Success Story: Eradication of Hydrilla at Lake Murray ( and continued success in the rest of the State) Western Regional Panel La Jolla, CA Sep 10, 2003

WRP 09/11/20032 Success Story CDFA legal authority to eradicate hydrilla Quick overview of hydrilla Lake Murray (thanks to Jeffrey Pasek from the City of San Diego Water Dept.) Overview of current hydrilla eradication projects

WRP 09/11/20033 Success Story: Lake Murray Why review Lake Murray ? –Good example of a successful large scale eradication effort –Demonstrates essential components of a successful eradication program

WRP 09/11/20034 CDFA Hydrilla Eradication Program Legal authority –California Food and Agriculture Code Section 6048: Secretary of Agriculture authorized to survey and eradicate hydrilla (1977) Section 405: Secretary of Agriculture authorized to prevent introduction and spread of noxious weeds –California Code of Regulations Section 4500: lists hydrilla as State noxious weed –Title 7, Code of Federal Regulations Section 360: lists hydrilla as Federal noxious weed (1974)

WRP 09/11/20035 Hydrilla: a Federal and State Aquatic Noxious Weed Two forms –Monoecious –Dioecious Forms impenetrable mats Tubers form a long term bank Spread mostly by human activity

WRP 09/11/20036 Lake Murray 171 surface acres 65 feet, max water depth 3.2 shoreline miles

WRP 09/11/20037 History of the Project Hydrilla first detected in Lake Murray in 1976 Limited quarantine imposed in 1977 Full quarantine imposed in 1979  Lake closed to water-based public recreation  Boats, fishing, water contact prohibited Project goals  Prevent spread of hydrilla to other waters  Eradicate hydrilla in Lake Murray

WRP 09/11/20038 History of the Project - cont. Eradication began in 1979  : reservoir water level drawdown  : herbicide applications  : mechanical removal using SCUBA divers and suction dredge  : on-going inspections Water-based recreation gradually re-established, beginning in mid-1980’s Last plant found July 1991 Declaration of eradication November 1994

WRP 09/11/20039 Initial Infestation: 1977 Covered 80 acres (of a total of 170 surface acres) All of the lake area less than 20 feet deep Continuous mat along shoreline Probably introduced from aquarium

WRP 09/11/ W ater Level Drawdown: Water level dropped 30 feet Late summer Exposed plants killed by drying Some roots and tubers survive

WRP 09/11/ Water Level Drawdown

WRP 09/11/ Vapam Herbicides: Komeen ® ®

WRP 09/11/ Eradication: Initial Phase Combination of water level draw downs and herbicides reduced infestation by 90% By 1984 only isolated individual plants remained Herbicides and drawdown not effective for remaining infestation

WRP 09/11/ Underwater Inspections,SCUBA

WRP 09/11/ Suction Dredging: SCUBA divers removed individual plants Labor intensive Removed remaining 10% of infestation

WRP 09/11/ Suction Dredging

WRP 09/11/ Eradication Complete:

WRP 09/11/ Success Story: Lake Murray

WRP 09/11/ Success Story: Lake Murray

WRP 09/11/ Project Costs Direct Costs $5,700,000  1979 – 1984: ~$200K per year –herbicide applications, quarantine, drawdown  1985 – 1991: ~$600K per year –mechanical removal, SCUBA inspections, drawdown  1992 – 1994: ~$90K per year –on-going surveys and draw downs ~$71,000 per acre of original infestation

WRP 09/11/ Project Costs Indirect costs  Reduced use of Lake Murray as a water supply reservoir  Loss of revenue from public recreation program  Loss of use of Lake Murray for public recreation

WRP 09/11/ Lessons Learned Quarantine can be effective to prevent spread Methods used for initial eradication probably won’t work in final stages Eradication can be a long and costly effort

WRP 09/11/ Success Story: rest of the State

WRP 09/11/ Status of Hydrilla in California COUNTY * YRWATER BODYSIZESTATU S CALAVERAS Bear Creek/ and 3 ponds Two ponds Bear Creek, 2 ponded areas 23 acres 0.6 acre 26 acres Survey Active IMPERIAL ponds/reservoirs Imperial Irrigation System 270 acres 600 miles of canals, ditches Survey Active LAKE 94Clear Lake1,440 acres / 43,000 acres Active LOS ANGELES Eight ponds One pond 2 acres <1 acre Erad. MADERA/ MARIPOSA 89Eastman Lake Chowchilla River 100/1,800 acres 26 miles Active MONTEREY 78Private pond0.01 acreErad. RIVERSIDE One pond Three ponds <1 acre Erad.

WRP 09/11/ Status of Hydrilla in California SAN BERNARDINO 88One pond<.01 acreErad. SAN DIEGO77 Lake Murray One pond 160 acres <1 acre Erad. SAN FRANCISCO 88One pond2 acresErad. SANTA BARBARA One pond 0.12 acre <.01 acre Erad. SHASTA Seven ponds Four ponds Two ponds Four ponds 133 acres 23.5 acres 13 acres 39 acres Erad. Survey Active SONOMA84Spring Lake72 acresErad. SUTTER85One pond<.01 acreErad. TULARE93 96 Three ponds Seven ponds 0.6 acre 20 acres Erad. Active YUBA Lake Ellis One pond 13 ponds and two spill basins 30.8 acres 6.0 acres 20 acres and 3.1 miles of canal Erad. Active

WRP 09/11/ Springville ponds, before/after Komeen treated lanes

WRP 09/11/ Chowchilla River, before/after 1989 Dec 2001

WRP 09/11/200328

WRP 09/11/ Lake County Project Surveys in Clear Lake –Visual, Grappling hook –2001, 1042 surveys –2002, 790 surveys Treatments: aquatic herbicides –Fluridone slow release pellets –Copper ethylenediamine

WRP 09/11/ Clear Lake

WRP 09/11/ Success Story: rest of State Lessons learned –Eradication is feasible –Requires early detection and rapid response –Requires long-term dedication of funds and manpower –Requires technology appropriate to the situation and phase of eradication

WRP 09/11/ Success Story: Lake Murray Many thanks to Jeffrey Pasek for his slides for this portion of presentation Thanks to City of San Diego and the San Diego County Agricultural Commissioner for their support in the eradication of hydrilla from Lake Murray.

WRP 09/11/ COOPERATORS U.S. Department of the Interior-Bureau of Reclamation U.S. Department of Agriculture-Animal and Plant Health Inspection Service U.S. Army Corps of Engineers- Eastman Lake Dept. of Boating and Waterways Dept. of Water Resources Yolo County Flood Control and Water Conservation District County Dept.s of Agriculture