Zebra musselsin a Nebraska Lake

Steven SchainostNebraska Game and Parks

8 January 2009

So where are we?

Bellevue and Offutt AFB at

center right, just south of Omaha

Offutt Base Lake and environs

Timeline

• Date: 3 April 2006• Event: message from the Kansas

ANS Coordinator• Message: they had received a tip on

their web site that someone had seen zebra mussels in the Offutt Air Force Base Lake

Timeline cont.

• I contact Offutt AFB via their public email information system

• Phone call from Karl Morris which leads to setting up site visit

• Early site visit on 25 and 26 April 2006 where zebra mussels are confirmed and the situation is discussed with Base personnel

Offutt Base Lake - dead zebra mussels

Dead shell under rocks

Located on darkened waterline

About 2 feet above 25 April 2006 waterline

Offutt Base Lake - lives up close

Live zebra mussels on

rock collected

about 1foot below 25

April 2006 water

surface

Offutt Base Lake - closeup of shells

Offutt Base Lake - discharge to river

Offutt Base Lake - lake side of discharge

Bottom of discharge

culverts are 3.5’ above

lake level on this date

26 April 2006

Offutt Base Lake - channel to river

Discharge channel to Missouri River in

background

26 April 2006

Offutt Base Lake - 1999

USGS photo19 April 1999

Offutt Base Lake - 2006Long view of boathouse and dock

Offutt Base Lake - south shore

Note darkened waterline. No zebra

mussels were found above

this line.

Offutt Base Lake Actions to Control Situation

• Since only Base personnel may use lake, there is a higher level of control on use. Base personnel fishing lake must have a fishing permit issued on site.

• Boat docks were closed• Brochures, etc., were made available in

boathouse• The outlet was plugged with concrete in the

Spring of 2007

Offutt Base Lake Bathymetric map

NGPC mapping

crew constructed

map in summer

2006

Offutt Base LakeWater Quality12 June 2006

6 sites

Calcium - 32.3 to 50.6 ppmPotassium - 7.2 to 8.8 ppm

Conductivity - 409 to 414 uS/cmpH - 8.39 to 8.47

Offutt Base Lake - First meeting8 March 2007

• Introductory meeting, statement of problem• General presentation on zebra mussels• Brian Watson, Virginia Coordinator of

Millbrook Quarry eradication• General discussion of problem and options

Millbrook Quarry, Virginia

• 12 acre, 93 feet deep

• Just west of Manassas, VA

• Privately owned and used for sport diving

Millbrook Quarry, Virginia

• Zebra mussel population discovered 2002• Flooding from adjacent creek or dive

operations would have spread zebra mussels to other waters

• Decision made to attempt eradication

Millbrook Quarry, Virginia

• Eradication in Feb. 2006

• Potassium chloride (potash)

• Target concentration of 100 ppm

Millbrook Quarry, Virginia

• Cost was $365,000

• Target concentration of 100 ppm well under EPA level of 250 ppm

• No impact on fishes or groundwater

Offutt Base LakeMeeting participants

• Offutt environmental and legal staff• USFWS• USACOE• USEPA• Iowa DNR• Nebraska Game and Parks• Nebraska Department of Environmental Quality• Nebraska Department of Agriculture• Public Power - Nebraska• MidAmerican Energy - Iowa• Kansas City Board of Public Utilities• State Senator’s office• Local government

Offutt Base Lake - Second meeting16 May 2007

• Another general discussion of treatment options

Offutt Base Lake - Third meeting3 October 2007

• Another general discussion of treatment options• Concluded that new options were being presented

at each meeting which was slowing process• Decided to cut off discussion at four treatments

and develop spreadsheet with pros and cons of each

• Spectrus CT1300, Endothal, potash, copper sulfate

Offutt Base Lake - Fourth meeting31 January 2008

• Discussed spreadsheet with pros and cons of each of four options

• Deleted Spectrus CT1300 (Clamtrol) due to cost and concerns about efficacy

• Deleted Endothal because available information was that it will be banned by end of year

• Discussed pros and cons of remaining two treatment options: copper sulfate and potash

Potash• Successfully used at Millbrook Quarry• Maintains long-term toxicity• Minimal impact on other species• No impact on public use• Great quantity needed (640 tons)• Concerns about how to get into lake• Cost has risen from $100/ton to $500+/ton (640

tons x $500 = $320,000)

Copper sulfate

• Crystals will sink to bottom and increase toxicity at surface of substrate where ZM live

• Less material needed (32,000 lbs)• Lower cost (@$1.98/lb = $63,360)• Toxicity dissipates quickly• Recommended to treat twice (spring and fall)• EPA concerns about whole lake treatment

Offutt Base Lake - Fifth meeting27 March 2008

• Copper sulfate was selected• DOD will have to pay all costs• Need to move quickly to earmark available

funds for this year• Target date for treatment is before 1 May 2008• Possible second treatment in fall

Offutt Base Lake - Treatment17 September 2008

• Consultant (URS) hired to carry out project planning, obtain permits, write EIS, etc.

• subcontracted actual lake application to Natural Habitats Unlimited

28,000 lbs. CuSO4

Shoreline done by pontoon boat

Mid-lake by boat with seeder

Treatment

• Day of treatment was perfect. No wind, no rain, full sun.

• Boats were guided by GPS• Target was a whole-lake concentration of

1.0 ppm copper

Forklift loading pallet of bags

Lake levels were up from 2006

But were down from earlier in year

All solid substrates were infested

Fish kill began next day

URS personnel picked up all fishWith a major airbase across road, Offutt

required that all fish be picked up to avoid attracting fish-eating birds

to eliminate possibility of

bird-strikes on base

And buried them

Most surprising find was the Bighead carp

- Results -Copper concentrations in lake

Date Location Range Mean17 Sept Random 1.7 ppm (max) 0.70 ppm

19 Sept Seven sitesTop/mid/bottom

0.00 to 0.73ppm

0.25 ppm

17 Oct Same seven sitesTop/mid/bottom

0.04 to 0.20ppm

0.10 ppm

- Results -Zebra mussel mortality

• Six live colonies placed in minnow pails at six locations prior to treatment

• Examined at 24 and 72 hours and 7 days

• 24 hours - 30% dead• 72 hours - 70% dead• 7 days - 100% dead

- Results -Zebra mussel mortality

• Clean bricks and concrete blocks set out before treatment:

• No new settling found

• >100 rocks, etc. examined at 96 hours:

• No lives found

- Results -Veliger sampling

• Samples collected from three locations post-treatment

• 80 micron net w/ 20 cm opening• 50 meter oblique tow from bottom to

surface• No veligers found

• [too late in year for veligers??]

- Results -Fish Kill: Sport fish, etc.

Species Estimated weight (lb) Duration of kill

Largemouth bass 10 3 to 7

Freshwater drum 600 2 to 10

Crappie 3 Sporadic

Paddlefish 100 Sporadic

Walleye/saugeye 50 5 to 10

Catfish 5 15 to 20

- Results -Fish Kill: Nongame fishes

Bighead carp 6,000 lb. 3 to 25 days

Grass carp 200 lb. Sporadic

Common carp 3,000 lb. 2 to 20 days

Buffalo 28,000 lb. 2 to 40 days

White perch 300 lb. 3 to 7 days

Gizzard shad 200 lb. 1 to 3 days

Gar, bullhead 15 lb. 15 to 20 days

Fish kill summary

• Estimated 39,000 lb. or 320 lb/acre of which 95+% were nongame fishes

• 72% buffalo• 23% carp (bighead,

common, grass)• 0.4% sport fish

Cost?

Actual cost figures are not available but the estimate was ~$100,000 or

$820/surface acre

Double that for the second treatment plus monitoring, etc.

Future plans

• A second treatment is tentatively scheduled for the first week of April, 2009.

• Veliger monitoring, 2009

A side note

A side note

• Caught at DeSoto Bend (Missouri River oxbow lake on Nebraska/Iowa border)

• 76 pounds