Using USGS Stream Gauge Data

Question: I love paddling, but planning paddling trips is tough because I never know how much water is in the river. I’ve heard about online sources that can help me figure out current conditions of the river before I paddle it. What are they and how do I use them?

Answer: Great questions! A good place to look for answers is on the US Geological Survey website. The USGS maintains stream gauges all over the state which take regular readings of how much water is in the river. When you go to this website, you will see a bunch of dots on a state map of Georgia. Each dot represents a stream gauge. You’ll need to have an idea of where you want to paddle to identify which gauge or gauges you want to look at. It’s likely that you won’t find a gauge right where you plan to be on the river, so a good strategy is to look at one that is upstream and one that is downstream of where you plan to be.

Another quick tip – Hover your mouse over the dots and it will tell you the name of the river and location of the gauge. Once you click on a dot it will take you to page that will display graphs of what’s been happening at the gauge over a period of days. Here are a few quick tips for understanding the data displayed in the gauge readings in planning your next paddling adventure!

There are four primary pieces of information you will be given. Here’s how to best understand the data:

Flood Stage/Gage Height: The most useful information on this graph is to know if the river level is rising or falling. The gauge height can also be useful if you’ve previously paddled the same stretch of water and want to compare where it is now to where it was then. Beware that the gauge height reported isn’t indicative of how many feet of water there is in the river everywhere - it’s only telling you how many feet of water there is in that specific location – which may be shallow or may be a deep pool or somewhere in between.

Discharge Stage: This tells the volume of water flowing past the gauge in cubic feet per second. So, this number tells you how much water there is and how fast it’s flowing. How high a particular river is at, say at 1000 cfs, is dependent upon the size of the river canal, of course. However, a good rule of thumb is… if below 100 cfs, it will be a tough paddle! A good measure to look at on this graph are the yellow triangles. They indicate what the mean flow has been over a number of years and should tell you if the river is running average, low, or high.

Percentile: This is the real-time percentage of distribution compared to the same day of the year historically. If the river you’re planning to paddle has this metric, it means there have been at least 30 years of data collected there.

Precipitation: It’s important to see how much rain the area has had recently. Of course, just because it rained at the gauge doesn’t mean it rained upstream or downstream or vice versa, but generally if it hasn’t rained you can expect that the river levels will drop and if it has they will rise – by how much depends on how much and how recently it has rained.

This “Real-Time” map displays only the current conditions.

Happy Paddling!