Eagle Lake Field Station and Environs:

An Introduction for Prospective Users


by Dr. Peter B. Moyle, UC, Davis


revised in 2003 by Raymond J. Bogiatto,  Station Manager, CSU, Chico



Eagle Lake Field Station


            The Eagle Lake Field Station (ELFS) is a collection of wooden, tin-roofed buildings by Eagle Lake, in remote Lassen County.  The buildings are scattered about an old beach terrace but are largely hidden from the lake by a sparse grove of Jeffrey pine and western juniper.  The original buildings were constructed over a period of several years, mostly by faculty, staff and students from California State University, Chico, so they have a summer cabin look and feel.  They keep out the elements to some degree, but not entirely.  The local wildlife is often as at home in them as the people who use them on a more temporary basis: deer mice, ground squirrels, bats, house wrens, barn swallows, and many others.  Yet the buildings are quite comfortable and function well for their intended purpose, which is to get students and faculty together in an isolated context where natural, rather than anthropomorphic, features dominate the landscape.


            The building closest to the lake, Vesta Holt Hall, is the principal laboratory (2100 ft2) for teaching and research, with five rooms in linear array.  Table and bench space is sufficient for sorting samples fresh from the field or for setting up simple experiments.  Power, water, and a limited amount of space is available for anyone needing to set up more sophisticated electronic equipment. A short distance from the laboratory building is a second building, Bob Ediger Hall (1400 ft2), containing a library in one half and compact dormitory space in the other.  The library is a quiet collection of desks and tables surrounded by shelves containing several thousand books, journals, and reprints. The library also serves as a lecture hall and study area for ELFS user groups.


            A short distance from the library building is the 1300 ft2 dining hall with its functional, well equipped kitchen.  The dining room is the meeting place for large gatherings, for card or cribbage games, for letter writing, for conversation, for study, or even for playing a polished, if off-key piano.  Adjacent to the dining hall is the 1800 ft2 dormitory building, Shepherd Hall, a barracks style building with two large rooms.  Each room holds 12 cots, thinly partitioned from one another, and is equipped with electricity, hot running water, 2 bathrooms, and 2 showers.


            Nearby, in a cluster, are five cabins for faculty, staff, special visitors, and long-term researchers.  One of the best of them is the winterized, two story A-frame cabin, Omicron Cabin, inhabited by the resident Steward and Cook.  This 900 ft2 cabin is quite comfortable and homey.  Around the A-frame are three additional full-sized cabins, Alice Stone, Theta, and Epsilon Cabins, each about 400 ft2, with a bedroom, bathroom, and kitchen/living area. The furniture and appliances (electric) are of a variety of vintages, some old and some new, yet quite functional.  The atmosphere in the cabins is that of a place where you do not hesitate to take off your boots, toss them in a corner, and put your feet up.  The roofs keep the rain off and the windows intercept the light and the lake breezes.  In short, the cabins are old-shoe comfortable.   Other buildings about the place include a small 142ft2 cabin (Roger Lederer Cabin) with a single bed, a small living space, and a bathroom (without a shower), a wash house with a washer and dryer for station staff, a storage shed, and a Quonset Hut which serves as both a garage and the Steward's repair shop. In addition, a new 1500 ft2 Conference Center, with a deck that overlooks the lake, was added to the ELFS in 1999.


            The buildings of the field station are centered on a 63 acre plot of mixed forest of Jeffrey pine, western juniper, mountain mahogany, Great Basin sage, and gray rabbit brush.  The original 23 acre parcel  was purchased from the U. S. Bureau of Land Management (BLM) in 1964 by students and faculty of Omicron Theta Epsilon, the CSU, Chico Biological Sciences Honor Society.  An additional 40 acre parcel was subsequently purchased from the BLM in 1970; the ELFS property is currently surrounded by both private and BLM land.  The field station parcel has been divided up into a permanent grid of  50m squares, using numbered steel posts, to facilitate long-term field studies.


            Although the buildings of the station make it an attractive, functional facility, perhaps its most desirable feature is its isolation.  It is a one hour drive to Susanville, the nearest town, and 16 km from the nearest paved road.  The 16 km is a long 16 km because much of it is unimproved dirt road, barely passable by passenger cars during the dry summer and sometimes requiring a four wheel drive vehicle in winter.  There are no public telephones at the field station although a phone is available in case of emergency.  The nearest neighbor to the station is the Lassen County Youth Camp about one km to the north.  Otherwise, the station is surrounded by wild lands and a wild lake.



The Field Station Environment


            The most spectacular part of the station environment is, of course, Eagle Lake itself, with its large expanse of clear, frequently turbulent, water.  The shore of the lake near the station is made up of a mixture of basalt boulders, smooth pebbles, and granitic sands.  There is enough sand in places to land a boat in quiet weather and plenty of large boulders to smash the keel of an untethered boat in windy weather.  To the south of the station is a long, privately owned sandy beach, one of the best on the lake.  The beach is divided by a short canal that leads to the now-blocked Bly Tunnel through the basalt ridge to the east.  The canal and tunnel were part of a 1920's scheme to siphon off Eagle lake water to irrigate the Honey Lake Valley.  The scheme failed, primarily because lake levels dropped too low for diversion during a long 1930's drought.  Now blocked off, tunnel seepage continues to help keep Eagle Lake from rising to its former levels.  This tunnel seepage manages to augment the flow down Willow Creek, about 3km east of the station.  A more effective plug was installed in Bly Tunnel in August 1986, but the BLM still maintains relatively constant water releases through a control structure at the site of the new plug.  The channel leading to the closed tunnel is deep (3-4m) and clear.  It is usually full of tui chubs, Lahontan redsides, and Tahoe suckers, which makes for interesting snorkeling.  Beyond the channel and sandy beach, the lake shore rises steeply on the basalt covered slopes of Black Mountain, a prominent feature of the shoreline.


            North of the station, the shoreline becomes increasingly rocky, until it becomes a solid outcropping of large geometrical lava boulders.  In the strong afternoon winds, the waves smash against the black rocks and gulls cry overhead, so the feeling is more like being on the North Coast rather than at 1570m above sea level on the Modoc Plateau.  Continuing along the shoreline past the youth camp, one eventually comes to a sagebrush covered point that projects into the middle basin of the lake.  In the lee of this point are large beds of hard-stemmed bulrush and rocky beaches that serve as roosting, nesting, and foraging areas for many water birds.  Behind these beaches, over a low ridge, is a meadow/marsh system, the south end of which is just a short walk from the station.  This marsh, an extension of the old lake basin, is a breeding area for waterfowl, as well as black terns, Wilson's phalaropes, and yellow-headed blackbirds during high water years.  The marsh is surrounded by sagebrush-covered flats, the home of California kangaroo rats and Great Basin pocket mice.  On nearby trees, power poles, and cabins are at least 6 active osprey nests, conspicuous as large, untidy piles of sticks defended with whistles and screams by these fish-eating raptors.


            To the east of the station is a steep ridge of basalt boulders, partly overgrown, that must have once marked an old shoreline.  At one location, near the station's well, there is a deep overhang of rock (partially boarded up during the 1920's and used as a storage area and even as living quarters for workers of the Bly Tunnel Project) in which hundreds of small bats, western pipistrels, hang out during the summer and fall months.   The tangle of boulders, trees, and shrubs on the ridge is an ideal habitat for small mammals which are abundant there.  The large piles of sticks created by woodrats are common, as are the white ridges of dried rat urine (urinite) on conspicuous rocks that have been marked repeatedly by generations of rats.  The ridge rises up into large tracts of second growth mixed conifer forest, home to mule deer and other forest wildlife.


            The summer climate of the ELFS is quite pleasant, with warm days and cool nights.  When it starts getting warm in the afternoon, the breeze from the lake is refreshing.  In winter, it stays cold enough for long enough to cause ice to form on the surface of the lake, in most years.  Snowfall and snow accumulation is generally light, although cross-country skiing is occasionally possible.  The air is clear so the night skies are spectacular.  Because the station faces west, the sun sets across the lake, providing an aesthetically pleasing  experience every evening.



Eagle Lake


            Eagle Lake is, behind Lake Tahoe, Clear Lake, and Goose Lake, the largest freshwater lake in California.  It has a surface area of around 11500ha (although this fluctuates) and is about 22km long and 4-7km wide.  Its drainage basin is relatively small, about 1500 square kilometers.  Eagle Lake consists of three interconnected basins, each with its own limnological characteristics.  In all, however, the water is clear - the bottom can usually be seen at 4-6m - and cool, rarely exceeding 20 degrees Celsius, except near the surface on calm days.  The northern two basins are comparatively shallow (6-10m) and surrounded by sage-covered hills, while the larger southern basin (on which the station is located) is much deeper (to 30m).  Despite daily winds, the southern basin usually thermally stratifies each summer.  The productivity of the lake is impressive.  Caddisflies, mayflies, and aquatic moths may hatch at times in enormous numbers, carpeting the surface of the lake on calm mornings.  Zooplankton may "bloom" in such numbers that they are clearly visible to the naked eye, especially swarms of pale green water fleas, Daphnia spp., and copepods, Diaptomus spp. Occasionally, Daphnia  aggregations may be so dense near shore that in a gentle breeze they wash up on the beaches in small windrows, making it possible to pick them up by the handful.  Feeding on the zooplankton close to shore are large schools of juvenile fishes, often numbering in the thousands.  In deeper water, larger fishes of five species are also abundant, all of them native to the lake (an unusual situation in California).  These fishes in turn attract astonishing numbers of birds that prey upon them.  Fish-eating birds such as western and Clark's grebes, eared grebes, and osprey breed in larger numbers here than at most places in the western United States, while other birds such as bald eagles, American white pelicans, double-crested cormorants, Forster's terns, California and ring-billed gulls, great blue herons, snowy egrets, and common mergansers are common.  These birds and their constant pursuit of the fishes are one of the most conspicuous biological features of the lake.  Their numbers are enhanced in the spring and fall when migratory shorebirds and waterfowl use the lake by the thousands.


            The professors at then Chico State College (Drs. Vesta Holt and Thomas Rodgers) who founded ELFS showed remarkable perception and persistence in starting a teaching and research facility at this remote and little known lake.  They began teaching classes at Eagle Lake in 1945 but were not able to acquire the land for the present station until 1960.  They were obviously attracted to the lake by its wild and beautiful nature, and by the abundance and diversity of plants and animals that inhabit the lake and its basin.  These same features continue to make Eagle Lake an attractive place to teach and study natural history, particularly because the lake is one of the least disturbed large lakes in the western United States.  This is not to say that it is a pristine system.  The forests and rangelands of the surrounding drainage have been repeatedly logged, burned, criss-crossed with roads, and heavily grazed.  The lake level has been artificially lowered through the Bly Tunnel project and through diversions of its principal tributary, Pine Creek.  Despite these (and other) repeated insults to its integrity, the lake has shown remarkable resistance to change and resilience from efforts to alter it.  The keys to the maintenance of Eagle Lake's physical, chemical, and biological integrity are (1) its water chemistry, (2) the high percentage of public ownership of its shoreline, (3) its remoteness, and (4) its frequent unsuitability for most conventional types of aquatic recreation.


            Water Chemistry:  Eagle Lake is a terminal lake, like many lakes in the interior of western North America.  Water flows in but does not flow out, except through ground water.  As a consequence, the minerals in the inflowing water, from precipitation, streams, and springs, are concentrated by evaporation (106cm/year), thus making the lake highly alkaline.  Its pH is generally around 9 and its total alkalinity is in the 400-500 range.  The winds keep the shallow upper basins well mixed most of the time, but the south basin does thermally stratify, so the water below the thermocline can become depleted of oxygen.  In winter, the lake often freezes over.  Overall, Eagle Lake is a difficult environment for most freshwater organisms.  Partly as a consequence, its biota is relatively depauperate, consisting of species evolved to live there.  The present fish fauna, for example, consists of five species, all native.  Attempts have been made to introduce about 12 other fish species into the lake at one time or another, but these introductions have failed.  Usually, the introduced fish died within a few hours or days, but a few (e.g. large-mouthed bass) actually established populations for a number of years, only to succumb to the lake's increased alkalinity in low water years.


            Public Ownership:  About 80 percent of the shoreline of the lake is publicly owned and managed, either by the BLM or the U.S. Forest Service.  Except for campgrounds and a couple of areas leased for summer housing, this land is undeveloped. Even much of the privately owned land around the lake has not been developed, although it has been logged and grazed. Some of the private marshlands are leased for hunting, so they have been maintained in reasonably good condition.  The largest housing tract on the lake is Spaulding Tract, near the mouth of Pine Creek.  Spaulding is a collection of cabins and house trailers, with a resort and airport nearby.  This little-used airport is built on the shoreline and is likely to be flooded if the lake level continues to rise.


            An important factor in keeping the lake in good condition is the increasingly protective attitudes of the local, state, and federal agencies that have some responsibility for it.  Lassen County, for example, is in the process of requiring sewage treatment for the settlements around the lake, to prevent contamination from septic tank leachings.  The California Department of Fish and Game (DFG) is now actively managing the lake's fish populations to maintain the high quality fishery for Eagle Lake rainbow trout, and is opposed to attempts to introduce new species into the lake.  DFG also funded (through the Wildlife Conservation Board) the 1986 construction of a valved block in Bly Tunnel, in order to help maintain relatively high lake levels.


            Isolation:  Eagle Lake is located in eastern Lassen County, one of the most thinly populated counties in the state.  The county contains vast acreage of desert, steppe, mountain, and forest, with much of the terrain sculpted by recent volcanic activity.  Water is generally scarce, as much of the county lies within the rain shadow of the Cascades and Sierra Nevada.  This type of country simply cannot support large numbers of people, although it is very attractive for summer recreation.  The lake, however, is well off the main tourist routes; it is served mainly by narrow two-lane county highways and numerous dirt roads.  Lake Tahoe, with its polluting casinos, some two hours to the south, attracting much of the lake and mountain oriented tourism, as does highly developed Almanor Reservoir an hour to the west.  Lassen Volcanic National Park is only an hour or so from the lake, but it is one of the least visited national parks in the lower 48 states.  The end result is that few people have even a casual opportunity to become acquainted with Eagle Lake and its environs, thus keeping it isolated.


            Unsuitability for Recreation:  With its large and attractive setting, Eagle Lake would seem to be an ideal place for water oriented recreation, especially that requiring boats.  It has a major problem, however:  wind.  In the summer the wind usually starts blowing between 0930 and 1330 hrs.  The wind comes up quickly; the lake can go from a flat calm to a sea of whitecaps in less than half an hour.  So serious is the problem created by the wind that the Lassen County Sheriff maintains a large, seaworthy boat on the lake.  Its purpose is largely to patrol the lake after the winds pick up and tow in smaller boats unable to make it to the marinas in time.  The summer winds usually blow from the southwest, but can suddenly switch.  Once the wind starts blowing, it generally blows strongly until after dark, and the lake usually does not become calm until after midnight.  This wind regime leaves the cool mornings as the only time open for water skiing and power boating.  Because the water temperature is also on the cool side, it is difficult to stay warm after getting wet.  The lake is not even particularly good for sailing, as it is either flat calm or blowing a gale.  The principal boaters on the lake are fisherpersons who go out in the early morning after trout.  On a good weekend, there will be several hundred fishing boats on the lake, most of them congregated in a few 'hot spots'. As soon as the wind starts blowing, the fishing boats stream into the marinas and the lake becomes deserted except for the pelicans and grebes.


Research and Teaching Opportunities





            The landscape around Eagle Lake is primarily volcanic in origin.  Much of the lake shore is basalt outcroppings, and Black Mountain, next to the ELFS, was an ancient caldera.  However, there are also some granitic outcroppings on the south shore of the lake.  The lake was created by a combination of faulting and the damming of Willow creek by a lava flow. During the Pleistocene, Eagle Lake was connected via its old outlet (about 2km north of the ELFS) to Lake Lahontan.  The lake basin lies within the southwestern corner of the Modoc Plateau.  To the immediate south of the lake, the crest of the Sierra Nevada joins the southern end of the Cascades.  Close by is Mt. Lassen Volcanic National Park.  The mountains around Eagle Lake rise to about 2100m.  East of the lake, is the typical basin and range topography of the Great Basin.








            The rich ecological diversity of Eagle Lake and the western fringe of the Great Basin Desert has been of interest to Field Biologists and Ecologists for many years.  The area has also become a major locus for research in Archaeology.  As is the case ecologically, the Eagle Lake region is "ecotonal" for many Native American cultures including the Northern Maidu, Northern Paiute and Pit River Indians.



Aquatic Environments


            Eagle Lake, with its three basins, is a fascinating place to study limnology. Much about the lake remains unknown, however, including the ecology and systematics of the abundant zooplankton and benthic invertebrates including sponges, isopods, amphipods, leeches, free-living flatworms, hydrozoans, gastropods, and many types of insects.  In the hills around Eagle Lake are a number of ponds, mostly fishless, that contain rich invertebrate faunas including Conchostracans, Anostracans, and Notostracans, as well as abundant amphibian larvae.  Within a half-hour to one hour drive of the station are ponds located in Dean's Meadow, Mahogany Lake, Coleman Reservoir, as well as three playa lakes known as the Dry Lakes, all favorites of invertebrate biologists who come to the ELFS.


            The closest stream to the ELFS is Willow Creek, which starts in a series of springs about 5km from the station.  Despite trampling of the riparian areas by cattle, the stream is rich in aquatic life.  There are dense beds of macrophytes such as watermilfoil, coontail, and water cress, with large populations of snails, dragonfly naiads, and other aquatic invertebrates.  The abundant fishes find cover in these beds and show some segregation by temperature.  Rainbow trout and Paiute sculpin, for example, are found mainly where there is cool, inflowing water.  Amphibians, garter snakes (three species), and waterfowl are also quite abundant there.  Another interesting system is Papoose Creek, near Gallatin Beach, which originates in a couple of large springs in Papoose Meadows.  Its upper reaches are full of speckled dace that chase one another through the legs of cattle which graze in adjacent wet meadows.  In summer, the lower reaches of Papoose Creek are dry.  Most distant from the field station is Pine Creek, the principal tributary to the lake and spawning grounds for several of the lake fishes.  At its mouth, DFG operators a fish trap to capture Eagle Lake trout, in order to collect eggs for rearing in a hatchery.  There is no longer enough water in the stream during most years for successful spawning and/or survival of the eggs and young.  The lower reaches of the stream dry up completely, but the middle reaches are intermittent and the upper reaches (around Bogard Campground) are a delightful cold water brook trout stream.




Plant Communities


            Although Dr. Robert Ediger, Professor Emeritus in the CSU, Chico Department of Biological Sciences, has prepared a key to the plants of the Eagle Lake Basin, new species are constantly being added to the list.  A number of distinct plant communities are readily accessible from the ELFS:  (1) Sage/Juniper Steppe; (2) Montane Coniferous Forest dominated by Jeffrey pine, incense-cedar and white fir in the transition, and red fir and western white pine in areas above 7000ft (e.g. Antelope Mountain); (3) Basalt Ridgeline habitats dominated by dense stands of mountain mahogany; (4) Montane chaparral dominated by shrubs such as greenleaf manzanita and tobacco bush; (5) Great Basin Desert habitats dominated by sage, bitterbrush, shadscale, and black greasewood; (6) Wet meadows of sedges, rushes and various flowering plants;  (7) Riparian woodland, with alders, cottonwoods, and willows; and (8) Freshwater marshlands dominated by bulrush, cattails, rushes, and sedges.


            For the study of plant succession and the effects of forest fires, there are numerous burns in the area, the closest (3km) being the Willow Creek Burn of August 1985.





            As indicated, a large variety of aquatic and of course, terrestrial invertebrates exist in Eagle Lake and the surrounding environs. The hatches of aquatic insects from the lake and streams can be spectacular, quickly clogging light traps at night.  In general, the insects and other invertebrates of the area have been little studied.




            Eagle Lake is home to five species of native fishes, all abundant.  Most abundant is the tui chub, which occurs in large pelagic schools.  A plankton and detritus feeder, it attains nearly 50cm in length.  Also reaching 50cm is the Tahoe sucker, a bottom feeder.  Two small minnow species that occur mainly in shallow water are the speckled dace and Lahontan redside.  The only piscivorous fish in the lake is the Eagle Lake rainbow trout, a variety of rainbow trout uniquely adapted for life in alkaline waters.  Of necessity, its population and fishery is artificially maintained by DFG.  The only other species in the drainage basin is the brook trout, found in the headwaters of Pine Creek, which cannot survive in the lake.  Willow Creek hosts essentially the same fish fauna as Eagle Lake, with the addition of the Paiute sculpin and the exotic brown trout.



Amphibians and Reptiles


            Some five species of amphibians and 15 species of reptiles are commonly observed within the Eagle Lake Basin.  The most common amphibian is the pacific treefrog, whose tadpoles appear in most small bodies of water, although large bullfrogs (exotic) are becoming more and more abundant in Willow Creek.  The amphibians are preyed upon by three species of garter snakes, which have been intensively studied at Eagle Lake.  Western fence lizards, sagebrush lizards, and western skinks are abundant on the rocks and within the woodland. Gopher snakes and racers are common, and western rattlesnakes are observed occasionally as they move about in pursuit of, among other things, the abundant rodent fauna of the region.





            The Eagle Lake region has a rich and varied bird fauna because of the wide variety of habitats, its location on major migratory corridors, and the productivity of the lake itself.  Most conspicuous are the water oriented birds.  Osprey are constantly visible during the spring, summer, and early fall months, because of nests close to the station as well as the numerous nests in the Osprey Management Area across the lake from the field station.  Eared, western, and Clark's grebes form one of the largest breeding colonies of grebes in North America, and many western waterfowl species including Western Canada geese, gadwall, and lesser scaup also breed in fairly large numbers. American white pelicans and double-crested cormorants are a constant presence during the breeding season as well.  Swallows of five species achieve high densities feeding on emerging aquatic insects.  In the spring and fall, thousands of migratory birds of all types stop over in the basin, making it a destination for both birders and hunters.





            The mammals of the region have been poorly studied aside from a few M.S. theses of California State University, Chico students.  Over 70 species have been listed as possibly occurring in the area, but less than half that number have been confirmed.  Sightings of carnivores are relatively uncommon, but rodents and rabbits are quite abundant at the field station and in surrounding woodland habitats.  Common mammalian taxa frequently observed at the ELFS include mule deer, striped and western spotted skunks, raccoon, coyote, mountain cottontail, 3 species of woodrats, 3 species of white-footed (deer) mice, the California kangaroo rat, great basin pocket mouse, as well as several species of bats. The western pipistrelle is the most common bat species at the ELFS, using a rocky outcrop just to the east of the facilities as a summer roost site.


Environmental Planning


            The Eagle Lake basin is an environmentally sensitive area that would benefit from land-use studies of many types.  Lassen County planners and administrators have been supportive of the field station and welcome additional research efforts, especially those centered on the lake itself.  Information that can be used in long-range planning of lakeside developments is especially needed.





            The Eagle Lake area with it's wide diversity of habitat types is a wonderful place to teach courses in Ecology, Field Biology and Archaeology.  This region is also an excellent place to conduct basic research in these disciplines.