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. 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 ~430 Minimum <4.8 ~480 Scratchy <5.1 ~560 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.
Note: As a result of the two hundred-year-flood events in the fall of 2006 and spring of 2007 the riverbed near the gage has changed.The table above appears to no longer be valid. New observations will be posted as they are accumulated.
Date/Time Gilsum Gorge Surray Lake Interpretation
visual gage Inflow cfs
6-Apr-08 4PM ~4.7 785 (FS 10cfs/hr) Medium
(FR=Falling Rapidly, FS=Falling Slowly, S=Steady, RS=Rising Slowly,
RR=Rising Rapidly)
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.
| Name | Range | Difficulty | Updated | Level | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ASHUELOT RIVER NEAR GILSUM, NH | ||||||||||||
| usgs-01157000 | 430 - 1700 cfs | III-IV | 00h37m | cfs | ||||||||
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| When | River/Gauge | Subject | Level | Reporter |
|---|---|---|---|---|
| 4y258d22h07m | Ashuelot [NH] |
Gilsum Gorge |
5.6' visual | Bob Dunn |
| 5y96d22h07m | Ashuelot [NH] |
Surprise Rapid |
6.5 | Mark Lacroix |