It was a bummer of a summer for the broadcast nets, which are promoting their fall fare to an ever-decreasing number of viewers.

The unofficial 14-week summer season, which ended Sunday, saw the combined young-adult audience of the Big Four broadcasters decline 11% year-to-year. Fox held up best, down just slightly, but ABC, CBS and NBC were all down by double-digit percentages, according to Nielsen.

In the very sleepy final week of summer, which included the start of the long Labor Day holiday, CBS prevailed in adults 18-49 for the first time since the week it carried the Super Bowl in early February.

While the summer reality shows for the other nets have wrapped, CBS is still going strong with “Big Brother 8.” In addition, gameshow “Power of 10” is a solid performer, and the net also does better in reruns than its rivals.

Eye won the frame with a mere 1.8 rating/6 share in adults 18-49, topping Fox (1.6/5), followed by ABC (1.4/5), NBC and Univision (both 1.4/4) and ESPN (1.2/3). While CBS barely avoided its lowest-rated week on record, Fox and NBC hit new low-water marks, while ABC matched its weakest showing.

The Eye was the week’s leader in adults 25-54 (2.3/7) as well as total viewers (6.8 million), while Univision moved to the lead among adults 18-34 for the first time. By winning Monday through Friday, the Spanish-language net — led by telenovelas “Amar Sin Limites” (Love Without Limits) and “Destilando Amor” (Essence of Love) — edged out Fox for the frame (1.6/6 to 1.5/5).

CBS comedy “Two and a Half Men” was the week’s No. 1 program in adults 18-49 (3.3/9), edging out Tuesday’s “Big Brother” (3.2/9). It was also the frame’s most-watched show overall (10.31 million) — a good sign of its repeat popularity heading into its syndication launch this fall.

CBS actually had the week’s top five programs in 18-49, also including Tuesday’s “Power of 10” (2.9/9, 9.89m), as the rookie hit a high with an episode featuring contestants from “Big Brother” (Daily Variety, Aug. 30).

Fox, which won the summer season among adults 18-49, finished meekly following the conclusion of its reality hits “Hell’s Kitchen” and “So You Think You Can Dance.” Last week, net was led by an hour of “Family Guy” repeats on Sunday (2.6/08 in 18-49, 5.48m) and Tuesday’s encore of “House” (2.6/7, 7.95m).

ABC has just two programs among the top 20 in 18-49: Monday’s repeat of “Wife Swap” (2.3/7, 5.62m) and Tuesday’s repeat of “Just for Laughs” (2.2/7, 7.19m). Net won Saturday with the preem of “Saturday Night Football” featuring the college matchup of Tennessee at California (1.8/7, 4.95m).

And NBC may be positioned to win the current week with a pair of regular-season NFL contests, but it was an afterthought last week when it was paced by “Last Comic Standing” (2.6/7, 6.49m). Its only other top-20 performer in the 18-49 demo was Tuesday’s repeat of “Saturday Night Live: The First 5 Years” (2.1/6, 5.88m).

CW’s inaugural summer was a disappointing one, with the net merely performing on par with the WB in its lame-duck summer season of a year ago. Top performers for the week were Friday’s firstrun “Friday Night Smackdown” (1.3/5 in 18-49, 4.00m) and Monday’s hour of “Girlfriends” repeats (0.9/2, 2.03m).

Among the cable nets, ESPN enjoyed a rare first-place primetime finish in adults 18-49 (1.17 rating), paced by Sunday’s NASCAR Nextel Cup race (2.3/8 in 18-49, 6.38m), Monday’s NFL preseason game between Cincinnati and Atlanta (2.1/6, 5.23m) and Thursday’s college football opener between LSU and Mississippi State (1.4/5, 3.09m).

TBS ranked second in 18-49 (0.93 rating) thanks to a weekend triple play of “Hitch” and original episodes of laffers “House of Payne” on Wednesday (1.3/3, 2.98m) and “The Bill Engvall Show” (1.1/3, 2.57m).

MTV’s “The Hills” (2.4/7, 4.16m) was the week’s No. 1 cable program among adults 18-49 (ranking 11th among all primetime telecasts) and was the top draw overall in persons 12-34 (3.7/11).

TNT’s “The Closer” was cable’s top scripted program of the week in key demos (1.7/5 in 18-49 and 2.3/6 in 25-54) and easily the most-watched cable show overall (7.78 million).