As river levels drop and creeks warm up across western Montana, you might wonder where all the water went.
A new U.S. Geological Survey interactive map lets viewers trace the nation’s waterways – both where they go and where they come from.
Click on little Beaver Creek in the Mission Mountains, and see its contribution spread throughout the Flathead Basin to the Columbia River.
Reverse the process at St. Louis, Mo., and see how Missouri River barge traffic depends on all of eastern Montana for source water.
“Connectivity is underappreciated,” said U.S. Army Corps of Engineers research ecologist Jock Conyngham. “A lot of people tend to focus on the big trunk channels. This is a good way to remind people of the significance of small tributary channels.”
The map can zoom in to the level of almost any named stream or creek, and out to encompass the entire nation. A click on the mouths of major rivers like the Columbia, Mississippi or Colorado divide the country into huge drainages.
Downstream displays aren’t as dramatic, unless you consider the point of view of a fish.
“If you’re interested in bull trout in the Flathead system, you can see how many river miles they might have to travel up from Flathead Lake to the North Fork (of the Flathead River) where they spawn,” said Diane Whited, a GIS remote sensing analyst at the University of Montana’s Flathead Biological Station. “You can see how much habitat is available to them in river mileage.”
To use the Beaver Creek example, a report the map produces shows its water passing 294,264 people in 34 cities, six counties and three states before crossing the Canadian border in northeastern Washington. That’s a 415-mile run, and it doesn’t count its return trip in the Columbia River as it flows south into the United States.
“That is one quirk of the map, looking at our local watershed,” said Andrew Wilcox, director of UM’s River Center. “For the western Montana watershed, you can’t get the full picture of how the water flows out to the ocean, because it doesn’t show it coming back in on the Columbia.”
Wilcox did much of the geomorphology research on sediment flows after Milltown Dam was removed from the Clark Fork River east of Missoula. He said the USGS map was a handy way of checking what upstream waterbodies contributed gravel and silt to points downstream. It can also illuminate where a still-troubled waterway like Silver Bow Creek might send its mining deposits.
The Streamer map lets users locate points of interest by name, GIS coordinates, USGS streamflow gauging station number or simply scanning the map for regions. It can print images of upstream or downstream traces, along with reports of the river miles, populations affected and other details about a selected waterbody. It gives historic and current streamflow figures derived from those gauging stations.
“Unlike our nation’s road network, which provides many choices for traveling between two locations, America’s surface waters are somewhat like a network of one-way streets,” a USGS press release stated. “You can certainly navigate upstream, but all water flows one way – downhill. Use Streamer to trace downstream along that downhill path or use Streamer to trace upstream to highlight rivers at higher elevations that flow to your starting point.”
That said, Conyngham pointed out the flip-side of the coin. Rivers are passageways for fish, and fish are the only nutrients that can move upstream.
“It’s good to remind people that until fragmentation got to a certain point, we had anadromous (fish that spawn in freshwater but live in the sea, like salmon) and adfluvial (fish that spawn in creeks but live in lakes, like bull trout) populations coming all the way to the big lakes in northern Idaho not long ago,” Conyngham said. “The ecology of those headwaters systems were fundamentally altered by the dams, when there were no longer those populations coming back. Those were big nutrient pumps, derived from the oceans all the way to these headwater streams. Now they’re impoverished.”