## A Review and Assessment of the Results of Water Monitoring for Herbicide Residues

For the Years 1991 to 1999 USFS Region Five

David Bakke Regional Pesticide-Use Specialist

February, 2001Page 2 

### Abstract

Water quality monitoring has long been associ ated with herbicide use in Region 5 of the Forest Service. The 1989 R5 Vegetation Mana gement for Reforestation FEIS Record of Decision requires the consideration of wa ter quality monitoring. This has led to monitoring surface and ground water on severa l operational herbicide projects since

1991.

There have been eight Forest reports on glyphosate monitoring, and five reports on triclopyr monitoring. Results from these repo rts indicate that glyphos ate and triclopyr are rarely detected in surface water. This resu lt is expected from the respective herbicide

characteristics. Detections have been asso ciated with use within riparian areas or not following established Best Management Practic es. There have been nine reports on hexazinone surface water monitoring and eight on ground water monitoring. Hexazinone

has been detected numerous times in both surface and ground water, which is also expected, based on the herbicide characteristics . If label direction and Best Management Practices are followed, detected amounts of he xazinone are very low. Projects utilizing hexazinone should be carefully designed to reduce the chances of unintentional direct

introduction of hexazinone into surface water.

Many of the herbicide water monitoring proj ects in R5 have not consistently used adequate quality controls. The accuracy of th e data must be considered in that light.Page 3 

### I. Introduction

In February 1989, the Record of Decision (R OD) was signed for the Final Environmental Impact Statement on Vegetation Management for Reforestation (R5 FEIS). This ROD allowed the local land manager to utilize all available tools, including herbicides, for the management of competing vegetation in conife r plantations in Region 5. Included in the ROD (page 12) was the requirement that each project involving the use of herbicides in proximity to water conduct monitoring of wate r quality, as defined in the project’s site specific environmental analysis. This was a reiteration of the water monitoring described in the R5 FEIS, on page 2-32, in which the m onitoring was intended to “identify patterns of herbicide persistence and mobility at sens itive sites”. Monitoring can also include implementation monitoring, to determine whet her mitigations that are supposed to be implemented actually are completed.

Since the R5 FEIS was signed, several Forests have initiated herbicide treatments that have resulted in water monitoring. Sin ce 1991, about 113,000 acres have been treated with herbicides to aid in reforestation; th ese acres have occurred on well over 30 separate projects. There have been three herbicides that have been mo nitored: glyphosate; triclopyr; and hexazinone. The documentation of this monitoring has been recorded in various formats and at varying frequencies since the first monito ring was conducted in the Region after 1989, on the Eldorado NF, in 1991. Considerable effort and financial resources have been expended to collect these monitoring data, and develop these reports. This review is intended to pull together th e various reports comple ted over the past 10 years, and compare the results with the assump tions in the R5 FEIS as well as to develop

conclusions or recommendations that can be passed on to project managers.



### II. Assumptions in the R5 FEIS

The R5 FEIS assumes, for the purposes of an alyzing effects to human health and wildlife (including fish and other aquatic organism s), that certain amounts of any applied herbicide will drift to nearby wa tercourses. The amount considered in the R5 FEIS as the

realistic water contaminati on rate is 10 parts per bill ion (ppb) per 1-pound active ingredient (lb ai) applied ( pg F-84). The 10 ppb rate is a conservative rounding-up of 7 ppb, calculated by assuming that 1% of any a pplied herbicide would move to the other side of a 50-foot unsprayed buffer strip as a result of a 5 mph cro sswind. The resulting

water concentration is based on this errant herbicide being de posited into a 6” deep creek (page F-84).

Table 4-11 in the R5 FEIS (page 4-49), shows ‘realistic’ and ‘worst case’ concentrations in water based on the drift assumptions and us ing the mid-range (realistic) rate of use (from Table F-27, page F-93), or the label ma ximum rate (worst case) as well as a 1.21 multiplier to represent mixing and overlap errors. [There is an error in this table, for the realistic concentration of hexazinone; the mid -range application rate is 2.25 lbs/ac for hexazinone, which should equate to 0.022 parts per million (ppm), instead the value in Table F-27 shows 0.011 ppm.] The values for glyphosate from Table F-27 are 2.75 lbs and 5 lbs for mid-range and for label maximum; the values for triclopyr are 4 lbs and 8Page 4 lbs; and for hexazinone are 2.25 lbs and 3 lbs. This results in concentrations for glyphosate (from Table 4-11) of 0.028 and 0.061 pp m for realistic and worst case. For triclopyr, they are 0.040 and 0.097 ppm, and for hexazinone (corrected) they are 0.022 and 0.036 ppm.

Table 4-2 in the R5 FEIS (page 4-8) shows th e results of water quality monitoring in the period 1974 to 1984. During this period, glyphos ate and hexazinone were sampled, but triclopyr was not. Of 50 glyphosate samples, only 1 had detected residues, and that was below 10 ppb. Of 29 hexazinone samples, only 1 had detectable residues, and that was at 2 ppb. Of the total water monitoring conducte d during this period (1,237 samples, most of which involved 2,4-D), 90% of samples had no detections, 9.7% ha d detections at or below 10 ppb, and 0.3% of samples had levels up to 40 ppb (R5 FEIS, pages 4-8 and 4- 11).

The R5 FEIS expects that storm runoff may result in brief increases in herbicide

concentrations but that because such increa ses are transitory and because the R5 FEIS assumes relatively little herbicide exposure contributed by drinking water (as opposed to other sources of exposure), “runoff is unlik ely to significantly contribute to human exposure and it is not consider ed in this analysis” (page F-87). This is referring to surface runoff, not subsurface movement. On page 4-10, the R5 FEIS states, “Contaminated sediment, leached soil water, and surface water have not been shown to produce significant concentrations of herbicid es.... Accidental direct application and drift are the most likely ways detect able amounts of herbicides coul d enter forest streams.”

The R5 FEIS (Table 4-3, page 4-9) assu mes that glyphosate has a half-life in the environment, in both soil and water, of less th an 3 months. Triclopyr is assumed to have

a half-life of less than 3 months in soil, and only 7 days in water. Hexazinone has a halflife up to 12 months in soil and 8 months in water.Page 5 

### III. Summaries of Monitoring Reports – 1991 to 1999

The following summaries are taken from the av ailable written reports as of December 2000, as well as some personal communications on results not yet incorporated in final reports. A reference number follows each study title; refer to the Re ferences (Section V) for the complete identification of these re ports. This section is broken into four subsections: hexazinone ground water resu lts; hexazinone surface water results; glyphosate surface water results; and triclopyr surface water resu lts. In this section, if field quality control (spike and blank samples) was implemented, it is noted.



### A. Hexazinone Ground Water Results

Sierra NF Study (Reference 8)

Background – Stand 728-505. Lewis Creek Wate rshed, Mariposa RD. 4400’ elevation.

Holland Soil. 3 lbs/acre hexazinone a pplied March 15, 1994. Formal study with lysimeters installed, catchment basin to measure hexazinone movement into ‘vadose zone’ (above water table, unsaturated soils) as well as surface flow. Test plot at edge of 25’ buffer along Class 4 streamcourse. Lysimete rs set up at edge of buffer, 10’ and 20’ into buffer at 2, 4, and 6 feet deep. Surface wa ter runoff was collected 15 feet into buffer. By April 29, 1994 (about 6 weeks after treatment), dead target vegetation in treated plot

indicates that hexazinone has moved into soil. Laboratory analysis limit of detection (LOD) = 0.10 ppb in water.

Results:

- Non-detection (ND) on April 5 (20 days after treatment (dat)) and April 15 (30 dat).

- May 2 (47 dat), picked up hexazinone at both 2 and 4 feet depth and at edge and 10’ into buffer, 0.5 – 2.1 ppb.

- May 2 picked up hexazinone at 6 feet de pth and 20 feet into buffer, from ND to 0.2 ppb.

- May 26 (71 dat), ND at 6’ depth; 0.2 – 1 ppb at 2 and 4 foot depth.

- June 9 (85 dat), 0.2 – 0.5 ppb at 2 and 4 foot depth at edge and 10 foot in, 1 detect at 6 feet depth, 20 feet into buffer (0.10 ppb).

Conclusions – This study used soil lysimeters that measured hexazinone at soil depths of 2-6 feet, which is within the rooting zone of target vegeta tion. This study is different than the other groundwater results involving 10 to 45-foot deep monitoring wells, which focused on measuring water in shallow gr oundwater, but outside the rooting zone. “Subsurface water transported hexazinone verti cally and laterally in the soil profile.” Movement is at least 20 feet horizontally and 6 feet vertically. Highe st level detected in groundwater - 2 ppb. Didn’t measure water conc entrations in surface water, so cannot compare with R5 FEIS assumption, but very low concentrations in subsurface water and surface runoff would indicate any amount cont ributed to surface water would be very

low.Page 6 Eldorado NF Amador RD Study (Reference 4)

Background – Unit 123-44, 6200’ elevation. Ap plication October 12, 1993, rate and formulation unknown (but likely Pronone, at 2-3 lbs ai/ac), 50-foot buffer on creek. Chosen as likely unit to see hexazi none movement subsurface because: 1) volcanic/granitic contact zone; 2) close to a perennial creek; 3) close to a meadow: 4) presence of water-loving vege tation. Soils are DG or andesitic lahar, sandy loams. Three shallow groundwater wells esta blished: #1, 20 feet from cr eek, 17 feet deep; #2, 30 feet from creek, 21 feet deep; #3 in the treated unit, 100 feet from creek, 28 feet deep. Quality control (QC) included spikes/blanks. LOD = 0.2 ppb.

Results: Samples were taken once a month through J une 1994, then December 1994 and February

1995.

- Well #1 had 3 positives 0.5 – 0.96 ppb, first de tection 5 months after treatment, last one in December 1994 (about 14 months after treatment).

- Well #2 had 1 positive 0.29 ppb (March 1994, 5 months after treatment)

- Well #3 had 1 positive 0.2 ppb (March 1994, 5 months after treatment)

- No detections in wells in February 1995 (last sample, 16 months after treatment)

- The stream didn’t show any positives (the hydrologist assumed dilution resulted in ND)

Conclusions – “...hexazinone did enter the gr oundwater and traveled a distance of at

least 50 feet...” “Hexazinone ha s the ability to ente r shallow aquifers and be transported through the saturated zone. Th e study also shows that hexa zinone can persist on site for over a year [14 months].” Hi ghest level detected in groundw ater - 0.96 ppb. Hexazinone leached at least 28 feet deep. No detections in surface water, so within assumptions of

R5 FEIS. Low concentrations in su bsurface water would indicate any amount contributed to surface water would be very small.

Stanislaus NF – Paper (Reference 11)

Background – Hunter and Duckwall Creeks, 3000 – 5000 foot elevation. Two wells established as part of this project; locat ed near surface water monitoring point HU30. Wells established March 8, 1996: 10 feet and 25 feet deep. Unit treated March 17, 1996, with 3 lbs/acre hexazinone (Pronone) aerially applied. Buffers were 100 feet if stream has flowing water, otherwise no buffer.

Results:

- ND on day wells established (pre-treatment)

- ND on April 18, 1996 (30 dat)

Conclusions – Very limited sample size, little to be concluded.Page 7 Stanislaus NF – Hamm-Hasloe (Reference 12)

Background – Moore Creek, Big Creek, Deer Li ck Creek and Jordan Creek. Project involved 817 acres of ground-based hexazi none (Pronone) applica tion in March 1996 (rate not shown). Buffers – 50 feet if water is in channel, otherwise 10 feet. Two wells established, one in Moore Creek and one in Big Creek watershed. Big Creek well (MW26-12) at 3200-foot elevation establis hed October 19, 1994 and 30 feet deep. Moore Creek well (MW26-21) at 3000-foot elevation, established March 3, 1995 and 15 feet deep. LOD = 0.1 ppb.

Results:

- Pretreatment samples on March 11 showed ND in both wells.

- Big Creek well showed ND on May 8 (a bout 60 dat) and June 6, 1996 (about 90 dat).

- Moore Creek well showed 0.18 ppb on April 18 (about 30 dat), and ND on June 6, 1996 (90 dat).

Conclusions – Consistent with other studies , with very low levels (0.18 ppb) or nondetect in relatively shallow wells. Hexazi none leached between 15 and 30 feet deep.

Low concentrations in subsurface water would indicate any amount contributed to surface water would be very small.

Stanislaus NF – Ruby (Reference 14)

Background - Rose Creek Watershed. Tr eatments in 1997-98-99. In 1997, 3 lbs hexazinone (Pronone) applied aerially on 1167 acres, 220 acres by ground. 100-foot buffer for aerial, 50-foot buffer for ground. QC – blanks, no spikes. Private lands had previously been treated. Two wells es tablished in March 1997 to monitor 1997 application, RU1 (32 feet deep) and RL 1 (22 feet deep). LOD = 0.1 ppb.

Results:

- Baseline sample taken in March 1997 (a bout 2 weeks after treatment) from RU1 showed ND; pretreatment sample ta ken from RL1 had 0.31 ppb but hydrologist

determined it to be a result of the cont amination of sample, since no precipitation

had occurred after treatment.

- Samples taken in each well May, June 1997 and May 1998; all ND.

Conclusions – After 14 months, no detectable levels of hexazinone at this depth. Consistent with other studies, with very low levels or non-detect in relatively shallow

wells.

Stanislaus NF – Domingo (Reference 10)

Background - San Domingo Creek watershed, Ca laveras County. 3000-foot elevation. 440 acres treated with hexazinone (Vel par L) by ground application, March 1995.Page 8 Buffers 80-100 feet on San Domingo Creek, 50 feet on tributaries. LOD = 0.1 ppb. QC – blanks/spikes. One ground water well (SD-36 ) established at base of unit 35, 17 feet deep. Noted that well dries out quickly between storms and in summer.

Results:

- ND during pretreatment sample

- Detections on May 3 (0.2 ppb) and Ma y 9, 1995 (0.21 ppb) (about 2 months after application)

Conclusion – Consistent with other studies, with very low levels or non-detect in relatively shallow wells. Low concentrati ons in subsurface water would indicate any amount contributed to surface water would be very small.

Sierra NF – Mariposa (Reference 7)

Background – Miami Creek watershed, 4000 foot el evation. Chosen as likely unit to see hexazinone movement subsurface because: 1) shallow aquifer yielding flow to nearby perennial creek; 2) aquifer like ly to flow rapidly due to slope steepness; 3) access to

wellheads. Soils are DG. 2 wells established in Unit 103 (37 feet deep and 17 feet deep); 2 wells in Unit 115 (45 feet deep and 10 feet deep), all established March 31, 1993. 2.6 lbs/acre hex applied in unit 103 on March 10, 1993; 1.6 lbs/acre hex applied in unit 115 on March 23, 1993. LOD = 0.1 ppb.

Results:

- 3 of 4 wells sampled March 31, 1993 (one well was dry) (21 dat, 8 dat) – all ND

Conclusion – Geologist had determined that enough rainfall had occurred to move hex into ground water (unit 103 had 5.7” rain, un it 115 had 4.5” rain between treatment and sample). Geologist assumed only days need ed to do so, which, based on other studies may not have been correct, especially for samp le taken 8 dat. In any case, consistent with other studies, with very low levels or non-detect in relatively shallow wells.

Eldorado NF – Peddler Hill (Reference 2)

Background – Peddler Hill Springbox located about 450 feet downhill from unit treated November 1991 with hexazinone by ground (rate and formulation unknown (but likely Pronone, at 2-3 lbs ai/ac)). LOD = 1 ppb.

Results:

- first post-treatment sample was May 20, 1992 (6 months after treatment), showed 1.7 ppb

- Samples taken June 22, June 29, and June 8, 1992 showed ND

- Sample taken July 13, 1992 showed 1.4 ppb

- Samples taken July 21, July 27, and December 21, 1992 showed ND

- No further results published.Page 9 Conclusion - Consistent with ot her studies, with very low leve ls or non-detect in a spring.

Low concentrations in subsurface water would indicate any amount contributed to surface water would be very small. Movement up to 450 feet in groundwater.Page 10 

### B. Hexazinone Surface Water Results

Eldorado NF – 1991 (Reference 2)

Background – Hexazinone (Pronone 10G) applie d via ground-based methods in various

units on the Eldorado NF in October and Novemb er of 1991, at rates of 2-3 lbs ai/acre. Buffers: Class 1, domestic – 200 feet; class 2, 3 – 100 feet; class 4 – 50 feet. LOD = 1 ppb.

Results:

- 1 of 29 sites had a detection as a result of a storm (3.5 – 5” rain) within days of application (treated October 25, samp led October 26). Detected 1.8 ppb.

- 6 of 36 sites had detections from spring snowmelt runoff, with rates ranging from 1.3 to 2.8 ppb.

- 0 of 14 sites had detections in fall, 1992 (about 1 year after treatment)

Conclusions – Results were below assumption in the R5 FEIS. Overland flow as result of

storms can contribute to surface water contamination.

Eldorado NF – 1992 (Reference 3)

Background - Hexazinone (Pronone 10G) applie d via ground-based methods in various

units on the Eldorado NF in late October and early November of 1992, at rates of 2-3 lbs ai/acre. Buffers varied by district: class 2, 3 – 100 feet (Class 2 - 200’ Georgetown); class 4 – 50 feet. QC – blanks and spikes. LOD = 1 ppb.

Results:

- 0 of 12 sites had detections as a result of first st orm within 1-1.5 months of

treatment

- 8 of 25 sites had detections from sp ring snowmelt, ranging from 1.3 to 19 ppb (one sample was >10 ppb).

- 3 of the 8 sites with spring snowmelt detections dropped to ND by August, 1993. 5 of these 8 had detections 1 year later, ranging from 1.1 to 15 ppb.

- 3 of the 5 with detections after 1 year have been continuously showing low levels of detection, with no appare nt seasonal trends, for 24 months after treatment (at levels mostly below 4 ppb) [NOTE – based on personal communication with Cheryl Mulder, Eldorado hydrologist, monitoring through Spring of 1997 has shown very low (0.74 – 1 ppb) but continuing detections.]

Conclusions – Levels detected were belo w assumption in the R5 FEIS. However, persistence has been longer than anticipate d, but absence of QC in later samples and

levels near LOD should be considered. Groundwater is likely source of continuing contamination but hexazinone groundwater st udies have not detected similar lengthy persistence times.Page 11 Sierra NF Study (Reference 8)

Background - Stand 728-505. Lewis Creek Wate rshed, Mariposa RD. 4400’ elevation. Holland Soil. 3 lbs/acre hexazinone (Vel par L) applied March 15, 1994. Formal study with lysimeters installed, catchment basi n to measure movement into ‘vadose zone’ (above water table, unsaturated soils) as well as surface flow. Test plot at edge of 25’ buffer along Class 4 streamcourse. Surface water runoff was collected 15 feet into buffer. LOD = 0.10 ppb in water, 10 ppb in soil. By April 29, 1994 (about 6 weeks after treatment), dead target vegeta tion in treated plot indicates that hexazinone has moved into

soil.

Results:

- Surface water runoff indicates overland fl ow, with detections during the period from March into May (2 months after treatment) at levels of 0.11 to 1.0 ppb,

fifteen feet into buffer.

- Surface soil collected in buffer on May 3 rd also had detections, indicating surface movement of hexazinone out of unit (11 to 15 ppb five feet into buffer, ND to 13 ppb ten feet into the buffer).

- By June 3, surface soil showed ND in buffer.

- In contrast, surface soil in the unit showed 900 ppb on April 1; 600 ppb on May 3 and 360 ppb on June 3, 1994.

Conclusions – Results were below assumption in the R5 FEIS. Normal rainfall and snowmelt patterns can move hexazinone, in solution, over soil surface with runoff.

Distance traveled in this case was at least 15 feet (no further distances measured), but at very low levels. [NOTE – Continuing Phase II study is in progress.]

Stanislaus NF – Paper (Reference 11)

Background - Hunter and Duckwall Creeks, 3000 – 5000 foot elevation. Nested monitoring design: 3 subwatersheds (1 in Du ckwall, 2 in Hunter) with high proportion of area treated, plus various point s along collector creeks. Incl uded one point (HU 50) that monitored water flowing from private land that was described as a 375 acre subwatershed

that was 100% treated in November 1994 w ith aerial application of 30 lbs Pronone 10G/acre (3 lbs/ac hexazinone). Un it treated March 17, 1996, with 3-lbs/acre hexazinone aerially applied. Buffers 100 feet if water is flowing in stream, otherwise no buffer. Day of application samples also take n at three points. Sa mples taken with both automated samplers and grab samples. LOD = 0.1 ppb.

Results:

- Private land monitoring (HU 50) showed detections of 4.8 to 14 ppb from March 1996 to June 1996, which is 16-18 months after treatment.

- Day of treatment samples at all three sites showed detections, ranging from 6.5 ppb in Hunter subwatershed with 98% treated (HU 15) to 0.7 ppb in another subwatershed (HU 30), while mainstem of Hunter Creek showed 1.3-1.8 ppb (HU 10), although this point is below private land monitored at HU 50.Page 12 - Pre-treatment samples at HU 10 and HU 20, on the Hunter Creek mainstem, showed 1.2 and 1.9 ppb, and are also receiving water from private land.

- Subwatershed HU 15 continued showing detections, peaking at 43 ppb during a storm event (March 28, 1996, 11 dat), droppi ng below 10 ppb after. Last reading June 5, 1996 (about 80 dat) showed < 1 ppb.

- Subwatershed HU 30 continued showing detections, peaking at 36 ppb during a storm event (April 16, 1996, about 30 da t). Last reading on June 5, 1996, < 1 ppb.

- Subwatershed DU 5 began showing detecti ons within 10-14 days after treatment, showing 6.8 ppb on March 28. Detections were consistent, but lower, through April. Last sample on June 5, 1996 showed ND.

- HU 20 and HU 10, on mainstem Hunter Creek, showed detections, all below 5 ppb between treatment and June 5, 1996, ex cept for storm peaks (16 ppb on April 16 at HU 20, and 28 ppb on March 28 and 6.5 ppb on April 18 at HU 10). DU 10

on mainstem of Duckwall Creek showed a peak of 15 ppb on March 28, otherwise all detections below 5 ppb, with ND on June 5.

Conclusions – Water from private lands show ing detection after 16-18 months is in line with other results showing detec tions for up to 2 years. Day of application detections in HU 15 and HU 30 indicate applications to surfac e water, which is not consistent with Best Management Practices (BMPs). Day of application detection in HU 10 is partially or wholly due to private land treatment, although some contribution from the Paper project could be possible, depending upon the timing of sample and water travel time. Peak levels above 36 ppb are in excess of R5 FEIS worst-case estimate of detection, but the estimate was based on drift, not direct a pplication. Storm peak flows were consistent throughout both watersheds with pulses of hexazinone (notably March 28 and April 16- 18), however whether this is due to s ubsurface leaching, overl and surface flow, or deposition into dry drainages that subsequently ran water is unknown.

Stanislaus NF - Hamm-Hasloe (Reference 12, 13)

Background - Moore Creek, Big Creek, Deer Li ck Creek and Jordan Creek. Project involved 817 acres of ground-based hexazi none application in March 1996, with 3 lbs/acre hexazinone ground applied. Buffers – 50 feet if water is flowing in channel, otherwise 10 feet. Nested monitoring desi gn: 5 subwatersheds (all in Moore Creek drainage) with high proportion of area treate d, plus various points along collector creeks. LOD = 0.1 ppb.

Results:

- Subwatershed MO-T1 (90% treated) ha d two samples taken in May 1996, with 0.79 ppb to ND. [NOTE – Reference 13 indi cates detections during storm flows in November 1996 through early January 1997 of 59 to 150 ppb.]

- Subwatershed MO-T2 (40 acres, 100% tr eated, except buffers) had several high peaks during storms: April 1, 1996 – 140 ppb; April 18, 1996 – 52 ppb; May 16, 1996 – 600 ppb. Readings on May 16, afte r peak of 600 ppb, dropped to 6.9 ppb by end of day. Baseflow readings in June 96 showed ND or < 1 ppb. [NOTE –Page 13 Reference 13 indicates detections du ring storm flows in November 1996 through early January 1997 (10 months after treatment) of 76 to 110 ppb.]

- Subwatersheds MO-T4 (353 acres, 38% treated), MO-T5 (8% treated), and MOT6 (29% treated) showed detections that were 5.2 ppb or less between the

treatment date and June 1996. MO-T4 wa s fairly heavily monitored: 19 of 26 samples in 2 months after treatment showed detects between 0.1 and 5.2 ppb; base flow readings dropped below 1 ppb.

- The main channel of Moore Creek, belo w all these subwatersheds had 9 of 23 samples with detections dur ing the 2 months after trea tment, ranging from 0.2 to 2.7 ppb. During day that subwatershed MO-T2 peaked at 600 ppb, this main channel peaked at 1.2 ppb.

- Other drainages monitored showed very low (< 1 ppb) or ND for all samples.

Conclusions – Analysis in Hamm Hasloe EIS, using the PRZM model, predicted maximum detections of 700 ppb at peak stor mflow, with 1-10 ppb at baseflow (Hamm Hasloe FEIS, page 4-130), although the wate r monitoring write-up mentions expected rates of less than 100 ppb at stormflow. As a result of high readi ngs in subwatershed MO-T2, a review was conducted, which determined that the results were due to areas of

shallow soil that shouldn’t have been treate d, steep slopes that fac ilitated movement of herbicide, and likely misapplication, due to poor footing and steep slopes. Day of application monitoring was not done, so cannot determine whether misapplication actually occurred. Hydrologists on both Stanis laus and Eldorado think that there may be a predictor of hexazinone in water flowing fr om a subwatershed based on the percentage

of the watershed treated and the size of the watershed. Same day comparisons of results

show the effects of dilution on concentra tion of hexazinone: MO-T2 peaks at 42 ppb on March 28 and 140 ppb on April 1; station MO-M 1 on the mainstem of Moore Creek (4 miles downstream) records peaks of 0.1 ppb and 2.7 ppb on these same days.

Stanislaus NF – Ruby (Reference 14)

Background - Rose Creek Watershed. Tr eatments in 1997-98-99. In 1997, 3 lbs hexazinone applied aerially on 1167 acres, 220 acres by ground; in 1998, 245 acres was treated by ground; in 1999, 591 acres was trea ted aerially. Monitoring design included three points that monitored water flowing fr om private land that had been previously treated with hexazinone (extent or timing not described). Ot her monitoring sites were at various points on mainstem of Rose Creek. Da y of application samples were taken at two points (one in 1997, one in 1999). QC – blanks only, no spikes. 100-foot buffer for aerial, 50-foot buffer for ground. LOD = 0.1 ppb.

Results:

- Private land monitoring (RC-15, RC-30, RC-40) showed ND or very low levels of detection (< 1 ppb). The report doesn’ t indicate when the private land was treated. RC-15 had 5 samples between March 1997 and November 1997, all ND. RC-30 had 10 detects out of 16 samples taken between March 10, 1997 and March 12, 1999, last detect was Octobe r 1, 1998 (19 months after sampling began). RC-40 had 3 detects out of 13 samples taken between March 10, 1997Page 14 and March 12, 1999, last detect was June 22, 1998 (15 months after sampling began).

- Monitoring during application showed a detect at RC-12 on March 17, 1999 at 15 ppb. From March 23 to July 7, 1999, 4 more samples were taken, showing a peak of 5.2 ppb, with summer baseflows at ND or < 1 ppb.

- Monitoring during application at RC-10 (the mainstem of Rose Creek) during the 1997 application (March 18, 1997) had 3 of 5 samples with detects, the highest at 3.1 ppb. The same point was monitored during the 1999 application, with 4 samples, all detects, with a peak of 32 ppb. Subsequent sampling at this point showed fast and sharp decline (March 23 – 2.2 ppb, April 1 – 1.2 ppb, May 20 – 0.31 ppb, July 7, 1999 – ND).

Conclusions – Day of applicati on detections would indicate misapplication of hexazinone to surface water, as private land contributions appear not to be a factor. This was cause for investigation of project af ter 1999 application, which did determine that contractor

did not maintain buffers and that Pronone wa s applied to surface water. The subsequent

decline in detections would indicate that th is pulse of hexazinone was rapidly removed from the system. Private land contributions in dicate a persistence of at least 19 months, assuming that private land was treated prior to the beginning of sampling.

Stanislaus NF – Domingo (Reference 10)

Background - San Domingo Creek watershed, Ca laveras County. 3000 foot elevation. 440 acres treated with hexazinone (Vel par L) by ground application, March 1995. Buffers 80-100 feet on San Domingo Creek, 50 f eet on tributaries. Nested monitoring design: one 35 acre subwatersh ed (SD 20) with 100% of ar ea treated except buffers; and various points along mainstem of Sa n Domingo Creek. LOD = 0.1 ppb. QC – blanks/spikes.

Results:

- The subwatershed SD-20 had 10 of 15 samples with detects, ranging from 0.2 to 1.6 ppb, with first detect 2-3 weeks afte r treatment (April 6, 1995). The last sample taken was about 1 year after treatment, and showed 0.3 ppb.

- SD –10, the point on the mainstem imme diately below all spraying, showed detections for 4 of 11 samples from mi d-April to mid-May 1995 and then dropped to ND in baseflow through March 18, 1996.

- The other two sample points were downst ream, and had very few samples taken,

but showed levels at the limit of detection (0.1 – 0.11 ppb) in May of 1995.

Conclusions – The project EA had anticipated 30-50 ppb. The first storm had shown ND, detections began with second stor m, and levels in creased with 3 rd , 4 th storms, and then dropped off. Indicates that subsurface moisture was likel y driving hexazinone through system. No samples taken day of application, but low levels in subsequent samples from SD-20 would indicate a proper applicati on. Results were below realistic water contamination assumption in the R5 FEIS.Page 15 Lassen NF – Lost Fire (Reference 5)

Background – March of 1992, 200 acres treated with hexazinone (Pronone) in Proctor Creek watershed. During the fall of 1992, an additional 2,200 acres was treated.

Results:

- Monitoring of 200-acre application in May 1992 involved two points and one sample in each; both showed ND.

- Monitoring of the 2,200-acre a pplication in March 1993 at two stations showed one with a detection, at 1.6 ppb. Subs equent monitoring in May 1993 at 4

locations showed ND at all.

Conclusion – Very small sample size, but re sults consistent with other monitoring. Results were below realistic water contamination assumption in the R5 FEIS.

Sierra NF – Mariposa (Reference 6)

Background – Miami Creek watershed, 4000-foot elevation. 2.6 lbs/acre hexazinone applied in Unit 103 on March 10, 1993; 1.6 lb s/acre hex applied in Unit 115 on March 23, 1993. QC – Blanks/spikes. LOD = 0.1 ppb.

Results:

- Pretreatment monitoring at 4 points below Unit 115 – ND in 4 samples.

- During first storm after treatment (March 29), samples taken at same 4 points, all

ND.

Conclusion – Unknown whether suffi cient rainfall occurred in this storm to move the hexazinone into soil solution. Monitoring occu rred less than 1 week after treatment.Page 16 

### C. Glyphosate Surface Water Results

Sierra NF – Mariposa (Reference 6)

Background – Application of glyphosate dur ing June and July 1992. Miami Creek watershed. QC – blanks/spi kes. Unknown buffer width.

Results:

- Pretreatment samples show ND (2 samples)

- Day of treatment sample (July 10, 1992) on unit 728-501 shows ND.

- Samples collected following storms in July (sampled July 12) and October (sampled October 27) show ND (4 samples)

- Sediment samples collected after October storm also show ND.

Conclusions – No detections in any samples.

Eldorado NF – 1991 Program (Reference 2)

Background – Glyphosate applied in various un its around the Eldorado in June-August of 1991. Buffers, class 1 – 200’; class 2,3 – 100’; class 4 – 50’. Rates applied from 1.1 to 2.1 lbs/acre. LOD = 14 or 25 ppb, depending upon the lab used. Pretreatment samples, 48-hour post-treatment samples and samples afte r the first storm within 90 days were

collected.

Results:

- 16 pretreatment samples - all ND.

- 7 48-hour post-treatment samples - all ND

- 16 first storm samples - all ND (taken October 26, 1991)

- Sediment samples (pretreatment (18 sample s) and after first storm (18 samples))

all ND.

Conclusions – There was some concern that glyphosate would be transported to streams through drift or overland flow and settle in streambed sediments. There is no evidence

that this is the case. No detections in a ny samples. Results may be below realistic water contamination assumption in the R5 FEIS (11 to 21 ppb), but LOD may be higher than these assumed levels (information about tr eatment rates per unit above each sampling station are not in the reference).

Eldorado NF – 1992 Program (Reference 3)

Background – Glyphosate, 2 lbs/ac, applied in various units around the Eldorado in MayAugust of 1992, and May-June 1993 on Georgeto wn RD. Buffers varied by District: class 2 – 200’ on Georgetown RD, 100’ on Pl acerville RD, 50’ on Pacific RD; class 3 – 100 feet (50’ Pacific RD); class 4 – 50 feet (25’ Pacific RD). Pretreatment samples, 48 hour post-treatment samples (Georgetown RD only) and samples after the first storm within 90 days were collected. LOD = 14 or 25 ppb, depending upon the lab used.Page 17 Results:

- 17 pretreatment samples - all ND.

- 3 48-hour post-treatment samples - all ND

- 7 first storm samples - all ND (taken June 1992, May 1993)

- Sediment samples after first storm (5 samples) had one detection (88 ppb), although this was ascribed to either c ontamination of sample or private land

contribution.

- [NOTE: communication with Eldorado hydrol ogist Cheryl Mulder indicates that 1993 - 1998 results show ND for glyphosate.]

Conclusions - No detections in any sample s. Results may be below realistic water contamination assumption in the R5 FEIS, but LOD may be higher than assumed levels

in R5 FEIS.

Stanislaus NF – Domingo (Reference 10)

Background – glyphosate applied in March – Ma y 1995. Buffers 20 feet on all streams. LOD = 9 ppb. QC = blanks/spikes.

Results:

- 8 post-treatment water samples, all stormflow - all ND.

- 1 post-treatment sediment sample – ND

Conclusions - No detections in any samples. Re sults are likely to be below realistic water contamination assumption in the R5 FEIS, but exact rate of application not known (assumed greater than 1 lb/ac ai.

Stanislaus NF – Hamm-Hasloe (Reference 12)

Background – glyphosate applied in March 1995 (ra te not specified). Buffers 10 feet. LOD not specified in report.

Results:

- 4 pre-treatment water and sediment samples – all ND

- 25 post-treatment storm flow water sa mples (April 13 – May 13, 1995, and March 28 – April 1, 1996) – all ND

- 11 post-treatment storm flow sediment samples – all ND

Conclusions - No detections in any sample s. Results may be below realistic water contamination assumption in the R5 FEIS, but LOD and rate applied not specified in the report. It appears that ve ry small buffers can effectively prevent glyphosate movement into streams, although wind speed and direc tion during this application are not known.

Stanislaus NF – Groveland 1992 (Reference 9)Page 18 Background – Glyphosate applied June 1992 (rate not specified). Buffers 15 feet. LOD = 24 ppb (water) and 50 ppb (sediment). QC = limited use of spiked samples.

Results:

- No detections in any post-treatment water samples (samples from June through December, 1992) (17 samples).

- No detections in any post-treatme nt sediment samples (10 samples).

Conclusions - No detections in any sample s. Results may be below realistic water contamination assumption in the R5 FEIS, but exact rates applied are not specified in the report, therefore the LOD may be higher than assumed levels in R5 FEIS.

Stanislaus NF – Rogge-Ackerson (Reference 15)

Background – Application of glyphosate in J une 2000 (rate not specified). Buffers 10 feet where water is present. QC – blanks. LOD not specified.

Results:

- 11 day of application water samples – all ND

- First storm after application, within 90 days (2 samples) – ND

Conclusions - No detections in any sample s. Results may be below realistic water contamination assumption in the R5 FEIS, but L OD and rate of application not specified.

Angeles NF (Reference 1)

Background – Not a reforestation project, bu t a noxious weed c ontrol project. Glyphosate applied to noxious weed Arundo donax adjacent to and within riparian areas

in the summer of 1995. 13 acres treated with 80 lbs glyphosate (6 lbs/ ac), with <1 acre actually aquatic (in-channel) application. LOD = 6 ppb.

Results:

- Sample taken 1⁄4 mile downstream (1 sample) – ND

- [NOTE – memo from Forest Pesticide Coordinator, Joe Gonzales, on 5/25/00 indicates monitoring at San Francisqu ito Canyon in 1996, after 10 acres treated with 4 lbs/ac glyphosate – ND.]

- [NOTE – personal communication 12/13/00 with Joe Gonzales, he indicated that in 1997, in San Francisquito Canyon, there was one detect of 12 samples, showing 15 ppb.]

Conclusions – Appears that riparian app lication of glyphosate r uns small risk of detectable concentrations in adjacent water (1 of 13 samples). Don’t know the exact rate of application in subsequent applications, but likely greater than 1.5 lbs/acre, so results are likely below assumption in R5 FEIS (e ven though treatments o ccurred up to and in the stream channel).Page 19 

### D. Triclopyr Surface Water Results

Eldorado NF – 1991 Program (Reference 2)

Background – Triclopyr applied in various units around the Eldorado in August of 1991. Buffers, class 1 – 200’; class 2,3 – 100’; class 4 – 50’. Rate applied 1 lb/acre. LOD = 1 ppb. Pretreatment samples, 48-hour post-treatment samples and samples after the first storm within 90 days were collected.

Results:

- 6 pretreatment samples – all ND

- 5 48-hour post-treatment samples – all ND

- 6 samples after first storm (samples co llected October 26, 1991) – 5 had ND, 1 had 82 ppb (Station 55J91)

- 55J91 remeasured on December 11, 1991 - ND

Conclusions – The detection at 55J91 was dete rmined to be the result of not establishing a buffer along the ephemeral portion of the h eadwater of a drainage. When the storm occurred, this portion of the drainage likely ra n water. No detections in other samples. With the exception of the one detection, the results are below realistic water contamination assumption in the R5 FEIS.

Eldorado NF – 1992 Program (Reference 3)

Background - Triclopyr, 1 lb/ac, applied in various units around th e Eldorado in JuneAugust of 1992, and May-June 1993 on George town RD. Buffers (class 2 varied by District): class 2 – 200’ on Georgetown RD, 100’ on Placerville and Pacific RDs; class 3 – 100 feet; class 4 – 50 feet. Pretreatment samples, and samples after the first storm within 90 days were collected. LOD = 0.1 and 1 ppb. QC – spikes and blanks.

Results:

- 11 pretreatment samples – all ND

- 1 sample after first storm – ND

Conclusions – Very small sample size, as only one monitoring point had precipitation within 90 days, which was a spring stor m after an application in May 1993.

Stanislaus NF – Domingo (Reference 10)

Background – Triclopyr applied in the spring (April-May) of 1995 (report noted that on many days, the applications were interrupted wi th rain). Buffers – 20 feet. QC – blanks and spikes. LOD 0.4 ppb.

Results:

- 8 post-treatment water samples (May through mid-June), mostly stormflow sampling – all NDPage 20 - 1 sediment samples – ND

Conclusions – No detections in samples. Alt hough application rate is not specified, it is likely that with the low LOD, results are be low realistic water contamination assumption

in the R5 FEIS.

Stanislaus NF – Hamm-Hasloe (References 12 and 13)

Background – Triclopyr applied in summer of 1996 on 413 acres in tank mix with glyphosate (rate not specified). Bu ffers 10 feet. LOD not specified.

Results:

- MO-T9 (Tributary to Moore Creek, nearSmith Ridge), shows following postspray detections: June 4, 1996 – ND; June 26 – 0.6 ppb; October 25 – ND; November 17-18 – 0.6-2.4 ppb (4 sa mples); December 10 – 0.6-0.8 ppb; December 11 – ND; December 30 – 0.47 ppb. The detections in June, October and November are indicated as being during stormflows.

- NM-T1 (Tributary of NF Merced, near Jackass Mountain), shows following detections: December 5, 1996 – 0.63 ppb; December 10 – 0.6-0.7 ppb; December

11 – ND

Conclusions – Buffers may have been insufficien t to keep triclopyr out of streamcourses, although detected amounts are below R5 FEIS realistic water contamination assumptions (assuming 1 lb ai/acre ap plied and a LOD < 1ppb).

Stanislaus NF – Groveland 1992 (Reference 9)

Background – Triclopyr applied June 1992. Bu ffers 15 feet. LOD = 0.1 ppb (water) and 1 ppb (sediment).

Results:

- Five stations monitored for tric lopyr; pretreatment samples – ND

- One station (54O) showed a detection after storm in December 1992, at 1 ppb. No other detections in any post-treatmen t water samples (6 samples from June through December, 1992).

Conclusions - Buffers may have been insufficien t to keep triclopyr out of streamcourses, although detected amounts are below R5 FEIS realistic water contamination assumptions (assuming 1 lb ai/acre applied).Page 21 

### IV. Conclusions and Recommendations

As a foreword to this section, it must be noted that the inconsistent use of quality control practices involving the use of known blank a nd spiked samples makes some conclusions difficult to support. This has been recogni zed as a problem by the hydrologists in the Region and is more a logistical problem to be solved than one of understanding the need for such quality control practices.

Overall, one can conclude from this monito ring that when Best Management Practices are correctly implemented, monitoring results indicate that the R5 FEIS realistic water contamination levels of 10 ppb per pound active ingredient applied are easily met and can be considered very conservative in any effects analysis. In most of the monitoring that is documented here, the majority of samples were either clear of de tectable levels of herbicides, or were at very low levels. Th e exceptions will be discussed below. Table 1 shows the number of samples collected, and the levels of detections for each herbicide. This table can be compared with Ta ble 4-2 (page 4-8) in the R5 FEIS.

Table 1 – Water quality monitoring of Region 5 herbicide projects, 1991 – 2000

1 No control or pretreatment samples have been included in this table.

2 ppb = parts per billion

3 Where limit of detection (LOD) may be higher than a reported concentration, the maximum has been listed as “less than” (<) the LOD. This is the case with glyphosate.



### Hexazinone

Hexazinone has been extensively monitored in Region 5 since 1991. As expected by its chemical nature, hexazinone goes into soil solution quickly and then some percentage moves through soil profiles into shallow ground water, or moves overland in surface water flow, and is subsequently found in surf ace water in streams. From Table 1, out of the total hexazinone samples, rough ly half showed no detections.

Once detected, the levels of hexazinone in groundwater are very lo w (see Figure 1). The highest level detected was 2.1 ppb (reference 8) in very shal low lysimeter holes (2 feet deep). 95% of detections are at levels very near limits of detection (<1 ppb). Lag time and amount of positive detections with depth vary considerably. Once hexazinone is in shallow groundwater, lateral movement can be extensive (example, Peddler Hill springbox was about 450 feet downhill from treat ed unit). It appears from the surface water data that groundwater can continue to feed hexazinone into surface water over a long period of time, regardless of implementa tion of BMPs to dire ctly protect surface

Herbicide Total Samples 1 With No

Detectable

Residues 0-10 ppb 2 11-

30 ppb 31-

50 ppb 51-

100 ppb 101-

600 ppb Maximum

observed

concentration 3
Glyphosate 104 103 1 < 25 ppb Triclopyr 43 30 12 1 82 ppb

Hexazinone

Surface

Ground 580

103 245

78 301

25 16 4 8 6 600 ppb 2.1 ppbPage 22 water. The FEIS did not consider this sour ce to be a substantial component of surface water contamination. Ground water monitoring however has not shown long persistence, although sampling for this purpose is limited in these reports.

Surface water monitoring of hexazinone over long periods shows very low levels of detected hexazinone, well below the expected 10 ppb/lb ai applied (often below 1-2 ppb total)(Figure 2), so regardless of source, the R5 FEIS assumptions of levels of contamination are very conservative. Ba sed on the surface water sampling, 90% of all hexazinone detections are below 7 ppb; 95% are below 15 ppb. Assuming that the average application rate is between 2 and 3 pounds per acre active ingredie nt, then 97% of the time, amounts of hexazinone were either below limits of det ection or at levels below what the R5 FEIS assumed (20-30 ppb) fo r this rate of applic ation. As a method of comparison, the current EPA Health Advi sory level (HA) is 400 ppb (the highest

concentration of hexazinone in drinking water considered safe for us to drink on a daily basis). In lab testing, some species of algae have seen gr owth effects at levels of hexazinone of 3 ppb, although any effects to aq uatic insects and fish are not expected until levels greatly exce ed 1 ppm (1,000 ppb).

Figure 1.

Cumulative Frequency Graph
Hexazinone in Groundwater, n=103

0.7 0.75 0.8 0.85 0.9 0.95

1

0.01 0.1 1 10

concentration (ppb)cumulative frequency

Figure 2.Page 23 Cumulative Frequency Graph
Hexazinone in Surface water, n=580

0.4 0.5 0.6 0.7 0.8 0.9

1

0.1 1 10 100 1000

concentration (ppb)cumulative frequency

400 ppb, current

EPA HA 3 ppb, effects seen in
one species of algae

Persistence of hexazinone in the environment may be longer than anticipated in the R5 FEIS (which assumed a half-life of 1 – 12 months), with fairly consistent results indicating at least an 18 – 24 month timeframe when hexazinone can be detected, and two studies indicating the potentia l for even longer timeframes . The Eldorado results (C. Mulder, Personal Communication) would indicat e persistence times of up to 4.5 years, and preliminary results from the Stanislaus (S.Apperson, personal communication) would indicate in one case, persistence in surface water of up to 4 years. None of the ground water monitoring results indicate such long persistence.

There is some thinking that the percentage of a subwatershed that is treated with hexazinone may be tied to levels of hexazinone detected in downstream water. However, in the cases where this has been observed (R eferences 11, 12), the untreated buffers that were in place along streams may have been inadequate to prevent overland flow into drainages. This conclusion is support ed by the results of one monitoring study (Reference 10) where a small subwatershed wi th 100% of the area ou tside of buffers, did not show high levels of downstream hexazinone , but also had wider buffers (i.e., 50 feet vs 10 feet or 0 feet on ephemerals) as compar ed to the two other st udies. Whatever the cause of the high rates from these subwatershed s, it does appear that high subwatershed levels of hexazinone are quickly diluted downs tream. It also appears that these small subwatersheds, if they have high levels of hexazinone detected in the first wet season, can have high pulses of hexazinone th e following year (Reference 12).

Erroneous applications direc tly to surface water result in high spikes in hexazinone concentration that quickly subside. This is in agreement with the discussion in the R5 FEIS (page 4-10).Page 24 Outside of an accidental misapplication of herb icides to water, it appears that treating a high percentage of a small subwatershed, in combination with placing buffers only on streams running water, represents the higher risk over the longer term of introducing

hexazinone at levels above assumed levels in the R5 FEIS. In sm all subwatersheds (<100 acres), consideration of this observed effect should result in heightened awareness of the need for a more effective buffer system.

It would seem advisable to continue to monitor hexazinone in surface water, including day of application sampling for new projects . The groundwater mon itoring may be better focused on resampling of existing wells to see if persistence of he xazinone for periods greater than 2 years can be determined. It is also recommended that any water monitoring program be consistent in its use of known blank samples and spiked samples. Any resampling of the streams with long hist ories of detection s hould be accompanied by a comprehensive quality c ontrol sampling scheme.



### Glyphosate

All sampling was done after ground-based appl ications. There were no detections in water or sediments in any samples taken af ter reforestation projects (that were not ascribed to sample contamination). The one type of project with a detection of glyphosate involved treatment of noxious weeds within the riparian zone. Even here, only one of twelve samples had a detection, and that was at a lo w level (15 ppb), below any level of concern for human health or aquatic resources (SERA, 1996a).

Recently, the amount of post-treatment sampling done for glyphosate has dropped considerably as most sampling protocols call for sampling only if a storm occurs within 90 days of application and causes a rise in stream levels. With glyphosate generally applied in late spring to late summer, this condition rarely occurs . Based on monitoring to date, glyphosate applications, as generally practiced in reforestation projects, will not

result in stream sediment or water contamination.

It would seem that the monitoring of ground- based applications of glyphosate outside of riparian areas, and absent any project-speci fic unique circumstances or concerns, should be discontinued, especially on the Westside of the Sierra Nevada range. If any aerial applications of glyphosate occur, they shoul d be monitored, including day of application monitoring, since there are no monitoring data on this combination of herbicide and application method. Implementation monitoring of BMPs should continue to be done on all projects.



### Triclopyr

All sampling was done after ground-based appli cations. The few positive detections in non-accidental or erroneous appli cations in water monitoring are all at low levels (highest 2.4 ppb). These levels are below the R5 FEIS r ealistic levels of wate r contamination, andPage 25 are below any aquatic levels of concern (S ERA 1996b, EPA, 1998). The use of untreated buffers of some minimal size on ephemeral drainages (ten feet is the smallest implemented buffer involved in these projects) is needed to avoid leve ls of triclopyr in water that exceed the R5 FEIS expectations. The detection that resulted in the highest level of triclopyr (82 ppb) was the result of an absence of an untreated buffer on an ephemeral stream. It would appear from thes e monitoring data that untreated streamside buffers of greater than 15 feet in width re duce risk of water cont amination to near zero, although it should be noted that the 82 ppb tran sient level does not represent a substantial

risk of harm to humans or the environment.

It would seem that the water quality monitoring of ground-base d applications of triclopyr outside of riparian areas, and absent any project-specifi c unique circumstances or concerns, should be discontinued, especially on th e westside of the Sierra Nevada range. If any aerial applications of triclopyr occur, they should be monitored, including day of application monitoring, since there are no monitoring data on this combination of herbicide and app lication method.

Implementation monitoring of BMPs should c ontinue to be done on all projects.Page 26 

### V. References

The following are the actual water monitoring studies summarized and numerically referenced in this report. General references follow.

1. USFS, Angeles NF. 1996. Untitled. Correspondence from Joe Gonzales, ANF Pesticide-Use Coordinator to John Borrecco, Regional Pestiicde-Use Coordinator, with copies of water quality testing resu lts for glyphosate. February 1996. 12 pp.

2. USFS, Eldorado NF. 1993. Water Monitoring Report, 1991 Herbicide Application Projects, Eldorado National Forest . Joan Carlson, Hal Fiore. September 1993. 33pp.

3. USFS, Eldorado NF. 1995. Water Monitoring Report, 1992 Herbicide Application Projects, Eldorado National Forest. Hal Fiore. January 1995. 32pp.

4. USFS, Eldorado NF. 2000. Hexazinone Detection in Groundwater Study – Amador Ranger District, Eldorado national Forest. Anne Boyd. February 2000. 10 pp.

5. USFS, Lassen NF. 1993. Lost Fire Fore st Recovery – Water Monitoring Results

to Date. Letter from Tom Simonson to La ssen Forest Supervisor, file code 2470, with attachments. August 1993.

6. USFS, Sierra NF. Undated. Monitoring Documentation – Site Preparation and Release. Earle Franks, Forest Hydrologist. 3 pp.

7. USFS, Sierra NF. 1993. Groundwater Monitoring Results for the March, 1993 Application of Hexazinone on the Mariposa Re lease Project, Mariposa RD, Sierra NF. April 1993. 53 pp.

8. USFS, Sierra NF. 1994. Phase I Results of Intensive Monitoring to Detect OffSite Migration of Hexazinone from Vege tation Management Sites, Mariposa Ranger District, Sierra NF. Jerome Degraff, Brent Roath, Earle Franks. June 1994.

9. USFS, Stanislaus NF. 1993. Water Quality Monitoring Report – 1992 Groveland Conifer Release Project. Michael Parent i, District Hydrologist. April 1993.

10. USFS, Stanislaus NF. 1996a. Water Qu ality Monitoring – He rbicide Application – Domingo Reforestation Project. Jim Frazier, Jerome DeGraff. June 1996.

11. USFS, Stanislaus NF. 1996b. Water Qual ity Monitoring – Herb icide Application – Paper Reforestation Project – Interim Re port Number 1. Steve Apperson, Jerome DeGraff. July 1996.

12. USFS, Stanislaus NF. 1996c. Surface Water, Ground Water, and Soil Monitoring Report – Herbicide Application – Hamm-Hasloe Reforestation Project –Page 27 Interim Report Number 1. Todd Ellsworth, Do ris Grinn, Jim Frazier, Jerome DeGraff.

October 1996. 13. USFS, Stanislaus NF. 1997. Groveland Conifer Release & Hamm-Hasloe Herbicide Monitoring Results – Summer/Fall 1996. Jim Frazier. February 1997. 2 pp.

14. USFS, Stanislaus NF. 2000a. Water Qu ality Monitoring – He rbicide Application – Ruby Reforestation Project – Interim Report Number 1. Sharon Grant, Jerome DeGraff. January 2000.

15. USFS, Stanislaus NF. 2000b. Water Quality Monitoring – Herbicide Applications – Rogge-Ackerson Reforesta tion – Wilson Loop Project Area. Sharon Grant, Steve Apperson. October 2000. 7 pp.

General References :

Apperson, Steve. Stanislaus NF Hydrologi st. Personal Communication. January 2001.

Gonzales, Joe. Angeles NF Pesticide Use Coordinator. Personal Communication.

December 2000.

Mulder, Cheryl. Eldorado NF Hydrologi st. Personal Communication. July 2000.

Syracuse Environmental Research Associ ates, Inc. 1996a. Selected Commercial Formulations of Glyphosate – Accord, Rode o, and Roundup. Risk assessment. Final Report. March 20, 1996.

Syracuse Environmental Research Associ ates, Inc. 1996b. Selected Commercial Formulations of Triclopyr – Garlon 3A and Ga rlon 4 – Risk Assessment. Final Report. March 31, 1996.

Syracuse Environmental Research Associ ates, Inc. 1997. Selected Commercial

Formulations of Hexazinone – Human Health and Ecological Risk Assessment. Final Report. March 4, 1997.

USDA Forest Service, 1989. Final Envi ronmental Impact Statement, Vegetation Management for Reforestation. Four Volumes.

US EPA, 1998. Reregistration Eligibility Decision (RED) – Triclopyr. EPA 738-R-98- 011. October 1998. 269 pages.