The USGS gauge referred to (at Leonore) is about 8 miles upstream of the put-in. It lists drainage area of 1251 square miles, which is only 2-3% less drainage area than at the put-in (and former gauge site) at Lowell. Thus, (other than for the lead/lag time associated with the intervening distance), the gauge at Leonore should generally be quite accurate for determining levels in the whitewater reach described here.
The suggested minimum (500 cfs) reflects the fact that the river is quite broad, so many areas will become quite a scrape below this level.
The suggested maximum (4,000 cfs) is set only to indicate levels above the 'norm'. Somewhere around this level some features will wash out (including Wildcat, normally the biggest drop on the river!), while others just get AWESOME! Thus, many boaters will thrill to see this river 'go purple'.
Most boaters historically have referred to a gauge painted on the bridge at (above) the put-in. There are approximations of the correlation of the Lowell bridge gauge to the USGS Lenore gauge at http://www.rivers-end.org/vermilion/ and http://www.wpr.pair.com/vermilion/
There was a USGS gauge at the Lowell bridge for forty years (1931-1971). While the nature of the overall watershed most certainly has likely changed somewhat in the interim (due to increased urbanization) and climate shifts may have some effect, the following analysis from that data period should still have some relevance.
|Gauge/flow analysis (based on USGS data, 1931-1971, at Lowell)|
|Drainage area at gauge||1,278 sq.mi.|
|Minimum daily mean flow during recording period (occurred 1961.02.01-05; 1963.12.21-24)||5 cfs|
|90% of time flow exceeds||11 cfs|
|10% of time flow exceeds||3,050 cfs|
|Maximum daily mean flow during recording period (occurred 1958.07.15)||25,600 cfs|
|10/90 ratio ('flashy-ness')
(under 3 is quite steady, over 10 is quite 'flashy')
|Average annual runnable (>min) days per year
based upon USGS historical data and the listed 'recommended minimum' level,
Note: some of those days may be winter, when ice would preclude safe paddling.
|virtual-96843||500 - 8000 cfs||II-III||00h20m||~ 173.151 cfs (too low)|
|Almost certainly too low for reasonable whitewater.|
Virtual gauge (if Leonore not reporting) approximates flow as 2.178*Pontiac based on relative drainage. (Might predict flow 24hrs later?)
|VERMILION RIVER NEAR LEONORE, IL|
|usgs-05555300||500 - 8000 cfs||II-III||00h18m||58.3 cfs (too low)|
|Too low for a decent run.|
Gauge(1251 sq.mi. drainage) is 6.75 miles upstream. Drainage at put-in is 1278 sq.mi., ~2% more, so listed flow should be quite accurate for this reach.
|Vermillion River [IL]||39475.jpeg||1165cfs||Nathan Anderson|
|Vermilion [IL]||Throwing ends in Wildcat||1200 cfs||Erik Johnson|
|8y164d18h55m||ermillion River from undercut rock to Oglesby take out [IL]||Vermilion River Closed by Buzzi/Unicem Cement Plant||n/a||0|
|> 10 years||Vermillion River [IL]||39479.jpeg||1165cfs||Nathan Anderson|
|> 10 years||Vermilion [IL]||Vermilion Put-in||2,500cfs||Dave Worth|
|> 10 years||Vermilion [IL]||Swimming Wildcat||around 5ft||craig carlson|
|> 10 years||Vermilion [IL]||Surfing Wildcat||4 feet||Erik Johnson|