Two Nimbus Locations in One Day, 09-21-20

I got up around 6:00 this morning, and headed out the door about 6:30 am to join my friend and fellow naturalist, Roxanne, for a walk at the Nimbus Fish Hatchery.  It was relatively cool outside, around 63°, and fairly clear. The air quality go worse later in the afternoon, though.   152 AQI (Unhealthy) . We stopped to get some coffee and a breakfast biscuit on the way.

As we got near the hatchery turn out, I mentioned that I’d read about a park that was supposed to be on Lake Natoma on the side of the street opposite the hatchery, the Nimbus Flat State Recreation Area/ Lake Natoma. I’d driven by the entrance once, but had never checked it out before, so we stopped there before going to the hatchery itself. 

Lake Natoma

According to “Recreation at Lake Natoma is managed by the California Department of Parks and Recreation under agreement with the Bureau of Reclamation. The Lake was created by Nimbus Dam across the American River. Lake Natoma is a regulating reservoir for releases from Folsom Lake. The Dam and Lake are features of the Central Valley project…”  

Lake Natoma is a small lake along the lower American River, between Folsom and Nimbus Dams in Sacramento County. The lake has 500 surface acres of water.  There are paved trails for jogging and bicycling, and unpaved trails for hikers and equestrians.  A dense 14 mile long riparian ecosystem encircles the lake.  Although fishing is a big pastime here, it’s generally “catch and release” because there is a high concentration of mercury in the fish here.

Because we were trying to save time to get over to the hatchery, we didn’t spend as much time at the rec area as we might have, and didn’t cover much of the trails.  We’re between seasons right now, so the park wasn’t showing itself off to its full potential, but I could absolutely see how intriguing it might be in the late fall, winter and early spring.

Gray Pine, Pinus sabiniana

The lake surface was pretty much devoid of birds, but we did see a flock of gulls and what looked like a hybrid goose.  Migrations are just starting, so hopefully there will be more birds on the water over the next few months. There were Canada Geese and Wild Turkeys on the shore and the part of the trail we covered. We heard a few other birds, but had trouble finding and photographing them.

CLICK HERE for the full album of photos.

In the water there were quite a few swimmers, many with swim buoys trailing from their backs. Besides providing them with a little protection –- the colorful buoys make the swimmers more visible in the open water – they also provide some drag, which helps to strengthen the swimmers as they work to pull the buoys along with them.  We also saw some kayakers and paddle-boarders on the water.

Kayakers on the water

 Throughout the riparian forest there were lots of cottonwood trees, oak trees, gray pines and alders with a smattering of sycamore, redbud and wattle trees throughout. Occasionally, we saw oddities – like a juniper tree growing on the side of the lake.

Some of the alder trees seemed to have very swollen portions on their limbs and one had some kind of dark ooze weeping out of it. So many different pathogens can cause this kind of damage, it’s hard for a lay person like me to correctly identify the cause. I thought at first that some of the swellings were in response to mistletoe, but not all of the trees had mistletoe on them. 

There’s an invasive pathogen called Phytophthora alni uniformis that only attacks alders. P. uniformisis indigenous to North America.  “…Symptoms are typical of Phytophthora root and collar diseases on broadleaved trees. This includes sparse foliage with abnormally small yellow leaves, dieback and canker at the base of the main stem… Black exudates ooze from spots across the canker surface. These tarry spots turn to a rust color with time…”  I don’t know if that’s what we were seeing, but it sounds close.

In one area along the trail, there were large piles of leaves, twigs, chopped up branches and seed pods.  We assumed that the workers whose job it is to clean up the place, were piling up the cuttings until they could be burned or hauled away. Everything was dried out and the different shapes, textures and colors were actually quite pretty to look at; very “autumnal”. 

There were some Lesser Goldfinches in among the debris, picking off smaller seeds and fluff.  We also saw a lot of Variegated Meadowhawk dragonflies in there, resting on the twiggy branches.

After we were done with our cursory walk at the rec area, we went over to the Nimbus Fish Hatchery.  There wasn’t a lot to see there because so much construction is underway there right now. 

In 2018, the Bureau of Reclamation (BOR) approved funding for a three-part construction project to take place at the hatchery. The two-year project was supposed to involve the construction of a fishway from the Nimbus Fish Hatchery to the stilling basin below Nimbus Dam and removing the existing diversion weir. The fishway would consist of three sections: a concrete flume fishway, a pool and drop fish ladder, and a rock-lined trapezoidal channel. 

“…The changes will also minimize American River flow fluctuations associated with installation and removal of the hatchery’s weir and eliminate health and safety concerns relative to the deterioration of the existing weir structure. The new spawning habitat opened up by the permanent removal of the weir will improve juvenile salmon production and increase harvest opportunities downstream… First, the fish passageway extension will be built. Second, operations and assessments of the passageway will take place before removing outdated facilities. Lastly, although not necessary, the removal of the existing weir would be considered by Reclamation once the new passageway is deemed successful for two seasons…”

Well, the whole project was supposed to be done by October of this year, but it looked to me like they left all of the work until the last minute.  I don’t know how they’ll get it all done before the salmon spawning season starts next month. They were still digging the trenches for the fishway. 

At the same time this major work is taking place, they’re also working on building an improved open-air theatre near the visitor’s center and a new boardwalk and viewing platform near the end of the trail.  We walked right by where they were working on the theater, but couldn’t get to where the viewing platform is going to be because fences had been erected to keep people out.

Because of all of the noise and personnel, there were only a handful of birds along the river in the area. I think we saw two Great Egrets, one Great Blue Heron, a handful of gulls, a single Green Heron, and a Black Phoebe.  No migrating waterfowl.

Great Blue Heron, Ardea herodias

We saw a couple of Double-Crested Cormorants perched on the wire across the river, what Cornell calls a “diurnal loafing site”. Hah!  While we watched them, the adult sat down then stood up next to the juvenile, doing its “gular flutter” thing, when it opens its mouth and causes the orange gular skin on its throat to vibrate.

“…Gular flutter supplements evaporation due to respiration, and involves a rapid vibration of the moist membranes of the gular region, driven by the hyoid…”

While the adult bird had its mouth open, you could see some of blue coloring inside the mouth and throat. This color increases to a brilliant blue during the breeding season.

Double-Crested Cormorant, Phalacrocorax auratus

We did catch glimpses of some of the early-arrival Chinook Salmon; their humped backs and dorsal fins came up on occasional swells across the water’s surface.  At the hatchery, all of the salmon and trout runs were closed. We think they were flushing out the runs and taking the opportunity of the closure to clean them up before putting new salmon and trout fry in them later in the year.  It will be interesting see, in another few months, if the hatchery is actually able to do any of their spawning work there this year.

Overall, I think we were out walking for about 3½ to 4 hours. Phew!

By about 11 o’clock, though, it was getting too warm for me outside, and I had to head back to the car. It seemed like the last 10 or 15 feet was almost impossible for me to get through. All I could feel was the heat coming off the asphalt in the parking lot.  I was starting to overheat, and getting kind of light-headed.  I made it, though, and Rox turned up the AC in the car to help cool me off. (She takes good care of me.)

Species List:

  1. Acorn Woodpecker, Melanerpes formicivorus [heard]
  2. Alder Tongue, Western American Alder Tongue Gall Fungus, Taphrina occidentalis
  3. Alder Tree Pathogen, Phytophthora alni uniformis
  4. Armenian Blackberry, Rubus armeniacus
  5. Ashe Juniper, Juniperus ashei [white berries]
  6. Belted Kingfisher, Megaceryle alcyon [saw one on a bridge]
  7. Black Locust Tree, Robinia pseudoacacia
  8. Black Phoebe, Sayornis nigricans
  9. Blue Elderberry, Sambucus nigra cerulea
  10. Brewer’s Blackbird, Euphagus cyanocephalus
  11. California Fuchsia, Epilobium canum
  12. California Ground Squirrel, Otospermophilus beecheyi
  13. California Pipevine, Dutchman’s Pipe, Aristolochia californica      
  14. California Sycamore, Platanus racemose
  15. California Towhee, Melozone crissalis
  16. California Wild Grape, Vitis californica
  17. Canada Goose, Branta canadensis
  18. Chinook Salmon, Oncorhynchus tshawytscha [in the river]
  19. Coffeeberry, California Buckthorn, Frangula californica
  20. Common Crow, Corvus brachyrhynchos
  21. Common Green Lacewing, Chrysopa coloradensis [eggs]
  22. Common Madia, Madia elegans [yellow flowers, some with red staining near center, smells like lemon]
  23. Cottonwood Leaf Gall Aphid, Pemphigus populivenae
  24. Coyote Brush, Baccharis pilularis
  25. Dallis Grass, Dallisgrass, Paspalum dilatatum
  26. Double-Crested Cormorant, Phalacrocorax auratus
  27. Doveweed, Turkey Mullein, Croton setiger
  28. Fennel, Sweet Fennel, Foeniculum vulgare
  29. Field Bindweed, Convolvulus arvensis
  30. Fig, Common Fig, Ficus carica
  31. Flat-Topped Honeydew Gall Wasp, Disholcaspis eldoradensis
  32. Fremont’s Cottonwood, Populus fremontii
  33. Fuzzy Gall Wasp, Disholcaspis washingtonensi [round faintly fuzzy galls on stems]
  34. Gold Dust Lichen, Chrysothrix candelaris
  35. Goodding’s Black Willow, Salix gooddingii
  36. Gray Pine, Pinus sabiniana
  37. Great Blue Heron, Ardea herodias
  38. Great Egret, Ardea alba
  39. Green Heron, Butorides virescens
  40. Hollyleaf Cherry, Prunus ilicifolia
  41. Hutton’s Vireo, Vireo huttoni
  42. Interior Live Oak, Quercus wislizeni
  43. Interior Sandbar Willow, Salix interior
  44. Killdeer, Charadrius vociferous
  45. Lesser Goldfinch, Spinus psaltria
  46. Little Rattlesnake Grass, Little Quaking Grass, Briza minor
  47. Live Oak Erineum Mite gall, Aceria mackiei [kind of looks like rust on the backside of the leaf]
  48. Live Oak Gall Wasp, 1st Generation, Callirhytis quercuspomiformis [spiky ball]
  49. Mallard duck, Anas platyrhynchos
  50. Mistletoe Gall, caused by Mistletoe  haustorium growing on a tree
  51. Mistletoe, American Mistletoe, Big Leaf Mistletoe, Phoradendron leucarpum
  52. Mourning Dove, Zenaida macroura
  53. Narrowleaf Willow, Salix exigua
  54. Netted Crust Fungus, Byssomerulius corium
  55. Northern Catalpa, Indian Bean Tree, Catalpa speciosa
  56. Nuttall’s Woodpecker, Picoides nuttallii [heard]
  57. Oak Apple Gall Wasp, Andricus quercuscalifornicus
  58. Pale Jumping  Spider, Colonus hesperus
  59. Panicled Willowherb, Epilobium brachycarpum
  60. Poison Oak, Pacific Poison Oak, Western Poison Oak, Toxicodendron diversilobum  
  61. Puncture Vine, Tribulus terrestris
  62. Purpletop Vervain, Verbena bonariensis
  63. Pyracantha, Firethorn,  Pyracantha coccinea
  64. Red Cone Gall Wasp, Andricus kingi
  65. Rio Grande Wild Turkey, Meleagris gallopavo intermedia
  66. Rock Greenshield Lichen, Flavoparmelia baltimorensis
  67. Ruptured Twig Gall Wasp, Callirhytis perdens
  68. Silver Wattle, Acacia dealbata
  69. Spiny Turban Gall Wasp, asexual, fall generation, Antron douglasii
  70. Spotted Towhee, Pipilo maculatus
  71. Toyon, Heteromeles arbutifolia
  72. Turkey Vulture, Cathartes aura
  73. Valley Oak, Quercus lobata
  74. Variegated Meadowhawk Dragonfly, Sympetrum corruptum
  75. Western Fence Lizard, Blue Belly, Sceloporus occidentalis
  76. Western Redbud, Cercis occidentalis
  77. Western Sycamore, Platanus racemosa
  78. Western Tussock Moth, Orgyia vetusta [cocoons]
  79. White Alder, Alnus rhombifolia
  80. White-Breasted Nuthatch, Sitta carolinensis
  81. Woodland Skipper, Ochlodes sylvanoides
  82. Yellow Starthistle, Centaurea solstitialis