228.22

8. 228.22

12. Municipal uses – Examined costs in 2 major urban areas: Southern California (Los Angeles south to San Diego) & Central Arizona (Phoenix)

16. 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

17. Flood control – $2.9 billion • Tamarisk stand trap sediments, which leads to a narrowing river channel, and narrowing of the flood plain • Narrower channels means channel can hold less water, which means floods at lower volumes of water • Plus the dense vegetation backs-up the water , spreading it out over a larger area • 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 times 55 years 1953 CHANGES IN RIPARIAN VEGETATION IN THE SOUTHWESTERN UNITED STATES: Floods and Riparian Vegetation on the San Juan River, Southeastern Utah-- USGS 1998

19. Sedimentation – Benefits of $0.07 billion • Tamarisk traps sediments, and hence increases lifetime of reservoirs • Dove hunting – Benefits of $0.02 billion • Doves like Tamarisk thickets • Increases value for hunting

20. Add up the total losses & 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 - $0.07 billion • Dove hunting - $0.02 billion • ________________ • TOTAL $7.3 – 16.1 billion loss

24. Case study: Klamath weed (Hypericumperforatum) • 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 • 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)

25. Case study: Eurasian watermilfoil (Myriophyllumspicatum) • From Eiswerthet 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 • Low & high economic values for 4 sites in • Lake Tahoe – Truckee – Pyramid watershed • If 100% infestation, lose $30-45 million per year • If 5% infestation, lose >$1 million per year

27. South African fynbos • Eucalypts, pines, Acacias, and other species have invaded the fynbos of South Africa’s Cape Province

28. Neotropicalshrub Lantana camara is invading east Africa

29. Parthinium weed (Partheniumhysterophorus)in Pakistan and Australia