Montana Creek valley

At the glacier’s elbow

Stream and forest habitats of the Montana-McGinnis watershed are very diverse. Below the rifle range, the creek twists through a deep, narrow canyon, then emerges to braid in several channels through a broad willow flat, too often flooded to grow spruce trees. Near the Community Garden, beavers have transformed a 1960s-era clearcut (pink outline) into some of Juneau’s finest fish and wildlife habitat. Lower Montana Trail weaves through an almost continuous band of large-tree spruce forest growing on well-drained stream deposits, detectable on this aerial photo by wider tree-crown diameters.

yazoo channels

From the Community Garden down to its mouth at Mendenhall River, Montana Creek has been heavily influenced by the recent Little Ice Age advance of Mendenhall Glacier. Broad flood plains like Mendenhall Valley are slightly domed in the center. Although human eyes can’t detect this, flowing water can. The result is “yazoo streams” like Montana and Jordan, elbowed by outwash against their valley walls. Many of Montana’s hydro/geo/ecologic features derive from this unique topographic configuration.

Faults, glaciation, sea level change

Glaciation sequence

Montana Creek valley was formed by glacial deepening of the Sumdum thrust (dashed pink line on second map above), a long shear zone that transects the entire CBJ. Mining began as early as 1881 in limey slate and schist threaded by gold-bearing quartz veins in the bottom of McGinnis Creek valley, and high up in the Grandchild Peaks basin.

Surficial deposits–color-coded on the above maps–are legacies of glaciers that buried all but the highest summits, and marine intrusions far into Montana and McGinnis valleys. The oldest known surficial deposit in the CBJ was found at the asterisk on the rightmost map in this series. Dated at 44,000 BP, a 9-foot-thick bed of alluvial gravel was found below the glaciomarine sediments (green-coded), indicating deposition during a warm interval before Wisconsin Glaciation.

Hair-trigger hydrology

Hair-trigger hydrology

The rightmost map above shows peak advance of the Little Ice Age. While Mendenhall Glacier loomed at the edge of today’s Community Gardens, delivering silty waters into Montana Creek, more outwash channels swept back and forth across the valley, dumping fine sediment (oy) that elbowed lower Montana against the hillside. It now has little room to migrate–the means by which bottomland creeks “let off steam.” The result is what hydrologists call a flashy, or “hair-trigger” system–easily over-topping its banks.

Trees and fish

In October 1998, Montana Creek experienced what some hydrologists considered a “100-year flood,” dropping many bankside spruce into the channel. (June, 1999)

On the nearly imperceptible grades below the rifle range canyon, (<1% on profile), the stream braids indecisively. At flood stage, energized currents eat into soft sand-gravel banks, undermining and toppling massive spruce trees, some spanning bank-to-bank. Unlike Mendenhall River, Montana Creek isn’t big enough to sweep them aside, so they accumulate in log jams.

The logs trap debris, and feed aquatic invertebrates who in turn feed fish. Large logs create topographically diverse channels with deep pools, clear glides, and shallow riffles. Pools and overhangs shelter overwintering salmon, trout and char.

Fish & wildlife hotspot

Panorama of beaver wetlands behind Community Garden. Photo from asterisk on 2006 aerial below.

Montana-McGinnis watershed is a thriving wildlife sanctuary from which salmonids, bears, beavers and mustelids (weasel, mink, otter) replenish the more heavily developed parts of Mendenhall Valley. The Lower Montana Trail passes through some of Juneau’s most majestic large-spruce forest, a good place to see the riparian salmon-eagle-bear community that’s been sadly diminished throughout the Southeast timberlands.

volume

An even more majestic spruce forest frames the braided channels of lower McGinnis Creek. This off-trail portion of the watershed is one of the few places near Mendenhall Valley where brown bears can fish in relative quiet.

Post-logging second-growth has a reputation for lousy habitat, but interestingly, that can’t be said of the clearcut surrounding Community Garden. Between 1940 and 1965, 100 acres of the valley’s best spruce forest were logged, as shown by pink outlines on the center-panel aerial photo. Thanks to Montana’s flashy hydrology, and industrious “beaver rehab,” this is now one of CBJ’s richest patches of fish and wildlife habitat, well known to birders for locally uncommon species like olive-sided flycatcher, Vaux’s swift, northern waterthrush, and saw-whet owl.

The antiquity of names

confluence

In 1989, an ancient fish trap was found on Montana Creek, just above its confluence with Mendenhall River. The 9-foot-long tapering basket of hemlock and spruce was dated at approximately 500- to 700 years BP. It was woven before the Little Ice Age advance of Mendenhall Glacier, when Montana Creek probably flowed directly to the sea.

The stream’s Tlingit name is Kaxdigoowu Héen, or “clearwater creek.” Today, at the confluence with murky Mendenhall water, it’s easy to understand this name. But in the Little Ice Age, “Kax” flowed turbid with silt from the western edges of the glacier, suggesting Kaxdigoowu Héen is a fairly recent name.

An Aerial View

Air photo comparison

Air photo comparison of the exceptionally dynamic reach below Community Garden. 1962 The Garden area–a CCC camp in the 1930s–became a mill site in the 1960s. The pink-tinted area had just been logged, leaving about 5% of the spruces standing, soon to be drowned by beaver. Red-tinted phase-2 spruces were cut shortly after this photo. The main channel of Montana Creek looped farther eastward than today. 2006 The main channel moved to its current position shortly after the logging. On drier cutover sites, 44 years can grow a tall, dense conifer forest with shade-inhibited understory. But here, flashy hydrology plus beaver activity resulted in a lush mosaic of shrub thicket, meandering sloughs, sedge marsh and young conifer/deciduous forest. For about 3 decades, beaver-drowned spruce snags were excavated by sapsuckers, providing homes for “secondary cavity nesters.” Most have since fallen; only one shows on the right in the panorama above.

Montana Creek valley Area Map

Access Information

Lower Montana
Distance: 1.3 miles
Elevation: 20 ft
Difficulty: easy
Ownership: CBJ, Juneau Youth Services
Notes: well marked; bears active at salmon time.

Middle Montana
Distance: 2.0 miles
Elevation: 180 ft
Difficulty: navigation challenge
Ownership: CBJ, State
Notes: frequent flooding obscures trail, damages bridges.

Upper Montana
Distance: 7.4 miles to Windfall Cabin
Elevation: 650 ft
Difficulty: difficult
Ownership: State, USFS
Notes: first part on old CCC road; possible to exit via Windfall Lake and Herbert River.

Kaxdigoowu Héen Dei
Distance: 2.1 miles
Elevation: 25 ft
Difficulty: easy
Ownership: CBJ
Notes: Paved; much more traffic than on Montana trails, including bikes.

Montana complex The 3 segments of the Montana Creek Trail total 11 miles, including short road segments. At the Windfall Lake Cabin, Upper Montana Trail meets the 3-mile Windfall Lake Trail.

Tread Lightly!
• Please do not pick or dig up
wild flowers.
• Do not feed wildlife.
Pack it out
• Carry out all trash.
• Please pick up after your pet.


Red-breasted sapsuckers Adult spotted frog