The Merck & Co. Inc. chemical spill and Wissahickon Creek fish kill in 2006 has led to a multimillion-dollar settlement, announced recently.

It's the public's good fortune that a sizable portion of Merck's $20-million-plus payment will go toward saving an endangered farm's meadows, streams and fields just outside Philadelphia.

In other words, the Merck settlement is no Blockbuster coupon deal. You may recall that the half-billion-dollar settlement of video-rental overcharges several years ago produced nothing more than $18 in rental coupons, when divvied up among the store's millions of customers.

The Merck settlement, though, will provide tangible benefits to untold numbers of park users in and around Montgomery County for years to come.

The company's $5 million contribution toward preserving a large swath of Erdenheim Farm, the 450-acre Whitemarsh Township estate of the late philanthropist F. Eugene "Fitz" Dixon Jr., just about seals the preservation deal.

With other funds from the state, county, township and private donors, the Whitemarsh Foundation, working with the Media-based Natural Lands Trust, should be able to purchase what's known as the 98-acre Angus Tract in the coming months.

Preservationists had been under a deadline to raise the $14.5 million needed to make the purchase, and it appears now that they'll cross the finish line in time.

Other funds from the Merck settlement will go toward environmental improvements along the Wissahickon Creek. But it will be the saving of the Dixon farm that is the most visible evidence of the firm's efforts - at the insistence of state and federal environmental agencies - to redress its accidental chemical spill. It's rare when an environmental mishap of this nature can be turned to such good public purpose.