Low reservoirs benefit threatened birds Enough rain fell across the Missouri River basin in July to maintain reservoir levels near the June levels and slightly increase total storage in the system of six dams and reservoirs.
Levels at Fort Peck and Garrison rose 0.2 feet and 2.3 feet respectively while Oahe fell a foot. Runoff in July above Sioux City, IA, was 2.6 million acre feet (MAF), 80 percent of normal.
�While runoff has improved this year, it remains unclear whether the drought is over yet,� said Larry Cieslik, chief of water management. �The three large reservoirs remain many feet below normal levels. Total storage on Aug. 1 was 38.5 MAF.�
As reported last month, the 2005 commercial navigation season will be shortened by 48 days. Minimum service flows will be continued throughout the season and then reduced in October and November to the minimum levels required for municipal and industrial water supply.
The runoff forecast for 2005 has been revised upward from 19.9 MAF last month to 20.1 MAF, 80 percent of normal. Normal runoff is 25.2 MAF.
While the current drought has hurt fish spawns and access to the reservoirs, it has benefited the protected least tern and piping plover. Record numbers of each species have been recorded on the reservoirs and along the river � 1756 terns and 904 plovers.
Efforts by the Corps to maintain lower releases throughout the nesting season, move nests threatened by rising river and reservoir levels, and protecting nests from predators and human disturbance have greatly benefited the birds. The construction of two sandbar complexes below Gavins Point Dam last winter in addition to a complex created in spring 2004 has been very successful. To date, these new sandbars have accounted for 116 tern and 59 plover nests.
Lower reservoir levels, especially in Garrison, have provided very attractive habitat for the plovers. Unfortunately, the level of the reservoir rose so quickly this summer that more than 100 eggs were inundated before all the threatened nests could be moved to higher elevation.
The reservoir has climbed more than 10 feet since mid-May. Releases from Gavins Point in July averaged 21,500 cubic feet per second (cfs), well below the long term average of 33,500 cfs.
Gavins Point reservoir will gradually rise to near elevation 1207.5 feet above mean sea level (msl) during August.
Fort Randall releases averaged 20,800 cfs in July. They will range from 21,000 cfs to 24,000 cfs as needed to maintain Gavins Point reservoir near its desired elevation.
Fort Randall reservoir ended July at 1353.8 feet msl. It will remain essential level during August. Big Bend reservoir will remain in its normal elevation range of 1420 to 1421 feet. Releases will be adjusted to meet hydropower needs.
Oahe reservoir fell slightly more than one foot during July, ending the month at elevation 1576.4 feet msl. It will fall about three feet through the month, ending Aug. 30 feet below average. The reservoir is more than two feet higher than last year at this time.
Garrison releases averaged 15,200 cfs during July, compared to the average of 25,100 cfs. Releases will remain near 15,500 cfs during August. Garrison reservoir rose more than two feet in July, ending the month at elevation 1817.2 feet msl. The reservoir will decline about a foot in August, ending the month 24 feet below average. The reservoir is a foot higher than last year at this time.
Fort Peck releases averaged 6,600 cfs in July, compared to the normal of 10,400 cfs. They were increased to 7,000 cfs early last month where they will remain throughout August. The reservoir rose 0.2 feet in July, ending the month at elevation 2203.2 feet msl. It will decline about 1.5 feet during August, ending the month 33 feet below average. The reservoir is a foot higher than last year at this time.