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Difficulty II-IV
Length 7.3 Miles
Flow Range 3.10 - 6.00 FT
Flow Rate as of: 29 minutes ago 2.12 [FT]
Reach Info Last Updated 05/10/2004 9:03 am

River Description

Good intermediate to advanced river section.

Technical info

Put in elevation........1167'
Take out elevation......875'
Total drop..............292'
1st mile................32'
2nd mile................7'
3rd mile................79' 
4th mile................46' 
5th mile................26' 
6th mile................33'
7th mile................46' 
7.3 mile................23' (77 average)
Average drop/mile.......40'
Distance................7.3 miles
River width average.....70'
River geology...........Small to medium granite boulders
River water quality.....good to excellent, clarity good.
Scenery.................Nice Mountain scenery, river parallels 
                        road most of the way
Wildlife................Deer, hawks, moose, beavers. 

Rapid Descriptions

Powerhouse Dam

Class - Mile - 1.8
Rapid Thumbnail Missing
An abandoned concrete dam with a sluice on the right side. The portage on river left is easier than the river right side recommended in Lessel’s New England Whitewater guide. Be careful here if the water is high water spills all the way across the dam and current is fast up to the lip. Launching below is also easier than the river right side but a strong recirculating eddy can make it difficult to ferry back out into the main current. As of late April 2003 a tree strainer was hung up on a boulder just around the corner and out of site from the eddy above. Make sure you are able to get to river right if this strainer is still present.

Powerhouse Rapid

Class - IV Mile - 2

Shortly downstream from the dam powerhouse rapid starts. The river narrows and pushes up against the left bank. The gradient is rather steep over large boulders creating a lot of turbulence with several holes to avoid. Scout from river right.


Class - III Mile - 2.7

An easy rapid the starts just above the Maplewood bridge. At the tail end of the rapid is a chute formed by a large rock on river right. The main flow at low to medium water levels pushes over a pourover in the middle of the chute. The pourover is easily avoided by catching the eddy behind the rock on river right. From here a jet ferry will carry you above the pourover into an eddy on river left. This eddy affords great access to a series of nice surfable standing waves just below the pourover.

Alderbrook rapids

Class - IV Mile - 6

After a long section of quickwater and class I the river approaches Alderbrook rapids. To recognize the start of Alderbrook look for a gray box like house on river right at a class II rapid. Note, in Lessel’s New England Whitewater guide this house is said to be pink, it has not doubt been painted since that writing. The rapid is not easy to describe so scouting is recommended, it generally requires a boater to start on river left move to river right then back left. Scouting is easiest from river left; portaging is easiest from river right.

Railroad rapids

Class - III Mile - 6.8
Rapid Thumbnail Missing
Just before the takeout is the last good rapid on the Ammo. The best route is generally on river right eddy hopping between boulders to avoid some rather large holes.


Gage Descriptions

USGS gauge located just upstream from the put in on river left. The Ammonoosuc starts high up on Mt Washington (6288') and runs later in the season than most other White Mountain rivers. Forecast Late April

 River Flow information

Gauge: USGS (Bethlehem) Minimum level: 3.1’/429 cfs

Low: 3.7’/660 cfs

Medium: 5.0’/1380 cfs

High: 5.5’/1800 cfs

Waterline: 1-800-452-1737 site code: 331114

Directions Description

We have no additional detail on this route. Use the map below to calculate how to arrive to the main town from your zipcode.

No Accident Reports



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Protecting Access to New Hampshire Rivers

Robert Nasdor

Northeast boaters can celebrate that another beloved whitewater gem has been protected. Paddlers on the Winnipeseaukee River are now assured that the put-in on the Lower Winni in Northfield, NH will be forever protected thanks to the donation of a parcel from Gloria Blais in memory of her husband Roger. Gloria donated the land to the Town of Northfield for the purpose of assuring that future generations of boaters will have access to the river. Protecting river access to the Winni is part of an ongoing effort by AW in the northeast region to protect river access.

article main photo

Bellows Falls (VT) Flow Study Reveals Hidden Whitewater

Robert Nasdor

A hardy group of northeast boaters climbed into the natural river channel below a hydropower dam to participate in a flow study designed to assess whether whitewater flows should be restored to this dewatered river reach on the Connecticut River. While significant obstacles remain, this site has the potential for providing instruction, playboating, and a big water feature that that could be run throughout much of the year and provide a much needed boost to the local economy. 

article main photo

AW, MVP Protect Land and Access on the Contoocook River (NH)

Robert Nasdor

American Whitewater and Merrimack Valley Paddlers have reached an agreement to purchase a 10-acre parcel fronting on Contoocook River in Henniker, NH. The land serves as an important launch point for whitewater paddlers enjoying the popular section of the river that runs from Hillsborough to Henniker. This section of the Contoocook River contains rapids ranging in difficulty from Class II to Class IV.


Skip Morris


Revision #Revision DateAuthorComment
1193478 05/10/04 Skip Morris