We use the USGS website to monitor current river flow levels for our launch location. Here's what you can expect based on the current river flow:

•  GREEN | Up to 500 ft³/s : The current is very slow. Paddling on the river will be similar to paddling on a lake except for a few sections (~50ft) with a little bit of current. Conditions are good. The river is typically at this level.
  
•  BLUE | 501-900 ft³/s : The current is slow. You will need to work a bit when traveling up stream against the current. Conditions are still good for almost all riders. The river is typically at this level for a few days after a moderate rainfall.
•  PINK | 901-1200 ft³/s : There is noticeable current in the river. You will feel the current pushing against you when paddling up stream, but we find it is still good conditions for most riders. We don't recommend these conditions for new kayakers, young children (8 and under), or adults who are not in good physical condition. Paddling upstream will be a workout! The river is typically at this level for a few days after a heavy rainfall.
•  RED | 1201 ft³/s or more : The river current is strong and potentially dangerous. The river is typically at this level for a few days after a very heavy rainfall or an extended heavy rainfall.
  

When rain falls to the north of the Dublin Bridge Park District (Jerome, Ostrander, Powell, Delaware, etc.) the water eventually flows into the Scioto River at our location. Rainfall in that watershed area has a direct impact on the river levels where we provide rides. A good way to predict whether the river flow will be too high for kayaking in our area is to check this rainfall map by weather.gov. If there has been more than an inch of rainfall in the area on that map in the last 7 days, there is a good chance the river will be too high for kayaking.

As you can see on the USGS website, when the river flow goes up high, it typically takes several days for it to fall back below safe levels. For example, if there is 2 inches of rainfall in the watershed area, it will probably take 5-7 days without any rain before the river is back to safe levels. Also keep in mind... When there is an increase in the river level due to rain, there is often an initial sharp surge in the river level that lasts for about a day and then the river starts dropping, but then a secondary surge starts about 1.5 days after the initial surge. That is likely due to water flow from the watershed finally making it to our location from many miles away.

Those are some of the reasons why it is difficult for us to predict when the river will be safe in our area for kayaking. :( And, that's why we constantly monitor the levels to make sure they are fun and safe for our riders. :) If we feel that will not be the case, we cancel our rides.