Year One Report - Laguna de Santa Rosa

Ludwigia Control Project Year One Report

January 2006

Prepared by

Table of Contents

Executive Summary 3 1. Introduction 4 2. Location and Description 4 3. Permitting 4 4. Public Notification 6 4.1 Public Workshops 6 4.2 Letters 6 4.3 Press 6 4.4 Tours 6 4.5 Email Notification and Website Updates 6 5. Contracting 7 6. Vegetation Monitoring 7 6.1 Vegetation Monitoring Methods and Discussion 7 6.2 Vegetation Monitoring Results and Discussion 7 6.3 Photo Monitoring 12 6.4 Daily Visual Monitoring 12 7. Herbicide Application 12 8. Vegetation Removal 16 8.1 Bellevue Wilfred Channel, SCWA 16 8.2 Main Laguna Channel, SCWA 17 8.3 Main Laguna Channel and Flooded Wetlands, CDFG 17 9. Vegetation Disposal 17 10. Best Management Practices 18 10.1 Herbicide Application – BMPs 18 10.2 Mechanical Removal – BMPs 18 11. Water Quality 19 11.1 Turbidity 19 11.2 Chemical Parameters 19 11.3 Soil Sampling 20 12. Recommendations for Year Two 20 12.1 Recommendations for SCWA Site 20 12.2 Recommendations for CDFG site 20 Tables

Table 1. Biomass sampling 9 Table 2. Species occurring within sample plots in the Laguna Wildlife Area 9

Ludwigia Control Project: Year One Report 1

Figures

Figure 1. General Locator Map for Ludwigia Control Sites 5 Figure 2. Vegetation Monitoring: Transect and Plot Locations in the Laguna Wildlife Area 8 Figure 3. Frequency distribution of Ludwigia cover and open water within the flooded wetlands of the Laguna Wildlife Area

10

Figure 4. Frequency distribution of non-target species cover in the flooded wetlands of the Laguna Wildlife Area

10

Figure 5. Water depth in the NE flooded wetland of the Laguna Wildlife Area 11 Figure 6. Water depth in the SW flooded wetland of the Laguna Wildlife Area 11 Figure 7. Canopy height as a function of water depth in the Laguna Wildlife Area 12 Figure 8. SCWA Photo Monitoring Locations 13 Figure 9. CDFG Photo Monitoring Locations 14 Appendix and Attachments

Appendix 1. Selected Photo Monitoring Attachment 1. 2005 Project Report: Ludwigia Control in Selected Areas of the Laguna de Santa Rosa (Prepared by Clean Lakes, Inc.)

Attachment 2. Sonoma County Water Agency and Laguna de Santa Rosa Foundation Herbicide Application, WDID No. 1B05047RSON 2005 Annual Report (Prepared by Blankinship & Associates)

Attachment 3. California Department of Fish and Game and Laguna de Santa Rosa Foundation Herbicide Application, WDID No. 1B05082NSON 2005 Annual Report (Prepared by Blankinship & Associates)


Executive Summary The Ludwigia Control Project commenced in summer 2005 under the direction of the Laguna de Santa Rosa Foundation (Laguna Foundation) on behalf of the California Department of Fish & Game and the Sonoma County Water Agency. Ludwigia plants within two heavily infested areas of the Laguna de Santa Rosa were treated with herbicide and then removed by mechanical means. The project operated under a NPDES permit issued by the North Coast Regional Water Quality Control Board. The Laguna Foundation made significant efforts to inform the public about the project including public workshops, mailed letters, email and website updates, press releases, and tours. Both quantitative and qualitative vegetation monitoring were done before and during the course of the project to provide a measure of change. Monitoring will be continued throughout the project period. Application of a glyphosate-based herbicide registered for aquatic use began in mid-July 2005. A total of 115 acres of channels and flooded wetland were treated using a variety of equipment suited to local conditions. The kill rate achieved by the herbicide was approximately 75%. This was likely due to a combination of limited efficacy of both the herbicide and surfactant, method of application, density of existing plants, and timing. In total 5,388 tons of Ludwigia were removed from a total of 44 acres at the two sites. Aquatic harvesters were used in the wider channels. Biomass from these channels averaged 55-60 tons/acre. In the narrower channels a long reach excavator was used to remove the vegetation. Biomass from these channels averaged 173 tons/acre. The vast difference in these values is probably due to the fact that the long reach excavator pulled out more of the sediment that was commingled with the Ludwigia. Site conditions in the flooded wetlands made biomass removal impossible. Vegetation disposal was successfully achieved at one site through drying, shredding and disking in nearby upland fields. The sediment laden biomass from the other site did not dry out and could not be disked in to the soil. The Laguna Foundation is working to convert the biomass into compost by late summer 2006. Best management practices were implemented throughout the project to ensure that impacts to water quality and other natural resources were minimized. Intensive water quality monitoring revealed very low levels of glyphosate and aminomethyl phosphonic acid (a metabolite of glyphosate) present following the application. Heightened turbidity proved difficult to avoid despite several efforts to reduce it. Plans for next year include a repeat of the methods used in the channels. The only change will be an earlier starting date. Because biomass cannot be removed from the flooded wetland, the Laguna Foundation is tentatively planning an experimental approach to that site in which the efficacy of glyphosate is compared against triclopyr. Details for the experiment are not yet complete. Attachment 1, prepared by Clean Lakes, Inc., provides a detailed account of the project in terms of equipment used, acreages sprayed, and volume removed. Attachment 2, prepared by Blankinship & Associates, provides a detailed account of the water quality monitoring as required by the NPDES permit.


1. Introduction The Ludwigia Control Project (LCP) is a three-year effort to reduce the extent and density of the non-native aquatic plant Ludwigia sp. in two key areas of the Laguna de Santa Rosa (Figure 1). The LCP is being carried out by the Laguna de Santa Rosa Foundation (Laguna Foundation) with funding from the Sonoma County Water Agency (SCWA), the California Wildlife Conservation Board, the Marin Sonoma Mosquito & Vector Control District, and the Santa Rosa Subregional Wastewater Treatment Plant. Ludwigia control methods include herbicide treatment followed by mechanical removal of dead biomass. The Laguna Foundation recognizes that this three-year effort will not eradicate Ludwigia but rather it aims to reduce the population to a manageable level. Over the longer term, the Laguna Foundation is working with its partners at the USDA-ARS Invasive Species Research Unit and Sonoma State University to understand and address the root causes of the invasion with the hope that restoration of key ecological functions will make the Laguna more resistant to invasion. This document details what took place in Year One and recommends a course of action for Year Two. The main body of the document was prepared by the Laguna Foundation and represents a complete summary of the entire project. Attachment 1 was prepared by Clean Lakes, Inc., and provides a more in depth description of equipment used and methods employed. Clean Lakes was contracted by the Laguna Foundation to carry out all aspects of herbicide application and vegetation removal. Attachment 2 was prepared by Blankinship & Associates and provides a detailed assessment of water quality testing and analysis as required by the NPDES permit. The Laguna Foundation contracted Blankinship & Associates to carry out water quality monitoring during the project. 2. Location and Description The treatment areas include two of the worst infested areas of the Laguna. The first is owned by SCWA and is located west of Rohnert Park near the intersection of Rohnert Park Expressway and Stony Point Road (Figure 1). It includes the main Laguna channel from its confluence at Hinebaugh and Gossage Creeks to the low flow channel located several hundred feet west of the Stony Point Bridge. Also included is the Bellevue Wilfred channel beginning at Millbrae Avenue and extending south to the main Laguna channel. The entire site comprises roughly 30 acres. The second site is owned by CDFG and is located between Occidental Road and Guerneville Road (Figure 1). This site includes both channel and flooded wetland. The flooded wetlands experience year round inundation. The CDFG site comprises roughly 100 acres. Ludwigia coverage at both the SCWA and CDFG sites is near 100%. 3. Permitting In April 2005, SCWA and CDFG each submitted an Aquatic Pesticide Application Plan (APAP) to the North Coast Regional Water Quality Control Board (RWQCB). Each APAP was prepared jointly by staff from each respective agency and the Laguna Foundation. On July 14, 2005 the RWQCB issued NPDES permits to both agencies. Both sites qualified for a categorical exemption under CEQA.


© 2005

Figure 1Cartography: Amber Manfree Map ID: LdSR-208-A II

City ofSebastopol

City ofSanta Rosa

City ofRohnert

Park

California Department of Fish & Game Treatment Area

Sonoma County Water Agency

Treatment Area

.within the Laguna de Santa Rosa

General Locator Map for Ludwigia Control Sites

Laguna Santade

Rosa

WILFRED

MILLBRAE

STO

NY

PO

INT

ROHNERT PARK EXPY

TAY

LOR

PRIM

RO

SE

WH

I STL

ER

LAN

GN

E R

HA

RG

RA V

E

B

el l

ev

ue

-W

ilfre

d F

lo

od

Co

ntr

ol C

hannel

H

inebau

gh Cree k

La

ba

th

Creek

FREI

OCCIDENTAL

HWY 116

HALL

SCOTTS

BARCAGLIA

La

gu

na

de

Sa

nta

Ro

sa

Town ofWindsor

tu101

California Department of Fish & Game Treatment Area

HWY12

HWY12

City ofCotati

LegendLaguna watershed boundary

Ludwigia treatment area

Water 0 0.5 1 1.5 20.25Miles

Sonoma CountyWater Agency

Treatment Area

Ludwigia Treatment Areas in the Laguna de

Santa Rosa Watershed

0 0.2 0.4 0.6 0.80.1Miles

0 0.2 0.4 0.6 0.80.1Miles

HWY116

4. Public Notification The Laguna Foundation took numerous steps to ensure that the general public was informed about the project. These steps are detailed below. 4.1 Public Workshops On April 21, 2005 the Laguna Foundation hosted a public participation meeting at the Steele Lane Community Center in Santa Rosa. This well-attended meeting included a general presentation by Sonoma State University professor Dr. Hall Cushman on the threats posed by invasive species followed by Laguna Foundation staff member Dr. Anna Sears’ presentation on how the Laguna Foundation proposed to address the Ludwigia invasion in the Laguna. Presentations were followed by a question and comment period facilitated by Rohnert Park Mayor Jake Mackenzie. A public workshop was given on May 12, 2005 at the offices of the Regional Water Quality Control Board. The purpose of the meeting was to allow the public to respond directly to the RWQCB regarding the proposed project. Dr. Anna Sears made a presentation on the project. Mike Blankinship of Blankinship & Associates gave a presentation on the ecotoxicology of glyphosate and surfactants. Members of the public then made comments to the RWQCB staff and board. 4.2 Letters The Laguna Foundation mailed informational letters to fifty-six landowners living directly adjacent to the treatment areas. Letters included information on the project, contact information, and an FAQ sheet. Letters were mailed roughly three weeks prior to herbicide application. 4.3 Press Press releases were made to the Santa Rosa Press Democrat (Santa Rosa), the Sonoma West Times, and the Rohnert Park Community Voice. Reporters for the Press Democrat and the Sonoma West Times visited the project sites and were given tours by land and water. 4.4 Tours Throughout the season the Laguna Foundation and Clean Lakes, Inc. provided tours to members of the public, grantors, regulatory agencies and local officials. Tours were given by boat, swamp cat or on foot. 4.5 Email Notification and Website Updates Each week the Laguna Foundation emailed a brief progress update to eighty individuals including members of the public, grantors, regulatory agency staff and local officials. The updates included information on the work accomplished each week as well as a forecast for the following week. More detailed reports were prepared each week by Clean Lakes and posted on the Laguna Foundation website.


5. Contracting The Laguna Foundation issued a Request for Proposals to four contractors (Clean Lakes, Aquatic Environments, Agri-Chem, and Pestmasters) for the tasks of herbicide application and vegetation removal. Two formal proposals were submitted and Clean Lakes, Inc. was chosen after interviews and careful evaluation of both proposals. Blankinship & Associates was selected for water quality monitoring based on its expertise and experience. 6. Vegetation Monitoring In order to measure project success the Laguna Foundation initiated both quantitative and qualitative vegetation monitoring. Quantitative monitoring included biomass sampling and data collection on species composition and cover. Qualitative sampling included photo monitoring. Each is detailed below. 6.1 Vegetation Monitoring Methods and Discussion Biomass Sampling In early August 2005, six above ground biomass samples of Ludwigia were collected within the floodplain adjacent to but outside of the herbicide treatment area (Figure 2). Three samples each were taken in low and high density patches using 0.25 square meter plots. Vertical stems were clipped using shears. The dense tangle of above-ground root mass was removed with the aid of a machete. Samples were bagged and taken to Sonoma State University where they were rinsed to remove sediment and then weighed. Wet weight was taken using a balance beam scale, accurate to within a pound or so. Samples were then dried using a standard method of oven drying for 48 hours. Biomass was then weighed again on electronic balance scale. Because wet weights are the most relevant to the LCP, only wet weight results are presented in this report. Plot Sampling Four transects were established within the two flooded wetland areas of the Laguna Wildlife Area (Figure 2). Two transect endpoints were randomly selected at the eastern edge of each floodplain and then followed to the western edge of the field. Each transect had a minimum of 10 plots. These 4x5 meter plots were established by walking a pre-determined distance from the endpoint (e.g. every 15 meters). The stopping point marked the southeast corner of the plot, which was mapped using a Garmin Etrex Vista GPS accurate to within ~15 feet. A total of forty-three plots were established. In each plot data was taken on species richness and cover. The area of open water was also recorded. Three measurements of both water depth and Ludwigia canopy height were taken and averaged within each plot. All data was collected on June 30 and July 1, 2005. 6.2 Vegetation Monitoring Results and Discussion Biomass Sampling Based on a treatment area of 115 acres, the Ludwigia biomass averaged roughly 2,500-5,700 tons depending on density with some areas showing much higher weights (Table 1). This equates to an average 22-49 tons/acre.


© 2006

Figure 2Cartography: Amber Manfree Map ID: LdSR-235A

Vegetation Monitoring: Transect and Plot Locations in the Laguna Wildlife Area .

!! !!!!!!!! !!

!! !!!!!!!! !!

!! !!!!!!! ! !!

!!!! !!!!!!!! !!

T4

T2

T1

T3

La gu n a de San

ta R

osa

Legend! Transect sampling points

Biomass sampling area


Water

Northeast Field

Southwest Field

0.1 0 0.10.05 Miles

Table 1. Biomass sampling of above ground biomass in the floodplain areas adjacent to the

lbs/m2 lbs/acre total lbs in treatment area total tons tons/acre

Low Density Sample 1 9 36,422 4,188,496 2094 18Sample 2 12 48,562 5,584,662 2792 24Sample 3 11 44,515 5,119,273 2560 22

Average 10.67 43,166 4,964,144 2482 22High Density Sample 1 34 137,593 15,823,209 7912 69Sample 2 23 93,078 10,703,935 5352 47Sample 3 16 64,750 7,446,216 3723 32

Average 24.33 98,474 11,324,453 5662 49

Laguna Wildlife Area. Figures are for wet weight.

1Based on a total area of 115 acres. Plot Sampling Species richness in the floodplain fields was low; only six species (including Ludwigia) were encountered in the plots. Except for Ludwigia, the cover and frequency of all species was also low (Table 2; Figure 3 and 4). In the case of cocklebur (Xanthium strumarium), most individuals found in the floodplain were skeletal stalks from the previous year. However, a large number of individuals of this native plant thrive adjacent to the flooded areas where the inundation period is shorter. Although this plant is well adapted to disturbance, it may not tolerate sustained inundation. Alternatively, it is being outcompeted by Ludwigia. Smartweed (Polygonum amphibium var. emersum), an aggressive and abundant native species in the Laguna, also appears unable to compete with Ludwigia. In the Aggio field, located north of the treatment area, smartweed occurs in profusion. In years prior to 2005, this field has been drained, plowed, and planted with corn. This year the water levels were too high to drain the field and smartweed quickly occupied the field. By the end of the season, however, Ludwigia also showed a significant presence in the field. If sustained shallow flooding conditions persist in this field in the coming years it is likely that Ludwigia will become the dominant cover. Other species observed within the flooded wetland but outside of the plots included Typha sp., Scirpus sp., Carex sp., and Polygonum persicaria, though none occupied large areas. Table 2. Species occurring within sample plots in the Laguna Wildlife Area.

Common Name Species Name Frequency of Occurrence (%)1

Native?

cocklebur Xanthium strumarium 2 Yes water plantain Alisma plantago aquatica 2 Yes

willow Salix sp. 2 Yes water primrose Ludwigia sp. 100 No

Smartweed Polygonum amphibium var. emersum 7 Yes knotgrass Paspalum distichum 4 Yes

1Based on the number of occurrences in forty-three sample plots.


05

10152025303540

Absen

t1-5

%6-2

5%

26-50

%

51-75

%

76-95

%

96-10

0%

cover class

# of

plo

ts

LudwigiaOpen water

Figure 3. Frequency distribution of Ludwigia cover and open water within the flooded wetlands of the Laguna Wildlife Area. A total of forty-three 20m2 plots were sampled.

05

1015202530354045

Absen

t1-5

%6-2

5%

26-50

%

cover class

# of

plo

ts

Polygonum amphibium var.emersumAlisma plantago aquaitica

Paspalum distichum

Xanthium strumarium

Salix spp

Figure 4. Frequency distribution of non-target species cover in the flooded wetlands of the Laguna Wildlife Area. A total of forty-three 20m2 plots were sampled. Species other than Ludwigia were absent in the majority of plots. Water depth varied between 0.1-0.9 meters across the flooded wetland. Transects 1 and 2 were located in the northeast field and generally showed increasing depth from east to west (Figure 5). This is expected since the flooded wetland meets the channel at its western edge. Additionally, water tends to pond on the upland side of a constructed berm, which separates the flooded wetland from the channel. During most of the 2005 season, however, the water level was higher than the berm.


0.000.100.200.300.400.500.600.700.800.901.00

1 2 3 4 5 6 7 8 9 10 11 12

plot number

wat

er d

epth

(m) T-1

T-2

upla

nd

berm

Lagu

na c

hann

el

Figure 5. Water depth in the NE flooded wetland of the Laguna Wildlife Area. The transects run east to west and exhibit increasing depth until reaching the berm, which separates the floodplain from the Laguna channel.

0.00

0.10

0.20

0.30

0.40

0.50

1 2 3 4 5 6 7 8 9 10 11 12

plot number

wat

er d

epth

(m)

T-3T-4

Lagu

na c

hann

elbe

rm

flood

ed fo

rest

are

a

Figure 6. Water depth in the SW flooded wetland of the Laguna Wildlife Area. The east-west bearing transects begin at the channel and end where the field transitions into flooded forest. Transects 3 and 4 were located in the southwest flooded wetland and ran from east to west. In this case, the channel berm marked the eastern edge of the field. The western edge of the wetland was unclear because it grades into a flooded forest area before transitioning into upland. Measurements in the field showed no consistent depth pattern (Figure 6). No data was collected in the forested area. Although a true understanding of the topography of the flooded wetlands would require greater than four transects, it is helpful to understand where the depressions are located as these could be enhanced into open water areas in future restoration projects.


Canopy height measurements did not show a clear relationship to depth (Figure 7). It appears that Ludwigia is not limited by the variations in water depth that occur in these flooded wetlands.

0.00.20.40.60.81.01.21.41.61.8

0.1 0.1 0.2 0.2 0.28 0.3 0.3 0.3 0.3 0.3 0.4 0.7

00.8

00.9

0

water depth (m)

heig

th o

f can

opy

(m)

Figure 7. Canopy height as a function of water depth in the Laguna Wildlife Area. 6.3 Photo Monitoring Thirty-four photo monitoring stations were established at known locations within the CDFG and SCWA treatment areas (Figure 8 and Figure 9). The purpose of photo monitoring is to record changes over time. Therefore we took photos before herbicide treatment, several weeks after herbicide treatment and again after mechanical removal. Multiple pictures can be taken at each station with the result that 51 photos were taken at the CDFG site and 23 at the SCWA site during each visit. Because of the large number of photos, only a sampling is provided in this report (Appendix 1). In addition to the above photo monitoring, 20 additional photo points were established to document the removal of willow trees for access to the main Laguna channel at the SCWA site. These were taken at the end of the mechanical removal period to document the removal, verify regrowth and determine whether mitigation will be required. 6.4 Daily Visual Monitoring The Laguna Foundation kept a Daily Visual Monitoring log book for each site. The log book provides a summary of the visual appearance of the water, plants and wildlife. 7. Herbicide Application A total of 115 acres were treated with herbicide. This included 29 acres of channels and 86 acres of flooded wetlands. A variety of equipment was used to suit particular conditions at each site. Trucks equipped with pumps and hoses were used along narrow channels, such as the Bellevue Wilfred Channel, while airboats were used in the wider channels. The CDFG flooded wetlands required use of a Marsh Mog, a machine similar in appearance to a snow cat used at ski resorts but designed to work in up to two feet of water. Amphibious Argo’s were also used in this section. Backpack sprayers were used


© 2005


Photo Monitoring Locationswithin the SCWA Treatment Area .0 0.1 0.2 0.3 0.4 0.50.05

Miles

Be

lle

vu

e W

ilfre

d F

loo

d C

on

tro

l C

ha

nn

el

PPL

PPK

PPJPPI

PPH

PPG

PPFPPE

PPD

PPC

PPB

PPA

WILFRED

MILLBRAE

STO

NY

PO

INT

P RI M

RO

SE

ROHNERT PARK EXPY

WH

ISTL

ER

TAY

LOR

LAN

GN

ER

HA

RG

RAV

E

MARTIN

PARK

LAN

GN

E R

TAY

LOR

Laguna de Santa Rosa

Hin

e

ba ug

h C

ree

k

La

ba

th

Creek

LegendSCWA photo points


Water

© 2005


2005 Photo Monitoring Locationswithin the CDFG Laguna Wildlife Area .0 0.1 0.2 0.3 0.4 0.50.05

Miles

PPF

PPE

La

gu

na

de

Sa

nta

Ro

sa

PPS

PPR

PPQ

PPPPPO

PPN

PPM

PPLPPKPPJ

PPI

PPH

PPG

PPDPPCPPB

PPA

HALL

OCCIDENTAL RD

SAN

FOR

D

AT

KINS ON

ALEM

Irw in C reek

Fre

i Creek

Smith Creek

LegendCDFG photo points


Water

NortheastField

SouthwestField

in hard to reach areas. (Additional pictures of the equipment can be found in Attachment 1.) In order for the airboat to move through the channels, it was first necessary to clear a path through the Ludwigia. This was done using a Cookie Cutter, which was lowered into and pulled out of each site with a crane.

The herbicide used was Glypro®, a registered aquatic herbicide with the active ingredient glyphosate. This was mixed with the surfactant Cygnet Plus®. Surfactants are designed to help the herbicide penetrate the plant’s waxy cuticle. A drift control agent was also mixed in to increase the density of the liquid which reduces drift potential. Finally, a blue marker dye was added so the liquid would be visible. The Sonoma County Agricultural Commissioner’s office oversaw the initial mixing to ensure compliance with all laws and regulations. More detail on the volume of herbicide used and dates of application are given in Attachments 1 and 2. The herbicide achieved roughly a 75% kill rate on the plants with which it came in contact (see Appendix 1 for before/after pictures). However, in many areas regrowth was seen quickly after the application. It is possible that what appeared to be regrowth was in fact new plants taking advantage of light gaps though there is no data to support this. There are several possible reasons for the incomplete kill and rapid regrowth.

• Efficacy of herbicide. Although glyphosate provides a desirable balance between reasonably high efficacy and low mobility and toxicity, it is possible that it did not have the strength to kill the plant entirely. It would be useful to compare the efficacy of glyphosate against other herbicides such as triclopyr.

• Efficacy of surfactant. Cygnet Plus® may also have had limited efficacy. Again, it would be useful to try an alternative surfactant.

• Method of application. One of the most desirable qualities of glyphosate is that it adsorbs readily to soil particles and therefore is not at risk of leaching. However, in applying the glyphosate with the Marsh Mog it was necessary to drive over the plants which covered some of them with muddy water. Because the spray hoses are located on the back of the Marsh Mog, the coating of muddy water occurred just before the spraying. In effect, the glyphosate may have been become bound


up as soon as it hit the plant. This would have rendered a significant portion of the glyphosate ineffective. Although aerial application of the herbicide would avoid this problem, it is not being considered due to its controversial nature. This reinforces support for trying an alternative herbicide.

• Canopy density. Ludwigia has been accumulating for 10-15 years in these areas and has become particularly dense in the past 5 years. It is possible that a significant number of the plants were never hit by the glyphosate because it was intercepted by the tallest plants. The canopy is expected to be less dense next year as a result of this year’s control effort.

• Timing. The first application of herbicide was July 18, 2005. By this point in growing season, Ludwigia had already added substantial biomass. If application can be made earlier in 2006 there will be less growth.

8. Vegetation Removal In most cases, the herbicide was given 3-5 weeks to kill the plants before mechanical removal began. The process of removal was extremely labor and equipment intensive. This was due in part to the nature of the work but also the sheer volume of biomass that had built up over the past decade. Woody stems from years past formed a solid mass from the channel base to the water surface. Living material extended up to 4 feet out of the water. In some cases the channels had to be cleared up to 3 times to remove all the biomass that floated up after the surface had been cleared. In the process of removal, a massive volume of garbage was also removed including furniture, camper shells, car bumpers, and a large number of tires. In total 5,388 tons of Ludwigia was removed from a total of 44 acres at the two sites. This works out to roughly 122 tons/acre, a number far higher than expected based on the biomass sampling (see Section 6.2). However, there was high variability between sites in terms of the tons/acre. Broad descriptions of the removal at each site are provided below with more detail available in Attachment 1. 8.1 Bellevue Wilfred Channel, SCWA In the Bellevue Wilfred Channel a 62.5 foot long-reach excavator was used to scoop the material with great effect. The excavator operated from access roads on either side of the channel. Approximately 2,764 tons of biomass and commingled sediment were removed from this 16-acre area of channel (average 173 tons/acre). The biomass was loaded into dump trucks and hauled to a nearby upland location for storage. Six hundred and ninety one dump truck loads were transported from the Bellevue Wilfred channel. Removal was generally done in an upstream to downstream direction. When the final strip of Ludwigia was removed within this channel the water level dropped 1-2 feet.


8.2 Main Laguna Channel, SCWA The majority of the main Laguna channel was cleared using aquatic harvesters. Because the harvesters are unable to effectively uproot the plant, the Cookie Cutter was brought in to chop the dead biomass before harvesting. Harvesters removed an estimated 660 tons of Ludwigia biomass from this section revealing 12 acres of clear channel that had not been seen in years (average 55 tons/acre). Low water levels in the upstream section of the main channel prevented access by the harvesters. Fortunately the long-reach excavator could access this area via the maintenance road on the north bank of the channel. The excavator removed an additional 1,012 tons of biomass and commingled sediment from this portion of the main channel. Transport to the storage site required another 253 trips by dump truck. 8.3 Main Laguna Channel and Flooded Wetlands, CDFG The same process of chopping the dead Ludwigia biomass followed by harvesting was used successfully to clear the main Laguna channel at the CDFG site. Success was less pronounced in the flooded wetlands where low water levels made biomass removal impossible in roughly 85% of the area. A total of 952 tons of Ludwigia was removed from this site to reveal roughly 16 acres of open water (average 60 tons/acre). 9. Vegetation Disposal At both sites the plan for disposing of the biomass was to windrow it in nearby upland fields, allow it to dry, shred it and then finally disk it in to the field. Because Ludwigia cannot grow in uplands, there is no threat of spreading the plant in these areas. At the CDFG site this worked well. Excavators were used to load the biomass into trailers, which were then hauled by tractors and placed in windrows. The biomass eventually dried sufficiently to enable it to be shredded and subsequently disked. This was done in October.

Sediment laden pile of Ludwigia

At the SCWA site the job was far more challenging. All of the biomass removed using the long-reach excavator was laden with silty sediment, which prevented the windrows from drying out. Knowing that the biomass could not be disked in to the soil, the Laguna Foundation partnered with Sonoma Composters and made a plan to turn the nearly 17,000 cubic yards of biomass into compost. Sonoma Composters hauled 8 truckloads of the biomass to its facility to experiment with different methods of converting it to compost.

In the meantime, the biomass was left to over winter in the field. The Laguna Foundation


and Sonoma Composters plan to have the compost ready by late summer 2006. While this process will have associated cost, it is far cheaper than hauling the biomass to the dump. Because the windrows occupied the field longer than expected, the Laguna Foundation compensated the tenant for lost crop income on roughly 27 acres. 10. Best Management Practices The Aquatic Pesticide Application Plans for each site described the Best Management Practices (BMP) to be implemented during the project. This section discusses BMPs used during herbicide application and vegetation removal. 10.1 Herbicide Application - BMPs

• A pesticide use recommendation was made by Tom McNabb, a licensed pest control adviser.

• Herbicides were applied by certified pesticide applicators. • All chemicals were carefully mixed using volumes specified by the pest control

adviser and the herbicide labels. Initially the measurement and mixing was done under the supervision of the Sonoma County Agricultural Commissioners office.

• Applicators wore protective equipment including skin and eye protection. • All spray operations ceased when wind speeds exceeded 10 mph. Wind meters

were used to check wind speed every 30 minutes. • A drift control agent was mixed in with the herbicide to increase the density of

liquid. This reduces the potential for drift. • Herbicide was applied from a downstream to upstream direction to avoid

accumulation of chemicals. • All applications were completed before October 1st to avoid contact with

salmonids. 10.2 Mechanical Removal – BMPs

• A minimum number of trees were trimmed to allow the long-reach excavator to access the main Laguna channel at the SCWA site. These trimmed trees will be monitored over the project period. If the trees do not regrow, they will be replaced at a 3:1 ratio per the direction of the Regional Water Quality Control Board.

• Two areas of channel bank within the SCWA site were disturbed enough to warrant erosion control measures. The first was located on the east side of the Bellevue Wilfred Channel about 150 feet south of the Rohnert Park Expressway. This area was entirely denuded of vegetation. To control erosion the banks were seeded with a mixture of 70% regreen (a sterile annual grass used widely in erosion control), 15% meadow barley (Hordeum brachyantherum), and 15% creeping wild rye (Leymus triticoides). Roughly 3600 sq ft of biodegradable erosion control cloth fastened in place with biodegradable stakes were installed over the seeded area. The second site was located west side of the Bellevue Wilfred channel about 250 feet north of Rohnert Park Expressway. This was seeded with the same mixture and covered with sterile hay. The slope of the bank did not warrant the use of erosion control cloth.


• Two areas were disturbed at the CDFG site as well. These were flat terraces above the channel bank. Both areas were seeded with the same mixture and covered with sterile hay.

• Several efforts were made to reduce turbidity during mechanical removal including:

o Instructing all equipment operators to reduce the speed of work. This had very little effect because the channels are so shallow and the sediment is easily disturbed no matter how slowly the equipment is moving.

o Deploying silt curtains downstream of the project area at both sites to contain the increased turbidity.

o Removing vegetation in an upstream to downstream direction. This was the most effective method of containing turbidity. Suspended sediments were immediately blocked from moving downstream by Ludwigia.

11. Water Quality To ensure that water quality was not compromised during the project, the Regional Water Quality Control Board (RWQCB) included substantial water quality monitoring requirements within the NPDES permit. This section summarizes results of the water quality monitoring for turbidity, glyphosate, aminomethyl phosphonic acid (AMPA), and limonene. Attachments 2 and 3 provide detailed water quality reports for the SCWA and DFG sites respectively. These were prepared by Blankinship & Associates. 11.1 Turbidity Turbidity was among the chief water quality concerns associated with this project. The NPDES permit stated that turbidity levels should not exceed greater than 20% above background levels. The nature of the work and the conditions within the Laguna channels made this a very difficult goal during the mechanical removal. Although the turbidity levels exceeded the goal on several occasions, BMPs were implemented to reduce the amount and extent of turbidity within and outside of the project area (see section 10.2). Intense monitoring revealed, however, that heightened turbidity levels did not last long after in-channel activity stopped. The Laguna Foundation kept regular contact with the RWQCB staff throughout the project to inform them of the violations and actions taken to reduce the heightened turbidity. 11.2 Chemical parameters Grab samples were collected upstream, within, and downstream of the project areas. Collections were made before, during and after herbicide application. This section presents results for three of the chemical parameters:

• Glyphosate. This is the active ingredient in the herbicide. The water quality objective (WQO) for glyphosate as stated in the NPDES General Permit is 700µ/L. Post-application sampling revealed levels of 27µ/L and 28µ/L at the CDFG and SCWA sites respectively. This level is 96% better than the WQO and 1/5000th the LC50 (lethal concentration that kills 50% of the organism) for rainbow trout.

• Aminomethyl-phosphonic acid (AMPA). This is the principal metabolite of glyphosate after it has broken down. Because glyphosate breaks down rapidly it


is important to know the volume of the metabolite present. Post-application sampling revealed 9µ/L at the SCWA site and no detection at the DFG site. There is no established WQO for AMPA.

• Limonene. This is the active ingredient in the surfactant Cygnet Plus®. Post-application sampling at both sites revealed no detection.

11.3. Soil sampling Although not required by the NPDES permit, the Laguna Foundation had three soil samples located beneath the windrows of Ludwigia tested for glyphosate, AMPA, and limonene. There was no detention of any of the chemicals in any of the samples. 12. Recommendations for Year Two Year one provided important practical experience in controlling Ludwigia within two very different habitat types with the Laguna: channels and flooded wetland. Although the herbicide applications were largely successful in killing the plant, significant areas experienced incomplete kill and in some cases rapid regrowth. The method of application may have played a role (see Section 7) but it does not account for incomplete kill in channel areas that were sprayed from shore. Undoubtedly the density of the canopy played a role by restricting herbicide penetration. Beginning earlier (i.e. June 15) in Year Two would ensure lower density in the canopy and is likely to enhance penetration. A second herbicide, Renovate (active ingredient triclopyr) is also being considered for use on an experimental basis in the flooded wetland area. It would be compared against glyphosate. Significantly less mechanical removal is expected in Year Two. To be sure this will depend on the level of regrowth but even heavy regrowth would not result in the density experienced in Year One, which resulted from many years of accumulation. 12.1 Recommendations for SCWA site Herbicide application will follow the same protocol as Year One. This includes the use of a glyphosate-based herbicide registered for aquatic use. Herbicide application will begin June 15 or as directed by NOAA fisheries, the RWQCB and the NPDES permit. Equipment used for mechanical removal will be the same. The long reach excavator may be modified to enable it to capture the center strip in the widest portions of the Bellevue Wilfred channel. Removed biomass will be loaded directly into trucks and hauled to the City of Santa Rosa’s Brown farm pending approval from the City. The biomass will be composted in place at the farm. The biomass piles from Year One will be turned and mixed by Sonoma Composters. Assuming the composting process in successful, the compost will be sold, given away, and/or disked in to the field. 12.2 Recommendations for CDFG site Herbicide application in the channel will follow the same protocol as Year One. This includes the use of a glyphosate-based herbicide registered for aquatic use. Herbicide


application will begin June 15 or as directed by NOAA fisheries, the RWQCB and the NPDES permit. The project area will be extended approximately 3,300 feet north to include the channel extending just north of the Gallo mitigation ponds. This is expected to further increase drainage in the channel and perhaps the flooded wetland area. Mechanical removal in the channel will also follow the same protocol. Except for the new area, it is expected that there will be far less biomass in Year Two. Mechanical removal will not be possible in the flooded wetland areas. Therefore the effort will focus on herbicide application only. In order to learn as much as possible about the efficacy of the herbicide application, the Laguna Foundation is tentatively planning an experiment to test the efficacy of two herbicides (glyphosate and triclopyr) in killing Ludwigia. Details of the experimental design are forthcoming.


Appendix 1: Select Photo Monitoring Series from CDFG and SCWA

Treatment Areas

CDFG Laguna Wildlife Area: Photo Point A-01

Pre-spray July 2005 This series of the

section of channel located adjacent to the Aggio field was not intended for treatment this year. Therefore it was not sprayed. Because of concerns that the untreated channel was causing a bottleneck and causing neighboring land to flood, Ludwigia was mechanically removed in October and the banks were subsequently sprayed.

Post-spray August 2005

Post-removal October 2005

CDFG Laguna Wildlife Area: Photo Point B-05

Pre-spray July 2005

This series was taken in the northeast floodplain field. Here the glyphosate worked quite well. Through mechanical removal, a large section of open water was opened up.



CDFG Laguna Wildlife Area: Photo Point C-11

Pre-spray July 2005

This series was taken in the northeast floodplain field. Here the glyphosate worked quite well. Unfortunately the water levels were too low to permit mechanical removal with aquatic equipment and too high for use of terrestrial equipment. Post-spray

August 2005


CDFG Laguna Wildlife Area: Photo Point H-26

Pre-spray July 2005

This series of photos shows how the herbicide reduces the vigor of the plant and causes some of it to sink. Mechanical removal requires many passes through the same area to get all of the sunken biomass from the previous year and from years past. Post-spray

August 2005


CDFG Laguna Wildlife Area: Photo Point K-35

Pre-spray July 2005

This series shows a section of channel where Ludwigia growth is not complete acrtoss the channel but it has a substantial presence on the bank. In the post spray some of the Scirpus sp. has died back and a significant cover of Polygonum sp. has appeared.



CDFG Laguna Wildlife Area: Photo Point L-38

Pre-spray July 2005

Another series showing a dramatic clearing of the channel following mechanical removal. Dying Ludwigia remains on the banks.



CDFG Laguna Wildlife Area: Photo Point Q-46

Pre-spray July 2005

This series was taken in the southwest floodplain field. Glyphosate had an obvious effect. Too little water present to remove the biomass. What is not visible is the regrowth occurring within the field, a shortcoming of glyphosate.



SCWA Channels: Photo Point B-02

Pre-spray July 2005

This series of the Bellevue Wilfred channel was shot looking northeast off the Whistler Bridge. The glyphosate appears to have damaged but not killed the Ludwigia. Mechanical removal was very successful in removing the biomass.



SCWA Channels: Photo Point C-04

Pre-spray July 2005

This series of the Bellevue Wilfred channel was shot looking north off the Wilfred Bridge. The glyphosate appears to have damaged but not killed the Ludwigia and Typha. Mechanical removal was very successful in removing the biomass. Post-spray

August 2005


SCWA Channels: Photo Point D-07

Pre-spray July 2005

This series was taken in the Bellevue Wilfred channel looking north toward the Wilfred Bridge.



SCWA Channels: Photo Point F-10

This series of the Bellevue Wilfred channel was shot looking north off the Rohnert Park Expressway. The open water area in the center of the photos remains from July to August indicating that the glyphosate did enough damage to prevent the plant from growing. Alternatively, the water may be deep enough that Ludwigia has difficulty colonizing it. Even with a 62 foot long reach excavator, a small strip down the middle evaded removal.

Pre-spray July 2005



SCWA Channels: Photo Point H-12

Pre-spray July 2005

This series of the main Laguna channel was shot looking east off the Stony Point Bridge. The open water section may be too deep for Ludwigia colonization. Aquatic harvesters were used to remove the biomass following the spraying.



SCWA Channels: Photo Point I-13

Pre-spray July 2005

This series of the main Laguna channel was shot looking west off the Stony Point Bridge.



Documents

Year One Report - Laguna de Santa Rosa