“While the problem is not as extreme among public universities, it is rapidly getting worse,” the report noted.At public institutions, the loss of state financial support and a rise in tuition play a big part in the trend of higher net prices, Burd said in an interview.But Burd said school documents show that “the drive for prestige is very strong as well.”Pennsylvania State University and the University of Missouri-Kansas City were among the most expensive public schools for low-income students. At Penn State, the net price for the lowest income group was $16,000 to $18,000 at schools in the statewide system.At the UM-Kansas City, it was $16,798.Officials at both schools said those numbers don’t tell the whole story.Twenty-eight percent of Penn State’s students receive federal Pell Grants. Full grants, worth $5,500 this year, go to low-income families. Partial grants go to people generally with incomes of around $50,000 or less.Penn State doesn’t admit students based on ability to pay or deliberately offer aid packages that don’t meet the need, said Lisa Powers, director of the school’s Department of Public Information.But tuition and state aid are the school’s only source of money, she said, and state appropriations last year were the same as they were in 1996, when the school had 15,000 fewer students.“The fact is, Penn State does not enroll enough ‘full pay’ students to produce the revenue needed to lower the net price for all low-income students,” Powers said, calling the school’s scholarship fund “modest at best.”At UM-Kansas City, Jennifer DeHaemers, the associate vice chancellor for student affairs, said the net price figure for two years ago is accurate but no longer relevant.As of the 2011-12 school year, the school effectively waived tuition for full-time students who receive Pell Grants and maintain good grades. The result is that the school is moving toward making a college education more affordable for Missouri’s lowest-income students, DeHaemers said.Penn State and Missouri weren’t alone, however, in showing high prices for low-income students, according to the latest College Navigator data.The average net price, for instance, for the lowest-income students was $15,415 at South Carolina State University; $11,071 at Winthrop University in Rock Hill, S.C.; and about $11,000 at the University of Southern Mississippi and at Mississippi State University.