I learned about hemlocks before I knew their name. I was a kid, and it was a practical relationship.

If I was in the woods and it started to rain, I’d head for a hemlock. The umbrella of branches kept me dry. If my boots grew heavy from a snowy forest floor, I’d find a hemlock with ponderous boughs —the ground below was shielded from the snow. When I played in the creek, I’d avoid them. The water was warmer in spots that escaped the shade of those thick green arms.

Hemlocks are evergreen trees, with sweeping branches and an abundance of small, soft cones that hang from the tips of their boughs. Dense cover is their defining characteristic. The strong lines of their limbs, combined with sparse undergrowth, make the trees an iconic sight in groves and along streams. Their shade cools the water and helps fish thrive. It’s no accident that healthy trout streams in Chesapeake Bay headwaters are often lined with hemlocks. But now, hemlocks are under attack.

A tiny insect called the woolly adelgid has been destroying hemlocks across the Eastern United States. Forest managers, scientists and volunteers are fighting back, applying pesticide treatments and releasing adelgid-munching beetles to prevent and reduce the damage. But large tracts of hemlocks, including those in Pennsylvania, Maryland, Virginia and West Virginia, have suffered great losses. (See “Tiny insect toppling region’s majestic hemlocks,” on page 1 of this issue of Bay Journal).

Amid the crisis, though, are places where hemlocks are quite literally holding ground. While the largest tracts are found along the westerly and mountainous Chesapeake headwaters, pockets of hemlocks also exist farther east.

The Hemlock Gorge in Baltimore County, MD, is one of those places. With roots that grip rocks and steep slopes with amazing tenacity, the hemlocks along this trail stand like guardians along a beautiful stretch of the Gunpowder Falls, which flows into the Prettyboy Reservoir.

The Prettyboy Reservoir is part of a three-reservoir system that provides drinking water to 1.8 million people in the greater Baltimore area. The gorge is among the 7,000 acres that surround the reservoir, owned and managed by Baltimore City to maintain a healthy forest that, in turn, protects the reservoir’s water quality.

Hiking, fishing, boating and stream-wading are permitted, but forest conservation is the priority. So while the Hemlock Gorge is accessible with a small amount of roadside parking near the trailhead, do not expect a groomed trail. The path is mostly clear and well-trodden, but the trailhead is unmarked and there are no blazes on trees to mark the way. You won’t find restrooms or trail maps, either. If you search for the Hemlock Gorge online, you will find that descriptions of this hike vary by length and route.

Clark Howells, who manages the reservoir’s land for the city of Baltimore, led the way on a loop of roughly 2.5 miles that began and ended beside a bridge on Gunpowder Road. It was a dramatic, invigorating hike on terrain more common in Maryland’s western counties. The full route is not a good choice for small children or people who can’t manage steep ground and long hills.

Luckily, you needn’t walk far to be rewarded. The Gunpowder Falls, a tributary of the Gunpowder River, is cool and intimate under the hemlocks. You could easily walk a short and mostly flat stretch to a waterside perch and spend time enjoying the shade, photographing small waterfalls and shallow pools, wading or having a picnic. (Be sure to leave no trace.)

We had barely begun the hike when a mink appeared on the opposite bank, scampering and swimming, and cautiously keeping pace with us as we walked.

We parted with the mink at the confluence of a smaller stream, called Walker Run. A rocky outcrop makes a nice viewing platform for the riffles and pool where Walker Run meets Gunpowder Falls. But some charred wood and a blackened sign stood nearby, signs of misuse and vandalism. “Kids come out here sometimes and damage the hemlocks,” Howells explained. “So we’ve been working hard to get people to understand and respect the value of these trees.”

The trail crosses Walker Run and continues along Gunpowder Falls, where the bank grows quite steep. We clambered over felled trees and peeked into small rocky crevices that pass for tiny caves. Here, the hemlocks themselves were a help — the stubs of broken boughs made good handles and the gnarled roots served as footholds.

The view of the stream below was lovely. “This is one of my favorite places,” Howells said.

Before long, the ground flattens out to a floodplain that, in spring, was filled with grasses and the tender green of young ferns. Then the trail hits Silver Run, another small tributary, and bears left to follow it on a wide, uphill path toward the top of the gorge.

A surprising sight, about half way up, is an old cemetery, fenced and neatly tended. It’s the resting place for the Hoffman family, who started a paper mill on Gunpowder Falls in the 1700s.

After a second climb, the trail returns to the road on a straight and steady downhill course. To the left, the land falls away toward the stream, providing another view of the tenacious hillside hemlocks.

Nearly all of the trees here have been treated with a pesticide to fend off the woolly adelgid. To protect the water, spray treatments are not allowed. So it’s a tree-by-tree battle, with trunk or soil injections applied by hand. “You can spend a lot of money per tree to protect them,” Howells said, “but otherwise you lose such an important asset.”

In other locations, you can find trails and overlooks named for the hemlocks that once grew there. Now, those names tell a story of loss. In Shenadoah National Park, the Hemlock Springs Overlook has become a view of dead trees mixed with other species that are taking their place. The “hemlock cathedral” in Pennsylvania’s Tuscarora State Forest is now bared to the sky, with the limbs of dead trees as rafters.

This Hemlock Gorge, however, is still true to its name. To find it, travel on Gunpowder Road on the west side of the Prettyboy Reservoir. A bridge crosses Gunpowder Falls just north of the intersection with Hoffmanville Road. Park beside the bridge and follow the trail downstream.

Hemlock hikes can also be found in other parks in the Chesapeake region, although you may have to look for them and consult with park staff for advice. In Virginia, try the Tye River Overlook at James River State Park in Buckingham County, where hemlocks have been protected by beetles that consume the adelgids. Many hemlocks in Shenandoah National Park have died, but healthy trees still stand near the southern entrance of the Skyland section. In Pennsylvania, visit the old growth forest in the Alan Seeger Natural Area near State College or Reeds Gap State Park in Mifflin County, where hemlocks still dominate.