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Aquatic/Biotic Resources Inventory Aquatic/Biotic Resources Inventory


Big Chico Creek originates on Colby Mountain and flows 45 miles to its confluence with the Sacramento River. Watershed elevation ranges from about 120 feet at the mouth to 6000 feet on Colby Mountain Mean precipitation ranges from 25 inches in the valley to 80 inches in the headwater region, where much of it falls as snow. Because of the precipitation gradient, the majority of the flow of Chico Creek enters in the upper third of the drainage. At base flow, discharge increases in a downstream direction from the headwater to the Sacramento Valley. As the creek flows across its out-wash delta and the valley floor, water is lost rapidly to infiltration so that, during many summers, no surface flow reaches the Sacramento River.

Mud and Rock Creeks originate at around 3800 feet elevation in foothills north of the Big Chico Creek drainage. Mud Creek flows 26 miles before joining Big Chico Creek. Rock Creek flows 28.5 miles before joining Big Chico Creek. Mud Creek, Rock Creek, and Big Chico Creek all join just before entering the Sacramento River. Rock Creek and Mud Creek are similar to each other but quite different from Big Chico Creek. Their channels are shorter and dendritic (branched like a tree). They drain from the surface of the tilted Tuscan Formation at relatively lower elevations than most of the Big Chico Creek drainage, and receive their precipitation chiefly as rain. Accordingly, they are more seasonal (flowing from about November to June in the Central Valley portion of their channels) and warm up much faster in spring.

Fish Zones

These gradients can be broken into three zones based largely on fish populations. Boundaries to the zones are formed partly by physiological limitations of the organisms but mostly by geological barriers. As the creeks carved their canyons, they cut down through tilted layers of rock to their present gradients. The harder layers, being less readily eroded, formed narrow canyons with rapids or waterfalls that may act as barriers to upstream movement of aquatic life. In Big Chico Creek, the most downstream barrier occurs where the creek crosses the Lovejoy basalt (Bear Hole to Brown's Hole in Bidwell Park). In this stretch, known as Iron Canyon, the valley narrows abruptly and the stream gradient increases. At its upper end, the basalt is undercut and huge boulders have tumbled into a jumble in the creek bed. This jumble of boulders acts as an impassable barrier to upstream movement of fish during normal creek flows. Under conditions of high flow, water fills in around the boulders and Iron Canyon may be no barrier at all. Steelhead, moving upstream between November and February, can usually pass the barrier. Spring-run salmon, squawfish, hardheads, and suckers, which migrate in March and April, are less likely to pass it most years. Smallmouth bass, which are inactive during the cold months, would never be expected to cross it. The Iron Canyon fish ladder, constructed in the 1950’s, and currently being evaluated for a possible upgrade, provides better access for salmonids, but requires continual maintenance.

The next upstream barrier begins at Higgin's Hole (about 1/3 mile upstream of Ponderosa Way) where the creek begins carving harder metamorphic rock. Again, the canyon narrows with big boulders, bedrock potholes, and waterfalls. In very unusual years when migration corresponds exactly with high flow, salmon or steelhead might get through this canyon to the waterfall at Bear Lake; there is one record of salmon being sighted at Bear Lake, but no evidence that other fish species ever got above Higgin's Hole.

The physical barriers divide Big Chico Creek into a mountain zone from the headwaters to Higgin's Hole, a foothill zone between Higgin's Hole and Iron Canyon, and a valley zone between Iron Canyon and the river. A fourth or river zone could be described for the deep slow channel from the confluence of Mud and Big Chico to the Sacramento River. This channel is part of the river at high flow and supports a diverse fauna derived from the river.

Mud and Rock Creeks can similarly be divided into biologic zones, but their mountain and foothill zones are shorter than those in Big Chico Creek. In Mud Creek, the main barrier is the 69-foot waterfall at Richardson Springs, which stops all upstream movement of fish, ending the valley zone. The Mud Creek foothill zone is extremely short, only extending from the top of the waterfall 1.1-mile to another series of falls. In Rock Creek, the upstream end of the valley zone for many years has been the diversion dam about 0.3 mile upstream of the Anderson Fork confluence. The Foothill Zone in Rock Creek is also short, ending in about 3 miles, but more gradually than the other creeks, first hardhead and squawfish drop out, then sculpin, and finally the roach until only rainbows remain, beginning the Mountain Zone (see Appendix A for species list).

Mountain Zone

The mountain zone of Big Chico Creek supports only resident rainbow and brown trout; at its lower end the two are more or less co-dominant, but the brown gradually becomes more dominant in an upstream direction and is the only fish species in small headwater tributaries. The rainbow/brown combination is biologically interesting. The two species are very similar in habitat requirements, but the brown wins the competition, possibly because it also preys on the rainbows. However, the brown spawns in fall while the rainbow spawns in early spring. The older (larger) young-of-the-year browns always control the best feeding stations. Over a series of years with no major winter floods, browns gradually become more and more prevalent. However, in years with winter floods (96-97 and 97-98), brown reproduction fails because eggs and fry are scoured out, and rainbow numbers increase because of reduced predation/competition. However, in the headwaters where the streams are spring fed and/or most precipitation is as snow, winter floods aren’t severe and browns have become the only fish (Maslin,1997b).

Brown trout were apparently never introduced into Mud and Rock Creeks. The mountain zones of both contain populations of little rainbows (maximum size 8-12 inches), which are probably comparable to what has been there for millennia.

Foothill Zone

Historically the foothill zone was dominated by migratory fish including three anadromous species, the spring run Chinook salmon, steelhead rainbow trout, and Pacific lamprey. Before populations were decimated by downstream and ocean events migratory salmonids were probably the dominant fish in the foothill zone. Unfortunately, there are no accurate records of historical populations of fish in Chico’s Creeks. In a September 1980 letter to the Army Corps former Game Warden Gene Mercer stated that good populations of salmon and steelhead trout were found in Big Chico Creek when he was transferred to Chico in 1938. In the same letter, he also stated that in 1938 and for many years after there were runs of steelhead and some salmon in Rock and Mud Creeks. Other long-time local residents have made similar statements. Sporadic estimates of run size for spring run Chinook in Big Chico Creek have been done since 1956 and are reproduced in Table 1. Only scattered anecdotes of people catching or observing steelhead and lampreys exist. The California Department of Fish and Game (DFG) has planted both spring run Chinook and steelhead trout in Big Chico Creek on a casual basis at least as far back as 1959. In the 1980s DFG began making attempts to count adult spring run Chinook and sporadic attempts to trap down-migrant juveniles. By then populations of spring run Chinook and steelhead trout were extremely low and continuing sporadic hatchery plantings made evaluation of the sustainability of populations difficult.

Table 1. Estimates of Spring-run Chinook Size for Big Chico Creek.

(California Department of Fish and Game, 1998)

Year Estimate Year Estimate Year Estimate
1956 500 1971 0 1986 NE
1957 248 1972 NE 1987 NE
1958 1000 1973 50 1988 NE
1959 200 1974 100 1989 7
1960 NE 1975 NE 1990 0
1961 NE 1976 NE 1991 NE
1962 200 1977 332* 1992 0
1963 500 1978 NE 1993 38
1964 100 1979 NE 1994 2
1965 50 1980 NE 1995 200
1966 50 1981 NE 1996 2
1967 150 1982 NE 1997 2
1968 175 1983 NE 1998 369
1969 200 1984 0
1970 NE 1985 0

Methods for estimation were neither consistent nor well documented, particularly in early years….

*transferred from Red Bluff ….NE no estimate.

Electrofishing samples by DFG biologists in 1983 and 1984 demonstrated large populations of Sacramento sucker, hardhead, California roach, Pacific lamprey, and riffle sculpins. Also found were modest populations of Sacramento squawfish, low populations of rainbow trout (probably steelhead), and a few brown trout in the foothill zone of Big Chico Creek. (The July-September timing of the sampling precluded finding salmon.) In October 1986, DFG, under Larry Preston and Richard Flint, used the pesticide, rotenone to kill all fish in the foothill zone of Big Chico Creek. Subsequent to the pesticide treatment, excess fry from the Feather River Hatchery were planted at Ponderosa Way to try to re-establish populations of anadromous (sea-run) salmonids. Each spring from 1987 to 1992, 100,000 to 500,000 spring run Chinook salmon fry were planted. In years 1987, 1988, and 1990 from 50,000 to 100,000 steelhead fry were planted. Although surveys by DFG were not consistently done, lay observers noted that few, if any, of the planted fish returned to Big Chico Creek to spawn. General drought conditions at this time certainly did not help, but the hybridized Feather River stock may also have been unsuited to Big Chico Creek conditions.

No estimates of steelhead spawners have ever been made for Big Chico Creek. Populations of both rainbow and brown trout have increased in the foothill zone since the rotenone treatment, especially in the lower end. There is no way to be sure whether the rainbows are migratory (steelhead) or resident fish, but their slightly lower growth rate relative to steelhead juveniles suggests they are mostly resident fish (Maslin, 1997a).

Re-establishment of native non-salmonid fish populations in the Big Chico Creek foothill zone has been slow. While all the other original species have been observed in the zone, hardheads, squawfish and suckers are scarce and the riffle sculpin has rebuilt its population only in the upper part of the zone. Only the California roach, with its high fecundity and short generation time, has re-established populations equal or above those present before treatment. (Maslin, 1997a)

The foothill zone of Rock Creek supports populations of Sacramento sucker, Sacramento squawfish, hardhead, California roach, riffle sculpin, Pacific lamprey and rainbow trout (all native species). The foothill zone of Mud Creek supports only California roach and rainbow trout. Anecdotal accounts suggest existence of former populations of steelhead and spring run Chinook salmon in both creeks. Although no formal counts have ever been done, probably only a few adults stray into Mud and Rock Creeks under present conditions. In summer 1998, 23 adults were counted in a single pool in Rock Creek and several anecdotes placed additional groups in other pools in both Rock and Mud Creeks. Mud Creek was probably never a very good stream for spring run Chinook salmon or steelhead trout because the Richardson Springs waterfall prevents them from reaching cooler waters at higher elevation. Perhaps a few might over-summer in the plunge pool of the waterfall itself. Except for the barrier created by a small diversion dam, Rock Creek seems to have greater potential, as there are several accessible deep pools. However, it is unlikely that either creek could sustain its own salmon population indefinitely; probably historical populations were lost in each series of drought years then re-established by strays from Big Chico Creek.

The inability of resident populations of Sacramento sucker, Sacramento squawfish, and hardhead to rebuild after the rotenone treatment in the foothill zone of Big Chico Creek and their absence above the Mud Creek waterfall suggest that maintenance of foothill populations may depend on migration from downstream or even from the Sacramento River. These species are certainly highly migratory, often moving in mixed groups from pool to pool for nearly a mile (Grant, 1992). Possibly, after reconstruction of the Iron Canyon Fish Ladder, migrations will again occur and populations will rebuild in the foothill zone of Big Chico Creek. The post-treatment equilibrium community that will ultimately develop there is still uncertain 12 years after the treatment.

Valley Zone

The valley zones of creeks in winter are salmonid streams, being utilized by migratory members of the salmon/trout family for spawning and/or rearing. The migratory Chinook salmon and steelhead rainbow trout are anadromous; they spend much of their life in the ocean but migrate into fresh water to spawn. The warm water-loving minnows and smallmouth bass are relatively dormant in winter, resting under cover such as cut-banks and root wads. Fall and late-fall run Chinook salmon spawn in the valley zone, typically between November and February. Salmon rarely came up Big Chico Creek before Thanksgiving historically, and valley reaches of the creeks are seldom cold enough for them to spawn successfully before that time.

Spawned Salmon
From Suzanne Gibbs

In winter and early spring, juvenile Chinook salmon of all races move from the Sacramento River where they were spawned into the tributaries for rearing (Maslin, et al. 1997). Some move upstream substantial distances (to Hicks Lane in Mud Creek; to Highway 99 in Rock Creek), although they are more numerous closer to the river. Maslin, 1998, estimated that around 50,000 juvenile Chinook salmon from the Sacramento River rear in the watershed. This number includes about 10,000 of the federally listed winter run salmon race. Juvenile Chinook salmon rearing in the tributaries grow faster and are in better condition than those remaining in the river, but in dry years they may become trapped. Spring-run juvenile Chinook, spawned in the foothill zone of Big Chico Creek, often move as fry down to the warmer and less turbulent valley zone where they rear to smolt size. Big Chico Creek spawned juvenile Chinook also move into Mud and Rock Creeks for rearing.

In summer the valley zone of Big Chico Creek is too warm for salmonids and supports native suckers, hardheads, squawfish, and sculpins as well as the exotic smallmouth bass, and green sunfish. Smallmouth bass are abundant in the valley reach of Big Chico Creek and the short (about 4.5 miles) permanent reach of Mud Creek just below Richardson Springs, but otherwise are generally absent except near the mouth of Mud and Rock Creeks. The predatory smallmouth bass eliminates the bite-sized California roach (found in valley reaches of many local streams) although the cryptic riffle sculpin, with its classic camouflage and habit of hiding, manages to coexist. In a series of drought years, smallmouth bass and green sunfish become more dominant and may consume nearly all young-of-the-year suckers and minnows during the summer. They probably also consume many juvenile salmon, particularly in late spring. However, in years with high winter flows most green sunfish and many smallmouth bass are scoured out of the streams. When several high flow years occur sequentially, it is particularly hard on the smallmouth bass. They spawn later due to delayed warming of the higher flows and consequently the young-of-the-year fish are smaller next winter and less able to withstand those high flows. Consequently, the exotic smallmouth is a severe problem for native species during dry years and only a minor nuisance after a series of wet winters (Maslin, 1997a).

Mud Creek’s tributary, Sycamore Creek, contains a small anthropogenic marsh in the region of the Cohasset Highway Bridge. This marsh has some permanent water with reproducing populations of mosquito fish and green sunfish and seasonal influxes of juvenile squawfish, hardheads, and suckers.

Many Sacramento River fish (see Table 2 and Appendix A) use the lower reaches of Big Chico (including Lindo Channel), and Mud and Rock Creeks as spawning and rearing channels in spring. They usually migrate back to the river before the seasonal creeks dry up, but sometimes become trapped, serving as a bonanza for egrets, herons, and raccoons. Seasonal stream reaches seem to be preferred over permanent water reaches for spawning and rearing, perhaps because they warm earlier in the season or because they don't support resident populations of predators. Adult suckers, squawfish, and hardheads all migrate from the river into tributaries to spawn. Most spawn in the valley zone, although some move all the way into the foothill zone. Some, particularly the late-spawning hardheads, will remain in the tributary over summer and return to the river when the creek comes up again in fall. The hitch, a medium sized minnow, uses the lower 2-6 km for spawning. There also is a localized resident hitch population in the upper valley zone of Rock Creek.


Most aquatic invertebrates can move over land or through the air during part of their life cycle, so are not restricted by barriers to specific zones. Instead, they are found wherever the habitat is suitable. In general, one finds relatively more stoneflies, mayflies, caddisflies, and blackflies in colder, swifter, upstream areas, and more dragonflies, damselflies, beetles, bugs, midges, and mollusks in the warmer, lower-gradient areas. To some extent, the separation shifts downstream in winter, particularly for species with a short life cycle. The invertebrate fauna found in the seasonal reaches of Mud and Rock Creeks is quite different than that found in comparable elevation reaches of Big Chico Creek, being composed of species tolerant of warm temperatures and seasonal de-watering. Appendix B lists invertebrates that have been identified in the watershed.


Amphibians also are restricted by habitat conditions rather than by physical barriers. The California newt and foothill yellow-legged frogs are creatures of the foothills, probably because the cooler habitat suits them better. Big Chico Creek is listed in the Status of the Sierra Nevada report as a watershed with especially high value for the conservation of foothill yellow-legged frogs (Jennings, 1996). The introduced bullfrog will eliminate the yellow-legged frog in reaches with low gradients. Since the bullfrog spends two or more years as a relatively weak-swimming tadpole, it is limited to low-gradient permanent water reaches of the streams. The transition zone between bullfrogs and yellow-legged frogs moves upstream during a series of dry years, when bullfrog survival is high and downstream during wet years when bullfrog tadpoles are scoured out by high flows.

Table 2. Approximate time of spawning for selected fish in the Big Chico Watershed (modified from Moyle, 1976).

Species Spawning Period
Pacific Lamprey March - May
Rainbow Trout (Steelhead) February
Spring-run Chinook Mid Sept.-Oct.
Fall-run Chinook Late Oct.–Dec.
Late Fall-run Chinook Jan.-Feb.
Brown Trout Oct.-Nov.
Sacramento Sucker  Jan.-March
Sacramento Squawfish  Feb.  - April
CA Roach May-June
Hardhead  April - June
Hitch April-May
Riffle Sculpin March-April
Smallmouth Bass Late April-June

The western toad can spawn in warm, slow areas of streams or ponds. The black, slow-moving tadpoles require about 2 months until metamorphosis. The Pacific chorus frog spawns in temporary water where its tadpoles are safe from predatory fish. Seasonal streams, backwater pools, and vernal pools all work for tadpole development as long as they hold water for at least two months. The western spadefoot toad favors open, arid environments. It needs pools or temporary streams to hold water for about a month for its fast growing tadpoles. Spadefoot breeding has been recorded in Sycamore Creek and the upper valley zone of Rock Creek.



Four reptiles are commonly associated with Chico area creeks: the western pond turtle, common garter snake, western terrestrial garter snake, and western aquatic garter snake. The western pond turtle lives in pools of streams and ponds and leaves the water only to bask on rocks or logs or to lay eggs in adjacent sandy or silty areas. The three garter snakes are all common around water. They feed on Mud Snake insects, tadpoles, frogs and small fish.


Beavers are common along the creeks, especially in the valley and foothill zones. While their dams can limit fish migration, they can be passed during high water events and seldom last through the winter season. River otters commonly move along the creeks, often following spawning runs of suckers or minnows, but sometimes taking up temporary residence. Muskrats are common in or near marshy habitats. Raccoons are common throughout the watershed, even in urban areas.



Many birds are associated with the Big Chico Creek watershed. Being highly mobile, all are part of larger populations. Birds found in association with streams in the watershed are listed in Appendix I. Some, such as most egrets and herons, breed elsewhere and just visit the watershed for feeding. (The green-backed heron nest locally.) Common mergansers and wood ducks are common nesters in the Foothill zone. Remnant pools in Mud and Rock Creeks and their surrounding riparian vegetation in the valley zone are used as breeding areas for mallard, cinnamon teal and wood ducks as well as many songbirds. Songbirds use the riparian corridors associated with these creeks as migratory routes.

Problems for Aquatic and Riparian Populations of the Big Chico Watershed

Professionals and watershed residents have listed the following as potential problems:

Biologic Concerns

Smallmouth bass definitely exclude California roach from the valley zone. They also take a significant toll of young-of-the-year hardhead, squawfish, and suckers, and probably prevent steelhead trout from rearing downstream of Iron Canyon (although temperatures there are above optimum for steelhead). Smallmouth bass become more of a problem after a series of dry years since high winter flows tend to scour our many of them.

Green sunfish also impact populations of native fishes, particularly in isolated pools of the seasonal reaches of Mud, Rock, and Sycamore Creeks.

Brown trout eliminate rainbow trout in the headwater tributaries, and substantially reduce their populations in other parts of the Mountain zone of Big Chico Creek.

Bullfrogs are probably responsible for the local extinction of the native red-legged frog from valley zones. They also restrict yellow-legged frogs from the lower ends of their natural range, and probably reduce populations of other species. Ponds, created by human-built dams, can extend bullfrog habitat to the destruction of native species.

Genetic contamination from hatchery raised stocked spring run Chinook salmon and steelhead trout may have reduced viability of the native strains.

Although there was notably more in the last two (floods) years, very little reproduction of western sycamore trees is occurring in the watershed.

Particularly in the urban area, native riparian vegetation is being replaced by invasive exotics such as tree-of-heaven, giant reed, Himalayan blackberry, catalpa, fig and mulberry. These exotics species provide less habitat food value for native animals than would the native plants they are replacing.

Passage Problems for Migratory Fish

The Lindo Channel Weir blocks upstream movement under low-flow conditions.

The fish ladders in Iron Canyon on Big Chico Creek need reconstruction and continued maintenance to remain functional.

Under spring low-flow conditions, down-migrant salmon and steelhead can enter the upper end of Lindo Channel but unable to proceed to the river because of high temperature or insufficient water. They then perish during the summer due to lack of water or elevated temperature.

The diversion dam at stream mile 18 in Rock Creek prevents further upstream movement of migratory fish under low and intermediate flow conditions.

A diversion dam between Ponderosa Way and Higgin’s Hole limits upstream movement of fish under flow conditions.

Various undersized culverts at logging or ranch crossings have caused downstream scouring, creating waterfalls that limit upstream movement.

Habitat Problems

Some valley reaches of Lindo Channel, Mud and Rock Creeks that are maintained by government agencies or landowners as floodways, lack sufficient riparian vegetation to maintain stream structure, provide shade to moderate temperatures, and provide input of terrestrial food for fish.

Water diversion at stream mile 18 in Rock Creek causes de-watering or reduced flows in downstream reaches, reducing fish habitat and contributing to the trapping of migrant salmonids.

Gravel recruitment downstream of the Five-Mile Flood Diversion Complex is reduced, perhaps impacting spawning by fall-run salmon. Gravel also becomes trapped in the One-Mile Pool, from which it is customarily removed, rather than moved downstream.

Extreme flows sent down Mud Creek from Big Chico Creek via the Sycamore Bypass scour out gravel, reducing spawning areas for fall run Chinook salmon, suckers, squawfish, and hardheads.

Early de-watering of Lindo Channel in dry years may strand juveniles of anadromous and river migrant fish, tadpoles of western toads, and juveniles of many aquatic insects. The resultant failure of emergence of adult insects reduces the food supply for riparian bats and fly catching birds. This de-watering is caused by diversion of low-flow due to buildup of gravel in the Five-Mile area just upstream of the Big Chico weir. The problem becomes severe when gravel removal is neglected. By contrast, increase in flow down Lindo Channel reduces the volume flowing via the Big Chico Creek channel, reducing habitat volume and permitting more temperature fluctuation, thereby degrading conditions for salmonids. While some sort of optimal flow split may be possible, there will never be enough flow to maintain “live” streams in both channels in summer.

Summer temperatures in Big Chico Creek are marginal at best for holding spring run salmon. Relatively high temperatures limit their ability to tolerate other stresses such as harassment by swimmers. This is most severe in drought years when temperatures tend to be higher and salmon may have been forced by passage problems to over-summer in pools downstream of the Iron Canyon ladder. Any watershed changes that might further increase summer temperatures would exacerbate this problem.

The practice of removal of large woody debris from urban and floodway stream reaches has reduced habitat and increased scouring.

Low-flow silt transport in the Big Chico Creek channel has been increased by swimming pool clean-out and summer water activity by humans, horses and dogs. Unlike high flow conditions in which silt only deposits where flow velocity is reduced in backwater and overflow sites, silt carried during low flow settles out in riffles and pools where it degrades the habitat for both fish spawning and fish-food organisms.

Upland Interactions

Grazing by cattle on stream banks in headwater meadows has resulted in stream incision with associated loss of local habitat and reduction of bank storage that, in turn, leads to reduced summer flow, exacerbating downstream temperature problems.

Grazing by cattle on stream banks in the foothills zone, particularly in parts of Mud and Rock Creeks, has depleted riparian vegetation and increased scouring.

Overgrazing or grazing at wrong times of the year results in soil compaction, leading to increased runoff and erosion, contributing to flood scouring and reduced summer base flow downstream.

Home-site development and road building in the foothill zone of Mud and Rock Creeks has increased sediment transport and flood peaks.

Timber harvest, particularly clear-cutting, in the upper watershed has the potential to increase siltation and runoff, in turn leading to reduced summer flow, exacerbating downstream temperature problems for salmon and trout.

Notes on Fish Species

Anadromous Species

Adult spring run Chinook salmon enter Big Chico Creek between March and June although late arrivals often have difficulty getting upstream because of low flow. Even early arriving individuals are blocked by waterfalls from reaching high elevation. They spend the summer in deep pools from Iron Canyon to Higgin’s Hole and spawn in adjacent riffles when temperatures drop in early fall. Since water is relatively warm at the low elevation where they are forced to spawn, their eggs hatch quickly and juveniles grow rapidly. Nearly all juveniles have emigrated by the following spring unlike Deer and Mill Creeks where many juveniles emigrate in the wet season more than a year after being spawned.

Conditions for adult fall run Chinook salmon are less dependable. Fall run salmon can only spawn in the watershed when fall rains raise the flow enough so that they can get upstream. This could be as early as mid October, but may not occur before December. Fall run Chinook salmon spawn shortly after entering the creek and usually in the lower reaches, including Lindo Channel. When a large storm event brings many fish into the creek, some may go as far upstream as Bear Hole. In some years, when early rainfall starts Mud and Rock Creeks running in time, fall run Chinook salmon may also spawn in them. On April 25, 1988 Maslin’s ichthyology class captured two juvenile Chinook salmon (Fork Length 42 and 50 mm) in a pool on the Hall Ranch. On April 18, 1988, five juvenile Chinook salmon (Fork Length 52-58 mm) were captured in Mud Creek at Hicks Lane. Considering the size of the fish and distance upstream, these fish were almost certainly spawned in the creeks. Those sites were not sampled in other years so there is no way to know if the presence of locally spawned juveniles represented a rare or common event.

A few late fall run Chinook salmon enter the watershed under the high flow conditions typical of January and February. They spawn in the valley zone with juveniles being stimulated by rising spring temperature to migrate out as fry.

Steelhead trout adults migrate into the creeks between October and January. They usually spawn in the Foothill zone, but in low-flow years may spawn in the valley zone. Juveniles behave like resident trout, establishing home ranges and feeding stations and competing with resident trout for one to three years before emigrating. Historically, resident rainbow trout, being a fraction of the size of steelhead trout and producing about 10% of the eggs, would probably have been swamped out by steelhead within the stream reaches accessible to steelhead. The decline of steelhead has permitted their replacement by resident rainbows.

The third anadromous species, the Pacific lamprey, is not as limited by dams and waterfalls as typical fish. They will struggle part way up the face of a dam or waterfall, then attach with their oral sucker and rest before struggling further up and finally over. Lampreys spawn in both valley and foothill zones in March through May. The lamprey juvenile is a true larval form, having neither eyes nor teeth and remaining burrowed into sandy or silty backwater areas where they filter-feed on detritus. After about six years of this life style, they metamorphose into a free-swimming, parasitic form (with eyes and teeth), which migrates to the ocean. Substantially fewer larval lampreys have been collected in Big Chico Creek in the last two years. This could be due to the high winter flows or could reflect some change in the population.

Native Freshwater Species

The large native dominants of the valley and roothill zones (Sacramento sucker, hardhead and Sacramento squawfish) are similar in size and are highly migratory, often moving from pool to pool in mixed schools. The sucker is clearly demarcated by its under-slung mouth with fleshy lips for scrubbing algae and detritus from rocks. The squawfish and hardhead look superficially similar but have teeth (located back in their throats) specialized for quite different foods. The squawfish has long, piercing teeth for subduing active prey such as other fish, crayfish, and aquatic insects. The hardhead has blunt, molar-like teeth for crushing snails and grinding filamentous algae.

The much smaller (adult size about 4 inches) California roach and riffle sculpin are truly resident, probably completing their life cycle within a few meters of where they were spawned. The roach frequents the edges of pools, feeding on algae and small insects, while the sculpin hides under rocks in swifter water, eating any animal life that will fit into its cavernous mouth.

Data Gaps for Aquatic Species

Inadequate information exists on the following topics to allow them to be integrated into management decisions:

  • Amphibian breeding areas, particularly for spadefoot toad, California newt, and yellow-legged frog.
  • Fish communities in the mountain tributaries of Big Chico Creek.
  • Habitat loss due to flood control diversions and channel maintenance.
  • Current ability of Mud and Rock Creeks to support spring run Chinook salmon (temperature and passage data).
  • Numbers of steelhead spawners in the watershed.
  • Degree of small-mouth predation on anadromous salmonids.
  • Importance of tributaries in the life cycle of Sacramento splittail.
  • Efficiency of fish passage through the Iron Canyon ladders at different flow volumes.


Armor, C. S. (1976). Depressant Effect of Light on Drifting Behavior of Ephemeroptera Nymphs in a Mountain Stream. M. A. Thesis. CSU, Chico, CA.

Boze, M. J. (1991). The Nature of Bidwell Park. 77 pp.

California Department of Fish and Game. (1993, December). Habitat Survey – Big Chico Creek, Butte County. Office Memorandum. Department of Fish and Game Environmental Services Division Stream Evaluation Program.

CH2M Hill, (1993), Assessment of Big Chico Creek Salmon and Steelhead Production. Report prepared for the city of Chico, M&T Chico Ranch, and Parrott Ranch. CH2M Hill, 2525 Airpark Drive, Redding California.

California Department of Fish and Game. (1998, June). A status review of the spring run Chinook salmon (Oncorhynchus tshawytscha) in the Sacramento River Drainage. Report to the Fish and Game Commission. Candidate Species Status Report 98-01.

Castle, S. J. (1979). Laboratory Investigations of Two Species of Stoneflies (Plecoptera). M. A. Thesis. CSU, Chico, CA.

Grant, G. C. (1992). Selected Life History Aspects of Sacramento Squawfish and Hardhead Minnows in Pine Creek, Tehama County, California. M. S. Thesis. CSU, Chico, CA.

Guyton, J. W. and F. L. DeCourten. (1978). Introduction to the Geology of Bidwell Park. Univ. Foundation, CSU, Chico.

Jennings, M.R. (1996). Status of Amphibians. Sierra Nevada Ecosystem Project, Final Report to Congress, vol. II, Assessments and Scientific Basis for Management Options (Davis, University of California, Centers for Water and Wildland Resources. pp. 921-944.

Jewett, S. G. (1959). The Stoneflies of the Pacific Northwest. Oregon State Monogr. Stud. Ent. 3: 1-95.

Kainu, M. W. (1974). Zonation and Distribution of Acroneuria (Plecoptera) in Big Chico Creek, California. M. A. Thesis. CSU, Chico, CA.

Madux, D E. (1952). A Study of the Dobsonflies (Megaloptera) of the Chico, California Area. M. A. Thesis. CSC, Chico, CA.

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Maslin, P. E, W. R. McKinney and T. L. Moore. (1996b, July 2). Intermittent Streams as Rearing Habitat for Sacramento River Chinook Salmon. 1996 Update.

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Related Documents

Appendix A


Resident Game Fish Habitats

Anadromous Fish Habitats

Resident Non-Game Fish Habitats