U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2005-3127

November 2005

Upper Midwest Environmental Sciences Center, La Crosse, Wisconsin

Printed on recycled paper

A Voluntary Program to Curtail Boat Disturbance to 

Migrating Waterfowl on the Upper Mississippi River

An abundant food supply, relatively undisturbed resting sites, 

and strategic location make the Upper Mississippi River (UMR) 

an important staging area to waterfowl as they migrate to 

wintering areas each fall. The UMR hosts impressive numbers 

of canvasback (Aythya valisineria), tundra swan (Cygnus 

columbianus), lesser scaup (A. affinis), ring-necked duck (A. 

collaris), mallard (Anas platyrhynchos), and other waterfowl 

as they pass through the Mississippi Flyway (Figure 1). 

Lake Onalaska, the impounded area above Lock and Dam 

7 near La Crosse, Wisconsin, is one of the most important 

feeding and staging locations on the UMR and is within the 

Upper Mississippi River National Wildlife and Fish Refuge 

(UMRNWFR).

Because there are no seasonal restrictions on commercial and 

recreational boating activities on the UMRNWFR, a program 

asking the public to voluntarily avoid a portion of Lake 

Onalaska was initiated. A voluntary waterfowl avoidance area 

(VWAA) was established in 1986 by the La Crosse District 

of the UMR in cooperation with the U.S. Army Corps of 

Engineers, the Wisconsin Department of Natural Resources, 

La Crosse County Fishing Alliance, La Crosse County 

Conservation Alliance, Brice Prairie Conservation Association, 

and the Lake Onalaska Protection and Rehabilitation District. 

Each year boaters have been encouraged through the media 

and informational kiosks at boat landings to avoid an area of 

about 1,310 ha (3,237 acres) marked with buoys (Figure 2) 

from 15 October through mid-November. The VWAA program 

enhanced the sanctuary value of a portion of a larger area of 

Lake Onalaska that is closed to waterfowl hunting (Figure 3). 

Figure 2. Buoys mark the 

perimeter of the Lake Onalaska 

Voluntary Waterfowl Avoidance 

Area to alert boaters.

Figure 1. Impressive numbers of waterfowl use impounded areas, such as 

Lake Onalaska, along the Upper Mississippi River during fall migration.

Lake Onalaska is also an important recreation area and is 

heavily used by boaters. Unfortunately, boating may have 

appreciable negative consequences for waterfowl in terms of 

disruption of feeding activities, modification of activity patterns, 

displacement from preferred habitat, and the energetic cost of 

avoiding disturbance. Studies indicate repeated disturbance 

can result in a substantial increase in energy expenditure in 

combination with a reduction in rates of food energy intake. It 

has been estimated that canvasback on Lake Onalaska require 

a 19% increase in food intake to compensate for the energy 

demands of 1 hour of daily disturbance (which could be 

generated by as few as four disturbances), given adequate food 

resources are available. Therefore, increases in disturbance rates 

will reduce the quality of the area as a staging area. 

The U.S. Geological Survey and the U.S. Fish and Wildlife 

Service collaborated to monitor boater compliance with the 

VWAA program when the program was established (1986–88) 

and again in 1993, 1997, and 2004. Boating activity was 

observed daily each year from an elevated site on the Minnesota 

bluffs adjacent to Lake Onalaska during the 31-day program. 

Boating traffic on Lake Onalaska during the avoidance period 

has increased steadily from the 1981 level of 1.59 boating 

events per hour to 3.06 in 2004. Since the inception of the 

VWAA, the hourly rate of intrusion into the VWAA and rate of 

resulting disturbances have remained fairly constant (Figure 4). 

Consequently, the number of disturbances per boating event 

has declined noticeably. The lake-wide disturbance rate in 

2004 (0.08 disturbances per lake-wide boating event) was at 
For more information, contact:

Kevin Kenow, U.S. Geological Survey

Upper Midwest Environmental Sciences Center

2630 Fanta Reed Road, La Crosse, Wisconsin

Phone: 608.781.6278

Email: kkenow@usgs.gov

or 

James Nissen, U.S. Fish and Wildlife Service

 Upper Mississippi National Wildlife and Fish Refuge

555 Lester Avenue, Onalaska, Wisconsin 

Phone: 608.783.8401

Email: James_Nissen@fws.gov

the lowest point measured (Figure 5) and well below the rate 

of boating disturbance to waterfowl before establishment of 

the VWAA (0.30 disturbances per boating event). We also saw 

evidence of better boater compliance with the VWAA program 

in 1997 and 2004 compared to 1986–88 and 1993 as indicated 

by a decline in the proportion of boats that intruded into the 

VWAA.

Reduced boating activity in the VWAA, in turn, has probably 

contributed considerably to the value of the VWAA as 

a waterfowl refuge, a notion supported by the observed 

concentration of birds. Within the 2,975 ha (7,350 acres ) 

area closed to waterfowl hunting, birds concentrate within 

the 1,310 ha VWAA. About 2.5 million waterfowl use-days 

(a use-day is the use of the area by 1 bird for 1 day) were 

estimated for the Lake Onalaska Closed Area in fall 2004, 

with diving ducks (primarily canvasback and lesser scaup) 

contributing nearly 1.9 million of the total. This area is 

recognized as one of the four most significant fall staging areas 

for canvasbacks in North America.

http://www.umesc.usgs.gov/

The working goal of the VWAA program has been to minimize 

the number of boat intrusions into the VWAA, thereby reducing 

disturbances to waterfowl on Lake Onalaska and enhancing 

the opportunity for waterfowl to rest, preen, feed, and sleep. 

Monitoring conducted in 1986–88, 1993, 1997, and 2004 

indicate that the VWAA program has been successful in 

reducing disturbance to waterfowl and it has been evident that 

many boaters made an obvious effort to travel out of their way 

to comply with the VWAA. This program is an example of a 

management strategy that River managers and biologists may 

use to enhance the UMR as an important waterfowl staging 

area.

Figure 4. Rates of boating activity, intrusions into the Voluntary Waterfowl 

Avoidance Area, and resulting disturbance to waterfowl on Lake Onalaska in 

1981a, 1986-88, 1993, 1997, and 2004. a

Estimated from data collected prior to establishment of VWWA during 

autumn, 1981

Figure 5. Intrusions into the Lake Onalaska Voluntary Waterfowl Avoidance 

Area and lake-wide disturbances to waterfowl caused by boaters as the 

proportion of lake-wide boating events. 

 

Figure 3. Location of Voluntary Waterfowl Avoidance Area and area closed to 

waterfowl hunting on Lake Onalaska, Upper Mississippi River.

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