The 2000 Souris River Fish Kill Report July 20, 2000

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1 The 2000 Souris River Fish Kill Report July 20, 2000 Introduction During the morning of July 20, 2000, a stream enhancement crew that was working on the east branch of the Souris River near Harmony Junction noticed a number of dead fish in the tributary on which they were working. Researchers working on the lower end of the east branch of the Souris River also found dead fish near Gowan Brae. Department of Fisheries, Aquaculture and Environment (DFAE) staff were in the area and were notified about the fish kill. The environmental emergency response number was called to alert the other government agencies that needed to be notified. Investigation Response Additional DFAE staff responded and began an investigation of the fish mortalities. The Emergency Response Vehicle was dispatched to the site. DFAE Conservation Officers (COs) checked the river at various locations and identified that it was only the east branch of the Souris River that was affected. There had been a fish kill in the west branch of the Souris River in 1999, but this branch was not affected by the events on, and prior to July 20, The entire Souris River watershed is approximately 5300 hectares, but the area contributing to the East branch that was affected is only about 1500 hectares in size. The length of stream affected on the east branch was approximately five kilometres, with most of the fish discovered in the upper portion of the east branch in an unnamed tributary. The Department of Agriculture and Forestry maintains a meteorological station on the Souris Line approximately 0.8 kilometres from the unnamed tributary on the east branch of the Souris River. A total of 13.8 mm of rainfall was recorded between 12:00 pm on July 18, 2000 and 12 pm on July 19, The majority of this rainfall occurred in two downpours. The first occurred on the evening of July 18, 2000, when a total of 5.3 mm fell in 11 minutes. The second occurred on the morning of July 19, 2000, when 6.2 mm of rain fell in 9 minutes. Hail was also reported during the second precipitation event on the morning of July 19, Rainfall across the Island was quite variable during this same time period. A weather station in Harrington recorded 75 mm over the same 24 hour period, while only a negligible amount was recorded at the Charlottetown Airport. At the same time, there was enough precipitation in downtown Charlottetown to cause short-term localized street flooding. The trail of dead fish lead to a small unnamed tributary that enters the east branch of the Souris River just downstream of McVarishs Pond in Harmony Junction. The majority of the dead fish were found in the vicinity of this entry point of the unnamed tributary into the east branch of the Souris River. With the exception of this unnamed tributary, numerous live fish were found in all other stretches of the river. Figure 1 shows the portions of the stream that were affected by the fish kill.

2 Zealand NEW ZEALAND Gowan 306 GOWANBRAE 306 Souris Grant SOURIS WEST 305 HARMONY JUNCTION 305 SOURIS LINE ROAD 304 NEWHARMONY New Souris River - East Branch - Fish Kill July 20, 2000 Affected Portion of Stream Unaffected Portion of Stream Harmony Harmony Junction East Branch Souris River McVarishs Pond West Branch Souris River Gowan Brae Scale - 1 Kilometer Figure 1. Location of the Souris River Fish Kill, July 20, 2000 showing the location of the affected and unaffected portions of the river system. Measurements of dissolved oxygen and temperature were taken at several locations along the system by DFAE staff. Temperatures ranged from 9.6 C to 18 C, and dissolved oxygen measurements were from 9.5 mg/l to 10.6 mg/l. Oxygen saturation values at 10 C and 15 C are 10.9 mg/l and 9.7 mg/l, respectively. The individual readings are presented in Table 1 and the locations are shown in Figure 2. Table 1. Dissolved Oxygen and Temperature Reading on July 20, 2000 Location Time Temperature ( C) Dissolved Oxygen (mg/l) Notes JT#1 - McVarishs Pond 15: Taken at fish ladder outlet JT#2 - First stream crossing - Rails to Trails Crossing 15: Rail crossing of small tributary JT#3-3rd Bridge Crossing 16: JT#4-2nd Bridge Crossing 16: Where fish kill first observed Crossing Gowan Brae 16: East Branch at Gowan Brae 16:

3 Zealand NEW ZEALAND Gowan 306 GOWANBRAE 306 Sour is Grant SOURIS WEST 305 HARMONY JUNCTION 305 SOURIS LINE ROAD 304 Harmony NEWHARMONY R oad New Land use along the upper tributary near the origin of the fish kill was predominantly in hay and grain in There was however, a single potato field occupying two properties near the watershed boundary, above the unnamed tributary. During the investigation it was discovered that the farmer of the potato field was applying Dithane (a fungicide) on the morning of July 19, 2000, when an unforecast downpour occurred in the area. The applicator halted the application of the fungicide at the start of the rainfall. The farm weather forecast for the Souris Souris River - East Branch - Fish Kill July 20, 2000 Dissolved Oxygen and Temperature West Branch Souris River Gowan Brae JT #6 Figure 2. JT #5 JT #2 JT #4 JT #3 JT #1 Affected Portion of Stream Unaffected Portion of Stream Scale - 1 Kilometer Location of temperature and dissolved oxygen readings, Souris River fish kill, July 20, area on the morning of July 19, 2000 called for a chance of rain with a 29% probability of precipitation between 5:00 am and 8:00 am with 0% probability after that time. The application of the fungicide and the heavy downpour occurred after 8:00 am on the morning of July 19, No insecticides had been applied to the field prior to the fish kill. The potato field was not immediately adjacent to the unnamed tributary. The water course originates at least 500 feet below the potato field. However, runoff from the potato field would be directed by topography towards the unnamed tributary where the fish kill originated. The size of the potato field was approximately 90 acres, spanning two properties. The field was in a three-year rotation (potatoes/grain/hay), and conventionally tilled with fall moldboard plowing. The upper portion of the field had slope lengths of 640 metres on grades ranging from 1 to 8%. The potato drills ran up and down the slope on the field. The set up of the field resulted in the entire property being drained through a hollow in the field, and although gully erosion was not severe in the hollow, there was evidence of considerable flow and sediment movement. The hollow was grassed at the lower end, with considerable, well established growth. However, the potato rows ended approximately 15 metres from the grassed hollow, and the area between the potato rows and the grassed hollow was tilled and appeared to have been scraped after hilling. Flow from individual potato rows concentrated on this tilled headland area and entered the grassed hollow at a number of distinct locations. The grassed hollow on the lower adjoining property showed evidence of an approximately 3 metre wide swath of water leaving the potato field. Department of Agriculture and Forestry staff examined the potato field and determined that equipment used on the field caused the soil to be compacted between the rows. The compaction would reduce the rate of infiltration into the soil and may have enhanced the amount of runoff from the field. During the investigation, water, stream sediment, field soil and vegetation samples were collected by DFAE staff at various locations. The samples collected are listed in Table 2, and their locations are shown in Figure 3. Selected photographs are included in Appendix A.

4 Table 2. Samples collected during investigation into the Souris River fish kill, July 20, Station ID Location Description Samples Collected JT#1 McVarishs Pond a) 250 ml - Water - Plastic b) 1000 ml - Water - Plastic c) 1000 ml - Water - Plastic d) 1 L Water - Amber glass JT#2 First stream crossing - Rails to Trails Crossing a) 250 ml - Water - Plastic b) 1000 ml - Water - Plastic JT#4 2nd Bridge Crossing - where fish kill was first noticed a) 250 ml - Water - Plastic b) 1000 ml - Water - Plastic c) 1000 ml - Water - Plastic d) 1 L Water - Amber glass JPM#1 JPM#2 KM I Rails to Trails crossing of un-named tributary. Braided channel, standing water from side that has flow during high water. Potato field below Island Tel tower and above the unnamed tributary East Branch Souris River - Just above where the east and west branch meet a) 1 L Standing Water - Amber glass b) 1 L Standing Water - Amber glass c) 250 ml Sediment - mason jar a) 250 ml field soil - mason jar b) 250 ml sediment - mason jar c) 1 L Standing Water - Amber glass d) 1 L Standing Water - Amber glass e) Potato Leaves - mason jar a) 1 L Water - Amber glass KM II At confluence of east and west branch of the Souris River a) 1 L Water - Amber glass KM III KM IV Souris River at lowest road crossing just above the estuary. Un-named tributary of east branch of Souris River - south of east branch at road crossing a) 1 L Water - Amber glass a) 1 L Water - Amber glass RM 1 Stream crossing known as Second Bridge a) 1 L Water - Clean Mason Jar RM 2??? a) 1 L Water - Clean Mason Jar RM 3 RM 4 RM 5 Souris River at lowest road crossing just above the estuary. Souris River (combined east and west branches) at road crossing just below confluence of the two branches East Branch Souris River - Just above where the east and west branch meet. a) 1 L Water - Clean Mason Jar a) 1 L Water - Clean Mason Jar a) 1 L Water - Clean Mason Jar RM 6??? a) 1 L Water - Clean Mason Jar RM 7??? a) 1 L Water - Clean Mason Jar

5 Zealand NEW ZEALAND Gowan 306 GOWANBRAE 306 Souris Grant SOURIS WEST 305 HARMONY JUNCTION 305 SOURIS LINE ROAD 304 NEWHARMONY New Souris River - East Branch - Fish Kill July 20, 2000 Sample Collection Locations JPM 2 Affected Portion of Stream Unaffected Portion of Stream Harmony RM 2??? RM 6??? RM 7??? JT 4 & RM1 JT 2 JT 1 JPM 1 West Branch Souris River KM I & RM 5 KM 4 KM II RM 4 Gowan Brae KM III & RM 3 Scale - 1 Kilometer Figure 3. Location of sample collection during the investigation into the Souris River, east branch, fish kill - July 20, Atlantic Veterinary College - Water and Sediment Results Selected samples collected during the investigation were analyzed by the Atlantic Veterinary College (AVC). Table 3 summarizes the results from the AVC lab, and Figure 4 show the results in relation to where the samples were collected. The individual lab reports are included in Appendix B. Samples collected from the grassed area at the low point in the suspected potato field (JPM 2) showed evidence of both dithiocarbamates and metribuzin in standing water (131 ppb and 9.03 ppb, respectively), and in sediment (18,000 ppb and 247 ppb, respectively). A small amount of Deet was also detected in one sample but would have most likely come from insect repellant worn by one of the investigators. Dithiocarbamates were also detected in standing water (5.73 ppb) and sediment (> 916 ppb) from a high flow area next to the stream just below the Rails-to-Trails crossing of the stream (JPM 1). This area would have received flow during times of high flows, but when the water receded, a standing water puddle and the sediment that had accumulated remained. Dithiocarbamates were also detected in stream water (1.40 ppb) taken from the East Branch of the River in Gowan Brae just above where the East Branch meets the West Branch of the River (KM 1 & RM 5).

6 NEW ZEALAND Gowan 306 GOWANBRAE 306 Souris Grant SOURIS WEST HARMONY JUNCTION 305 SOURIS LINE ROAD 304 The maximum concentration of dithiocarbamates detected in standing water samples was well below the LC50 toxicity levels (2200 ppb) reported in the literature for mancozeb. Table 3. Pesticide analytical results for water and sediment samples - Souris River fish kill investigation, July 20, Sample ID Type of Sample Products Detected Concentration (ppb) LC50 96hr Rainbow Trout (ppb) JPM 1A & 1B Standing Water Dithiocarbamates &2 JPM 1C Stream Sediment Dithiocarbamates > JPM 2B Field Sediment Dithiocarbamates Metribuzin DDT Endosulfan Sulfate JPM 2C & 2D Standing Water Dithiocarbamates Metribuzin Deet 18, Trace Trace Est &2 64, , RM 5 & KM I Water Dithiocarbamates &2 (1) Environment Canada, 1999; (2) EXTOXNET, (3) Estimated because standard was not run during analysis. JPM2 Dithiocarbamates ppb (Standing Water) Metribuzin ppb (Standing Water) Dithiocarbamates 18,000 ppb (Sediment) Metribuzin ppb (Sediment) JPM1 Dithiocarbamates ppb (Standing Water) Dithiocarbamates >916 ppb (Sediment) RM5 and KM1 Dithiocarbamates ppb (Stream Water) Figure 4. Sample results shown in relation to where the samples were collected during the Souris River fish kill investigation, July 20, 2000.

7 Three water samples were also analyzed at the Department of Fisheries, Aquaculture and Environment, Environmental Services Lab. The results are included in Appendix C, and do not indicate anything out of the ordinary in terms of the inorganic chemistry of the water. Atlantic Veterinary College - Fish Examination Results During the investigation and clean up activities in the east branch of the Souris River, approximately 300 dead fish (in excess of 4") were collected. These fish included rainbow trout, speckled trout and salmon. The were numerous dead fish smaller than 4" that were not collected during the clean up, thus the number of fish affected would be much higher than the 300 fish collected. Samples of the dead fish were collected and transported to the Atlantic Veterinary College (AVC) for inspection by a fish pathologist. Examination of the fish at the AVC was limited by the condition of the fish. It was estimated that the fish had died 12 to 36 hours prior to being examined. Because of the deterioration of the samples little other information as to the cause of death could be determined. Infectious disease could not be ruled in or ruled out, and histopathologic examination of the samples could not be undertaken. Fish tissues from the Souris fish kill were analyzed by the AVC for both an organophosphate and organochlorine (OP/OC) scan and dithiocarbamates. Dithiocarbamates residues were detected in the fish livers at a concentration of 5.9 µg/g. However, there is a lack of reference information available in the literature to allow for an interpretation of what impact these levels may have had on the health of the fish. Cholinesterase activity levels on four brain samples ranged from 82% to 115% of the control samples. These results do not indicate a suppression in the brain cholinesterase activity levels. The analytical reports from the AVC are also included in Appendix B Discussion Several factors appear to have contributed to the fish kill in the east branch of the Souris River. While the total amount of rainfall was not large, there was an intense rainfall event prior to kill (13.8 mm over a 24 hour period, with 6.2 mm falling in 9 minutes). This thunderstorm was unforecast, and as a result, there was an application of a fungicide occurring immediately prior to the start of the rainfall event. The pesticide would not have had time to dry on the plant canopy, and as a result more of the product may have been lost in the runoff water than if it had been allowed to dry onto the plants. In addition, the equipment used in the field (a Gruise cultivator) tended to compact the soil in the bottom of the drill. With this compact soil, infiltration of water would be reduced and the amount of runoff water would be increased. A letter has been sent to the Island sales representatives for this equipment suggesting that a tine should be added behind the equipment to break up the compacted soil.

8 Several common factors with other other fish kill investigations in 1999 and 2000 were also present in the Souris River Fish kill investigation. The length of the potato rows were excessive (640 m) for the slopes present in the field (1 to 8%). The potato rows were running up and down the slope, and runoff water from the entire field drained through a hollow in the field. While the hollow had established growth, the area between the end of the potato rows and the hollow was bare, providing a pathway for the concentrated flow to leave the field. So despite the following facts: (1) the pesticide involved was only moderately toxic to rainbow trout, (2) the amount of rainfall was not excessive, and (3) the potato field was not immediately adjacent to the stream, a fish kill still resulted because the runoff potential on the field was increased due to length and slope of the rows and the compacted areas between the drills, and runoff from the entire field was allowed to collect and leaving the field in one small area.

9 Appendix A Selected Photos from the Souris River (East Branch) Fish Kill Investigation July 20, 2000

10 Figure A1. View of the potato field above the east branch of the Souris River. The view is from the bottom of the potato field across the grassed hollow towards Hwy 305 in the distance. The photo shows the length of the rows and the slopes on the field. (Souris River Fish Kill, July 20, 2000) Figure A2. Bared area between the potato rows and the grassed hollow. The photos show the amount of sediment that was moving down the field from each of the individual potato rows. (Souris River Fish Kill, July 20, 2000)

11 Figure A3. Close up veiw of the sediment and runoff path from the potato field into the grassed hollow. (Souris River Fish Kill, July 20, 2000) Figure A4. Photo of the sediment ladden standing water that remained in the grassed hollow in the potato field. (Souris River Fish Kill, July 20, 2000)

12 Appendix B Reports from theavc Related to the Souris River (East Branch) Fish Kill Investigation July 20, 2000

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17 Appendix C Reports from the DFAE Environmental Services Lab Related to the Souris River (East Branch) Fish Kill Investigation July 20, 2000

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