Gauge Description:

Gage just upstream of Gilsum Gorge, on the river-right retaining wall, according to the 18-year-old AMC River Guide. 3.5 is minimum; 5.5 is high.
This section of the Ashuelot lies above the Surry mountain flood control dam and therefore is a natural flow river.
The USGS gauge is located below this flood control dam 6 miles downstream from the take out, therefore it should only be used as reference since the Army Corps of Engineers could be discharging more or holding back water for flood control. To get a more accurate reading on the flow go to Army Corps of Engineers Ashuelot tabular data and look at the last reading under the "inflow cfs" heading. It is estimated you will need at least 430 cfs for a scratchy run. The usual gage for this section is on an outside staff of an abandoned USGS gage building just upstream on river right of the stone arch bridge entrance to Gilsum gorge accessed from NH route 10. People with good eyesight or a pair of binoculars can read the level from the river left bank.

Gilsum gorge    Surry Lake
visual gauge    Inflow cfs     Interpretation

   ~4.4           ~350            Minimum
   <4.8           ~450	          Scratchy
   <5.1           ~550            Low
   <5.4           ~700            Low to medium  
   <5.9           ~900            Medium
   <6.4           ~1200           Medium high    
   >6.4           ~1500           High
Thanks to Will Kranz for the information used to develop this table.

Estimated chance (%) of finding the river runnable.

Month............% chance.................comment 

January ............ 0%....frozen. 
February.............0%....frozen
March................20%....Usually frozen. 
April...............70%....Best chance 
May ................25%....Best chance in early May with rain. 
June.................8%
July.................5% 
August...............5%....Just a trickle
September...........10%....Tropical storms and their remains 
October........…....20%
November............35%....Fall rains, dormant trees 
December............30%....River starts freezing about Christmas. 

Be aware this is averaged out over several years. The % chance refers to the probability of finding the river running on any given day. For instance a 5% probability for August means on average you can only expect 1-1/2 days of water. One year there could be 3 days in August with water, other years none. Spring levels are usually higher than fall levels.