RIVER GAUGES
Real-time streamflow data is readily available online and through the use of mobile apps:
US Geological Survey (USGS) National Water Dashboard (Iowa)
Displays stream status (normal, above or below normal, etc.) as colored, clickable icons that may be useful for a quick assessment .
National Weather Service (NWS) River Observations and Forecasts (Iowa)
Color coded according to flood status, but the "National Stream Analysis Anomaly" Layer displays stream status as colored stream segments.
Iowa Flood Center (Iowa Flood Information System or IFIS) (IFIS Gauges also appear on the NWS Website)
RiverApp (One of several available Apple and Android Apps.)
Terms to Know:
Gauge Height (a.k.a. Stage) as provided by the NWS, USGS and USACE indicates the measurement of the water surface above a locally established reference point (e.g. the top of a bridge pier footing), NOT the stream depth as is often assumed. IFIS Gauges report the water surface elevation above sea level, from which stream depth at the gauge can be determined.*
Discharge (a.k.a. Flow or Streamflow), in cubic feet per second (cfs) is a calculated value that that can be useful when comparing values to other streams, but it isn't available at all gauge sites. The calculation involves measurements of stream velocity and the cross-sectional area of the stream (see How Streamflow is Measured for an explanation).
You may find that the USGS doesn't publish discharge data in winter, though it may be available on the NWS and USACE pages.
Before you read on:
It's important to remember that there can be hazards on the river even at normal and low flows. Most are easily avoided by skilled boaters, but river reading and boat handing skills become increasingly important as streamflow increases, and rescues and recoveries become increasingly difficult with increased velocity and depth.
Read more about Flows and Float Times here.
Know the flow before you go, and if you're unsure, it might be wise to postpone your trip!
Keep Notes!
By noting the relevant gauge reading(s) after each trip, paddlers establish a range of stream levels that suit their personal preferences. Lacking that knowledge or specific guidance from trusted sources (e.g. Paddling Iowa), they might choose to avoid anything above or below normal, depending on their skill level, that of their paddling partner(s), current conditions, etc. (Read on to get a sense of what might be "normal.")
Digging Deeper:
There's a wealth of information available within these online resources. For example, on many of the USGS "Legacy" Pages (such as the South Skunk above Ames) you'll see a table comparing the current discharge (the Most Recent Instantaneous Value) with historical data for that gauge and day of the year. Here's a table clipped from the South Skunk above Ames Gauge some years ago.
