Warden’s Report #76 Fraser River – September 15, 2024

ER #76 Fraser River – September 15, 2024

Report by Bev and Bill Ramey

Sunshine, a few clouds in morning, clearing to full sun, 15 to 21^o C
Walking distance about 10 km, but most of this distance measured by the GPS was back and forth traverses across the accreting gravel bars, now covered with clay-silt-sand, and where we were closely observing herbaceous plants, so distance was not a linear distance. The GPS also recorded our moving time as 4½ hours and our resting time (when observing plants) as 5½ hours, so our day on the islands was largely focused on the plants.

Water level at Mission gauge: 0 m to 1.75 m (Fraser is tidal at Mission)
Water level at Hope gauge: 3.9 m
Participants: Frank Lomer (plant expert), wardens Bill & Bev Ramey

It was a lovely fall day to examine plants on the islands and the clear air provided good visibility to surrounding and distant mountains. We arrived at the parking lot at 9 am, loaded gear and paddled to the islands, arriving on islands by 9:45 am.

Our walk about the islands was a route of back and forth diagonals across accreting sandbars and former channels, examining plants. Our first three hours on site covered only a portion of the northwestern accreting shoreline (from our kayak landing location and up to the Burrowing Owl sand dune).

While Frank and Bev examined plants in this area, Bill walked further up to the northeastern tip, observing birds. We then all headed across the central area of the islands and then along the dry channels to the southwestern, downriver tip of the islands, again taking time to look carefully at the many herbaceous plants growing along the former river channels, now filled with sediments. These channels still flood during freshet, but with increased build-up of sediments they remain dry for much of the year. Finally, we walked back up the northwestern shoreline, arriving back at our kayaks by 7:00 pm.

We think some of the very soft material deposits (fine sand, clay and silt) were recently deposited on Aug 6^th when Chilcotin River water raised the water level of this gravel reach of the Fraser, following the breach of the landslide dam on the Chilcotin River. See the Environment Canada water level graph copied following, which shows the spike in Fraser River flow at Hope up to 6 m (an increase in height of about a metre for August 6^th). The water gauge today was 3.9 m at Hope, so the Chilcotin deposits would have reached the accreting shoreline where we were walking today. The height rise at the ER islands would not have been the full two metres recorded at Hope, because the Fraser River is much wider here with greater area for the river to spread over than at the Hope gauge.

The fine sand/silt/clay deposits were deep in places and we could see the tracks where deer, coyote and bear had sunk in. We too experienced this ‘sinking’ along our route on the northwestern shoreline, when walking back up towards our kayaks from the downriver tip, that is, we too were sinking down 5 cm and deeper, which made for difficult walking.

From Environment Canada water gauge, Fraser River at Hope, shows the water levels from June 16 through to Sept 16, including the annual freshet in early July, the dramatic August 6^th water level rise from the Chilcotin River and then reduced flows through to time of our Sept 15 visit.

We were impressed by the extensive growth of herbaceous plants on what had been the accreting gravel bars. These areas received considerable fill of sands and silts after the November 2021 atmospheric river floods. Although the height of these floods was not up to Fraser River freshet levels, the level was sufficiently high to deposit considerable amounts of sediments, especially sands and silts, over the gravel bars. Our report from March 6, 2022 visit to the ER, included these notes describing the amount of fill deposited on the accreting shorelines:

March 2, 2022 ER visit:  The islands look to have benefited from the upriver November flood erosion, that is, the north and northwestern accreting sides of the islands have had their height increased considerably with deposits of sand, silt and clays. The volume of deposited sediments is enormous. A very rough estimate is in the order of 15,000 gravel truck loads! (This crude estimate is based on 16.5 cubic yards per gravel truck, and area filled is about 1000 yards x 500 yards x .5 yard deep) . . .. The height increase of deposits has been estimated based on filling that has taken place adjacent to what had been a bank that rose steeply upwards (about a metre in height) to the vegetated islands of horsetail, willow and cottonwood. Now with the new sediment deposits, the river bed is almost the same level as the vegetated islands. In addition, where colonizing cottonwoods or willows, had been vegetating the river bed, these young trees now have sand deposits rising up their small trunks and their lower branches now arise from below the new surface of the sand. . ..  These sediments would have settled out from the fast flowing Fraser River as it reached the slower flowing reach where the Ecological Reserve islands are located. That is, the gradient of the river flow gradually slows downriver from Hope, and especially at the ER islands, as here the Fraser can expand to its widest width, about 1.5 kilometres across from mainland dykes on its southern and northern shores.

For herbaceous plants to establish, their seeds would have floated downriver in the June/July freshet 2022, or possibly blown, then germinating after that, so there would now have been two or three growing seasons. The huge size and extent of biennials, such as the White Sweet Clover (Melilotus alba), which today was observed growing in thickets with height over a metre tall, could be due to the two good growing seasons with fertile soils. This is in contrast to previous colonization on the gravel bars, which was largely plants struggling to survive and grow in gravels at lower elevations. For the lush growth of plants, the August 6^th Chilcotin River influx of new nutrients, through silt and clay sediments, further boosted growth.

With careful examination of plants, Frank Lomer added 126 new plants to the existing plant list for this ER. As we covered only a small portion of the islands and did not have time to walk inland to examine the treed areas of the islands, we plan to make another trip soon, with further focus on plants.

Mammals

Tracks of:
Deer – four adults and two young
Beaver – prints seen in a few areas, also a few freshly gnawed upon trees
Coyote – at least three adults and one young
Black Bear – adult sized and young-sized tracks

Amphibians and Reptiles

7 mid-sized Western Toad
1 Tree Frog
No snakes seen, but we spent almost no time on higher vegetated ground

Molluscs
Two freshwater mussel shells found (Western River Pearl Mussel) near upriver tip of islands. Likely these float down from upriver, possibly the Harrison River.
Several introduced snails, likely Brown-lipped Snail (Cepaea nemoralis)

Insects
Countless honey bees, likely from the approximately 1000 hives stored for winter on Nicomen Island beside the car park area
Shimmering green-blue beetles feeding on the willow (Salix sessilifolia) were likely Altica bimarginata
Ladybeetles
No butterflies
Grasshoppers: Carolina (Dissosteira carolina), Migratory (Melanoplus sanguinipes), and Pallid-winged (Trimerotropis pallidipennis)
Tiger Cranefly (Nephrontoma sp.)
Variegated and White-faced Meadowhawk Dragonflies (Sympetrum corruptum and Sympetrum obtrusum)
Enallagma sp. Damselfly

Fish

No pink spawning salmon this year as it is an even-numbered year.
In the several land-locked pools, several species swimming, likely similar to those identified in 2017:
Northern Pike minnow,
Juvenile Suckers,
Larval Lamprey,
and Juvenile Sculpin

Plant Species

126 new plant species were identified by Frank Lomer. These are included in the revised plant list, dated October 2024. Approximately 200 photos have been uploaded onto iNaturalist for 71 plant species from this September 15^th visit.

https://www.inaturalist.org/observations?place_id=132525&user_id=bevramey

Birds

Birds have been entered on eBird at hotspot:

https://ebird.org/canada/hotspot/L844938

American Wigeon at dusk, about 40 flying eastwards
Glaucous-winged Gull 8 throughout the day, then with dusk about 100 flying overhead westwards
Ring-billed Gull 2
Great Blue Heron 3
Bald Eagle 1
Osprey 1
American Kestrel 1
Turkey Vulture 4 soaring overhead
Northern Flicker 2
Belted Kingfisher 1
Common Raven 2
Black-capped Chickadee 6
White-crowned Sparrow 6
Savannah Sparrow 1

And observed at nearby Nicomen Island boat launch and nearby

Downy Woodpecker 1
Killdeer 2 seen as we began driving, in gravel along gravel road edge at dusk
Nighthawk 1 flying about where car was park, together with bats
American Robin 1
American Goldfinch 1

The following photos show extent of plant growth this September and also included are comparison photos from 2021 and 2022, to show deposits from the November 2021 Atmospheric River.

September 15, 2022 showing lush plant growth and where the second year of biennial White Sweet Clover (Melilotus alba) behind the person has grown to height taller than the person. Photo taken on northwestern accreting shore looking towards the downriver tip of the ER treed island, with Chilliwack Mountain in the background.

September 15, 2022 this photo also shows the lush herbaceous growth on the northwestern accreting shoreline. Photo direction looking upriver, northeast towards Harrison Knob and mouth of Harrison River.

By contrast, this April 11, 2021 photo, looking upriver the same direction towards Harrison Knob, was taken before the November 2021 Atmosphere River deposits and shows mainly gravel with almost no colonizing vegetation.

Photo from before the Atmospheric River flooding, taken April 11, 2011 looking downriver along the inner swale between the two lower islands, with considerable ponded water. Compare with photo below, taken October 1, 2023, same location, where channel is now filled with silt/clay/sand following the November 2021 Atmospheric River and where herbaceous plants are beginning to establish.

Photo March 6, 2022, after the Atmospheric River deposits, from the islands’ northwestern accreting shoreline, looking downriver to lower tip of ER treed island, with Chilliwack Mountain behind, angling down from photo top left.

Sept 15, 2024, showing inner swale with extensive colonizing plants