Supplemental Figures and Tables

Online Resource 1 Information about study sites, including land uses in the watershed

Site Name / Municipality / Coordinates / Floodgate Description / Camera
Set-Up / Dist. from the Ocean (km) / Water-shed Area (km2) / Land Use (% of Watershed Area)
Agr. & Rural / Urban / Undevel. Areas, Parks & Protected Areas / Other Human Use (e.g. Roads, Industry)
De Boville Slough / Coquitlam/ Port Coquitlam / 49° 16.850'N
122° 42.938'W / N/A / N/A / 43.6 / 8.64 / 16.69% / 20.01% / 49.35% / 13.95%
Nathan Creek / Langley/ Abbotsford / 49° 9.726'N
122° 29.310'W / N/A / N/A / 59.1 / 35.19 / 94.46%b / 0.23% / 2.56% / 2.66%
Silverdale Creek / Mission / 49° 8.044'N
122° 21.370'W / N/A / N/A / 69.8 / 21.87 / 26.02% / 26.35% / 43.07% / 4.56%
West Creek / Langley / 49° 9.724'N
122° 31.837'W / N/A / N/A / 56.2 / 15.32 / 70.65% / 0.15% / 9.73% / 19.48%
80th Avenue Slough / Delta / 49° 8.788'N
123° 0.116'W / 4 Side-mounted gates / Camera focused on 1 pair of gates / 16.6 / 5.17a / 21.15% / 0.00% / 0.00% / 27.53%
Chillukthan Slough / Delta / 49° 5.570'N
123° 5.106'W / 6 side-mounted gates / Camera focused on 5 of 6 gates / 8.4 / 13.66a / 70.94% / 15.83% / 3.45% / 9.79%
Crescent Slough / Delta / 49° 6.268'N
123° 4.330'W / 4 side-mounted gates / Camera focused on 1 pair of gates / 11.7 / 18.94a / 41.05% / 7.58% / 28.55% / 22.83%
Duncan-Bateson / District of Kent / 49° 14.838'N
121° 55.898'W / 1 side-mounted gate / Camera focused on 1 gate / 111.6 / 5.73 / 29.31% / 17.97% / 0.71% / 52.01%
Fenton Slough / Pitt Meadows / 49° 17.197'N
122° 40.073'W / 1 side-mounted gate / Camera focused on 1 gate / 46.2 / 3.34 / 90.78% / 0.00% / 1.01% / 8.21%
Harbour Creek / Port Coquitlam / 49° 14.153'N
122° 45.883'W / 2 side-mounted gates / Camera focused on both gates / 36.6 / 3.98 / 0.00% / 27.47% / 10.07% / 62.47%
Hatzic Slough / Mission / 49° 8.577'N
122° 14.152'W / 4 top-mounted gates / Camera focused on all gates / 79.8 / 83.83 / 83.80% / 3.48% / 8.37% / 4.35%
Katzie Slough / Pitt Meadows / 49° 14.500'N
122° 44.001'W / 2 side-mounted gates / Camera focused on 1 gate / 38.8 / 34.93a / 54.65% / 13.96% / 13.18% / 18,21%
Manson Canal / Surrey / 49° 11.828'N
122° 54.039'W / 2 side-mounted gates / Camera focused on both gates / 26.3 / 8.46 / 0.00% / 38.77% / 16.99% / 44.25%
McLean Creek / Coquitlam / 49° 16.848'N
122° 42.502'W / 4 top-mounted gates / Camera focused on 3 gates / 43.8 / 4.05 / 55.26% / 0.00% / 43.09% / 1.65%
Mountain Slough / District of Kent / 49° 14.193'N
121° 51.402'W / 3 manual sluice gates / N/A / 113.4 / 29.07 / 45.29% / 3.90% / 0.03% / 50.78%
Mundy Creek / Coquitlam / 49° 14.448'N
122° 48.446'W / 1 side-mounted gate / Camera focused on 1 gate / 35.4 / 3.84 / 0.00% / 36.44% / 49.14% / 14.42%
Nathan Slough / Langley/ Abbotsford / 49° 9.874'N
122° 27.786'W / 2 side-mounted gates / Camera focused on both gates / 61.7 / 15.55 / 94.37%b / 0.10% / 4.00% / 1.53%
Spencer Creek / Maple Ridge / 49° 12.074'N
122° 34.704'W / 1 automated sluice gate / N/A / 51.8 / 2.58 / 28.79% / 23.22% / 31.75% / 17.24%
Sussex Creek / Burnaby / 49° 11.819'N
123° 0.431'W / 1 side-mounted gate, 2 top-mounted gates / Camera focused on all gates, but only evaluated side-mounted gate / 16.2 / 3.21 / 0.00% / 41.57% / 29.70% / 28.74%
Tamboline Slough / Delta / 49° 5.731'N
123° 8.927'W / 2 top-mounted flap/sluice hybrid gates / Camera focused on 1 gate / 5.2 / 1.70a / 97.34% / 0.15% / 0.83% / 1.68%
Wilson’s Farm Tide Gate / Port Coquitlam / 49° 14.198'N
122° 48.040'W / 2 side-mounted gates / Camera focused on the self-regulating gate / 34.6 / 1.97 / 0.00% / 22.99% / 68.34% / 8.67%
Yorkson Creek / Langley / 49° 11.464'N
122° 39.331'W / 2 side-mounted gates / Camera focused on 1 gate / 45.4 / 17.13 / 39.82% / 26.74% / 16.93% / 16.51%

aThese areas are very flat; consequently the ArcGIS watershed tools were unable to predict the watershed boundaries. These estimates are based on hand-drawn polygon estimating the watershed outline using comparisons between layers in ArcGIS and Google Earth.

b Nathan Slough and Nathan Creek watersheds cross the boundaries between Langley and Abbotsford and consequently have different available data. Land Uses in the Abbotsford portions of these watersheds were estimated based on lands lying within the Agricultural Land Reserve and areas covered by roads, water, and built environment land covers (Metro Van Land Cover Classification 2010). The Langley portions of the watershed were estimated based on the Metro Vancouver Land Use 2011 database, which does not cover the City of Abbotsford.

Online Resource 2. Time series of observed floodgate openings for each site from July 2014 through July 2015. Sites are ordered by increasing distance from the ocean. Blank periods are due to malfunction, vandalism, or preventative removal in late winter

.

Online Resource 3 Summary of fish captured – including the total individuals captured from each species, taxonomic groupings used for analyses, and the number of sites where each species was observed.

Taxonomic Grouping for Analysis / Family / Species / Total Captured / Present Above Floodgates (# of sites) / Present Below Floodgates
(# of Sites) / Present at Ungated Sites (# of Sites)
Native Taxa
Suckers / Catostomidae / Largescale sucker / 10 / 1 / 3 / 1
Unidentified juvenile sucker / 21 / 1 / 5 / 1
Sculpins / Cottidae / Prickly sculpin / 182 / 4 / 10 / 3
Unidentified juvenile sculpin / 45 / 2 / 9 / 3
Native Minnows / Cyprinidae / Brassy minnow / 1 / 1 / 0 / 0
Unidentified juvenile minnow / 1416 / 10 / 15 / 3
Peamouth chub / 112 / 1 / 9 / 1
Northern Pikeminnow / 193 / 5 / 11 / 3
Redside shiner / 40 / 3 / 3 / 1
Shiner surfperch / Embiotocidae / Shiner surfperch / 1 / 0 / 1 / 0
Three-spine stickleback / Gasterosteidae / Threespine stickleback / 4757 / 16 / 18 / 4
Starry flounder / Pleuronectidae / Starry flounder / 19 / 0 / 3 / 0
Bull trout / Salmonidae / Bull trout / 3 / 0 / 0 / 1
Chinook salmon / Salmonidae / Chinook salmon / 1 / 0 / 0 / 1
Chum salmon / Salmonidae / Chum salmon / 11 / 0 / 2 / 2
Coho salmon / Salmonidae / Coho salmon / 17 / 1 / 1 / 1
Cutthroat trout / Salmonidae / Cutthroat trout / 1 / 0 / 0 / 1
Whitefish / Salmonidae / Mountain whitefish / 1 / 0 / 0 / 1
Non-Native Taxa
Largemouth bass / Centrarchidae / Largemouth bass / 22 / 1 / 4 / 1
Sunfish / Centrarchidae / Black crappie / 31 / 2 / 0 / 0
Pumpkinseed sunfish / 410 / 12 / 9 / 3
Unidentified juvenile sunfish / 388 / 8 / 9 / 3
Carp / Cyprinidae / Common carp / 6 / 4 / 0 / 0
Brown bullhead / Ictaluridae / Brown bullhead / 6 / 3 / 1 / 1
Unidentified
Unknown / - / Unidentified larval fish / 1 / 0 / 1 / 0
- / Unidentified juvenile flatfish / 1 / 0 / 1 / 0

Online Resource 4 Summary of floodgate operations (mean proportion of the day gates opened) and fish sampling values that were used to calculate the log-response ratios. Richness is calculated based on the number of species in that group, but including all minnows and all sunfishes pooled together due to the large number of unidentified juvenile individuals in these groups.

Site / Mean proportion of the day gates opened / Up/Down-stream / Total Fish Captured / Total Biomass (g) / Total Richness / Native Fish Captured / Native Fish Biomass (g) / Native Fish Richness / Non-native Fish Captured / Non-native Fish Biomass (g) / Non-native Fish Richness
Sites without floodgates
De Boville Slough / N/A (1.000) / Upstream / 69 / 264.07 / 4 / 45 / 22.295 / 2 / 24 / 241.77 / 2
Downstream / 82 / 1006.62 / 4 / 5 / 8.07 / 2 / 77 / 998.55 / 2
Nathan Creek / N/A (1.000) / Upstream / 25 / 57.28 / 5 / 24 / 50.46 / 4 / 1 / 6.82 / 1
Downstream / 74 / 180.27 / 7 / 73 / 167.81 / 6 / 1 / 12.46 / 1
Silverdale Creek / N/A (1.000) / Upstream / 109 / 464.47 / 7 / 30 / 89.98 / 6 / 79 / 374.49 / 1
Downstream / 55 / 536.64 / 6 / 17 / 106.54 / 4 / 38 / 430.10 / 2
West Creek / N/A (1.000) / Upstream / 66 / 14.94 / 6 / 64 / 13.8125 / 5 / 2 / 1.13 / 1
Downstream / 17 / 290.77 / 4 / 17 / 290.77 / 4 / 0 / 0.00 / 0
Sites with floodgates
80th Avenue Slough / 0.013 / Upstream / 739 / 285.39 / 5 / 735 / 222.93 / 4 / 4 / 62.46 / 1
Downstream / 32 / 34.93 / 3 / 32 / 34.93 / 3 / 0 / 0.00 / 0
Chillukthan Slough / 0.187 / Upstream / 864 / 727.85 / 5 / 859 / 517.50 / 3 / 5 / 210.35 / 2
Downstream / 127 / 456.59 / 6 / 124 / 438.69 / 5 / 3 / 17.90 / 1
Crescent Slough / 0.205 / Upstream / 16 / 34.30 / 3 / 14 / 24.86 / 2 / 2 / 9.44 / 1
Downstream / 127 / 254.44 / 6 / 106 / 138.68 / 5 / 21 / 115.76 / 1
Duncan-Bateson / 0.731 / Upstream / 644 / 190.19 / 2 / 644 / 190.19 / 2 / 0 / 0.00 / 0
Downstream / 78 / 73.95 / 3 / 78 / 73.95 / 3 / 0 / 0.00 / 0
Fenton Slough / 0.007 / Upstream / 5 / 2.79 / 2 / 1 / 0.74 / 1 / 4 / 2.05 / 1
Downstream / 124 / 920.75 / 4 / 25 / 57.66 / 2 / 99 / 863.09 / 2
Harbour Creek / 0.064 / Upstream / 832 / 60.57 / 5 / 823 / 59.40 / 3 / 8 / 1.17 / 2
Downstream / 33 / 25.46 / 4 / 32 / 25.16 / 3 / 1 / 0.30 / 1
Hatzic Slough / 0.527 / Upstream / 174 / 133.29 / 3 / 1 / 5.96 / 1 / 173 / 127.33 / 2
Downstream / 202 / 100.10 / 5 / 96 / 22.97 / 4 / 105 / 77.13 / 1
Katzie Slough / 0.010 / Upstream / 5 / 31.71 / 4 / 2 / 1.05 / 1 / 3 / 30.66 / 3
Downstream / 67 / 17.85 / 4 / 66 / 5.92 / 3 / 1 / 11.93 / 1
Manson Canal / 0.049 / Upstream / 44 / 12.85 / 2 / 44 / 12.85 / 2 / 0 / 0.00 / 0
Downstream / 14 / 0.98 / 3 / 14 / 0.98 / 3 / 0 / 0.00 / 0
McLean Creek / 0.017 / Upstream / 9 / 180.81 / 2 / 0 / 0.00 / 0 / 9 / 180.81 / 2
Downstream / 63 / 421.76 / 5 / 36 / 275.24 / 4 / 27 / 146.52 / 1
Mountain Slough / 0.559 / Upstream / 845 / 302.12 / 4 / 844 / 300.47 / 3 / 1 / 1.65 / 1
Downstream / 239 / 79.08 / 3 / 239 / 79.08 / 3 / 0 / 0.00 / 0
Mundy Creek / 0.854 / Upstream / 199 / 55.48 / 3 / 199 / 55.48 / 3 / 0 / 0.00 / 0
Downstream / 98 / 83.83 / 6 / 97 / 77.67 / 5 / 1 / 6.16 / 1
Nathan Slough / 0.351 / Upstream / 57 / 64.23 / 4 / 53 / 40.22 / 2 / 4 / 24.01 / 2
Downstream / 92 / 490.93 / 5 / 88 / 208.94 / 2 / 4 / 281.99 / 3
Spencer Creek / 0.271 / Upstream / 371 / 125.43 / 3 / 359 / 57.27 / 1 / 12 / 68.16 / 2
Downstream / 38 / 96.23 / 4 / 21 / 4.35 / 2 / 17 / 91.88 / 2
Sussex Creek / 0.566 / Upstream / 25 / 6.63 / 2 / 25 / 6.63 / 2 / 0 / 0.00 / 0
Downstream / 118 / 13.78 / 2 / 118 / 13.78 / 2 / 0 / 0.00 / 0
Tamboline Slough / 0.019 / Upstream / 150 / 109.23 / 3 / 149 / 79.24 / 2 / 1 / 29.99 / 1
Downstream / 53 / 191.80 / 7 / 48 / 174.70 / 6 / 5 / 17.10 / 1
Wilson's Farm Tide Gate / 0.319 / Upstream / 73 / 1073.63 / 3 / 2 / 3.16 / 2 / 71 / 1070.47 / 1
Downstream / 278 / 353.69 / 5 / 233 / 170.58 / 3 / 45 / 183.11 / 2
Yorkson Creek / 0.105 / Upstream / 92 / 60.76 / 2 / 87 / 39.04 / 1 / 5 / 21.72 / 1
Downstream / 105 / 73.45 / 4 / 100 / 56.51 / 3 / 5 / 16.94 / 1

Online Resource 5Results of analyses of Fish community data and dissolved oxygen concentrations using floodgate operations data from July and August 2014 only.

Response Variable / Parameter / Parameter Estimate / 95% Confidence Interval / Parameter Weight
Bray-Curtis Community Dissimilarities / Intercept / 0.58 / 0.39 to 0.78 / NA
Mean Proportion Open / -0.20 / -0.40 to 0.00 / 0.55
Watershed Area (km2) / 0 / -0.01 to 0.00 / 0.32
Number of floodgates / 0.02 / -0.04 to 0.08 / 0.19
% Watershed with Developed Land Use / 0.07 / -0.33 to 0.48 / 0.14
Distance Upriver (km) / 0.00 / 0.00 to 0.00 / 0.13
Native Species Richness log-response-ratio / Intercept / -0.36 / -0.87 to 0.16 / NA
Mean Proportion Open / 0.50 / 0.00 to 0.99 / 0.54
Number of floodgates / -0.09 / -0.22 to 0.04 / 0.31
Watershed area (km2) / -0.01 / -0.02 to 0.00 / 0.23
Distance Upriver (km) / 0.00 / -0.01 to 0.01 / 0.14
% Watershed with Developed Land Use / -0.05 / -1.00 to 0.90 / 0.13
Upstream Dissolved Oxygen / Intercept / 3.31 / 0.36 to 6.26 / NA
Mean Proportion Open / 6.07 / 2.75 to 9.39 / 0.98
Distance Upriver (km) / -0.03 / -0.07 to 0.01 / 0.23
Watershed area (km2) / 0.03 / -0.03 to 0.1 / 0.15
Number of Floodgates / 0.29 / -0.76 to 1.34 / 0.13
% Watershed with Developed Land Use / -0.52 / -6.76 to 5.72 / 0.09