Wading is walking through the stream and getting yourself to locations that are advantageous for catching fish. This is likely the most physically demanding aspect of fly fishing, and wading has significant risk for injury or worse. Walking through a flowing stream or river provides a few obstacles. Flowing water can easily knock you off balance or lift you off your feet. A general rule I consider when wading is “the rule of ten”. For most adults (over 5 feet and 120 lbs.), once a combination of flow depth and velocity is exceeded, you won’t be able to keep your feet on the stream bed in flowing water. That combination is where the ten comes to serve as a guide. Once the product of the velocity (feet per second) and the depth (feet) exceeds ten, you should not wade in that portion of a stream. Depth is easy to measure, either through gradually seeing the depth increase as you wade across a stream, or by using a wading staff or stick to estimate depth. A good trick in measuring velocity is to estimate a length of ten feet in front of you and to throw a stick in the water at the beginning of that ten foot length. You simply count until the stick makes it past the ten foot limit. Divide ten by the time you counted for the stick to travel the distance, and you have an estimate of velocity. As an example, you count to five as the stick moves ten feet, so the velocity is 10/5 or 2 feet per second. This is a small velocity, so you could likely wade safely only up to a depth of approximately five feet at that speed since the rule ten would be exceeded if the stream was any deeper (2 feet per second * 5 feet = 10 square feet per second). As I notice any difficulty in wading I typically will run through that quick computation in my head. If I am even close to ten, it is time to slowly back out and find a safer spot to fish.
Another obstacle to safe wading is the substrate and slippery biofilms that accumulate on the surfaces. Stream bed substrate in many trout streams is comprised of cobble, boulders and gravel. The mixes in substrates generally coarsen in size as the slope and currents of a channel increase. Large boulders can lock together in a clast of material that form great habitat for trout but are very dangerous to walk on. The surfaces can be very rounded or unpredictably angular. They can also shift under your weight. When the substrate is slippery or inconsistent, it is incredibly helpful to have a wading staff and to fish with a friend for safety. Local rivers that are difficult to wade that I have fished include the Savage River below the reservoir and Penns Creek.
When crossing a stream when wading, it is important to select wider and flatter sections of the river. You also need to take smaller steps than you think are necessary and take your time. Flowing water generates more force when a larger area is exposed to the flow. Taking shorter steps and turning sideways to the flow help reduce your exposed profile. It takes much less physical exertion to wade in a downstream direction, although it is easier to get your feet swept out from under you, so it is helpful to wade across a channel at a slight downstream angle to conserve energy. Taking breaks to save energy also allows you to observe the stream flow and bed, making sure that you can see where and what you will be walking on. Wading into water where you can’t see your feet or the bed is not advisable.
I recommend using a wading staff in any stream where you will have to spend time in the channel where depths will be consistently two feet or deeper or when the substrate is slippery and uneven. I am in the practice of checking USGS gage sites at or near streams I fish to determine water levels prior to leaving for a fishing trip. Local fly shops are also good resources for information on the safety of wading at a particular stream. On the Gunpowder River, the folks at Backwater Angler post frequent fishing reports, and they will state when conditions are unsafe for wading on the river. Fishing reports from Great Feathers will also state which local streams in Central Maryland are safe to wade. Orvis and Simms make great wading staffs that my friends and I have used, and they are reliable, easy to use and tremendously increase the safety of wading in challenging streams. Other good (and entertaining) resources on safe wading include the Huge Fly Fisherman’s YouTube channels episode on wading https://www.youtube.com/watch?v=d_DgGfJqNZk and the great podcast and website blogs from 2 Guys and a River https://2guysandariver.com/the-10-commandments-of-wading/.