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Robert T. Milhous

Publications and source records attributed to Robert T. Milhous.

At least 19 recordsLinked to original sources
USGS2010

Channel Maintenance and Flushing Flows for the Klamath River Below Iron Gate Dam, California

The Klamath River is a major river in northern California and southern Oregon. Iron Gate Dam divides the river into the two subunits where there is a significant change in utilization of the river. Downstream of Iron Gate Dam, the river is very important for the propagation of salmon. To address concerns relating to substrate conditions in the mainstem Klamath River below Iron Gate Dam, the Arcata, California, office of the U.S. Fish and Wildlife Service contracted with the U.S. Geological Survey (USGS) to determine flushing flows required to improve and maintain quality spawning and rearing habitats for salmon, and to reduce the abundance of preferred habitats of the polychaete worm suspected of being the intermediate host for Ceratomyxa shasta, a species of bacteria that infects fish. Historically, the river has had the capacity to move sediment just below Iron Gate Reservoir, but there have been periods when the capacity was very low. The results indicate that if the future is more like the pre-1961 period (low transport capacity) than the more recent period, there will be significant sediment issues in the Klamath River below Iron Gate Dam. It seems that during normal or wet years, winter months, and periods of high flow, sediments are flushed either downstream or deposited on higher surfaces. The recent drought conditions during 2000-2005 probably resulted in extensive fine-grained sedimentation along the river, which in turn may have caused increased establishment of aquatic vegetation and increased concentrations of C. shasta. It appears that releases from Iron Gate Dam as far downstream as Seiad Valley are important in maintaining flow conditions to flush the fines and clean the gravels in the river during summer months, or during drought years. Sediment transport studies indicate that supplemental flows during dry or drought conditions may provide some flushing flows in reaches downstream of the dam. For purposes of flushing fine sediments during drought years or dry summer months, flows in the range of 2,500-5,000 cubic feet per second during a period of days may be necessary. Providing these types of flows in a manner similar to a storm pulse would provide the best opportunity to flush the fines and clean some of the gravels given the upper ranges of flows are achieved.

Open-File Report↗
USGS2008

Simulation of Flow Regimes to Reduce Habitat for T. tubifex

Whirling disease has had a significant impact on trout fisheries of the American west by reducing the numbers and quality of rainbow trout in infected streams. A critical factor in the life cycle of the whirling disease parasite is the fine sediment that provides the optimum habitat for Tubifex tubifex, an oligochaete worm that acts as an intermediate host for the disease. This report presents a model for the simulation of flushing flows required to remove undesirable fines and sand from a pool. Undesirable fines may also need to be flushed from runs, the surface layer, and backwater areas. Well-defined links of specific particle sizes to oligochaete worm abundance is needed to justify the use of flushing flows to move sediment. An analytical method for estimating the streamflows needed to remove the fine sediment is demonstrated herein. The overall steps to follow in removing fines from a stream are: Step 1. Determine size of the sediment that is the habitat for oligochaete worms. Step 2. Determine location of the sediment that is the habitat for oligochaete worms. Step 3. Determine streamflows needed to flush (remove) the sediment that is the habitat for oligochaete worms. The case study approach is used to present the method and to demonstrate its application. The case is derived from the sediment and oligochaete worm habitat of Willow Creek, a tributary of the Upper Colorado River located in Grand County, Colo. Willow Creek Reservoir (an element of the Colorado-Big Thompson Project) controls the streamflows of the creek and is just above the study site.

Open-File Report↗
USGS2004

Transferability of tubifex limiting factor models

Dense populations of T. tubifex are generally associated with habitats dominated by fine sediments and enriched organic material (e.g. Krueger, 2002). Management of whirling disease positive systems is entering a new phase where channel modifications are being implemented to reduce or isolate this type of habitat. These management actions have the potential to cause new areas of sediment deposition. Descriptions of sediment characteristics associated with high numbers of T. tubifex can help engineers design channel modifications that minimize situations where altered velocity distributions inadvertently create optimum worm habitat. Ongoing studies in two Colorado Rivers with very different flow regimes and watershed characteristics provide preliminary evidence that a median sediment particle diameter greater than 1.4mm in conjunction with at least 30% (dry weight) of sediment with a diameter less than 0.3mm limits T. tubifex densities to approximately less than 10% of maximum densities.

Colorado↗
USGS1998

Modelling of instream flow needs: The link between sediment and aquatic habitat

Instream flows are needed to remove undesirable accumulations of sediment. Fines and sand accumulate on and in gravels during periods of low flow and must be removed (flushed) periodically in order for the gravel to continue as suitable habitat for aquatic animals. Sediment of all sizes can also fill pools in the river and must be removed in order to maintain pool habitat. A new technique relates the sizes of sediment important in the biological process to the size transported as wash, suspended and bed loads. The technique has a biological component, a hydraulic component and a selection component that links the two. The technique was used to determine the instream flows needed to maintain habitat for Colorado squawfish in the Gunnison River in western Colorado. Flows included a flushing flow to remove course sand form the riffles where Colorado squawfish spawn, to remove fines and sand from the river in general, to remove gravel from pools, and to scour side channels. The Gunnison River has a mean discharge of 73 m 3 /s and the flows of both sediment and water in the river have been modified by the construction of reservoirs and by major diversions for irrigation. The flows needed to maintain the spawning habitat for the Colorado squawfish by removing fines and sand from the riffles is 355 m 3 /s, to remove sand and fines from the river is 354 m 3 /s, to remove gravel from pools is 484 m 3 /s and to scour side channels is 210 m 3 /s. The flow required to maintain the riffles during spawning is 210 m 3 /s. These flushing flows are not required each year but they are required periodically (usually not less than once in every 3 years); and the maintenance flow is needed every year.

Regulated Rivers: Research & Management↗
USGS1998

Sediment transport capacity as an objective of reservoir operations

A sediment transport capacity index was developed as a part of a program to develop methods of flushing flow analysis. The index can be used to develop reservoir operation strategies that consider the movement of sediment as one of the reservoir management goals. The sedimentation transport capacity index determines the instream flow for the maintenance of the substrate below a reservoir in a condition needed by a desirable ecosystem. It can also be used in investigating the impacts of reservoir on the river channel downstream of the reservoir. The method allows a reservoir operator the flexibility of meeting the streamflow needs with a mix of streamflows.

Conference Paper↗
USGS1998

On sediment and habitat in the Upper Animas River watershed, Colorado

The Upper Animas River watershed in southwestern Colorado is located in the San Juan mountains and has been intensively mined. Active mining has essentially ceased but the impact of past mining on the aquatic ecosystem continues. This paper presents initial results from a study to determine the characteristics of the physical habitat for aquatic animals and the sediment characteristics as related to the habitat. The habitat for trout is limited by high streamflows and by winter conditions. Only the winter habitat limits are considered. The characteristics of the sediment in the river limit the winter habitat along with metals within the substrate.

Conference Paper↗
USGS1997

Low shear stress gravel-bed river

A low stress gravel bed river is a river where the cross-sectional average dimensionless shear stress (??*) rarely exceeds 0.047. That is the case for the Gunnison River below Delta in Western Colorado. The cross-sectional average ??* in the Gunnison River has not exceeded 0.047, except at one cross section during one year, in the 87 years of record. A ??* of 0.047 is the critical ??* in the bed-load equation considered to be most applicable to gravel/cobble bed rivers (the Meyer-Peter, Mueller equation). According to this equation, there has been no bed-material movement in the Gunnison River since 1920; in fact there has been bed-material movement and this movement is biologically important. Bed-material is moved when the ??* is 0.016 or larger. Streamflows that cause a ??* of at least 0.016 maintain the aquatic habitat in a low shear stress river.

Conference Paper↗
USGS1994

Sediment balance and flushing flow analysis: Trinity River case study

The use of sediment yield as one aspect of a flushing flow analysis is explored in a case study of the Trinity River in northwestern California. Understanding sediment balance can help in the development of a flushing flow need, but hydraulic analysis must also be done. The most important flushing flow need for the Trinity River is to increase the Trinity River flows when flows in Grass Valley Creek and other tributaries draining the Shasta Bally Batholith are high. The goal is preventing deposition of sand and fines. These flows should be followed by clear-water flushing (i.e., flushing flows when the tributaries are not high) to remove fines and sand from the stream bed.

Book↗
USGS1993

Streamflow and sediment dynamics of the Middle Rio Grande Valley, New Mexico, in the context of cottonwood recruitment

The cottonwood gallery forests of the Middle Rio Grande floodplain in New Mexico provide important habitats for birds and other animals. Over the last century, these forests have changed significantly due to invasion of exotics such as salt cedar and Russian olive, which compete with native cottonwoods, and changes in water use both in the valley and upstream. To successfully germinate and establish, cottonwoods require an adequate water supply, abundant sunlight, and bare, litter-free substrate. Native cottonwoods are adapted to a natural snowmelt hydrograph characterized by spring floods in late May or early June and gradually receding streamflows throughout the remainder of the summer. The natural streamflow pattern has been significantly modified by water management in the Rio Grande basin. The modified pattern is less conducive to establishment of cottonwoods than the natural pattern. In addition, exotic species now compete with native cottonwoods, and the modified flow pattern may favor these exotics. The overall objective of this study was to investigate the possibility of enhancing cottonwood establishment and recruitment along the Middle Rio Grande through streamflow manipulation and reservoir releases. The work integrates concepts of cottonwood establishment, water resources management, and river morphology, and investigates how water management might be used to preserve and enhance cottonwood gallery forests along the river. Specific objectives of the work reported herein were to: (1) develop a technique to calculate flows that will produce channel characteristics necessary to restore and sustain cottonwood gallery forests; (2) develop a model to determine a flow pattern, or sequence of flows, that will improve the potential for cottonwood establishment and recruitment; and (3) determine if the water resources can be managed to produce the desired channel characteristics and flow pattern identified in (1) and (2).

Report↗
USGS1992

Determining the minimum instream flow for hydro peaking projects

A new analytical technique is available for quantifying and predicting the effect that a proposed hydro peaking operation, or a change in an existing project's operation, will have on physical habitat for aquatic populations downstream of the project. The technique, known as the dual flow analysis, is based on elements of the US Fish and Wildlife Service's Physical Habitat Simulation System (PHABSIM). PHABSIM is used to calculate the physical habitat for aquatic organisms in a stream. The assumption behind the development of this technique is that if the effects of a proposed project on physical habitat are known, one can better understand the effects on aquatic organisms. Thus, a defensible selection of an instream flow requirement can be made. The technique was developed as a result of a joint study by the US Fish and Wildlife Service and Niagara Mohawk Power Corp. at the 26.4-MW Bennetts Bridge and the 7.8-MW Lighthouse Hill developments on the Salmon river in upstate New York.

Hydro Review↗