Canaan Sewage Lagoon Dam Reservoir Report

Last Updated: December 14, 2025

Located in Canaan, New Hampshire, the Canaan Sewage Lagoon Dam is a significant earth dam completed in 1991 with a height of 13 feet and a length of 1240 feet.


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Summary

Owned by the local government, this dam serves a primary purpose of "Other" and is regulated by the NHDES Dam Bureau. With a normal storage capacity of 5.4 million gallons and a hazard potential rated as "Significant," this dam plays a crucial role in managing water resources in the area.

The dam, designed as an earth structure with a buttress core type, is inspected regularly by the state regulatory agency, with the last assessment conducted in June 2015, showing a satisfactory condition. Despite its high risk assessment level of 2, the Canaan Sewage Lagoon Dam has not experienced any major modifications or incidents. With no spillway and a surface area of 0.77 acres, this dam is an essential component of the local water infrastructure, ensuring the safe containment and management of wastewater.

In the event of an emergency, the dam does not have an Emergency Action Plan (EAP) prepared, raising concerns about the readiness for potential risks. However, with state jurisdiction, permitting, and enforcement in place, the Canaan Sewage Lagoon Dam remains a crucial structure for water management in Grafton County, New Hampshire. For water resource and climate enthusiasts, understanding the role and maintenance of dams like this is essential for sustainable water management in the region.

Year Completed

1991

Dam Length

1240

Dam Height

13

River Or Stream

NA

Primary Dam Type

Earth

Surface Area

0.77

Nid Storage

9

Hazard Potential

Significant

Foundations

Unlisted/Unknown

Nid Height

13
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.