See also:

Porcupine River Ice-free Period
 
Temperatures at Old Crow
 
Peel River Ice Bridge
 
Waterfowl, Old Crow Flats

Arctic Borderlands Ecological Knowledge Co-op

What is happening?

• This graph shows that there is variation from year to year, but no overall trend in the timing of the ice-free period over the past 29 years. There is also no trend in the length of the ice-free season which averages 130 days.
• The start of the ice-free period in 2005 was May 17th (estimate), which is about 10 days earlier than average, and the end of the ice-free season was October 4th, which is the long term average. This resulted in an extended ice-free season of 140 days (10 days longer than average).

Why is it happening?

• The timing of winter freeze and spring break-up depends on weather conditions in the river basin in fall, winter and spring. Long-term trends in these weather conditions can be expected to affect the river's ice conditions.

Why is it important?

• Dates of spring break-up recorded for the Old Crow River are related to the timing of ice break-up in the Old Crow Flats, an important breeding ground for many waterfowl populations (Canadian Wildlife Service, unpublished report).
• Timing of spring break-up and of winter freeze affects nesting waterfowl, river crossing and travel conditions for people and migrating animals, and conditions in the river such as growth of algae.
• The length of the ice-free season affects summer habitat for animals using open running water.

Technical Notes

• The ice-free period of the river is defined as the period during which ice formation does not affect river flow by more than 5% compared to flow during open water conditions. Thus, the break-up and freeze-up times presented here reflect the final stage of ice break-up and first stage of ice freeze-up on the river.
• The data presented here are from the Old Crow River near the confluence with the Porcupine River, and were obtained from Water Survey, Environment Canada. The beginning of the ice-free period in 2003 was estimated due to equipment failure.