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Trout Habitat

There are not enough good-sized trout in the Little Deschutes to make it a good river for fishing.  Though several factors undoubtedly limit the fish population, it is difficult to determine which factors are the most limiting or most important.  One of the goals of the ranch stream bank stabilization programs, undertaken using grants administered by the Oregon Water Enhancement Board (OWEB), is to provide better trout habitat.

Historical Trout Population

Claude Vandevert, who was born on the ranch in 1923 and grew up here, reports the following:  “Until the early 30's the fish in the river were almost exclusively rainbow trout.  I remember well the first German Brown we caught.  We didn't know what it was so took it to Bend to the Fish & Game Commission to identify it.  After that, they rapidly expanded.  There were only a few Dolly Varden.  Dad would fish specifically for them during the high water season in the mouths of inlets to the sloughs.  They seemed to lie there eating the minnows that were going in and out of the sloughs.  There were no Eastern Brook; they seemed to like the colder high mountain steams and lakes.  But about every 3 years the whitefish would school up into the river as part of their reproductive cycle.  Since they were a trash fish, there was no limit on them and we could snag them with triple hooks.  We would catch about a washtub full and then smoke them.  Even though they were very bony, smoking them made them crisp and we could eat them, bones and all.”

It isn’t clear whether the brown trout appeared in the 1930’s because they were introduced into the Deschutes River drainage at that time or because the character of the Little Deschutes gradually changed after Crescent Lake Dam was built in 1922 and reduced the volume of spring flooding. 

The Deschutes Water Alliance report on Instream Flows in the Deschutes Basin reports, “Bull trout historically spawned in the Little Deschutes River and its tributaries, but they have been extirpated from this reach.”  Bull trout, a type of char, are very similar in appearance to the Dolly Varden trout.

Current Trout Population

Information about the current trout population in the river is anecdotal.  The ranch foreman reports seeing both brown and rainbow trout in the river.  They are sometimes visible from the bridge and have been spotted darting away during bank restoration work.

The most avid and knowledgeable fisherman on the ranch reports, "I walk the river all the time.  I see fish significantly over two pounds in the river all year except in July and August when the river warms up.  In July and August, I only see fish in the 4-7 inch range.  It seems one can only catch large fish when the water is cooler.  I did catch a four pound brown trout in my back yard at the very end of May 2007."  In 2008, the river was open for trout fishing from May 24 through October 31.    

The local fish biologist with the Oregon Department of Fish and Wildlife (ODFW) advises there are a few large brown trout in the river on the ranch but virtually no small ones.  When the river drops in October there are very few pockets of slow water and insufficient cover for the fish population.  The big fish eat the small fish.  He says there are no rainbow trout because the rainbows require more gravel to spawn than do the browns and there isn’t enough for them.

In 1990 or 1991 ODFW collected and reported habitat and electrofishing data for the river within the ranch.  The ranch has the cover letter, dated February 8, 1991, but the actual data and report are no longer available. 


In the 2005 ODFW fish habitat assessment as part of the final report on the OWEB bank stabilization project, ODFW reports that early land clearing (presumably by the Vandeverts) destabilized the stream.  Channel simplification decreased the stream complexity.  Stream complexity (i.e. the variety of environments within the river) is beneficial for fish.  Cattle grazing, of course, prevented recovery of the eroded banks.  Gradually sloped banks do not provide good fish habitat and continuing erosion provides sediment that fills the spaces in the gravel and reduces spawning success.

ODFW has advised the river is Stream Type “E” within the Rosgen Classification System (http://www.fgmorph.com/fg_6_37.php).  An E type stream meanders through broad valleys and meadows with well vegetated streambanks.  It has a low gradient and a low width/depth ratio (it is relatively narrow for its depth).  The authors will investigate this classification further because it seems to fit the Little Deschutes except for the low width/depth ration.  In fact the river appears to be relatively shallow for its width.

Factors Limiting Trout Population

The factors that may be limiting the trout population are described below in order of most likely to least likely, in the judgment of the authors.  There are still many unknowns.  The relative importance of the different factors is subject to debate and can only be better understood through further investigation.

1.      Shortage of dissolved oxygen – From the mouth of the Little Deschutes up to approximately its junction with Crescent Creek, the river is listed with the EPA for low levels of dissolved oxygen.  The shortage of oxygen limits the number and size of trout the river can support.  It limits the energy trout can expend getting food and slows their growth.

2.      Shortage of undercut banks – Undercut banks, where the bank projects out over the river, are good environments for trout because they generally have slower water, the water is often out of the direct sunlight, and the bank provides some protection from predators.  The river may gradually develop more undercut banks as it recovers from historical grazing.  The OWEB stream restoration projects will accelerate this process and the submerged trees will help substitute for undercut banks in the meantime.  The extent of undercut banks may be naturally limited on the ranch by the pervasiveness of sandy soils that readily slump.  Fortunately sloping banks are good environments for willows that hold the earth and slow erosion. 

3.      High water temperature – This stretch of the river is not listed by the EPA for high water temperature but, for much of the summer, the water temperature is higher than the 57 degrees to 62 degrees Fahrenheit that is ideal for trout.  The most knowledgeable fisherman on the ranch believes water temperature is the primary reason there are not more big fish to be had during fishing season.  High water temperature contributes to lowering the levels of dissolved oxygen.  Further investigation needs to be done on what the water temperature is by season, location along the river, and depth.

4.      Lack of good spawning environment – Trout ideally spawn where the river bottom is clean gravel or gravel mixed with cobbles.  The gravel provides crevasses that the eggs lodge in while being supplied with fresh oxygen.  The newly hatched trout (the fry) can find food in the gravel while not being swept away by the current.  There is very little gravel or cobble in the river here although gravel is plentiful in some other stretches of the river (e.g. the south end of Deschutes County).  To the extent there may be gravel, the river bottom on the ranch is “impacted” by fine sediments that fill up the crevasses between the rocks and gravel and make the river bottom a less productive hatchery.  Because the flow of the river is controlled at Crescent Lake Dam, the peak flow during the year is not as high as it would be naturally and is not as effective at washing out the sediments.  Brown trout are better able to spawn in somewhat impacted spawning environments than are rainbows.   

With the approval of ODFW, and probably of the Department of State Lands and the Army Corp of Engineers, the ranch could place gravel and rock in the river.  This was done on Spring River for spawning rainbow and may have been done at Crosswater as well.

5.      Inadequate places for fish to rest – The ideal spot for a fish is a seam where fast water and slow water are right next to each other.  The faster water brings more food past the fish while the slower water gives the fish a place to rest.  Conventional wisdom suggests the ideal trout stream will consist of 50% pools (slow water) and 50% riffles (fast, turbulent water).  Many successful trout streams depart from this ratio.  In the ODFW letter of February 8, 1991, the fish habitat biologist reports that pools (slow water) make up only 9% of the length of the river while glides (non-turbulent faster water flowing smoothly) make up 91%.  Riffles are virtually non-existent.

Direct observation qualifies ODFW's findings somewhat.  While the main flow never pauses to form a lake-like pool, there are many good-sized pockets of slow water along the twists and turns of the riverbanks.  Depth measurements show an average river depth of about four feet with many eight-foot deep holes where the deeper water must flow more slowly.

Any shortage of slow water would be particularly important in the winter when trout metabolism slows down, the fish eat far less, and they prefer to spend almost all their time in slow water.  The low stream flows in the winter mean the pools are not as big or as deep.  Trout are territorial and competitive.  The bigger and stronger trout eat many of the younger and smaller trout and drive others downstream.  Eliminating the younger fish in the winter yields a smaller fish population in the spring and summer.

The OWEB-sponsored stream restoration projects increase slow water along the banks and, by directing more flow to the center of the stream, dig deeper pools in the center of the river.  Placing more woody debris in the river, not always up against the banks, would increase stream complexity with more areas of slow water and some areas with water running faster than the general flow of the river.


Glide – An area of smoothly flowing water with moderately low velocity (10 to 20 cm. per second) and little or no surface turbulence.

Pool – Part of a stream slower than the main flow, often with deeper water than the surrounding area.

Riffle – An area where water flows swiftly over completely or partially submerged obstructions creating surface turbulence. 

6.      Lack of food – Trout primarily eat larval insects and very small aquatic animals that grow best in riffles where they get more oxygen and have cleaner rocks to cling to and hide under.  The lack of riffles undoubtedly limits food production in the stream but the lack of dissolved oxygen that riffles would produce appears to be a far more important factor in limiting the summer trout population.  There are no significant pollutants in the water.  The mosquito abatement program is mosquito specific and environmentally conscientious.

7.      Shelter from predators – Osprey and otters are the primary fish predators in the area.  The shortage of deep pools in the river give the otter something of an advantage.  But the fish are faster and there is no reason to think otter predation is any greater here than in other rivers where trout are thriving.  Fish in midstream are clearly visible to osprey but willows provide good cover along most of the banks and are growing thicker every year.

8.      Unseasonable stream flows – Aside from the effects on the temperature and the spawning environment described above, there is no reason to believe the higher than natural flows in the summer and lower than natural flows the rest of the year have a direct effect on the trout.  

9.      Pollution – Except for low levels of dissolved oxygen, the river is not listed by the EPA for any pollutants and there is no other evidence that the river is polluted.

Good sources of additional information include the following:

Hunter, Christopher J., Better Trout Habitat: a guide to stream restoration and management, Island Press, Covelo, CA

Izaak Walton League of America, A Handbook for Stream Enhancement and Stewardship, The McDonald and Woodward Publishing Company, Blacksburg, VA

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