Are you comparing apples to apples? Which towns are you comparing Dumont to, towns of comparable socioeconomic status, like Bergenfield or New Milford, or much wealthier towns, like Tenafly or Leonia? The sad reality is wealthier towns are much more likely to be ranked higher. The parents in these towns have the means to provide their children with more opportunities both inside and outside of school.
Check out this chart:
http://php.app.com/satall/results.ph..._orderby=total
This chart shows 2007-2008 SAT scores for all of the "FG" districts in Bergen County. (For those who don't know, the NJ Department of Education ranks all districts on a socioeconomic scale called a District Factor Group, using census data. "A" districts are the poorest, "J" districts are the wealthiest. The "FG" districts are pretty solidly middle-class.)
Dumont is ranked 3rd out of the six "FG" districts in Bergen County. Not too bad. Right in the middle.
It's similar on the state level: Dumont is 23rd out of 44 districts:
http://http://php.app.com/satall/res..._orderby=total
Now if you compare these scores to "J" districts, you're going to find that the "J" districts score much higher overall. For example, the top "FG" district, Pittman, has a 1580 total average score. The top "J" district, Millburn, has an 1835 total average score. But it's not a fair fight when you compare these districts to wealthier ones.
Dumont is a decent town. The schools are not going to be in the same league as in wealthier towns, but they're not bad when compared to simlar school districts.