The phrase "as it dwindled" is correct and usable in written English.
You can use it to describe a gradual decrease or reduction in size, quantity, or intensity over time.
Example: "The light from the campfire flickered softly as it dwindled, leaving the surrounding darkness more pronounced."
Alternatives: "as it diminished" or "as it faded away".
All eyes tracked the shot as it dwindled against gray clouds.
As it dwindled, Mr. Gingrich moved toward the crowd around the cold buffet table, catching anyone who wanted a word.
The couple shared an online bank account and, for months after the breakup, Ms. Hill pored over the balance as it dwindled to $10.
And their strategy was to hold on to the lead that the networks announced election night, even as it dwindled in size through various recounts and a Florida Supreme Court order.
Over time, depending on who dies first, the court will swing back and forth between liberal and conservative, as it dwindles from eight, to seven, to maybe six justices.
Just as retirement loomed, it dwindled to nothing.
New York City Opera has delayed announcing its 2011 fall season as it assesses its dwindling finances.
In addition, it's likely that repeat business for the film will start to finally soften as people get their fill, while the potential pool of new viewers who waited but will finally go see it dwindles as well.
The group talked for hours as it gradually dwindled in size, interrupted only by the recorded sounds of the call to prayer over the mosque speakers.
Fairness about keeping some semblance of the income we've gained over the years, even as it has dwindled over the past decade, and greed of the Alliance of Motion Picture Television Producers (AMPTP), who seem determined to take back the royalties we've won by employing deceitful tactics that seek to take advantage of the new technologies in the entertainment business.
Ultimately the power of the supply chain exists very much closer to the rich consumers, and it dwindles as you get closer to some of the poorer growers.
