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Sense of Place: Understanding Microclimates in the Gallatin Valley

Most people are aware of regional differences in climate. The Southeast is hot and humid. The Southwest is hot and dry. But in the Intermountain West, mountains affect air currents and moisture distribution to create many microclimates within just one valley. Visitors don’t recognize those microclimates. Most residents find out about them by trial and error.

At the Museum of the Rockies in Bozeman, I met a couple in their mid 30’s that were visiting from Las Vegas. They said they were tired of the rat race and were looking for a place with a little acreage, to garden and maybe raise some livestock. The first question they asked me was “How much snow do you get here?”

“It depends on what part of the Gallatin Valley you are in,” I replied. They looked at me blankly.

“The climate isn’t the same across the whole valley,” I explained. “Why do you ask?”

“We’re wondering if we’d be snowed in all winter here,” the lady added.

“Not likely.” I replied. “But how much snow we get is the least of your worries. You need to ask different questions – questions about growing season, temperature, depth to water, soils, and land prices.” So I gave them a quick “lay of the land” for the Gallatin Valley.

The mountains and Bozeman Pass get the deepest snow, but south and southeast parts of the Gallatin Valley get the most valley accumulations because that’s where the storms bump into the mountains and drop their load of moisture. As you go west in this valley, the snow depth tapers off, but the temperatures are colder. It gets to minus 20 or colder in winter, but it doesn’t last long, only a few days to a week. Wear layers of clothing. It’s a dry cold.

Some of the actual climate relationships defy logic. Higher elevations usually mean colder temperatures. But cold air sinks, so it is actually colder at my house down near the West Gallatin River than it is here at the Museum. I get a good crop of apples off my apple trees about once every 3 years, because the flowers freeze in spring. But along the west face of the Bridgers, at a higher elevation, apple trees produce very well, year after year. It’s warmer there, even though the elevation is higher.

“The growing season is about 90 days here. I plant on Memorial Day and expect frost anytime after Labor Day, though I’ve had 28 degrees on the 23rd of June and my potatoes have frozen flat on the 16th of August. I pick my tomatoes green and let them ripen in the house. But I garden in a cold spot.

Manhattan and Three Forks have a longer growing season. In spring, it greens up two weeks earlier in Three Forks than in Belgrade. The lilacs bloom in Belgrade before they bloom at my house.

The north side of the Valley has a high water table. On the return trip of Lewis and Clark Expedition, Sacajawea told Clark to go to the south to avoid swamps along the East and West Gallatin Rivers. In the 30’s and 40’s, drain ditches were dug in this area to reduce subsoil moisture. Much of the valley floor is greener than Clark found it, due to extensive development of irrigation canals since the first white settlement in 1864. Most of the valley was irrigated by flood irrigation. As sprinkler and center pivots have replaced flood irrigation (and subdivisions replace agriculture altogether), water tables have dropped in some areas. Homeowners in some subdivisions northwest of Bozeman have had to deepen their wells.

Some of the best agricultural soils in the State are on Huffine Lane west of Bozeman, where the MSU Ag Experiment Station has the Post Farm. That area is rapidly being converted to commercial development. The foothill soils up toward Springhill to the north, Amsterdam-Churchill to the west, and south of Bozeman are deep and have good water holding capacity. But the oldest water rights are not always associated with those places.

Along the West Gallatin River, one would expect deep, rich alluvial soil, but that isn’t the case. The soil at my house and extending east to Belgrade is shallow and full of stream tumbled rocks up to bread loaf size. I can’t flood irrigate. The water goes ten feet and sinks out of sight. But gravel is plentiful and I’m told that the groundwater supply in the Belgrade area is better than in Bozeman. Of the towns in Gallatin County, only Bozeman is using surface water (from Hyalite and Sourdough Creeks south of town) for its water supply. All the rest depend mostly on groundwater wells and some springs.

The oldest water rights (1864-1890) are centered near Central Park where the West Gallatin River crosses I-90. Some of these rights have been transferred upstream in the drought years of the 1930’s. Water rights in the Churchill-Amsterdam area date from 1890 to about 1912, when that area was settled by Dutch immigrants.

Land isn’t cheap here. Small parcels are hard to find. The cheapest lots are in Ponderosa Pines north of Three Forks. It is cheap because it is remote and dry. Access is by graveled, clay gumbo road (over 10 miles of it). The area has bus service to Three Forks schools, rural mail delivery, and a volunteer fire department, but no commercial services. It’s a long way to a job.

“Your question about how deep the snow will get in winter is a good one,” I advised. “Make sure you know if the parcel you want to buy has year round access, who plows the snow, and how often. (And who pays for it?) None of that is guaranteed. (Also be sure you are in a fire district.)”

“Wow,” the man said. “I’ve learned more from you in 15 minutes than I got out of reading homesteading magazines for three years.”

“Your welcome,” I replied.

Next Time: Microclimate variations in your Backyard.

Susan Duncan lives on a 76-acre irrigated farm in the Gallatin Valley of Montana that she and her husband Richard built from a fallow grain field since 1976. They raised registered and commercial cattle, sheep, and hay. Now they are niche market entrepreneurs of Dexter cattle and some produce. From 1999-2004 Susan was a country lifestyle columnist for the Bozeman Daily Chronicle “Fencelines” Section. She holds a B.S. Degree in Forestry from the University of Montana. For the last 20 years she has been an active participant in local efforts to envision a viable future and guide exploding development.

Read some of Susan Duncan’s previous columns:
Sense of Place: Understanding the Risks of Where You Live
Can Urban and Rural Develop a Shared Sense of Place?
Discovering Your Sense of Place

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2 comments

  1. Bridget in Bozeman

    Susan,
    I really enjoyed your piece. We operate a farm on that southern front you mentioned and just marvel at the different weather patterns and affect on vegatation, agricultural practices, lifestyles and real estate prices. I look forward to your next installment!

  2. I loved your article. The topic of microclimates also applied to our ranch. My late mother-in-law could grow tomatoes and corn at the upper place, on the side of a hill, but only cabbage and strawberries prospered at the ranch house site. I gave up gardening at the place after covering it all 7 times in July one year. My in-laws had moved to a lower climate, and luxuriated in the gardens they could grow. I have a question: Do you have CSAs there? They are an increasingly popular source of food in Boise, driven by very successful downtown summer markets. All are either certified organic, or are “organically grown.” One store sells all local produce, when available, unlike all of the corporate supermarkets.