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Drought

Issued 2021.09.23

The past week saw some much needed precipitation in a large portion of the Winnipeg River basin. According to the U.S. Drought Monitor, drought categories for some Minnesota portions of the basin improved from Exceptional to Extreme Drought or from Extreme to Severe Drought.

Data Source: Canadian Regional Deterministic Precipitation Analysis (RDPA)

However, due to the widespread drought conditions, little of this rainfall has reached streams and larger tributaries in the basin. Substantial rainfall is still needed to resolve the underlying drought conditions in the landscape and return flows to normal.

Water levels in key reservoirs upstream of Lake of the Woods, Rainy Lake and Namakan Lake, rose modestly but remain below regulatory targets set by the International Joint Commission. As a result, there has been no increase in the very low seasonal outflows from the dams at these lakes.

Flows in the Rainy River and its main tributaries, the Big Fork River and Little Fork River, saw very small responses to the rainfall. Inflow to Lake of the Woods has not increased significantly as a result.

Rainy River from International Falls, MN. Sep 22, 2021. Photo: Lee Grim

The current level of Lake of the Woods is 322.50 m (1058.1 ft), a 5th percentile level for this time of year. The lake level declined by 1 cm (1/2 in) over the past week and is expected to decline by 1-3 cm over the next week with forecasted dry weather. Lake of the Woods authorized outflow is 100 m³/s, with no outflow changes currently scheduled.

In the English River basin, the rainfall led to a greater rise in tributary flows in some areas, for example near Sioux Lookout and the Chukuni River where flows are now in the normal range for late September. Other tributaries remain well below normal, as does the level of Lac Seul and the mainstem of the English River as measured at Grassy Narrows.

The current level of Lac Seul is 355.62 m (1166.7 ft), less than 5th percentile for this time of year. The lake level rose by 6 cm (2 in) over the past week and is expected to rise by 1-3 cm (1 in) over the next week. Lac Seul authorized outflow is 75 m³/s with no changes currently scheduled. A planned regional power outage scheduled by Hydro One will result in fluctuations in outflow from Lac Seul on September 26 and 27, varying between 39 and 107 m³/s before returning to the authorized 75 m³/s.

Issued 2021.08.12

The past week saw some precipitation across the basin, with the greatest amounts near the English River downstream of Lac Seul.

7-day precipitation as of August 11, 2021. Data from the Regional Deterministic Precipitation Analysis (RDPA) by Environment and Climate Change Canada.

Across the entire Winnipeg River watershed, however, drought conditions remain. The July 31 classification of drought by the North American Drought Monitor shows the entire watershed as either in severe or extreme drought. The latest update (August 12) from the U.S. Drought Monitor shows a swath of the Rainy River watershed now in the Exceptional Drought category.

Source: North American Drought Monitor

Precipitation statistics from NOAA indicate that county-wide precipitation for Lake of the Woods and Koochiching counties in Minnesota were the lowest on record for July, June-July, and May-July. Records date back to 1897.

Lake of the Woods County, MN precipitation statistics May-July 2021
Source: https://www.ncdc.noaa.gov/cag/county/rankings/MN-077/pcp/202107

The LWCB’s watershed-wide statistics mirror this data.

Low flows and water levels persist across the watershed. Natural (undammed and unregulated) rivers are exceptionally low as are inflows to Lake of the Woods and Lac Seul. The Big Fork River and Little Fork River, key tributaries to Rainy River and Lake of the Woods, set new calendar day low flow records several times over the past few weeks, with record-keeping there by the USGS dating back over 100 years.

  • Big Fork River at Big Falls, MN. August 12, 2021. Photo: Lee Grim

LWCB regulation of outflows from Lac Seul and Lake of the Woods and flows along the Winnipeg and English Rivers in Ontario is being carried out according the low flow scenarios in the adopted Regulation Strategy. With the ongoing drought conditions, the primary focus remains on conserving water in these lakes for future river supply.

The current level of Lake of the Woods is 322.55 m (1058.2 ft), a 10th percentile level for this time of year. The average lake level fell by 2 cm (1 in) over the past week and is expected to decline by 1-2 cm (1 in) over the next week.

Lake of the Woods authorized outflow is 130 m3/s.  A reduction in outflow, to 120 m³/s, is scheduled for Monday, August 16. The Winnipeg River immediately below the Norman Dam is expected to decline by 1-2 cm (1 in ) as a result of this flow reduction.

The current level of Lac Seul is 355.50 m (1166.3 ft), a 5th percentile level for this time of year. The average lake level rose by 4 cm (2 in) over the past week and is expected to rise by 1-2 cm (1 in) over the next week.

Lac Seul authorized outflow is 60 m3/s. No changes to outflow from Lac Seul are currently scheduled.