Drainage: 22.7 square miles

As calculated by USGS StreamStats (V.4.3.8), drainage at the dams (outlet of Lake Leota) is 22.7 square miles.

Since there is no USGS gauge on Allen Creek, we reference the gauge on Badger Mill Creek (17.8 miles to the NW) where draingage is listed as 20.3 square miles, thus flow in Allen Creek could (on average) be just a tad more than gauge shows. Of course, correlation is not assured.