Most North Star readers don’t realize there are investigations going on in their midst. They’ve been ongoing for decades. Investigators roll into North Danville frequently, trying to solve a series of mysteries going back over 50 years. While crime scene investigators would be combing for traces of DNA and other forensic curiosities, these investigators are looking for more obscure clues.
They are scientists trying to understand the natural processes playing out under our feet. They are part of the Sleepers River Research Watershed, one of the longest running continuous research programs for a cold-region area in the United States. In 1957, the Unites States Department of Agriculture (USDA) tasked its Agricultural Research Service (ARS) with looking for a watershed in which they could research hydrology (the science of how water moves) both above and below the ground. Here in North Danville was an entire watershed that typified the agricultural and forest land uses of this part of the country at the time. Aside from one very small village, the whole area was rural, with no industrial or commercial development. There were no lakes or significant ponds to affect how water moves over the surface and through the ground, into the brooks and on downstream. It was ideal for research. Former Gov. George Aiken championed the project for funding, in part to provide employment in the area.
The ARS set up shop here, opening an office in Danville village in 1958. Martin Johnson of Plainfield (later Secretary of Environment Conservation in Vermont) was in charge. The designers of the research project divided the watershed into 17 sub-watersheds, ranging in size from 115 acres to 27,554 acres. They began hiring locals to build the structures necessary to measure a wide range of hydrologic processes. Meteorological and hydrologic data gathering stations were built. Tom Machell and Roland Berube were put in charge of construction and maintenance. Over the next few years, they built concrete weirs across streams, and small buildings to house the desired instrumentation. Land for weirs was leased from landowners. The weirs are the shallow V-shaped dams that cross several of the brooks in the watershed. They are designed to accurately measure the flow from that watershed, data which can then be used to figure out how the stream reacts to rainfall and snowmelt events. The main weather station was built on the McReynolds farm but is no longer there. The most remote weather station was on Stannard Mountain to record high elevation weather.
During the summers, local students were hired to help. Art Brooks graduated from St Johnsbury Academy in 1961 and went to work that summer mixing concrete for the weirs, some of which had to be carried a considerable distance into the pucker-brush to reach the more remote sites. In subsequent summers while he was in college, Art helped monitor the instruments all over the watershed, bouncing around in a jeep collecting data to be brought back to the researchers. By today’s standards, research methods in the early days were somewhat crude. Martin Johnson was the principle investigator those first years, and Art remembers an experiment in Goss Hollow. Johnson’s primary interest was in fluvial geomorphology, or how stream flow shapes the channel and flood zone. The weir at Goss Hollow had a plug in the bottom to allow the water behind the weir to be drained. Johnson used this feature to simulate a sudden high flow by pulling the plug. To collect the data he wanted, he simply stationed 10 students at intervals downstream and they observed and measured the rise and fall of the surge of water.
Both Tim Ide and his sister Mary were also part of the summer crew. Tim remembers building weirs beginning in 1958. Several years later, Mary worked in the office analyzing data from some of the ongoing experiments. Dan Swainbank was also on the crew that summer of 1966, and Dan and Mary hit it off. Fifty years later, they have come full circle, having built their retirement home on a slope above Pope Brook and two of the research weirs.
In the 59 years since 1957, there have been some changes in the Sleepers River Watershed. There are many fewer active farms, and some more houses. There are probably about the same number of cows and people, but farming practices have changed dramatically. Most of the hilly pasture that existed in 1958 has grown up to trees. Consulting the stats from the U.S. Geological Survey (USGS) the watershed encompasses 43 square miles, is 67 percent forest, ranges in elevation from 660 feet where the Sleepers spills over Emerson Falls to 2,592 feet at the apex of the Kittredge Hills. One major change has been in precipitation. The 32-average precipitation in St Johnsbury in 1960 was about 34 inches, whereas by 2010 it had risen to 39.5 inches, an increase of over 15 percent.
In the 1960s the ARS Soil and Water Conservation Research Division’s primary goal here was to “provide more knowledge of the behavior of natural watersheds and to seek solutions to watershed management problems of formerly glaciated soils of the Northeastern United States.” The 17 sub-watersheds each represented a different land use pattern that might influence the hydrology. The National Weather Service (NWS) entered on the scene in 1966 when their Office of Hydrology began administering the site. The NWS did modeling studies of how snowmelt runs off. Data was collected in all the sub-watersheds into the 1970s. By 1979, only two of the sub-watersheds were still operating. At that point, the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL, located in Hanover) took over administering the watershed and continued the NWS snowmelt work.
Beginning in 1991, USGS began sustained research into the complexities of WEBB (an acronym that stands for Water, Energy, and Biogeochemical Budget; you can see why they use the acronym). CRREL stepped back in 2001 and since then USGS has been in control of the facilities. Researchers have continued collecting data in four of the sub-watersheds.
The Sleepers River is one of five WEBB sites managed by USGS across the country as part of the US Global Change Research Program. That research continues today, led by research hydrologist Jamie Shanley, who has worked for USGS out of Montpelier since 1991. Work is concentrated in the W9 sub-watershed, in the forested landscape of the upper Pope Brook watershed. The U.S. Forest Service helps out with lab work, and a variety of collaborators bring in projects all the time. Currently, a researcher from Syracuse University has re-started some of the abandoned gauges and hopes to maintain them for his ongoing research.
Shanley cites three major objectives of the USGS climate change research at Sleepers River. First, he hopes to forge a better understanding of the carbon cycle, especially the role of streams as a conduit for organic carbon from the uplands to the ocean; all components of the carbon cycle need to be better understood to improve climate models. Second, it is important to maintain long-term datasets to assess trends in climatic indicators such as snow depth, precipitation, streamflow, and stream chemistry. And third, USGS wants to assess water availability and water quality in extreme wet and extreme dry years as a proxy for what may happen under future climate scenarios.
The Sleepers River has hosted research by a variety of agencies and universities. All sorts of meteorological and hydrologic data have been collected, including temperature and precipitation, soil temperature, snow density, frozen ground depth, and various chemical analyses of snow and water. A major reason that this watershed is so valuable for research today is the long record of hydrologic conditions, now dating back over 50 years.
It is helpful to know a few basics about the hydrology in this area. First, precipitation increases with elevation, so while the average annual precipitation at the Fairbanks Museum is now about 40 inches, all of us living uphill from there receive more. In the Sleepers River watershed annual precipitation ranges up to 60 inches at the heights of the Kittredge Hills.
Second, evapotranspiration has a huge effect on our water balance. This is the water that evaporates from the surface or is transpired by plants during the growing season. Generally, over half of our annual precipitation is returned to the atmosphere through evapotranspiration. Our groundwater is usually the lowest toward the end of summer when evapotranspiration is at its greatest. An inch of rain in August is quickly sucked up by plants and then transpired back to the atmosphere. But as soon as the leaves turn, plants are no longer transpiring, and that same inch of rain will sink into the soil and recharge the groundwater. Those cold, cloudy, rainy days of late October and November are vital to this process.
Third, groundwater is vital to our lives. Outside of St. Johnsbury, nearly all of us get our drinking water out of the ground. Our gardens and agriculture rely on groundwater (as opposed to being irrigated from surface water). So whether our precipitation sinks into the ground to recharge the groundwater or runs off the surface into the rivers is very important. Here in the Northeast Kingdom, about 25 percent of our precipitation falls as snow. During the frozen conditions of winter, the water table falls until snowmelt recharges it in the spring. Snowmelt also usually produces the peak runoff event of the year. Whether snowmelt sinks into the ground or runs off depends on when and how hard the ground freezes and how warm and fast the melt happens. In most years, the ground only freezes a few inches before being insulated by snow, and often it thaws under the snow, thus allowing a gradual melt to sink into the soil. One of the facets of Sleepers River research has been to understand how much of the flow in our streams comes from precipitation running directly off the land (new water) and how much comes from water seeping out of the ground (old water). Seeps are the result of precipitation first sinking into the ground and then moving down slope through the soil.
So the next time you drive into North Danville village from St Johnsbury, look to your right as you cross the bridge and notice the concrete weir and the small building next to it. You are looking at one of 17 similar structures scattered around the brooks of North Danville. They are a lasting reminder of our need to understand the world around us, or in this case, the world under our feet.
Tim McKay is a conservationist, tree farmer, furniture maker, and writer who has lived in Peacham since 1977. Tim retired in 2010 from a career with the USDA Natural Resources Conservation Service field office in St Johnsbury.