4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Water loss to Tamarisk:
– 3000-4600 m3/ha/yr more than native vegetation
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Water loss to Tamarisk:
– 3000-4600 m3/ha/yr more than native vegetation (willow/poplar)
- This amount comparable to TOTAL annual precip (2000-4500
m3/ha/yr) throughout invaded region
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Water loss to Tamarisk:
– 3000-4600 m3/ha/yr more than native vegetation
- This amount comparable to TOTAL annual precip (2000-45000
m3/ha/yr) throughout invaded region
- Increases water use in several ways: more transpiration,
accesses deeper water, creates more areas of dense vegetation,
and traps sediment creating banks that it then colonizes (further
increasing vegetation along river)
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Economic losses related to
• Consumptive use by municipalities
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Economic losses related to
• Consumptive use by municipalities
• Consumptive use for irrigation
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Economic losses related to
• Consumptive use by municipalities
• Consumptive use for irrigation
• Non-consumptive use for hydro power and recreation
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Economic losses related to
• Consumptive use by municipalities
• Consumptive use for irrigation
• Non-consumptive use for hydro power and recreation
• Additional cost of increased flooding and flood mitigation
• Impact on threatened species
• Benefits: reservoirs (reduced sedimentation)
habitat for game birds
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – Examined costs in 2 major urban areas: Southern
California (Los Angeles south to San Diego) & Central Arizona
(Phoenix)
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses
(1) Southern California – Metropolitan Water District of S.
California plans to line 2 canal systems to conserve water plus
build a desalination plant for drainage water from agricultural
fields (this would ‘replace’ losses to tamarisk)
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses
(1) Southern California – Metropolitan Water District of S.
California plans to line 2 canal systems to conserve water plus
build a desalination plant for drainage water from agricultural
fields
Amount of water involved
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses
(1) Southern California – Metropolitan Water District of S.
California plans to line 2 canal systems to conserve water plus
build a desalination plant for drainage water from agricultural
fields
Amount of water involved
Amount of $$ involved
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses
(1) Southern California – Metropolitan Water District of S.
California plans to line 2 canal systems to conserve water plus
build a desalination plant for drainage water from agricultural
fields
Amount of water involved
Amount of $$ involved
Estimate of cost per a.f. per year = total$ / (a.f. * 55 years)
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses
(1) Southern California – total costs $1.2 – 3.2 billion over 55
years ($22-58 million per year)
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses
(1) Southern California – $1.2 – 3.2 billion over 55 years
(2) Central Arizona – Metropolitan Water District buying farmland
and fallowing it at ~$150 per a.f.
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses
(1) Southern California – $1.2 – 3.2 billion over 55 years
(2) Central Arizona – Metropolitan Water District buying farmland
and fallowing it at ~$150 per a.f.
Based on local Tamarix infestations & water use, costs $5-10
million per year
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses
(1) Southern California – $1.2 – 3.2 billion over 55 years
(2) Central Arizona – Metropolitan Water District buying farmland
and fallowing it at ~$150 per a.f.
Based on local Tamarix infestations & water use, costs $5-10
million per year, or $270-530 million over 55 years
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses
(1) Southern California –
$1.12 – 3.20 billion over 55 years
(2) Central Arizona –
$0.27 – 0.53 billion over 55 years
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses
(1) Southern California –
$1.12 – 3.20 billion over 55 years
(2) Central Arizona –
$0.27 – 0.53 billion over 55 years
___________________________
TOTAL
$1.4 – 3.7 billion
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses
(1) Southern California –
$1.12 – 3.20 billion over 55 years
(2) Central Arizona –
$0.27 – 0.53 billion over 55 years
___________________________
TOTAL
$1.4 – 3.7 billion + other metro areas
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses
More difficult to estimate because:
(1) what crops are planted vary around the area and through
time
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses
More difficult to estimate because:
(1) what crops are planted vary around the area and through time
(2) Some crops are cheap (e.g. grains) whereas others are
more costly (e.g. melons)
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses
Low & high estimates of value of irrigation water based on
lowest & highest reported values of crops in each region
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses
Low & high estimates of irrigation water value
Next, 2 estimates of total annual losses:
(1) Low estimate based on low irrigation water value and low
(1.0 a.f.) Tamarisk water use
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses
Low & high estimates of irrigation water value
Next, 2 estimates of total annual losses:
(1) Low estimate: low irrigation water value and low water use
(2) Mean estimate using a 80:20 of Low:High value of irrigation
water and mean (1.5 a.f.) Tamarisk water use
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
Low & high estimates of irrigation water value
Next, 2 estimates of total annual losses:
(1) Low estimate: low irrigation water value and low water use
(2) Mean estimate using a 80:20 of Low:High value of irrigation
water and mean (1.5 a.f.) Tamarisk water use
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power
Used values from the literature on how much it would cost to
replace the power generated by 4 dams along the Colorado
River
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power
Cost to replace hydropower along the Colorado River
Next, estimated the amount of acreage in Tamarisk upstream
from dam and the corresponding amount of water used by
Tamarisk
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power
Cost to replace hydropower along the Colorado River
Amount of water used by Tamarisk upstream from dam
Then calculated the economic value of lost hydroelectric
power generation
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
Cost to replace hydropower along the Colorado River
Amount of water used by Tamarisk upstream from dam
Economic value of lost hydroelectric power generation
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
Cost to replace hydropower along the Colorado River
Amount of water used by Tamarisk upstream from dam
Economic value of lost hydroelectric power generation
Only a part of the hydroelectric power generation in the area
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation
Again, limited in data availability
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation
Limited data availability
Some uses (e.g. fishing) are not an issue until water becomes
extremely limited (which is not likely to be due to just
Tamarisk)
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation
Limited data availability
Some uses (e.g. fishing) are not an issue until water becomes
extremely limited (which is not likely to be due to just
Tamarisk)
Rafting and kayaking are more sensitive to flows, and studies
are available that have determined the value that boaters
are willing to pay for increased flows
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation
Limited data availability
Some uses are not valuable, but rafting and kayaking are valuable
For Green River and Colorado River above Lake Mead, value of
lost water for boating estimated at $0.5 – 2.3 million per
year
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
Limited data availability
Some uses are not valuable, but rafting and kayaking are valuable
For Green River and Colorado River above Lake Mead, value of
lost water for boating estimated at $0.5 – 2.3 million per year
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
Limited data availability
Some uses are not valuable, but rafting and kayaking are valuable
For Green River and Colorado River above Lake Mead, value of
lost water for boating estimated at $0.5 – 2.3 million per year
Underestimates total value because only considers part of system
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control
Tamarisk stand trap sediments, which leads to a narrowing
river channel, and narrowing of the flood plain
1953
CHANGES IN RIPARIAN VEGETATION IN
THE SOUTHWESTERN UNITED STATES:
Floods and Riparian Vegetation on the San
Juan River, Southeastern Utah-- USGS
1998
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control
Tamarisk narrows river channel and flood plain
Narrower channels means channel can hold less water, which
means floods at lower volumes of water
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control
Tamarisk narrows river channel and flood plain
Narrower channels means more frequent floods
Plus the dense vegetation backs-up the water , spreading it
out over a larger area
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control
Tamarisk narrows river channel and flood plain
Narrower channels means more frequent floods
Dense vegetation means larger floods
Thus get more frequent and large floods
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control
Tamarisk narrows river channel and flood plain
Thus get more frequent and large floods
Used Army Corps of Engineer’s conservative estimates of
extra flood damage due to Tamarisk of $52 million per year
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control – $2.9 billion
Tamarisk narrows river channel and flood plain
Thus get more frequent and large floods
Used Army Corps of Engineer’s conservative estimates of extra
flood damage due to Tamarisk of $52 million per year
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control – $2.9 billion
• Wildlife
Estimated impact for 3 federally-listed endangered and 1
candidate threatened species
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control – $2.9 billion
• Wildlife
Estimated impact
Used a “Willingness To Pay” (WTP) method to estimate worth of
wildlife habitat
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control – $2.9 billion
• Wildlife
Estimated impact
Used a “Willingness To Pay” (WTP) method to estimate worth
For willow flycatcher, discounted worth by 50% to account for
possibility that people perceive less value in small
songbirds than in “charismatic” eagles, cranes, and
bighorn sheep
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control – $2.9 billion
• Wildlife
Estimated impact
Used a “Willingness To Pay” (WTP) method to estimate worth
Annual cost of $3.7 – 8.7 million
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control – $2.9 billion
• Wildlife – $0.09 – 0.37 billion
Estimated impact
Used a “Willingness To Pay” (WTP) method to estimate worth
Annual cost of $3.7 – 8.7 million
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss and benefits
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control – $2.9 billion
• Wildlife – $0.09 – 0.37 billion
• Sedimentation
Tamarisk traps sediments, and hence increases lifetime of
resevoirs
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss and benefits
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control – $2.9 billion
• Wildlife – $0.09 – 0.37 billion
• Sedimentation – Benefits of $0.07 billion
Tamarisk traps sediments, and hence increases lifetime of
resevoirs
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #3 – Convert water loss into economic loss and benefits
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control – $2.9 billion
• Wildlife – $0.09 – 0.37 billion
• Sedimentation – Benefits of $0.07 billion
• Dove hunting
Doves like Tamarisk thickets
Increases value for hunting
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Economic losses and benefits
• Municipal uses – $1.4 – 3.7 billion
• Agricultural uses – $2.1 – 6.7 billion
• Hydroelectric power – $0.8 – 2.4 billion
• Recreation – $0.03 – 0.13 billion
• Flood control – $2.9 billion
• Wildlife – $0.09 – 0.37 billion
• Sedimentation – Benefits of $0.07 billion
• Dove hunting – Benefits of $0.02 billion
Doves like Tamarisk thickets
Increases value for hunting
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Add up the total cost
• Municipal uses
$1.4 – 3.7 billion
• Agricultural uses
$2.1 – 6.7 billion
• Hydroelectric power
$0.8 – 2.4 billion
• Recreation
$0.03 – 0.13 billion
• Flood control
$2.9 billion
• Wildlife
$0.09 – 0.37 billion
• Sedimentation
- $0.07 billion
• Dove hunting
- $0.02 billion
________________
TOTAL
$7.3 – 16.1 billion loss
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Step #4 – What are the costs to eradicate Tamarisk?
• Used a 20-year, progressive eradication program
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Put it all together
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Put it all together
Economic losses
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Put it all together
Economic losses, even when take out the “non-use” values
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Put it all together
Economic losses, even when take out the “non-use” values,
are greater then the costs to eradicate
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Put it all together
Economic losses greater then the costs to eradicate
Thus economically beneficial to eradicate
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Put it all together
Economic losses greater then the costs to eradicate
Thus economically beneficial to eradicate
Benefits 2-3 times greater than costs
4) Impacts
b) Economic
Case study: Tamarix – Will economic benefits justify costs?
Put it all together -- Benefits greater than costs even up to 6%
discount rate
4) Impacts
b) Economic
Case study: Klamath weed (Hypericum perforatum)
• Broad-leaved, perennial herb
• Introduced to North America from Europe in 1793
• Reached California in late 1800’s
Jim Stasz @ USDA-NRCS PLANTS Database
4) Impacts
b) Economic
Case study: Klamath weed (Hypericum perforatum)
• Broad-leaved, perennial herb
• Introduced from Europe in 1793; reached California late 1800’s
• Extremely invasive
• Toxic to wildlife & livestock
Photos: Ian Davidson
©Norman E. Rees, USDA ARS,
www.forestryimages.org
From northwestweeds.nsw.gov.au
4) Impacts
b) Economic
Case study: Klamath weed (Hypericum perforatum)
• Broad-leaved, perennial herb
• Introduced from Europe in 1793; reached California late 1800’s
• Extremely invasive; toxic
• By early 1940’s: 5 million acres of rangeland in western North
America infested
4) Impacts
b) Economic
Case study: Klamath weed (Hypericum perforatum)
• Broad-leaved, perennial herb
• Introduced from Europe in 1793; reached California late 1800’s
• Extremely invasive; toxic
• By early 1940’s: 5 million acres of infested rangeland
• Biological control in California
1945/1946: 2 leaf feeders introduced
1950: root feeder introduced
4) Impacts
b) Economic
Case study: Klamath weed (Hypericum perforatum)
• Broad-leaved, perennial herb
• Introduced from Europe in 1793; reached California late 1800’s
• Extremely invasive; toxic
• By early 1940’s: 5 million acres of infested rangeland
• Biological control in California
1945/1946: 2 leaf feeders introduced
1950: root feeder introduced
Total Cost: $750,000
4) Impacts
b) Economic
Case study: Klamath weed (Hypericum perforatum)
• Broad-leaved, perennial herb
• Introduced from Europe in 1793; reached California late 1800’s
• Extremely invasive; toxic
• By early 1940’s: 5 million acres of infested rangeland
• Biological control in California: 1945-1950 @ $750,000 total cost
• By early 1960’s in California, insects had reduced Klamath weed
acreage to <1% of peak acreage
4) Impacts
b) Economic
Case study: Klamath weed (Hypericum perforatum)
• Broad-leaved, perennial herb
• Introduced from Europe in 1793; reached California late 1800’s
• Extremely invasive; toxic
• By early 1940’s: 5 million acres of infested rangeland
• Biological control in California: 1945-1950 @ $750,000 total cost
• By early 1960’s in California, insects had reduced Klamath weed
acreage to <1% of peak acreage
• Annual benefits estimated @ $3,500,000 per year in California
4) Impacts
b) Economic
Case study: Klamath weed (Hypericum perforatum)
• Broad-leaved, perennial herb
• Introduced from Europe in 1793; reached California late 1800’s
• Extremely invasive; toxic
• By early 1940’s: 5 million acres of infested rangeland
• Biological control in California: 1945-1950 @ $750,000 total cost
• By early 1960’s in California, insects had reduced Klamath weed
acreage to <1% of peak acreage
• Annual benefits estimated @ $3,500,000 per year in California
Total Benefits (1965 – 2005): $140 million
Benefit : Cost ratio = 187 : 1 (not adjusted for inflation)
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Aquatic weed
• Submersed, rooted perennial whose stems branch near water
surface and form dense mats. Grows in waters up to 6 m deep,
depending on light penetration.
• Best suited for still waters (lakes, ponds), but does well in
rivers and irrigation ditches
fwcb.cfans.umn.edu
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Aquatic weed that forms dense, floating mats
• Native to Europe, Asia, & North Africa
• Introduced to Chesapeake Bay in 1880’s
• Today, in 45 of the 48 continental states
Colette C. Jacono and M.M. Richerson
USGS
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Aquatic weed that forms dense, floating mats
• Introduced to Chesapeake Bay in 1880’s; now widespread
throughout US
• Spreads primarily by plant fragments
Fragments float downstream, growing leaves and stems until it
settles in and roots
Fragments also adhere to boats & trailers, and thus are
transported from lake to lake
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Aquatic weed that forms dense, floating mats
• Introduced to Chesapeake Bay in 1880’s; now widespread
throughout US
• Spreads primarily by plant fragments
• Population reported at Tahoe Keys Marina since 1960’s
Virtually all marinas & shorelines areas around Lake Tahoe are
now invaded
In 1999, found near Verdi and at Stillwater
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Aquatic weed that forms dense, floating mats
• Introduced to Chesapeake Bay in 1880’s; now widespread
throughout US
• Spreads primarily by plant fragments
• Population reported at Lake Tahoe since 1960’s
• Economic impacts include
↓ recreational activities (fishing, boating, swimming, etc.)
Clog irrigation canals, gates, etc.
↓hydroelectric generation by clogging intake pipes
Non-use value: degradation of Lake Tahoe
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Aquatic weed that forms dense, floating mats
• Introduced to Chesapeake Bay in 1880’s; now widespread
throughout US
• Spreads primarily by plant fragments
• Population reported at Lake Tahoe since 1960’s
• Economic impacts include
↓ recreational activities (fishing, boating, swimming, etc.)
Clog irrigation canals, gates, etc.
↓hydroelectric generation by clogging intake pipes
Non-use value: degradation of Lake Tahoe
Study only focused on recreational uses
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Economic impacts on recreational activities
• Used “Benefits Transfer Approach”
Used economic values for activities that were developed in
other studies and applied them to this case (rather then
conduct new and expensive studies)
But used local visitation records to calculate the total
economic value
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Economic impacts on recreational activities
• Used “Benefits Transfer Approach”
• Estimated low & high economic values
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Economic impacts on recreational activities
• Used “Benefits Transfer Approach”
• Estimated low & high economic values for only 4 sites on the
Tahoe-Truckee-Pyramid watershed
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Economic impacts on recreational activities
• Used “Benefits Transfer Approach”
• Low & high economic values for 4 sites on watershed
• Baseline economic value of 4 areas = $30-45 million per year
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Economic impacts on recreational activities
• Used “Benefits Transfer Approach”
• Low & high economic values for 4 sites on watershed
• Baseline economic value of 4 areas = $30-45 million per year
If 100% infestation, lose $30-45 million per year
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Economic impacts on recreational activities
• Used “Benefits Transfer Approach”
• Low & high economic values for 4 sites on watershed
• Baseline economic value of 4 areas = $30-45 million per year
If 100% infestation, lose $30-45 million per year
If 5% infestation, lose >$1 million per year
4) Impacts
b) Economic
Case study: Eurasian watermilfoil (Myriophyllum spicatum)
From Eiswerth et al. (2000) Weed Technology 14:511-518
• Economic impacts on recreational activities
• Used “Benefits Transfer Approach”
• Low & high economic values for 4 sites on watershed
• Baseline economic value of 4 areas = $30-45 million per year
If 100% infestation, lose $30-45 million per year
If 5% infestation, lose >$1 million per year
Only part of watershed in economic analysis
4) Impacts
b) Economic
Other examples include:
Fires due to invasive species
• Loss of property & resources
• Loss of human life
• Fire suppression & rehabilitation costs
http://dcnr.nv.gov/graphic/waterfall_fire4.jpg
4) Impacts
b) Economic
Other examples include:
Fires due to invasive species
Loss of ecosystem functions
• Wetland degradation (water purification)
• Habitat loss and consequences for TES protection & mitigation
4) Impacts
b) Economic
Other examples include:
Fires due to invasive species
Loss of ecosystem functions
Agricultural losses
• Weeds in crops
• Weeds in pastures
• Weeds that have escaped from crops/pastures