BARNES LAKE INTEGRATED AQUATIC VEGETATION MANAGEMENT PLAN 2016 Prepared for City of Tumwater’s Barnes Lake Management District Prepared by Herrera Environmental Consultants, Inc. Note: Some pages in this document have been purposely skipped or blank pages inserted so that this document will copy correctly when duplexed. BARNES LAKE INTEGRATED AQUATIC VEGETATION MANAGEMENT PLAN 2016 Prepared for City of Tumwater’s Barnes Lake Management District Tumwater City Hall 555 Israel Road Southwest Tumwater, Washington 98501 Prepared by Herrera Environmental Consultants, Inc. 1220 Fourth Avenue East Olympia, Washington 98506 Telephone: 360-754-7644 April 1, 2016 ACKNOWLEDGEMENTS The City of Tumwater wishes to acknowledge the significant contribution provided by the members of the Barnes Lake Steering Committee toward the completion of the 2016 Barnes Lake Integrated Aquatic Vegetation Management Plan. Barnes Lake Steering Committee: Gary Bodeutsch (Chair) Linnea Madison (Vice Chair) William Baxter Dana Day Bob Gillette Jody Keys Judith Loft Kathy Peterson Tom Sparks Cathy Weaver Dan Smith, Staff Representative The Barnes Lake Steering Committee expressly thanks the Tumwater City Council for their support of the lake management district formation and management goals. Tumwater City Council Pete Kmet, Mayor Joan Cathey Ed Hildreth Nicole Hill Neil McClanahan Tom Oliva Debbie Sullivan Eileen Swarthout The LMD would also like to thank the City of Tumwater staff including John Doan, City Administrator; Jay Eaton, Public Works Director; and Ursula Euler, Finance Director; for their support of the LMD and assistance in providing for the routine management of this project, helping to build community among all the neighbors of Barnes Lake. CONTENTS Executive Summary ..................................................................................... ES-1 1. The Problem, As Redefined By The Lake Management District In 2015 ....................... 1 2. Lake Management District Goals .................................................................... 3 3. Public Involvement Methods ......................................................................... 5 4. Watershed Characteristics ........................................................................... 7 5. Water Quality .......................................................................................... 9 6. Aquatic Plant Community ........................................................................... 11 6.1. Aquatic Plant Map and Characterizations .................................................. 11 6.2. Plants Targeted for Control .................................................................. 16 6.2.1. Fragrant Waterlily (Nymphaea odorata) ........................................ 16 6.2.2. Spatterdock (Nuphar polysepala) ................................................ 17 6.2.3. Watershield (Brasinea shreberi).................................................. 17 6.2.4. Swollen Bladderwort (Utricularia inflata) ...................................... 18 6.2.5. Reed Canarygrass (Phalaris arundinacea) ....................................... 19 6.2.6. Nightshade (Solanum sp.) ......................................................... 21 6.2.7. Yellow Flag Iris (Iris pseudacorus) ............................................... 21 6.2.8. Purple Loostrife (Lythrum salicaria) ............................................. 22 7. Wildlife on Barnes Lake ............................................................................. 23 8. Beneficial Uses of Barnes Lake ..................................................................... 25 9. Barnes Lake Water Rights ........................................................................... 29 10. Vegetation Management History ................................................................... 31 11. Aquatic Plant Control Options ...................................................................... 35 11.1. No Action ....................................................................................... 35 11.1.1. Advantages and Disadvantages .................................................. 35 11.1.2. Suitability for Barnes Lake ....................................................... 36 11.2. Herbicides ...................................................................................... 36 11.2.1. Advantages and Disadvantages .................................................. 38 11.2.2. Permits and Costs .................................................................. 38 11.2.3. Other Considerations .............................................................. 39 11.2.4. Suitability for Barnes Lake ....................................................... 41 11.3. Manual Methods ............................................................................... 42 11.3.1. Advantages and Disadvantages .................................................. 42 11.3.2. Permits .............................................................................. 43 11.3.3. Costs ................................................................................. 44 11.3.4. Other Considerations .............................................................. 44 11.3.5. Suitability for Barnes Lake ....................................................... 44 11.4. Diver Dredging ................................................................................. 44 11.4.1. Advantages and Disadvantages .................................................. 45 11.4.2. Permits .............................................................................. 45 i pjj 15-06097-000_barneslakeiavmp2016.docx 11.4.3. Costs ................................................................................. 45 11.4.4. Other Considerations .............................................................. 45 11.4.5. Suitability for Barnes Lake ....................................................... 46 11.5. Bottom Screens ................................................................................ 46 11.5.1. Advantages and Disadvantages .................................................. 47 11.5.2. Permits .............................................................................. 47 11.5.3. Costs ................................................................................. 47 11.5.4. Other Considerations .............................................................. 48 11.5.5. Suitability for Barnes Lake ....................................................... 48 11.6. Grass Carp ...................................................................................... 48 11.6.1. Advantages and Disadvantages .................................................. 50 11.6.2. Permits .............................................................................. 51 11.6.3. Costs ................................................................................. 51 11.6.4. Other Considerations .............................................................. 51 11.6.5. Suitability for Barnes Lake ....................................................... 52 11.7. Mechanical Methods ........................................................................... 52 11.7.1. Advantages and Disadvantages .................................................. 52 11.7.2. Permits .............................................................................. 53 11.7.3. Other Considerations .............................................................. 53 11.7.4. Suitability for Barnes Lake ....................................................... 53 11.8. Drawdown ...................................................................................... 53 11.9. Nutrient Reduction ............................................................................ 54 12. Selected Treatment Option ......................................................................... 55 13. Integrated Treatment Plan ......................................................................... 57 13.1. Floating-Leaved Plant Management ........................................................ 59 13.2. Emergent Plant Management ................................................................ 60 13.2.1. Noxious Emergent Plants ......................................................... 60 13.2.2. Native Emergent Plants ........................................................... 60 13.3. Noxious Submerged Weeds ................................................................... 61 13.3.1. Raking ............................................................................... 62 13.4. Floating Mat Management .................................................................... 63 13.4.1. Aquamog Dredging ................................................................. 65 13.4.2. DinoSix Dredging ................................................................... 65 14. Public Outreach ...................................................................................... 67 14.1. Exotic Plant Prevention ...................................................................... 67 14.2. Lakeside Stewardship Education ............................................................ 68 14.3. Watershed Protection/Pollution Prevention .............................................. 69 15. Plan Elements, Costs, and Funding ................................................................ 71 15.1. Source of Funding ............................................................................. 72 15.1.1. Barnes Lake Management District Assessments ..............................