Secrets of the River Bush

Irish whiskey has, for centuries, been duking it out with Scotch whisky for bragging rights as to where the water of life or uisce beatha, as it’s known in Gaelic, was first distilled. Whoever got there first, whiskey has been made in Ireland for a very long time, possibly as far back as the 12th century. Which makes it even more impressive that Bushmills, the world’s oldest licensed whiskey distillery — dating back to 1608 — is issuing Secrets of the River Bush. Aged for 46 years, it’s the longest-aged Irish single malt ever released. 

It’s a small miracle that the whiskey exists at all. When Secrets of the River Bush (named after the river from which the distillery gets its water) was distilled and laid down in a pair of oloroso sherry butts in 1978, the entire Irish whiskey category was on the verge of extinction.

Aside from Bushmills, only one distillery was producing whiskey in all of Ireland. Much of that was lighter grain whiskey (made from grains other than barley) or single pot still whiskey (a mix of malted and unmalted barley). Bushmills itself was still five years away from launching its first single malt expression. “Probably the worst possible time that this whiskey was born into,” says Alex Thomas, Bushmills’ master blender. “But we’ve always been passionate about single malt, and we’ve always felt the distillery was never getting the credit it deserved. So we’ve tried to focus since the 1970s on growing that category, nurturing and carrying our single malt and our blends at the same time, but wanting to introduce people to what we think makes an absolutely amazing whiskey.” Today, there are more than 50 distilleries making whiskey across Ireland — much of it single malt.

Unlike many whiskeys, which are initially aged in ex-bourbon American oak before a second maturation in sherry casks, Secrets of the River Bush was aged entirely in 500-liter oloroso sherry European oak butts. Close to half a century of influence from the sherry and the wood has given it a color so dark it resembles Coca-Cola more than a typical whiskey. But the Bushmills DNA has come through intact, says Thomas. 

“Oloroso is just such a well-rounded sherry,” she says. “That balance of flavors that brings you those lovely dried fruits — it’s got a level of sweetness that doesn’t overpower our spirit. Our spirit is very delicate and fruity and white. So you want to ensure that that stays there in the distillate as well as the cask when you actually taste it.”

That this whiskey was able to age for so long without getting overly oaked or overwhelmed by the sherry’s influence is a testament to several factors. The casks are almost two-and-a-half times as large as an American ex-bourbon barrel, and European oak is tighter-grained and less porous than American oak. Both the size and the type of wood provide less interaction between wood and liquid than a bourbon barrel. 

Location also plays a factor. The two casks were in the center of Warehouse 8 — which Thomas notes is the oldest warehouse in the distillery — where the temperature fluctuation is at a minimum. This was aided by the fairly consistent climate on the north coast of Ireland, where Bushmills is located. Extreme swings in temperature hasten the aging process, while stable temperatures slow it down. 

Thomas started with Bushmills in 2004, when the casks were a comparatively youthful 26 years old. “I’d predominantly been in maturation before becoming a master blender,” Thomas says, “so being able to go in every now and then and have a little check to see how it was doing was just fantastic.” 

As the casks got closer to their optimal time for bottling, the monitoring intensified. “It was every three months a few years ago, and then it was tightened up. So before it was bottled, it literally was every week I was going in, saying, ‘Yeah, it’s almost there!’ I was checking the weather, seeing what it was going to be like, to know what impact that would have on it.”

Secrets of the River Bush is bottled at a cask strength of 46.3% ABV, having been entered into the cask in 1978 at 63.4%. Many older whiskies lose so much proof while in the barrel, thanks to alcohol evaporating at a different rate and under different conditions than water, that they threaten to fall below the legal minimum of 40% ABV. Thomas credits the relatively robust proof of this whisky to the quality of the cask. “In that maturation process, we’ve drawn in all of these lovely climate changes that we’ve had over the years,” she says. “Where it’s a storm, those water droplets are inside the air, they’re attached to it. So as the cask breathes and they’re coming in, if that cask wasn’t a good quality cask, it would have brought in so much more moisture. The wood management side of things is really, really important.”

Thomas won’t reveal if Bushmills has even older single malts still in oak waiting to set a new record — “Like the River Bush keeps its secrets, that’s mine” — but with more than half a million barrels currently aging in its many warehouses, anything is possible.