Water Monitoring Bulletins

Bulletins updating on water levels, water flow, and snow monitoring

Spring Water Level Outlook

The Department of Environment and Climate Change (ECC) conducts on-the-ground snow surveys at the end of winter every year across the territory to inform flood monitoring, wildfire prediction, year-to-year variability and research. The amount of snow received over winter is an important variable that influences water levels and flow on lakes and rivers during spring break up. The summary values from these surveys are included in the NWT Spring Water Level Outlook each year.

Snow survey work in the Snare River basin is completed in partnership with Northwest Territories Power Corporation.
ECC also compiles snow data collected at climate stations operated by Environment and Climate Change Canada. These data are published between October and March in monthly NWT Water Monitoring Bulletins.

Snow Survey Methodology

At each snow survey location, a snow sample is taken at 10 pre-determined points. Two measurements are recorded at each point: snow depth and snow water equivalent (SWE). SWE refers to the depth of water (in millimetres) that would be produced if that snow sample was melted. Heavy and wet snow has a higher SWE than light and fluffy snow. The SWE value is obtained by weighing the snow using a calibrated snow scale. The average density of the snowpack at each point is calculated by dividing SWE by the depth of the snow.

SWE values for each of the 10 points are averaged into one SWE value for that snow survey location. This average value is what is included in the summary data.

Accessing Snow Data

A summary of snow survey data can be found in each year’s NWT Spring Water Level Outlook. This document also includes snow survey data from neighbouring jurisdictions for shared basins (e.g. Slave River, Hay River, Liard River and Peel River). Recent years’ snow survey summary data can also be viewed and downloaded in table format using the Government of the Northwest Territories Open Data Portal.

Latest Outlook Report

The Water Monitoring and Stewardship Division distributes monthly NWT Water Monitoring Bulletins. These bulletins provide an update of water flow and level data at select NWT Hydrometric Network gauge stations across the Northwest Territories. During the winter months, these also include monthly precipitation data for six communities in the NWT.

You can also subscribe to our distribution list to receive the NWT Spring Water Level Outlook and monthly NWT Water Monitoring Bulletins by email. Email us at nwtwaters@gov.nt.ca.

Environment and Climate Change snow survey locations

Water Survey Partnership

he Department of Environment and Climate Change has a long-established partnership with the Water Survey of Canada to collect stream flow, water level and lake level measurements routinely across the territory, including at locations where there are communities at risk of flooding. These data are available to the public here. A summary of these and other data and information are provided regularly to territorial and regional emergency managers to help understand the status of waterways near communities at risk of flooding in the lead-up to, and during spring break-up – the highest-risk period for flooding in the Northwest Territories.

Report Publishing Schedule

Spring Water Outlook

  • Annually each April

Regional water level and flow updates * Monthly – year-round

  • Weekly May 1 – June 15

  • Daily if flood risk is extremely high

When emergency protocols are in-place due to flood danger, the reports will be distributed as part of public safety bulletins from MACA.

Understanding Flood Risk

Water levels and flow do not necessarily predict flooding – especially at spring break-up, when most floods in the Northwest Territories take place.

Most flooding in the NWT occurs because of ice-jams forming in a river during break-up of the river ice. These floods can happen regardless of the water levels.

However, the consequences of an ice jam can be more severe in at-risk communities when the over-winter water level is already high.

Communities at High Risk

Any community near a body of water is at risk of a flood. However, several communities are considered to be at higher-risk of flooding. A list is maintained by the public safety division of the Department of Municipal and Community Affairs. Note that this list is current as of publishing. The most up-to-date list can be found here.

  • Hay River (Hay River)

  • Kátł’odeeche (Hay River)

  • Nahanni Butte (South Nahanni River, Liard River)

  • Fort Liard (Liard River)

  • Fort Simpson (Liard River, Mackenzie River)

  • Aklavik (Mackenzie River)

  • Fort Good Hope (Mackenzie River)

  • Tulita (Mackenzie River)

  • Jean Marie River (Mackenzie River)

Factors Influencing Flood Potential

The potential occurrence and severity of flooding during the spring break-up depend in large part on the weather through springtime and how it interacts with existing water levels and snow pack amounts.

Warmer than normal temperatures, extreme rain, or rain on snow events can increase the likelihood of flooding.
Flooding in the NWT can also occur in open water conditions because of high rainfall.

Interpreting the Water Bulletin

These updates are not your source for knowing whether there will be a flood. We cannot predict a flood before the situation begins to unfold. There are too many factors at-play. We may provide information on whether conditions are changing in certain areas that may influence flood potential based on information we have about water levels, flow, snowfall, and any ice jams detected. Your local government and emergency management officials will use information contained in this report and any other community specific information to help them decide what level of risk a community is at. They will consider many other observations on-the-ground, and communicate with you about what everyone should do to stay safe.

Emergency Preparation and Safety

Get information about risk in your community, and what you should do:

Updated: Mar 12, 2026