Islewood Dam Reservoir Report

Last Updated: December 15, 2025

Islewood Dam, located in Skagit, Washington, is a privately owned structure primarily used for recreation.


°F

°F

mph

Wind

%

Humidity

Summary

Built in 1971, this earth dam stands at a hydraulic height of 17.6 feet and a structural height of 12.3 feet, with a length of 120 feet. The dam has a storage capacity of 39 acre-feet, with a normal storage level of 24 acre-feet and a surface area of 8 acres. It serves the purposes of irrigation and recreation, impacting the drainage area of 0.13 square miles in the Tr-Lake Erie watershed.

Despite being privately owned, Islewood Dam falls under the regulatory oversight of the Washington Department of Ecology, with state jurisdiction, permitting, inspection, and enforcement in place. The dam is classified as having a high hazard potential, yet its condition assessment is rated as fair as of the last inspection in September 2020. The emergency action plan for the dam was last revised in July 2010, and it meets regulatory guidelines.

Congressional District 02, represented by Rick Larsen (D), encompasses the area where Islewood Dam is situated. With its picturesque location and recreational opportunities, this dam is a significant feature in the Skagit region of Washington for water resource and climate enthusiasts to explore and appreciate.

Year Completed

1971

Dam Length

120

River Or Stream

Tr-Lake Erie

Primary Dam Type

Other

Surface Area

8

Hydraulic Height

17.6

Drainage Area

0.13

Nid Storage

39

Structural Height

12.3

Hazard Potential

High

Foundations

Soil

Nid Height

18
       
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.