While the major broadcasters were slogging through the dog days of summer, Univision scored a network first in winning last week among young adults.

Powered by its weeknight novelas “Soy Tu Duena” (Women of Steel) and “Hasta que el Dinero Nos Separe” (For Love or Money) as well as a Futbol Liga Mexicana soccer game on Saturday (Mexico vs. Ecuador), the Spanish lingo-broadcast leader bested ABC, CBS, NBC and Fox in adults 18-49, according to Nielsen. Univision’s 1.6 rating topped runner-up ABC (1.4), while CBS, NBC and Fox averaged a 1.3.

Univision had broken through in the 18-34 demo before but had never won outright in the prime advertising demo of 18-49 that the major nets target. Last week among adults under 35, it beat second-place Fox by a whopping 50% (1.8 vs. 1.2).

For Univision, its strength among the younger half of the 18-49 demo is partly due to population trends, as Hispanics remain the fastest-growing minority nationwide.

And Nielsen estimates another large increase for Hispanic TV homes in the 2010-11 season (nearly 400,000 homes): The 3.1% growth for Hispanic homes outpaces the total 0.9% gain (or 1 million homes) for the upcoming season.

Meanwhile, the week of Aug. 30-Sept. 5 capped the unofficial summer TV season, which saw the Big Four broadcasters stop the bleeding on a year-to-year basis.

Thanks in part to a strong NBA Finals (ABC) and the earlier telecast of the Primetime Emmys (NBC), the major nets edged up a tick in combined primetime 18-49 averages (6.7 rating vs. 6.6) after posting declines pretty much every year for the past two decades.

Fox edged out ABC in adults 18-49 (1.9 to 1.8), with the former flat and the latter rising a nifty 20% vs. last year. While a seven-game NBA Finals certainly helped, the Alphabet was up year to year virtually every week.

NBC was third (1.6, flat vs. last year) while CBS ran fourth (1.4, down 13%), even though the Eye’s “Big Brother” enjoyed a strong summer and the net won the season in total viewers.

The top shows in adults 18-49 were Fox’s “Hell’s Kitchen,” NBC’s “America’s Got Talent” and ABC’s “The Bachelorette.” The top broadcast newcomers were extensions of two of those shows: Fox’s “Masterchef” (the latest from Gordon Ramsay) and ABC’s “Bachelor Pad” (an offshoot of “The Bachelor”).

In total viewers, “America’s Got Talent” led the way (11.8 million), with “The Bachelorette” and repeats of CBS drama “NCIS” next in line, drawing about 10 million apiece.

Looking at last week, which included some lightly watched nights leading into Labor Day, MTV’s unscripted Thursday smash “Jersey Shore” surged to series highs (3.3/11 in 18-49, 6.54m) and was primetime’s No. 1 show in 18-49 while racking up a 22 share in persons 12-34.

Another cable standout was Disney Channel’s original movie “Camp Rock 2: Final Jam,” which was Friday’s top program in both adults 18-49 (1.4/5) and total viewers (7.96 million). It also ranked as cable’s most-watched program of the week and was second to “Jersey Shore” among all primetime shows for the week in persons 12-34 (2.9/12).

In its target youth demos, it drew 3.1 million kids 6-11 and 3.2 million tweens 9-14.

Bravo’s “Real Housewives of New Jersey” reunion spec on Monday delivered the best numbers for any episode in the “Housewives” franchise to date (2.0/5 in 18-49, 3.85m), leading all of television among young adults in the 10 o’clock hour. It was up about 15% in all key categories vs. the show’s season finale of the previous week.

At TNT, “Leverage” ended its summer season Sunday before an aud of 3.74 million (up 11% from its year-ago conclusion). And on the front end of the week, net’s “The Closer” (1.4/3 in 18-49, 7.61m) had a strong showing, standing as cable’s No. 1 scripted series telecast of the week in both adults 25-54 (2.1/5) and total viewers.

Lifetime’s “Project Runway” hit season highs on Thursday (1.7/5 in 18-49, 4.00m), rising by double-digit percentages vs. its prior season average and logging the show’s best scores in female demos since its sixth-season finale last November.

Among the broadcasters, “America’s Got Talent” stood as the No. 1 program in 18-49 (3.0/9, 11.50m for Tuesday’s performance show), edging past CBS’ “Big Brother” (2.9/10, 7.87m for its Wednesday seg), with the latter posting its best score in adults 18-34 on any night in three years (2.7/10).