The 1999 Fish Kill in a Tributary of the Souris River
The Department of Technology and Environment (DT&E) was informed by a staff member of a fish
kill on Wednesday July 14, 1999, in a tributary of the Souris River below the Manning Road. A
watershed group had been working on the tributary and encountered dead fish in the early afternoon.
The Environmental Emergency number (response 1-800-565-1633) was contacted to advise the
Department of Fisheries and Oceans (DFO) and Environment Canada of the fish kill.
Response and Investigation
Additional staff from the DT&E were dispatched to the fish kill location as the watershed group
continued the investigation. The section of the stream that was affected was approximately one
kilometre in length and was at the head of a spring fed tributary. The location of the spring that acts
as the origin of the tributary is located at the bottom of a large potato field. Because it is spring fed,
the temperature of the stream is cool and would be in the range of approximately 10°C
The watershed group and additional DT&E staff collected fish from the affected portion of the
stream, and a few of these fish were sent to the Atlantic Veterinary College (AVC) for a visual
inspection. Signs of various stages of decay were noted in the fish that were collected, indicating
that the fish kill may have occurred a few days prior to its discovery by the watershed group. There
had been a heavy down pour in the area on Saturday, July 10, 1999 (the same day as the Valleyfield
and Orwell River fish kills). Rainfall records from Souris indicate that 24.8 mm of precipitation was
received over a six hour period on Saturday, July 10, 1999 and that there was an additional 7.1 mm
of rain over a nine hour period on Tuesday, July 13, 1999. In total, between 250 to 300 fish were
collected from the affected portion of the stream, although this would be a conservative number in
terms of the actual number of fish affected by the fish kill.
Several water, soil and plant tissue
samples were collected during the
investigation from five different
locations. The sample locations are
described in Table 1 and are shown
in Figure 1. Only selected samples
were analyzed, and the results of
these analyses are discussed later in
the report.
Affected Stream
Bear River
BEAR
RIVER
Site 5
Site 4
ni ng
Man
Site 3
Site 2
307
Ro a
d
Road
Site 1
Tom
Jim
Road
Figure 1 also indicates that the fish
kill affected only the upper portion
of the tributary. Live fish were
observed in the stream below the
point where the tributary joins with
the next segment of the stream.
Hwy 307
Scale: 1 Kilometer
358
Figure 1
Sampling locations for the Souris River Fish
Kill, July 14, 1999.
Site
Location
Site Description
Samples Collected
Site 1
South of Manning Road, before the Y with
the side stream from the North. Water and
sediment samples from the stream.
M1 - 1L Amber Glass - Water
M2 - 1L Amber Glass - Water
M3 - 1 L Plastic - Water
M4 - 250 mL Plastic - Water
M5 - 250 mL Glass - Sediment
Site 2
North of Manning Road. Water and sediment
samples collected from the stream just before
it enters the culvert under the Manning Road.
M6 - 1L Amber Glass - Water
M7 - 1L Amber Glass - Water
M8 - 1 L Plastic - Water
M9 - 250 mL Plastic - Water
M10 - 250 mL Glass - Sediment
Site 3
Water and sediment samples from the stream
on the farm road between the two potato
fields at the culvert crossing between the two
fields.
M11 - 1L Amber Glass - Water
M12 - 1L Amber Glass - Water
M13 - 1 L Plastic - Water
M12B - 250 mL Plastic - Water
M15 - 250 mL Glass - Sediment
Site 4
Soil samples collected from the end of the
potato rows from the potato field at the back
of the property.
M20 - 250 mL - Soil
M21 - 250 mL - Soil
Site 5
Standing water, sediment and vegetation
samples from between the two potato fields at
the upper end of the wetland.
M16 - 1L Amber Glass - Water
M17 - 1L Amber Glass - Water
M18 - 1 L Plastic - Water
M19 - 250 mL Plastic - Water
M22 - 250 mL Glass - Soil
M23 - 250 mL Glass - Soil
M24 - 250 mL Glass - Vegetation
The producer who was growing potatoes in the field above the spring-fed origin of the field provided
investigators with his pesticide spray records. Both endosulfan and manzate were applied to the field
on Thursday, July 8, 1999. It was observed that the rows in the potato fields were running up and
down the slope, and that the lengths of these rows were excess for the slopes of the field. A grassed
waterway, had been left in the low area on the field, but the rows did not run into the grassed
waterway. A bare turning area had been left between the end of the potato rows and the grassed
water way. It appears that a large amount of water and sediment may have moved into the stream,
before the runoff water could benefit from the filtering action of the grassed waterway. Several
pictures of the site are included in Appendix A at the back of this report.
Atlantic Veterinary College Lab Results
Pesticide Analyses - Water, Soil, Vegetation and Fish Tissue:
Sediment samples from the stream below the potato field indicate that Alpha- and Beta-Endosulfan
were discovered at concentrations of 7.3 and 7.2 ppb, respectively. Alpha- (266 ppb) and BetaEndosulfan (216 ppb) and dithiocarbamates (600 ppb) residues were detected from a soil sample
collected from the bottom of the rows in the potato field at the origin of the stream. Vegetation
samples from the same field were also analyzed and Alpha- (0.253 µg/m2) and Beta-Endosulfan
(1.04 µg/m2) were again detected.
Liver tissue from the fish was analyzed for several pesticides, however no pesticide residues were
detected.
Fish Examination: The necropsy by the AVC fish pathologist noted that the fish were in various
stages of decay, and that this would be a function of how cool the fish were kept after there death.
Estimates of the time of death of the fish were at least 24 to 48 hours prior to inspection, although
it is indicated that this is a subjective opinion, since the conditions to which the fish were exposed
after their deaths, and prior to their collection on Wednesday, July 14, 1999, is not known.
All the fish were brook trout and all were feeding prior to their sudden death. All sizes of fish and
both sexes were represented in those that were examined. There was no evidence of any concurrent
disease processes active in the fish at the time of their deaths.
The lab reports from the AVC have been included in Appendix B of this report.
Discussion
As with all of the other pesticide related fish kills in P.E.I. in 1999, there was a potato field at the
upper end of the fish kill that appeared to have lost a large amount of water and sediment to the
tributary of the Souris River. While the fish tissue (which may have sat for several days prior to
collection) did not reveal any pesticide residues in the fish, the visual evidence from the field, and
the water and sediment results suggest that the fish kill was pesticide related. It appears that several
factors may have been significant contributors to the fish kill: (1) The potato fields were large, with
rows running up and down the slope. (2) The row lengths were excessive in terms of potential soil
loss for the grades on the field and the agricultural practices used. (3) Pesticides that are highly toxic
to aquatic species were applied to the potato crop. (4) Intense rainfall events were recorded in the
area. (5) Headland management techniques allowed runoff from the field to enter directly into the
stream, prior to reaching a grassed waterway that may have reduced the amount of washoff from the
field.
The pesticides that were detected are known to sorb to soil and are known to be very toxic to aquatic
species. If fish kills are to be avoided in the future, significant work will be required to address the
contributing factors listed above, that are within the producers control.
APPENDIX A
SELECTED PHOTOS OF THE
SOURIS RIVER FISH KILL
JULY 14, 1999
Figure A1.
View of the headland at the bottom of the suspected field. The tributary to
the Souris River starts at the bottom of the field, shown in the wooded
area.
Figure A2.
Grassed waterway at the bottom of the suspected field. Water was able to
runoff directly into the stream along the bare levelled headland, and did
not receive any filtering that the grassed waterway might have provided.
Figure A3.
View showing the size and slope of the fields on the suspected property.
The tributary to the Souris River starts in the low, wooded area in the
center of the picture.
APPENDIX B
LAB RESULTS FROM THE
ATLANTIC VETERINARY COLLEGE