Suspended Silt Research Articles

Feeding, particle selection and carbon absorption inMytilus edulisin different mixtures of algae and resuspended bottom material

Abstract Mytilus edulis (average length 3.7 em) were fed mixtures of algae (10000 Phaeodactylum tricornutum cells · ml-1) and natural silt (0 to 55 mg · l-1), and the effects of silt concentration on filtration behaviour, food uptake and carbon budget were studied. Particle clearance averaged 66 ml · min-1 at 3.5 mg silt · l-1, and decreased at higher and lower concentrations. Increasing amounts of material were retained by the gills with increasing silt concentration, but an increasing proportion of this was rejected as pseudofaeces. Pseudofaeces was produced at silt concentrations above 1 mg · l-1, and the amount produced increased lineally with the amount of material retained (regression line: pseudofaeces produced (mg · min-1) = 0.98 x material retained (mg · min-1) - 0.057; r = 0.98). Dry matter ingestion increased with increasing concentration of silt. (Regression line: ingestion rate (μg · min-1) = 4.36 x In concentration (mg · l-1) + 31.98; r = 0.52). The mussels were able to select between algae and silt particles by clearing the material rejected as pseudofaeces of about 2/3 of the algae. At a low silt concentration (2 mg · m-1) the algae were concentrated in the material ingested by a factor ca. 3, and at a high concentration (55 mg · m-1) by a factor of about 30. Specimens from the Wadden Sea, having larger labial palps, selected between algae and silt with a significantly higher efficiency. The carbon ingestion tate increased considerably at a low concentration of silt (6.6 μg C · min-1) compared to a suspension of pure algae (4.4 μg C · min-1), and decreased at higher concentrations (to 4.5 μg C · min-1 at 55 rng · m-1). Carbon absorption efficiencies were high (between 59 and 65 %) up to a silt concentration of 25 mg · l-1, and decreased slightly at higher concentrations (to 52 % at 55 mg · l-1). The amount of carbon absorbed consequently increased by the addition of silt, from 2.9 μg C · min-1 in a suspension of pure algae to a maximum of 4.0 μg C · min-1 at a silt concentration of 2 mg · l-1 and decreasing to 2.4μg C · min-1 at 55 mg · m-1. It is concluded that Mytilus is well adapted to silt concentrations up to 55 mg · l-1. The potential food diluting effect of silt in suspension is effectively counteracted, especially by particle selection and increased ingestion, and Mytilus even benefits from concentrations up to 25 mg · l-1.

Mayan Urbanism: Impact on a Tropical Karst Environment

From the first millennium B.C. through the 9th-century A.D. Classic Maya collapse, nonurban populations grew exponentially, doubling every 408 years, in the twin-lake (Yaxha-Sacnab) basin that contained the Classic urban center of Yaxha. Pollen data show that forests were essentially cleared by Early Classic time. Sharply accelerated slopewash and colluviation, amplified in the Yaxha subbasin by urban construction, transferred nutrients plus calcareous, silty clay to both lakes. Except for the urban silt, colluvium appearing as lake sediments has a mean total phosphorus concentration close to that of basin soils. From this fact, from abundance and distribution of soil phosphorus, and from continuing post-Maya influxes (80 to 86 milligrams of phosphorus per square meter each year), which have no other apparent source, we conclude that riparian soils are anthrosols and that the mechanism of long-term phosphorus loading in lakes is mass transport of soil. Per capita deliveries of phosphorus match physiological outputs, approximately 0.5 kilogram of phosphorus per capita per year. Smaller apparent deliveries reflect the nonphosphatic composition of urban silt; larger societal outputs, expressing excess phosphorus from deforestation and from food waste and mortuary disposal, are probable but cannot be evaluated from our data. Eutrophication is not demonstrable and was probably impeded, even in less-impacted lakes, by suspended Maya silt. Environmental strain, the product of accelerating agroengineering demand and sequestering of nutrients in colluvium, developed too slowly to act as a servomechanism, damping population growth, at least until Late Classic time.

Relationships between seston, available food and feeding activity in the common mussel Mytilus edulis

The feeding and metabolic rates of Mytilus edulis L. of different body sizes were measured in response to changes in particle concentrations ranging from 2 to 350 mg l-1. Rates of oxygen consumption were not significantly affected by changes in seston concentration, whereas clearance rates gradually declined with increasing particle concentration. Pseudofaeces production was initiated at relatively low seston concentrations (<5 mg l-1). Marked seasonal changes were recorded in the composition of suspended particulates (seston) in an estuary in south-west England. Total seston was sampled at frequent intervals throughout an annual cycle and analysed in terms of: particle size-frequency distributions, total dry weight (mg l-1), inorganic content, chlorophyll a, carbohydrate, protein and lipid. The particulate carbohydrate, protein and lipid content provided an estimate of the food content of the seston. The results are discussed in terms of the “food available” to a nonselective suspension feeder, such as M. edulis, during a seasonal cycle. The effect of inorganic silt in suspension was mainly to limit by “dilution” the amount of food material ingested rather than to reduce the amount of material filtered by the mussel. In winter, the food content of the material ingested was 5%, and this increased to 25% during the spring and summer.

EARLY OBSERVATIONS ON SOME LIMNOLOGICAL CHARACTERISTICS OF THREE ORANGE FREE STATE IMPOUNDMENTS

SUMMARY The first limnological investigations on three impoundments in the Orange Free State are described. No thermal stratification was found and water temperatures below 8,6°C were not measured. The waters were turbid and the unfavourable underwater light climate was the major factor limiting algal growth. The catchment areas influenced the ionic composition of the waters and large quantities of ions were adsorbed onto the suspended silt.

Sediment Transport During the Winter on the Yukon Prodelta Norton Sound, Alaska

ABSTRACT Winter in the northern Bering Sea brings a drastic reduction in terrestrial runoff and a substantial decrease in air-sea momentum transfer (wind and waves) owing to the formation of shorefast and pack ice. Despite these changes, quantities of suspended silt and clay over the Yukon prodelta in the winter of 1978 were essentially the same as those observed during fair weather summer periods, when the sediment discharge of the Yukon River is at its maximum and there is no ice layer to inhibit surface waves. Furthermore, the regional transport pattern involving northward mean flow across the prodelta in Norton Sound remains unchanged in the winter. Bottom current and light scattering measurements obtained during the summer of 1977 showed that spring tides are capable of resuspending fine sediment at depths of about 18 m on the prodelta in the absence of significant surface wave action. We conclude that during the winter the suspended matter transport system is driven by tidal current reworking of sediments which were introduced by the Yukon River during the previous summer.

Comments on ’’Turbulent boundary layer bearing silt in suspension’’

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Sediment transport for desert watersheds in erodible materials

Sediment transport for five small watersheds in arid southern Israel, eroded into shales, chalks, anhydrites and alluvium is studied. Analysis includes data from three large watersheds in the southern United States. Results indicate that floodwater heavily laden with suspended load (10-60 per cent, by weight) is characteristic of watersheds cut in erodible materials. No correlation was found between environmental characteristics such as lithology, catchment area, angle of slope or rainfall intensity and suspended-sediment concentration or texture. The carrying capacity for sands, derived both from hillslopes and channel alluvium is greatly increased by high suspended silt concentration, the trend being (where R = ratio, % fines/% sand; Cs = suspended load concentration, per cent by weight). The high concentration of fine sediment effectively causes more sand transport than would normally occur. This is also true for transport of coarser clastics; higher velocities, typical of highly concentrated silt suspensions, increased competence for transporting pebbles and boulders. The action of a large variety of processes (splash, wash, rilling, gullying, sliding, mudflow) combine with low infiltration and high credibility to render every rainstorm erosionally effective, and high concentrations of washload increase both the capacity and competence of coarse clastic transport. Whole basins are thus subjected to high rates of denudation (2-10 mm/yr).

A study on diapause of zooplankton in a tropical river ‐ The Blue Nile

SUMMARY. The zooplankton of the Blue Nile overcomes the adverse conditions of the flood by entering into a state of diapause. Resting stages were found in the river bottom, flowing water and rain pools. They were blown to different localities by wind and can withstand long periods of desiccation. Some species of zooplankton go into diapause more than once a year, notably during their seasonal peaks of abundance. Release from diapause occurred in the temperature range 20–30°C and was facilitated by longer photoperiods and decreased concentrations of suspended silt. Various species of zooplankton were induced in facultative diapause when stored in complete darkness.

MORPHODYNAMICS OF A WAVE-DOMINATED RIVER MOUTH

The mouth of the Shoalhaven River on the southeast coast of Australia is subject to direct attack by high energy waves and offers a general model of wave-dominated river-mouth deposition. During river floods seawater is completely flushed from the lower reaches of the channel and significant quantities of sandy bed load and suspended silts are debouched into the Tasman Sea. However, breaking waves cause intense mixing between the effluent and ambient waters while wave-induced mass transport and setup oppose and partially impound outflow. Unusually rapid deceleration and lateral effluent expansion result. Sediments accumulate in the form of a broad creseentic river-mouth bar with its crest situated about 2 channel widths seaward of the outlet and as broad shallow subaqueous levees capped by swash bars. Post-depositional shoreward return of sands by shoaling waves produces a constricted outlet. During low river stage wave setup enhances flood tidal currents and partially inhibits ebb tide outflow. This leads to a gradual shoreward migration of the river-mouth bar, a narrowing of the constricted outlet and to upstream migration of river-mouth sands into the lower reaches of the channel.

Brushy Canyon Formation, Texas: A Deep-Water Density Current Deposit

In mid-Permian time, the Delaware basin was a nearly circular deep, about 160 km in diameter. It was ringed by banks or reefs, which were surrounded in turn by very broad shallow shelves, lagoons, sabkhas, and alluvial plains. Broad tectonic down-warping caused deposition of about 1,000 m of sediment in the basin and neighboring shelves in both the Leonardian and Guadalupian Series (an average of 75 m/m.y.), whereas distant areas received only a fraction of those thicknesses. Although the basin and adjacent shelves accumulated nearly equal sediment thicknesses, appreciable slopes existed at the basin margins throughout mid-Permian time. Thus, the basin waters are estimated to have been more than 100 m deep in Leonardian time and as much as 600 m in late Guadalupian time. Simultaneously, bordering banks were very shallow or even emergent, and they prograded basinward several kilometers. The basin margin is spectacularly revealed by a transverse fault in the Guadalupe Mountains. Here the relations of basin, slope, and shelf beds can be clearly seen. The quartzose siltstone and sandstone of the Brushy Canyon Formation (the lower one-third of the Guadalupian Series), where they wedge out at the basin margin, are the topic of this study. These beds have been variously interpreted as shallow marine or deep turbidity current deposits. In my estimation, they are neither. Rather, they have unusual features that suggest deposition in relatively deep water by saline and cold density currents. Surrounding shelves provided these dense water masses. Numerous basinward-trending channels are one product of these density currents. The channels are commonly 20 to 30 m deep, a kilometer or more wide, and extend far into the basin. Channel floors are flat, and the sides commonly slope 20° to 30°. The channels are filled in a special, though unordered, way. Finely laminated coarse-or medium-grained siltstone beds mantle channel floors, walls, and interchannel areas. Fine-grained, locally conglomeratic sandstone beds are confined to channel floors and abut the walls. Chaotic debris beds locally fill channels near the steepest basin slopes. The basin waters were apparently density stratified. Dense shelf water, spilling through channels in surrounding banks, flowed down marginal slopes and along the basin floor. These denser flows cut channels or deposited sandstone beds confined to channels. At other times, less dense shelf water spread over more dense, stagnant basin layers, raining suspended silt over the irregular basin floor. Characteristics that distinguish these density current deposits from the more common turbidity current deposits include (1) less evident proximal-distal changes (the same rock types and channel relations exist near the basin center as in outcrops 50 km away), (2) coarser porous sandstones confined entirely to channels (some channels have much sand and others little), (3) no levees or overbank deposits that would serve as channel proximity indicators, and (4) mostly ungraded sandstone beds that contain little finer matrix. Similar density current deposits have not yet been recognized in other areas or geologic systems. However, they may be anticipated wherever basin waters were restricted sufficiently to become density stratified and where broad evaporitic shelves or lagoons bordered such basins.

Measuring Water Quality and Predicting Well Impairment

The economic performance of a waterflood or a water disposal project can be significantly affected by suspended solids in the injection water. Here are methods and a theory that can be used to interpret water quality data obtained with membrane filters or cores and to predict well impairment caused by suspended solids. predict well impairment caused by suspended solids. Introduction In a waterflood or a water disposal project the possibility exists that suspended solids will cause the possibility exists that suspended solids will cause the injection wells to become impaired. Filtration can usually reduce the concentration of suspended solids; however, the cost of water treating should be balanced against the cost of other alternatives, such as periodic stimulation or replacement of injection wells. In some cases extensive water treating can be justified, but under other circumstances it will be more profitable to inject untreated water. Water quality is affected by several types of contaminants, including suspended silts, clays, scale, oil and bacteria. Any of these may be the predominant source of improvement in a particular injection water and environment. Formation cores, artificial cores. and membrane filters have been used in the industry to monitor suspended solids and to evaluate water quality. Some studies have defined water quality in terms of filtration rates or other experimental data. The disadvantage of these empirical definitions is that they cannot be directly related to well impairment. This paper proposes a measure of water quality that is defined as the ratio of the concentration of suspended solids to the permeability of the filter cake formed by those solids. The water quality ratio can be obtained directly from membrane or core filtration data and can be used to calculate the rate of formation impairment. Formation Impairment from Suspended Solids In considering the effects of suspended solids, some measure of the rate of impairment is needed. A convenient way to estimate how long an injector can be used before stimulation is required is to calculate its half-life. The half-life is defined as the time required for the injection rate to decrease to 50 percent of its initial value. The time required to reach some other fractional reduction in rate can also be calculated. Impairment from suspended solids is thought to occur by one of the following mechanisms (see Fig. 1): The solids form a filter cake on the face of the wellbore (wellbore narrowing); The solids invade the formation, bridge, and form an internal filter cake (invasion); The solids become lodged in the perforations (perforation plugging); and The solids settle to the bottom of the well by gravity and decrease the net zone height (wellbore fillup). Each of the four basic impairment mechanisms is modeled in Appendix A for a constant-pressure-drop process, Equations are derived that express the time process, Equations are derived that express the time required for the injection rate to decline to some fraction a of its initial value. For each mechanism, this time can be expressed as the product of the two function, F and G. P. 865

Siltation problems in relation to the Thames barrier

The problems confronting the Siltation Working Party of the Thames Flood. Prevention Investigation are stated, the need for an early solution necessitating rigorous limitation of the possible combinations of site, function and design of flood protection structure that could be studied. The reasons for excluding all schemes involving a perm anent barrage are given, the Hydraulics Research Station finally being asked to determine the effect on siltation of constructing a barrier at specified sites for use both as a simple surge excluding device and as a continuous half-tide control structure. The methods adopted by H .R.S. in tackling the problem are described. They include four large scale estuarine surveys; the establishment of stations for continuously monitoring the suspended solids content of the river; field and laboratory tests to determine the properties of Thames silt; the development of a mathematical model to study the effect of the tide control on the distribution of silt which is carried in suspension, and experiments on a physical model to establish the redistribution of bed sediments in the navigation channel likely to follow barrier construction and continuous half-tide control. The data from the field surveys demonstrate how current-velocity, suspended silt concentration, salinity and temperature at different depths along the estuary change throughout a spring and a neap tide during both high and low river flows. The results of the silt monitoring exercise supplement the survey data by indicating how the concentrations of suspended sediment in the estuary vary - with tidal range, with position in the bi-monthly spring-to-neap cycle and with seasonal variations in freshwater discharge. The tests to determine the properties of Thames silt provide values for the four parameters describing the processes of silt movement needed to develop the mathematical model. The indications from the physical model studies are that the construction of a well-designed barrier used only to exclude surges should produce no insuperable siltation problems. Both mathematical and physical model results show that continuous tide control leads to increased siltation, the zone of greatest deposition depending on the barrier site.

Particle Size Sorting of Proglacial Eolian Materials

AbstractBagnold proposed that there is a critical size separating particles moved by saltation from those carried in suspension. This theory was tested in proglacial deposits near the Wabash and White Rivers in Indiana. Here the westerly winds of glacial times piled the sand by saltation into a band of dunes and carried the silt in suspension and deposited it as loess east of the dunes. Soil C horizons were sampled in transects across the dune and loess belts of both areas and were analyzed for particle size using narrow size intervals. In both areas a zone between 40µ and 80µ diameter separates dune sand from loess. Between these limits the dune sands and loess are more than 94% exclusive of each other. Glacial till that is representative of the source of outwash, which, in turn, is the source of the eolian deposits, contains much 40 to 80µ material. This size fraction, however, is practically missing from both the dunes and the loess. Apparently this fraction was selectively removed by wind or by water and deposited elsewhere.

Role of Silt in Water Pollution

Silt is a major problem in at least two ways to the water industry in its handling of surface water supplies. First, the treatment plant must remove the suspended silt; and second, deposits of silt or sediment deplete reservoir storage capacity. This article discusses the use of soil conservation practices within the watershed that reduce the amount of silt that reaches the reservoir or treatment plant. Soil conservation work is being carried out by soil and water conservation districts and the Soil Conservation Service throughout Illinois.

A Study of the Phytoplankton of a Calcareous River

Compared with lakes, relatively little is known of the ecology of phytoplankton populations in rivers in Britain. A few of these have been investigated qualitatively, but none, apparently, quantitatively. Records were begun on the Thames by Fritsch (1902, 1903, 1905) and the work was continued by Rice (1938) with observations over the period 1928-32. Here, however, only the larger plankton algae were considered owing to the method of net sampling. Several rivers were studied by Butcher (1932 onwards), but mostly with regard to the benthic populations. Williams (1950, 1954) included nannoplankton forms in lists of phytoplankton from the River Dee at Chester. The Shannon was investigated extensively by Southern & Gardener (1938), but this river is not really comparable with those in England as it connects a series of large lakes and the flora contains many typical lake algae. The Severn and Stour (Suffolk) are currently under investigation and are proving to have considerable amounts of phytoplankton at times. The study of the River Lee, Hertfordshire, the subject of this paper, extended over two years and was undertaken in order to obtain quantitative information of phytoplankton populations in relation to chemical and physical data. This tributary of the Thames is 56 miles (90 km) long and its flow is considerably retarded by canalization. The river and its main tributaries (Fig. 1) arise in springs in the chalk escarpments of the Chilterns of Hertfordshire and Cambridgeshire and together drain an area of about 1500 km2 (Houston 1922). For most of its course the river flows through regions of Eocene clays of the London Basin, overlying chalk (Sherlock 1960). The bed is composed of small stones, gravel and mud and the water carries much suspended silt in times of high rainfall. The largest tributary, the Stort, enters at Feilde's Weir, near Hoddesdon. The part of the river covered by the present study is canalized, the first lock on the Lee being at Hertford, and on the Stort at Bishop's Stortford. At Feilde's Weir the average daily flow is about 763 000 m3 (Houston 1922). The upper part of the Lee receives a considerable amount of sewage effluent during its passage through Luton. During the period of the investigation a new sewage treatment plant was opened at Rye Meads, near Hoddesdon, which serves Welwyn Garden City and the new towns of Harlow and Stevenage. The effect of its effluent on the algal population was considered. Also observed was the influence of the warm water discharged at Dobb's Weir from Rye House Electricity Generating Station, which extracts water for cooling purposes from the river below Feilde's Weir.

Effect of Tidal Range, Temperature and Fresh Water on the Amount of Silt in Suspension in an Estuary

THE British Transport Docks Board Research Station has designed and made instruments which continuously record the concentration of silt in suspension. One of these instruments has been recording this information for several years in the Humber Estuary at King George Dock, Hull.

Unwatering Akosombo Cofferdams

A high and almost completely submerged rockfill and cofferdam was sealed by inducing artificial silting on its water face. First, the rockfill was placed by dumping, and carefully selected transition zone material was then placed on the slope of the rockfill. The water outside the cofferdam was rendered muddy by pumping clay and silt from the river bottom and discharging it near and along the water face of the cofferdam. At the same time, water was pumped from within the cofferdam, creating a differential head on the rockfill and the transition zone. Under the influence of this head, the suspended clay and silt penetrated the transition and made it watertight. The cofferdam was sealed and unwatered at an appreciable saving of time and money.

UNIFORM FLOW OF WATER IN ALLUVIAL CHANNELS.

The flow of water in canals and rivers in alluvial beds is analysed, and it is shown that the uniform flow of water in alluvial channels is of two types: (1) where bed material is not inm ovement and (2) where bedm aterial is in movement. It is shown that for (1) friction varies directly as velocity and Chezy's formula can be written as V=cRS. For (2) friction varies as the square of velocity and Chezy's formula retains its old form V= Cd/RSc; and C are constants for the particular type of bed material and are dependent on the coefficient of friction found by Froude from his experiments. The formulae V= cRS and V= Cd/RS are shown to be dimensionally correct. A formula for silt transportation iasr rived at tof ind out what maximum silt charge can be carried at a velocity. This formula is also shown to be dimensionally correct. The Froude coefficient of friction is correlated with diameter of bed material so that the values of c and C can be obtained from the average weighted mean diameter of bed material in millimeters. It is also suggested that a channel is stable when the velocity required to overcome friction equals the velocity required to transport suspended silt. The word silt used in the paper refers to inorganic matter carried by water either as bed load or in suspension.

Deposition of Silt by the Irrigation Waters of the Nile at Khartoum

Vast quantities of silt are brought down from the volcanic highlands of Abyssinia each year by the flood waters of several rivers: the Blue Nile and its tributaries, the Atbara, the Gash and the Baraka. The last two, which spread out on reaching the Sudan to form inland deltas, are the most heavily laden with silt, and may carry over 10,000 parts of silt per million (1 per cent.) in suspension, making the water look like liquid chocolate. As the waters of these rivers spread out, the silt is deposited to form a visible layer on the land. The Blue Nile and the Atbara form part of the Nile system and carry up to 4000 parts per million of silt in suspension, most of which is borne away to the Mediterranean. Some is deposited in parts of the flood plain, which however is rather small and discontinuous in the Sudan, and further deposition occurs on land which is not flooded but which is low enough to be irrigated by the Nile waters, either by the traditional shaduf or saqia, or more extensively by pump. Such land may be irrigated all the year round, thus receiving a deposit of silt every two or three weeks. It was thought to be of interest to determine just how much silt is added to these lands each year, to what extent continuous irrigation may be able to raise the level of the land, and what the composition of the deposited material is. Experiments.?The work was carried out on the New Farm of the University of Khartoum, 5 miles north of the junction of the Blue Nile and White Nile. The water used for irrigation comes from the east side of the river and for most of the year it consists entirely of Blue Nile water which flows side by side with the White Nile for some miles before mixing. Samples of water were taken in 4-litre tins at three points in the irrigation system: at the head of the main canal, at its tail and at a minor canal where the water is led directly on to the irrigation plots. Of these, only the last is necessary to determine the amount of silt deposited on the land, but it was thought to be of interest to know what happened to the silt during its course from the river to the irrigation plots. The water samples were allowed to stand for a day or more, then the bulk was poured off, and the remainder transferred to a beaker and again allowed to stand before pouring off. The sediment was then dried in an oven and weighed. Samples of irrigation water were taken every month and continued, with a few lapses, from March 1954 to February 1957, so that the results for most months may be regarded as fairly representative of average conditions. Samples in January, February and July were unfortunately only taken once during that time, and for the months of May and June the samples were not taken by the writer but by his labora? tory assistant. Results.?Averages of the weighings (Table on p. 221) show several interesting features. The high amounts of silt are restricted to the months of August and Sep? tember, though the river is in flood for a much longer time. The rise is not sudden as might be expected, but develops slowly from June onwards. The fall is also gradual, being apparent until October, after which the amount of silt in the water remains steady and low at about o-i g. per litre or less until the following June. During the flood months of August and September the bulk of the silt brought up by the pump is deposited in the canals, only about a third of the original amount reaching the plots. This silting up of the canals is a regular occurrence, and the silt has to be periodically dug out. During the remainder of the year, deposition is slight in the main canal, while in the minor channels there is frequently more silt than was contained in the water at the head of the canal. The reason for this is that the soil is

Fishes of the Little Missouri River

order to determine the species and distribution of fish before the river is altered, the senior author and his wife spent the months of June and July, 1950, collecting fishes from this river, in Wyoming and North Dakota. The Little Missouri River is a steep-gradient stream (average fall 4.6 feet per mile) flowing through a heavily eroded non-glaciated valley of picturesque badlands. Ordinarily, the river has a wide shallow bed composed of constantly shifting sand and silt. During drouth years and seasonal low precipitation periods, the stream flow often ceases, leaving a series of pools. The water is clear during periods of low water, as the silt settles when the flow diminishes. Melting snow in the spring and thunderstorms in the summer send large floods of siltladen water rushing into the stream. The average concentration of suspended silt is very high, approximately two and one-half times that of the Missouri River at Kansas City. The river was seined at 17 locations from the