Juniper management at Camp Creek resulted in overall improvement in soil, water, and vegetation conditions over time in the treated watershed. Here is what we measured and what we found.
Treated watershed (Mays) compared with the untreated one (Jensen). Select a tile to see the chart behind it.
Western juniper (Juniperus occidentalis) once grew mostly on rocky ridges and rimrock, where fire seldom reached. Over the last 130 years or so, its range has grown roughly tenfold, from about to around in central and eastern Oregon and adjoining states.
As it spread, vast areas of sagebrush steppe became juniper woodland. That shift changes how water moves through the land, lowers rangeland productivity, and adds to water shortages as the climate grows drier.
The Camp Creek Paired Watershed Study, started in 1994, tests what happens when juniper is removed. Its long record shows lasting gains after the cut: more perennial grass and shrub cover, more herbaceous forage, wetter soil, and more springflow and streamflow.
Roughly a tenfold increase. Bars drawn to scale. Source: Miller et al. 2005, OSU Agricultural Experiment Station Technical Bulletin 152.
A paired watershed study watches two similar, side-by-side drainages for years. Then one is treated and the other is not. Because both get the same weather, the difference between them after treatment shows what the treatment did.
At Camp Creek, Mays watershed had about of its western juniper canopy cut in 2005, measured from aerial photos taken before and after the cut.Jensen next door was left as it was. Before the cut, both had about the same number of mature junipers ().
The two watersheds have been continuously monitored for multiple soil, water, and vegetation variables since the beginning of the project in 1994. Learn more at ecohydrology.oregonstate.edu.
We study each watershed as one connected system. What grows on the uplands changes how much rain and snowmelt soaks into the soil, how much recharges the shallow and deep aquifers, and how much reaches springs and the stream in the valley.
The same view of the Mays watershed before the cut, two years after, and 21 years after.
2005 · before the cut
2007 · 2 years after
2026 · 21 years afterColor-infrared aerial photos of Mays, north at the top, with the watershed boundary in blue. Live junipers show as dark red. The outlet is at the top; the upper slopes are at the bottom. Aerial photos: Tim Deboodt, Crook County.
2004 · before the cut
2006 · after the cutTwo decades after the cut, Mays and its uncut neighbor Jensen look very different.
Mays · cut in 2005
Jensen · uncutPhotos: OSU Ecohydrology Lab.
The two cut trees came from a neighboring watershed in Camp Creek and were cut in September 2026, at the base. Approximate ages are based on tree-ring counts from enhanced images; the exact number of rings still has to be verified under a microscope. Photos: OSU Ecohydrology Lab.
Each point is the yearly water use of one tree or group of trees against its trunk diameter at the base. Water use climbs steeply with size, so a few big trees use far more water than many saplings.
Juniper keeps water from reaching the soil in two ways. Its dense canopy catches rain and snow, which then evaporates straight back to the air: on two Jensen plots the canopy caught 36 to 46% of what fell (Ochoa et al. 2018). And as an evergreen, it draws water from the soil whenever conditions allow, not only during the main growing season.
When the juniper is cut, both of those losses stop, and the water that is freed up can take two broad paths.
Green water is water that stays in the soil and is used by plants. It goes first, because the dry soil under juniper acts like a sponge that must fill up before anything moves on. It shows up as wetter soil, more grass, forbs and sagebrush, and more forage. Some of it also returns to the air through the new plants and from the bare, warmer soil.
Blue water is water that moves past the root zone. Once the soil sponge is full, the extra drains deeper to recharge groundwater, feeds springs, and reaches the stream. This happens mostly in normal and wet years, when there is enough water to fill the soil first.
How the freed-up water splits between these paths depends on the year's weather, the soil and geology, how much juniper was removed, and how fast new plants fill in. At Camp Creek we saw both: wetter soil and more grass in every year, and extra streamflow mainly in normal and wet years.
Each card compares Mays (cut) with Jensen (uncut). Open "More detail" for the numbers behind it.
Hover or tap a point for its value, or open "View these values as text" under any chart. Every chart follows the English / Metric units switch at the top of the page.
Vapor pressure deficit (VPD) measures how strongly the air pulls water from plants and soil; higher means thirstier air. Trend lines use the Sen slope, a fitting method that single extreme years do not distort.
Top: average soil moisture from May to September, as a percentage of soil volume. "Whole profile" averages the sensors at 20, 50 and 80 cm (8, 20 and 31 in); "top 50 cm" averages the 20 and 50 cm sensors, the root zone of most grasses and shrubs. Bottom: drought index for the same years, where bars above the line mean drier, hotter years and bars below mean wetter years. Jensen sensors were offline for part of 2025, so that point is an estimate.
Dry weight of clipped grasses and forbs. In the first view, the number above each year is how many times more grew on Mays than on Jensen; the second view shows the extra amount on Mays.
The two Camp Creek watersheds total about 524 acres (212 hectares). To learn what juniper management does at much larger scales, the lab has extended the approach to central and eastern Oregon. Clover Creek (Crook County) is about 8 times, and Drewsey (Harney County) about 27 times, the size of the two Camp Creek watersheds combined.
These sites let us estimate the effects of juniper management on streamflow and water use at much larger scales, using single-watershed and nested-watershed approaches (smaller watersheds measured inside larger ones). The projects started in 2023 and build on what we learned at Camp Creek.
Dr. Carlos Ochoa
OSU Ecohydrology Lab, Oregon State University
Photos and figures on this page: OSU Ecohydrology Lab, except the 2004 and 2006 aerial photos of Mays and the 2005 and 2007 views of Mays, which are by Tim Deboodt, Crook County.
We want to thank the Hatfield Hyde Land Trust and the U.S. Department of the Interior Bureau of Land Management—Prineville Office for their continuous support of this project and providing access to the field sites. We are also grateful to the multiple students from Oregon State University and volunteers who over the years have participated in the various field data collection activities related to this research. Funding support for this project has come from many different state and federal agencies and organizations over the years. Our most heartfelt thanks go to Doc Hatfield, Tim Deboodt, Michael Fisher, and John Buckhouse, who pioneered the establishment of the long-term CCPWS site in 1993.