Identification of constraints on river regulation.  Lock and Dam 9


Wilcox, D. B., and K. W. Willis.  1993.  Identification of
constraints on river regulation.  Lock and Dam 9 near Lynxville,
Wisconsin, Upper Mississippi River 9-Foot Channel Project.  Report
by the U.S. Army Corps of Engineers, St. Paul District-Minnesota,
for the U.S. Fish and Wildlife Service, Environmental Management
Technical Center, Onalaska, Wisconsin, August 1993.  EMTC 93-S012. 
91 pp.  (NTIS # PB94-103603)


ABSTRACT

The timing, amplitude, frequency, and duration of water level
fluctuations greatly affect river life.  On regulated rivers like
the Mississippi, water level and current velocity fluctuations are
caused by natural hydrologic events that change river discharge
and by operation of water control structures.  Opportunities exist
for modifying river regulation to improve habitat conditions and
productivity of the river ecosystem.  Modifications to the present
system of river regulation must be made within constraints imposed
by the hydrology of the basin, engineering characteristics of the
system, and within legal and administrative requirements. 
Hydrologic, engineering, legal, and administrative constraints on
river regulation at Lock and Dam 9 on the Upper Mississippi River
are described.  Potential for modification of hydrologic
constraints exists with operation of upstream dams.  Engineering
constraints have potential for modification, most at considerable
initial expense.  Increased water levels during lower flow periods
would require structural modification of Lock and Dam 9. 
Opportunity for reduced pool elevations is limited by the need to
maintain a 9- foot depth in the navigation channel.  The frequency
and amplitude of short term water level fluctuations will be
reduced with further improvements to the system of water control
management. Increases in pool elevation would require acquisition
of additional flowage easements.  Administrative constraints are
imposed by Corps of Engineers internal regulations which specify
Corps-wide management of water control systems and the process for
modifying water control plans.


KEYWORDS

Mississippi River, river regulation, water level management, river
habitat management, Pool 9