6 Rotenone monitoring

Rotenone application was performed in early October 2021 by ADF&G. The treated bodies of water included Vogel Lake, North Vogel Lake, and Miller Creek. ADF&G collected pre and post-treatment water samples as part of the treatment event, and Kenai Watershed Forum monitored degradation through Summer 2022.

Field sampling and analytical methods generally followed those described in (Couture et al. 2021). We collected a composite grab sample from two locations at a depth of 0.5 m near the center of each lake prior to rotenone treatment.

Following treatment, we collcted lake water samples at a depth of 0.5 m from two locations around the center of the lake either as a grab sample or with a Kemmerer sampler. For each strata of each lake, a single composite sample was created from the two locations. For benthic samples, the Kemmerer sampler was lowered to a depth within 2 m from the bottom in the two locations around the center of the lake. The collected water from tow locations was then combined into a single 1 L composite sample. All samples were collected into sterilized 1 L amber glass bottles, immediately chilled on ice, stored out of the light and transported to the Applied Science, Engineering and Technology (ASET) Lab located at the University of Alaska Anchorage (UAA) within 72 h of collection. Upon arrival to the lab all samples were stored in the dark at 4°C and analyzed via high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) within seven days of collection.

6.1 Sampling schedule

The rotenone sampling schedule is described in table 6.1 or may be accessed in a Google Sheet linked here: https://tinyurl.com/8ba94nrn. The schedule is current as of 2022-03-18.

Table 6.1: Vogel lake and Miller Creek rotenone sampling schedule
Field Sample Count Sample Field Sample Date Status Location Depth Notes
1 Rotenone 2021-09-27 Complete Vogel Lake Surface Pre-treatment
1 Rotenone 2021-09-28 Complete North Vogel Lake Surface Pre-treatment
1 Rotenone 2021-10-07 Complete Vogel Lake Surface
1 Rotenone 2021-10-07 Complete Vogel Lake Benthic
1 Rotenone 2021-10-07 Complete North Vogel Lake Surface
1 Rotenone 2021-10-07 Complete North Vogel Lake Benthic
1 Rotenone 2021-10-08 Complete Miller Creek Head Surface
1 Rotenone 2021-11-10 Complete Miller Creek Weir Surface
1 Rotenone 2021-11-10 Complete North Vogel Lake Surface Alternative sampling location due to thin ice
1 Rotenone 2021-11-10 Complete Vogel Lake Surface Alternative sampling location due to thin ice
1 Rotenone 2021-12-03 Complete Miller Creek Surface
1 Rotenone 2021-12-02 Complete North Vogel Lake Surface
1 Rotenone 2021-12-02 Complete Vogel Lake Surface
1 Rotenone 2021-12-03 Complete Miller Creek Benthic
1 Rotenone 2021-12-02 Complete North Vogel Lake Benthic
1 Rotenone 2021-12-02 Complete Vogel Lake Benthic
1 Rotenone 2022-01-05 Complete Miller Creek Surface
1 Rotenone 2022-01-05 Complete North Vogel Lake Surface
1 Rotenone 2022-01-05 Complete Vogel Lake Surface
1 Rotenone 2022-02-04 Complete North Vogel Lake Benthic
1 Rotenone 2022-02-04 Complete North Vogel Lake Surface
1 Rotenone 2022-02-04 Complete Vogel Lake Surface Surface location A
1 Rotenone 2022-02-04 Complete Vogel Lake Surface Surface location B
1 Rotenone 2022-03-11 Complete North Vogel Lake Benthic
1 Rotenone 2022-03-11 Complete North Vogel Lake Surface
1 Rotenone 2022-05-15 North Vogel Lake Benthic TBD if necessary
1 Rotenone 2022-05-15 North Vogel Lake Surface TBD if necessary

6.2 Rotenone sampling map

Map of sampling sites and table of coordinates forthcoming here


6.3 Rotenone concentration results

6.3.1 Sample results

6.3.1.1 Tables

Laboratory analysis of water samples is performed by the ASET Laboratory at the University of Alaska Anchorage Department of Chemistry in Anchorage, Alaska. Detailed analytical methods can be found in Couture et al. 2022.

Original results received from UAA are available for download at the following link:

A table of final results that have been integrated into a single dataframe and reshaped to a “long” format are available for download at the the following link:

A summarised version of the above downloadable table is displayed in Table 6.2. Values shown in Table 6.2 are averages of duplicate lab duplicate values (overall mean percent difference = 1.25 ± 2.44 %, mean ± SD).


Table 6.2: Rotenone results. See above download link for complete analysis results, including other parameters (rotenolone, deguelin, and others.)
sample_name field_sample_date waterbody strata rotenone_ppb detection_note
Miller Creek Weir 2021-11-10 Miller_Creek Creek 2.010
Miller_Creek_1 2021-10-08 Miller_Creek Creek 22.960
Miller_Creek_2 2021-12-03 Miller_Creek Creek 6.585
Miller_Creek_2 2022-01-05 Miller_Creek Creek 0.000 value <0.5 ppb
N_Vogel_Benthic 2021-10-07 N_Vogel_Lake Benthic 13.605
N_Vogel_Benthic 2021-12-02 N_Vogel_Lake Benthic 12.280
N_Vogel_Benthic 2022-01-05 N_Vogel_Lake Benthic 8.755
N_Vogel_Benthic 2022-02-02 N_Vogel_Lake Benthic 0.000 Not_Detected
N_Vogel_Benthic 2022-03-11 N_Vogel_Lake Benthic 0.000 Not_Detected
N_Vogel_Surface 2021-09-28 N_Vogel_Lake Surface 0.000 Not_Detected
N_Vogel_Surface 2021-10-07 N_Vogel_Lake Surface 26.900
N_Vogel_Surface 2021-11-10 N_Vogel_Lake Surface 15.335
N_Vogel_Surface 2021-12-02 N_Vogel_Lake Surface 13.710
N_Vogel_Surface 2022-01-04 N_Vogel_Lake Surface 9.000
N_Vogel_Surface 2022-02-02 N_Vogel_Lake Surface 8.765
N_Vogel_Surface 2022-03-11 N_Vogel_Lake Surface 0.000 Not_Detected
Vogel_Benthic 2021-10-07 Vogel_Lake Benthic 18.555
Vogel_Benthic 2021-12-02 Vogel_Lake Benthic 10.715
Vogel_Benthic 2022-01-05 Vogel_Lake Benthic 0.000 Not_Detected
Vogel_Surface 2021-09-27 Vogel_Lake Surface 0.000 Not_Detected
Vogel_Surface 2021-10-07 Vogel_Lake Surface 25.355
Vogel_Surface 2021-11-10 Vogel_Lake Surface 12.735
Vogel_Surface 2021-12-02 Vogel_Lake Surface 8.810
Vogel_Surface 2022-01-05 Vogel_Lake Surface 0.000 Not_Detected
Vogel_Surface 2022-02-02 Miller_Creek Creek 0.000 Not_Detected


6.3.1.2 Figures

Figure 6.1: Average rotenone concentrations in Vogel Lake and North Vogel Lake, Fall 2021 through Spring 2022.


Note on Miller Creek results:

  • Rotenone values for Miller Creek are not shown in a continuous time series figure due to more limited sample results from varying locations. See Table 6.2 for results from Miller Creek.

References

Couture, Jordan M, Zachary C Redman, Jake Bozzini, Robert Massengill, Kristine Dunker, Brandon R Briggs, and Patrick L Tomco. 2021. “Field and Laboratory Characterization of Rotenone Attenuation in Eight Lakes of the Kenai Peninsula, Alaska.” Chemosphere 288 (Pt 2): 132478. https://doi.org/10.1016/j.chemosphere.2021.132478.