11 May Interpreting River Flow (USGS) of the Missouri River Breaks.
What are good water flows in the Upper Missouri River Breaks? How do I interpret the Flows of the Missouri? Is the river too high? What are high water flows on the Missouri? What is USGS and what does it mean?
These are all questions that we get often. It is hard to know what those numbers mean unless you know a river. Unfortunately, for most people floating the Missouri River this is all foreign and new to information. Let’s start by looking at Montana as a whole. One of Montana’s greatest assets is that her natural resources are intact and abundant. In fact, we have about 170,000 miles of rivers flowing within our state lines. Of those miles, a mere 388 achieve the designation of being Wild and Scenic. The Missouri River in the Upper Missouri River Breaks National Monument claims 149 of those Wild and Scenic River miles. Not one of 149 miles is beyond class I whitewater. That said, paddling river stretches that are relatively free of obstructions, rock gardens, and complicated hydraulics can still have their own challenges.
I recall once running about 100 miles of the Stikine River in northern British Columbia and SE Alaska. This river is a North American epic and can steamroll 200,000 CFS of pure glacial water through some of the most awe-inspiring landscapes in the world. The upper stretch is considered the “Everest” of whitewater, and a successful run is newsworthy. I was guiding at-risk kiddos at the time. While we only ran the lower section, listed as class I, the stretch had taken on the colloquial designation of “class 1 death rapids.” This river was big, fast, wide, and deep. It was free flowing and had many snags, snares, and strainers. It required skill and planning to navigate its sloughy meanderings at high speed. Maneuvers had to be made well in advance, with an error potentially resulting in being pinned underwater for too long. This river had a classification that could be misleading and required a certain level of experience.
The Missouri does not have a colloquial designation of “class 1 death rapids.” In fact, I’ve made the joke that we have class 0.5 rapids. This river typically is the moving water equivalent of a saunter on an easy forest trail. It has dams upstream (7 times over), which keep the strainers and snags from accumulating. The Army Corps of Engineers dredged it over 100 years ago to aid steamboat traffic, which keeps boulder gardens at a minimum. Furthermore, its flows typically vary between 4000 and 20,000 CFS, which maintains warm and shallow water with a reasonable current.
A quick view of Missouri River flows at Virgelle Ferry
Looking at the USGS data from the Virgelle measuring station (near our typical put in), the river has approached 60,000 CFS once in the last 30 years and surpassed 30,000 CFS only a few times. The water release on this river is highly regulated by a myriad of agencies that must respect boaters and recreators, irrigators, endangered aquatic species, water resources for wildlands firefighting, and downstream effects of flooding when the Missouri hits the flat states.
30 Year Cubic Feet per Second (CFS) Data at Virgelle Site
(So how the heck do you read one of these graphs? First understand that cubic feet per second (CFS) is a function of volume and speed. One CFS is about the same size as a basketball. So, if the river is running at 15,000 CFS, imagine 15,000 basketballs bounding by every second. If the river gets bigger, it goes faster and gets higher; but twice the CFS doesn’t mean twice the height. A river bottom is a complicated and dynamic shape, which generally tapers out. Meaning it’s easier to fill out the bottom space than the ever outward expanding banks.)
By reading the above historical river flow graph, you can see a concentration in the 4000-8000 CFS range, with bumps into the 10,000+ CFS range during warmer months. Early summer is oftentimes the ideal time to run the river, with my personal preference being 12,000-15,000 CFS. At that volume and speed, the river moves along swiftly, but safely. You’ll still have good bank access but will fight the riverbank mud. Lewis wrote about the mud in this area as being “precisely like walking over frozen ground which is thawed to a small depth and slips equally bad.” As volume and speed dip below 10,000 CFS, you’ll have better luck finding gravel banks but will need to spend more time paddling as the current slows. Below 6000 CFS, you’ll start finding more river boulders, navigating around gravel bars, and you might get to camp a bit later- especially if you catch a headwind. Anecdotally speaking, you might expect a 2-3 mph current in the 4000-7000 CFS range and a 3-5 mph current in the 7000-20,000 CFS range.
Interpreting USGS Cubic Feet per second into Upper Missouri River Speed
(Please note, when calculating the river speed (not including paddling) add and subtract 1-2 MPH to each speed listed on the graph to get your speed range. The river is not consistent, some sections are quicker than others and vice versa.)
Over 20,000 CFS, you’ll find the water moves along at a still manageable, but heightened pace. You’ll have more time at camp or for hiking but will be navigating slippery banks and will have a more difficult time finding places to pop off to “pay the water bill.” At the biggest water I’ve seen (41,000 CFS), my group ran the 107 mile stretch of the white cliffs and the badlands. We absolutely sailed along, and my GPS read bursts of 13 mph in a loaded canoe when paddling hard through certain sections. This was a blast, but we were alert to the increased hazards, and it seemed as though we lost all that earned time by time spent safely unloading people and heavy coolers off submerged riverbanks. You can expect a 5+ mph current when in 20,000+ water levels, but even at 41,000 CFS, our floating speed was probably around 7-8 mph.
2022 Summer CFS Data
I have included CFS data from the 2022 season, which shows the typical rise, peak, and drop throughout the season. The Missouri has a large and low basin. As the spring warms and melts snow in the mountains, we see a big rise in CFS. Sometimes the river will peak in May, other times late June. Usually when it stops raining and crops need water, the river drops precipitously. This cycle can be complicated by the need to replenish upstream reservoirs based on the previous year’s fire season. However, we will almost always see CFS increase in late spring with a peak sometime in May or June and a precipitous drop once irrigation begins. Finally, we usually see a prolonged descent into stable and slow water that defines the end of season experience.
When considering Flows on the Missouri River.
Perhaps the most important piece of advice I can give for those with concerns about environmental hazards is to be mindful of the wind. The wind can flare at any point of the season, and at any water level. In my 70 or so trips, I have yet to see someone spill a boat as a result of high river levels or because big water made maneuvers too technical. While I have only observed a very small number of our guests upset their canoe on a guided trip, big wind accounts for most of them. On those days, the wind may remain constant as you meander the curves of the Missouri. This creates contstant dynamic conditions that fluctuate between headwinds, tailwinds, and crosswinds. When the wind picks up, be smart and stay nearer to the shore, cross the river only when needed, stay low in your boat, and have your best boater in the back of the canoe to steer. By keeping the nose of your canoe slightly into the wind, it will help to avoid getting blown broadside. Broadside is indeed a vulnerable place to be!
The river stretch through the Upper Missouri River Breaks Monument is a gem. It can be both a good time and a safe time, whether at 4000 CFS or over 20,000 CFS. Having more experience when running big water is helpful. However, understand that real boating troubles on this stretch are often the result of not wearing a personal floatation device and imbibing a bit too hard. So, when boating on big water days, stay sharp, save that extra beer for camp, and recognize that even if you spill your boat, it’ll probably be alright. As I tell my guests if the going gets tough, “you can have a good time or a good story!”
For a brief history of major flooding in Montana, check out this link about the 1908 flood, of which the troubles were statewide, raised the Missouri to an incredible 140,000 CFS, and took out the original turnstile bridge in Fort Benton:
For current water levels check out our current flows page. This gives you the USGS of gauges along the Upper Missouri River Breaks (3 locations). The gauge that we use the most is the Virgelle site.