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Wisconsin River Report June 8, 2006

Wisconsin Valley Improvement Company 2301 North Third Street Wausau, WI  54403 For more information contact Sam Morgan Phone: 715.848.2976, ex 301 Email: morgan@wvic.com

 

Late-Spring Rains Boost River Flow and Reservoir Storage

 

After an extremely dry early spring that saw river flows plummet below summer levels, rainfall returned to the Wisconsin River basin in mid-May and provided a critical boost for river flows and reservoir storage according to Wisconsin Valley Improvement Company of Wausau. Over the final 20 days of May, over 4 inches of rain was recorded in the northern river basin from Tomahawk north to Land O’ Lakes and almost 5 inches was reported in the central basin from Tomahawk south to Wisconsin Rapids. The largest May totals were reported at Rice Reservoir near Tomahawk with 5.75 inches and the Big Eau Pleine Reservoir near Mosinee with 5.12 inches. Despite the heavy rains in May, total rainfall for the year is still about 5% below normal in the northern basin and 15% below normal in the central basin.

River flows, which had been running 30% below summer levels in April, responded to the rains and jumped to nearly twice normal for the second half of May. However, with groundwater levels still well below normal because of the drought in 2005, river flows drop quickly after rainstorms. Following a few dry days in early June, flows are again returning to the below normal range.

Storage in the Wisconsin River Reservoir System now stands at 81% of capacity, up from only 64% of capacity in early May. Water levels in four of the five large man-made reservoirs are at or near the full mark. The Rainbow Reservoir near Lake Tomahawk is 1 foot below maximum, the Rice Reservoir north of Tomahawk is 0.5 foot below maximum, the Spirit Reservoir south of Tomahawk is 0.9 foot below maximum, and the Big Eau Pleine Reservoir near Mosinee is 1.1 feet below maximum. The only reservoir that has not refilled is the Willow Reservoir near Hazelhurst which remains 3.8 feet below maximum. Most of the natural-lake reservoirs in the northern basin are also near their summer operating levels except Twin lakes near Phelps which is 0.9 foot below the summer target level, Long and Sand Lakes near Phelps which is 0.7 foot below the summer target level, and the Minocqua chain of lakes which is also 0.7 foot below the summer target level. All three of these natural-lake reservoirs are very large water bodies in small drainage areas that require significant spring rainfall to fill completely.

Temperatures for the past week averaged 65 degrees in the north (4 degrees above normal), 66 degrees in the central basin (normal), and 65 degrees in the southern basin (5 degrees below normal). Water temperatures in the Wisconsin River are in the low to mid 70’s.

 

 

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