Illinois Streams Research Articles

Fish use of stage-specific fluvial habitats as refuge patches during a flood in a low-gradient Illinois stream

A stage-specific habitat classification scheme was developed emphasizing the ecological importance of habitat space as flow refugia for fish. Habitat units were based on planform and channel morphology and the resulting three-dimensional hydraulic patterns that form during floods. Fish were sampled in specific habitat patches using prepositioned areal electrofishing devices at two high-flow stages, near bankfull flow and one-half bankfull flow, during a flood. Fish were also sampled at baseflow immediately following the flood to compare changes in habitat use related to flow stage. During the bankfull stage, fish were found to use floodplain habitat units identified as vegetated point bars and concave-bank benches. During the one-half bank-full stage, fish density and biomass were greater in low-velocity habitat units identified as deflection eddies and expansion eddies than in the high-velocity habitat unit identified as the channel thalweg. Once flow returned to baseflow, fish density and biomass were greater in the main channel habitat units (pools, riffles, and glides) than in lateral habitat units identified as submerged point bars and lateral backwaters. This study provided a framework to quantify flow refugia in low-gradient streams, which is especially important in the restoration of anthropogenically disturbed watersheds that have lost habitat connectivity.

Macroinvertebrate Communities in Agriculturally Impacted Southern Illinois Streams: Patterns with Riparian Vegetation, Water Quality, and In‐Stream Habitat Quality

Relationships between riparian land cover, in-stream habitat, water chemistry, and macroinvertebrates were examined in headwater streams draining an agricultural region of Illinois. Macroinvertebrates and organic matter were collected monthly for one year from three intensively monitored streams with a gradient of riparian forest cover (6, 22, and 31% of riparian area). Bioassessments and physical habitat analyses were also performed in these three streams and 12 other nearby headwater streams. The intensively monitored site with the least riparian forest cover had significantly greater percent silt substrates than the sites with medium and high forest cover, and significantly higher very fine organics in substrates than the medium and high forested sites. Macroinvertebrates were abundant in all streams, but communities reflected degraded conditions; noninsect groups, mostly oligochaetes and copepods, dominated density and oligochaetes and mollusks, mostly Sphaerium and Physella, dominated biomass. Of insects, dipterans, mostly Chironomidae, dominated density and dipterans and coleopterans were important contributors to biomass. Collector-gatherers dominated functional structure in all three intensively monitored sites, indicating that functional structure metrics may not be appropriate for assessing these systems. The intensively monitored site with lowest riparian forest cover had significantly greater macroinvertebrate density and biomass, but lowest insect density and biomass. Density and biomass of active collector-filterers (mostly Sphaerium) decreased with increasing riparian forest. Hilsenhoff scores from all 15 sites were significantly correlated with in-stream habitat scores, percent riparian forest, and orthophosphate concentrations, and multiple regression indicated that in-stream habitat was the primary factor influencing biotic integrity. Our results show that these "drainage ditches" harbor abundant macroinvertebrates that are typical of degraded conditions, but that they can reflect gradients of conditions in and around these streams.

"Urbanization Influences on Aquatic Communities in Northeastern Illinois Streams," by Faith A. Fitzpatrick, Mitchell A. Harris, Terri L. Arnold, and Kevin D. Richards

JAWRA Journal of the American Water Resources AssociationVolume 41, Issue 1 p. 219-220 “Urbanization Influences on Aquatic Communities in Northeastern Illinois Streams,” by Faith A. Fitzpatrick, Mitchell A. Harris, Terri L. Arnold, and Kevin D. Richards2 G. Denise. Carroll, G. Denise. Carroll Respectively, Ph.D. Candidate and Associate Professor of Hydrology, University of Georgia, Warnell School of Forest Resources, Athens, Georgia 30602–2152 (E-Mail/Carroll: gdc7169@owl.forestry.uga.edu).Search for more papers by this authorC. Rhett. Jackson, C. Rhett. Jackson Respectively, Ph.D. Candidate and Associate Professor of Hydrology, University of Georgia, Warnell School of Forest Resources, Athens, Georgia 30602–2152 (E-Mail/Carroll: gdc7169@owl.forestry.uga.edu).Search for more papers by this author G. Denise. Carroll, G. Denise. Carroll Respectively, Ph.D. Candidate and Associate Professor of Hydrology, University of Georgia, Warnell School of Forest Resources, Athens, Georgia 30602–2152 (E-Mail/Carroll: gdc7169@owl.forestry.uga.edu).Search for more papers by this authorC. Rhett. Jackson, C. Rhett. Jackson Respectively, Ph.D. Candidate and Associate Professor of Hydrology, University of Georgia, Warnell School of Forest Resources, Athens, Georgia 30602–2152 (E-Mail/Carroll: gdc7169@owl.forestry.uga.edu).Search for more papers by this author First published: 08 June 2007 https://doi.org/10.1111/j.1752-1688.2005.tb03730.xCitations: 3 1 Discussion No. 02059D of the Journal of the American Water Resources Association (Copyright © 2005). 2 Paper No. 02059 of the Journal of the American Water Resources Association 40(2):461–475. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume41, Issue1February 2005Pages 219-220 RelatedInformation

REPLY TO DISCUSSION by G. Denise Carroll and C. Rhett Jackson.

JAWRA Journal of the American Water Resources AssociationVolume 41, Issue 1 p. 221-222 REPLY TO DISCUSSION by G. Denise Carroll and C. Rhett Jackson1 “Urbanization Influences on Aquatic Communities in Northeastern Illinois Streams”2 Faith A. Fitzpatrick, Faith A. Fitzpatrick Respectively, Research Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562; Ecologist (Harris) and Cartographer (Arnold), U.S. Geological Survey, 1201 West University Avenue, Suite 100, Urbana, Illinois 61801; and Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562 (E-Mail/Fitzpatrick: fafitzpa@usgs.gov).Search for more papers by this authorMitchell A. Harris, Mitchell A. Harris Respectively, Research Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562; Ecologist (Harris) and Cartographer (Arnold), U.S. Geological Survey, 1201 West University Avenue, Suite 100, Urbana, Illinois 61801; and Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562 (E-Mail/Fitzpatrick: fafitzpa@usgs.gov).Search for more papers by this authorTerri L. Arnold, Terri L. Arnold Respectively, Research Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562; Ecologist (Harris) and Cartographer (Arnold), U.S. Geological Survey, 1201 West University Avenue, Suite 100, Urbana, Illinois 61801; and Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562 (E-Mail/Fitzpatrick: fafitzpa@usgs.gov).Search for more papers by this authorKevin D. Richards, Kevin D. Richards Respectively, Research Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562; Ecologist (Harris) and Cartographer (Arnold), U.S. Geological Survey, 1201 West University Avenue, Suite 100, Urbana, Illinois 61801; and Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562 (E-Mail/Fitzpatrick: fafitzpa@usgs.gov).Search for more papers by this author Faith A. Fitzpatrick, Faith A. Fitzpatrick Respectively, Research Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562; Ecologist (Harris) and Cartographer (Arnold), U.S. Geological Survey, 1201 West University Avenue, Suite 100, Urbana, Illinois 61801; and Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562 (E-Mail/Fitzpatrick: fafitzpa@usgs.gov).Search for more papers by this authorMitchell A. Harris, Mitchell A. Harris Respectively, Research Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562; Ecologist (Harris) and Cartographer (Arnold), U.S. Geological Survey, 1201 West University Avenue, Suite 100, Urbana, Illinois 61801; and Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562 (E-Mail/Fitzpatrick: fafitzpa@usgs.gov).Search for more papers by this authorTerri L. Arnold, Terri L. Arnold Respectively, Research Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562; Ecologist (Harris) and Cartographer (Arnold), U.S. Geological Survey, 1201 West University Avenue, Suite 100, Urbana, Illinois 61801; and Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562 (E-Mail/Fitzpatrick: fafitzpa@usgs.gov).Search for more papers by this authorKevin D. Richards, Kevin D. Richards Respectively, Research Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562; Ecologist (Harris) and Cartographer (Arnold), U.S. Geological Survey, 1201 West University Avenue, Suite 100, Urbana, Illinois 61801; and Hydrologist, U.S. Geological Survey, 8505 Research Way, Middleton, Wisconsin 53562 (E-Mail/Fitzpatrick: fafitzpa@usgs.gov).Search for more papers by this author First published: 08 June 2007 https://doi.org/10.1111/j.1752-1688.2005.tb03731.x 1 Discussion No. 02059D of the Journal of the American Water Resources Association 41(1):219–220 (Copyright © 2005). 2 Paper No. 02059 of the Journal of the American Water Resources Association 40(2):461–475. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume41, Issue1February 2005Pages 221-222 RelatedInformation

Analysis of base flow trends in urban streams, northeastern Illinois, USA

Statistical analysis shows that mean annual base flows in three unregulated urban streams in northeastern Illinois do not display significant trends during periods of substantial watershed urbanization. However, statistically-significant upward trends in median annual base flow (probably emblematic of overall changes in the time-distribution of the base flow), characterized by increases in lower base flow rates, affected the flows in all three streams. The analysis reveals no trends in annual and monthly precipitation during these periods. These results are in contrast to results from studies of other urban streams that have shown decreases in base flow, but these results may be partially explained by the low permeability of the near-surface materials in the watersheds investigated. This study employs formal hypothesis-testing of Kendall tau-a trend statistics computed for monthly and annual base flow and precipitation rates to assess the impact of urban development on base flow rates.

Effective discharge recurrence intervals of Illinois streams

Abstract Effective discharge values are routinely used to characterize the geomorphic impact/work that different flows have on streams and watersheds. Effective discharge values are also routinely employed in stream restoration design. Reliable flow frequency and sediment-rating curves are needed to compute effective discharge values, but are not available for many streams. In lieu of regional effective discharge data, researchers/engineers often assume that a stream's effective discharge is the same as the 1.5-year flow event for that stream. However, research shows that this is not always true. Hence, demand exists for developing regional effective discharge values that can be applied at ungaged stream locations. A regional study of effective discharge values within Illinois is performed. Eighty-eight monitoring sites were identified as locations where effective discharge values could potentially be computed. Twenty of these sites were determined to have sufficient data to compute effective discharge values. For these stations, effective discharge values were computed using two different sediment–discharge relationships (a power curve and an alternative “mean approach”). The mean approach estimates effective discharge values that are, on average, 1.9 times larger than those estimated using the power curve. The sediment load carried by flows less than or equal to the effective discharge value are, on average, 2.7 times larger when the mean approach is used. Both the power curve and mean approaches typically yield effective discharge values greater than the stream's mean flow and less than its 1.1-year (annual maximum series) flow event. Some of the computed effective discharge values are less than the stream's mean flow. Computing effective discharge values remains a subjective process with large uncertainties involved. Class interval size, sediment-rating curve fitting techniques, and available sediment data influence effective discharge results. A paucity of monitoring data for Illinois streams draining <518 km 2 (where many geomorphic analyses and stream restoration projects take place) hinders the regional applicability of effective discharge results. The uncertainties associated with effective discharge values and the inability to validate effective discharge values as a stream's dominant discharge makes channel design using effective and dominant discharge theory problematic. Suggestions for improving regional effective discharge studies and effective discharge estimates are provided.

Transport and fate of nitrate in headwater agricultural streams in Illinois.

Nitrogen inputs to the Gulf of Mexico have increased during recent decades and agricultural regions in the upper Midwest, such as those in Illinois, are a major source of N to the Mississippi River. How strongly denitrification affects the transport of nitrate (NO(3)-N) in Illinois streams has not been directly assessed. We used the nutrient spiraling model to assess the role of in-stream denitrification in affecting the concentration and downstream transport of NO(3)-N in five headwater streams in agricultural areas of east-central Illinois. Denitrification in stream sediments was measured approximately monthly from April 2001 through January 2002. Denitrification rates tended to be high (up to 15 mg N m(-2) h(-1)), but the concentration of NO(3)-N in the streams was also high (>7 mg N L(-1)). Uptake velocities for NO(3)-N (uptake rate/concentration) were lower than reported for undisturbed streams, indicating that denitrification was not an efficient N sink relative to the concentration of NO(3)-N in the water column. Denitrification uptake lengths (the average distance NO(3)-N travels before being denitrified) were long and indicated that denitrification in the streambed did not affect the transport of NO(3)-N. Loss rates for NO(3)-N in the streams were <5% d(-1) except during periods of low discharge and low NO(3)-N concentration, which occurred only in late summer and early autumn. Annually, most NO(3)-N in these headwater sites appeared to be exported to downstream water bodies rather than denitrified, suggesting previous estimates of N losses through in-stream denitrification may have been overestimated.

Stream-barb installations for narrow channel bends — a laboratory study

Phase 1 of an ongoing laboratory study of a novel form of stream-bank protection structure is described. "Barbs" are dike-like stone structures designed to protect the (usually unstable) outside-bank regions of channel bends. These low-profile structures point upstream into the flow and typically extend to about 1/4-way across the channel. By disrupting near-bank velocity gradients they promote sediment deposition along the eroding outside-bank region. Their presence also modifies the "helicoidal"-type flow pattern of the bend such that secondary currents, which would otherwise attack the outside-bank, are redirected towards the center of the channel. This novel form of bank protection structure is currently undergoing field tests on selected bends on a number of shallow "wide" streams in Illinois, USA. While initial results are encouraging, additional studies are necessary to develop design criteria for their wider application. In phase 1 of this study, the effectiveness of different arrangements of barb groups, in both 90° and 135° moveable-bed bend sections of a hydraulically "narrow" rectangular channel, are investigated. For each hydraulic condition considered, the channel-bed scour profiles generated by the different barb groups are compared to corresponding "reference" profiles generated in the absence of barbs. Judging the effectiveness of the different barb groups in promoting long-term stability of the outside-bank region is based on two criteria: (i) percent reduction achieved in scouring in the vicinity of the outside-bank and (ii) degree to which the channel thalweg (deepest portion) is moved from the outside-bank region towards the center of the channel.Key words: barb, channel bends, local scouring, bank erosion, bank protection, secondary currents.

URBANIZATION INFLUENCES ON AQUATIC COMMUNITIES IN NORTHEASTERN ILLINOIS STREAMS1

ABSTRACT: Biotic indices and sediment trace element concentrations for 43 streams in northeastern Illinois (Chicago area) from the 1980s and 1990s were examined along an agricultural to urban land cover gradient to explore the relations among biotic integrity, sediment chemistry, and urbanization. The Illinois fish Alternative Index of Biotic Integrity (AIBI) ranged from poor to excellent in agricultural/rural streams, but streams with more than 10 percent watershed urban land (about 500 people/mi2) had fair or poor index scores. A macroinvertebrate index (MBI) showed similar trends. A qualitative habitat index (PIBI) did not correlate to either urban indicator. The AIBI and MBI correlated with urban associated sediment trace element concentrations. Elevated copper concentrations in sediment occurred in streams with greater than 40 percent watershed urban land. The number of intolerant fish species and modified index of biotic integrity scores increased in some rural, urbanizing, and urban streams from the 1980s to 1990s, with the largest increases occurring in rural streams with loamy/sandy surficial deposits. However, smaller increases also occurred in urban streams with clayey surficial deposits and over 50 percent watershed urban land. These data illustrate the potentially complex spatial and temporal relations among biotic integrity, sediment chemistry, watershed urban land, population density, and regional and local geologic setting.

PHABSIM analysis of a straight trapezoidal reach and a highly sinuous reach in a low-order agricultural stream in the midwest

The PHABSIM model was applied to adjacent straight trapezoidal and highly sinuous reaches in a third order agricultural stream in East-Central Illinois. A 30-year flow record was used to generate weighted usable area (WUA) estimates for six warmwater fish species for each reach. Supplementing PHABSIM analysis, detailed surveys provided planametric maps of each reach, and regular fish sampling both supported the selection of species modeled with PHABSIM and provided data for PHABSIM evaluation. Analysis of the 30-year WUA estimates supported the development of metrics for fish community analysis, and the analysis of selected fish species populations in each reach. Six monthly fish collections in each reach provided a basis for and a detailed description of the fish communities in each reach. Metrics developed for four of the six species modeled were positively related to the relative differences in numbers of fish present between the two reaches.

Depositional response of a headwater stream to channelization, East Central Illinois, USA

AbstractChannelization typically modifies the energy regime and sediment transport capacity of rivers, triggering morphologic adjustments. Most past studies of channelization have focused on erosional responses involving channel incision and widening. Depositional adjustments to channelization, although noted in previous work, have not been documented in detail. This study investigates the depositional response of the Spoon River, a headwater agricultural stream in Illinois, USA, to channelization. Historical aerial and ground‐based photography show that channelization of the Spoon River in the early 20th century produced a wide, deep trapezoidal drainage channel. Following this channelization, unvegetated alternate and mid‐channel bars developed on the bottom of the ditch. Sedimentological analysis of bar stratigraphy indicates that the bars grew through vertical accretion of horizontal sheets of sand‐and‐gravel bedload and organic‐rich drapes of fine‐grained suspended load. The horizontal sheets of sand and gravel are consistent with the braided conditions shown on historical photographs. Late‐stage bar growth appears to have been dominated by progressive overbank deposition of suspended load as indicated by the presence of a thick, fine‐grained organic‐rich A horizon immediately below the surface of each bar. The development of a soil layer also suggests that the bars are stable—an inference supported by the thick grass cover on the bar surfaces. The net result of the depositional response is the formation of a meandering channel flanked by a discontinuous floodplain on the bottom of the ditch.The construction of a wide ditch relative to original stream size is a key factor promoting a depositional response to channelization. Allowing or actively promoting floodplain elements to form in overwidened ditches may be a viable management option for improving the environmental quality of channelized agricultural streams. The Spoon River has a diverse fish community compared to channelized streams in East Central Illinois that lack a meandering low‐flow channel. This morphological configuration apparently enhances geomorphological and ecological variability while sustaining the drainage function of the ditch. Copyright © 2003 John Wiley &amp; Sons, Ltd.

Influence of a large woody debris obstruction on three-dimensional flow structure in a meander bend

A field experiment has been conducted to assess the influence of a large woody debris (LWD) obstruction on three-dimensional flow through a meander bend of a small stream in east central Illinois. Previous studies in unobstructed meander bends have shown that flow through a curved channel should develop a coherent three-dimensional structure characterized by large-scale helical motion. Many meander bends are complicated by naturally occurring persistent obstacles, such as LWD, that have the potential to profoundly disrupt flow structure. The results of this study show that the LWD obstruction systematically influences the three-dimensionality of flow through the bend, particularly the position of the high-velocity core and the development of helicity. The high-velocity core is positioned in the center of the channel upstream of and near the bend apex, but as flow approaches the LWD, it is steered toward the inner bank by the obstruction. Evolving helicity in the upstream portion of the bend is amplified by abrupt turning of the flow induced by the LWD. As the flow moves past the LWD, helicity diminishes rapidly and may even reverse its pattern of rotation. The net effect of the LWD obstruction is to reduce near-bank velocities along the outer bank downstream of the bend apex—a critical locus for bank erosion in meander bends. Given the persistence of the LWD obstruction, it probably has an important local influence on bend migration and evolution.

A multiscale conceptual framework for integrated ecogeomorphological research to support stream naturalization in the agricultural Midwest.

The complexity of fluvial systems necessitates interdisciplinary research in fluvial geomorphology and aquatic ecology to develop a fundamental understanding of interconnections among biotic and abiotic aspects of these systems. Integrated knowledge of this type is vital for environmental management of streams in human-dominated environments. A conceptual framework is presented for integrating geomorphological and ecological research on streams in East Central Illinois, USA, a glaciated low-relief agricultural landscape. The framework embodies a multiscale perspective in which a geomorphological conception of the fluvial system is used to define a hierarchy of characteristic spatial scales for exploring important linkages between stream geomorphology and aquatic ecology. The focus ecologically is on fish, because a rich body of historical information exists on fisheries in East Central Illinois and because past work has suggested that availability of physical habitat is a major factor influencing the community characteristics of fish in this human-altered environment. The hierarchy embodied in the framework includes the network, link, planform, bar unit, bar element, and bedform/grain scales. Background knowledge from past research is drawn upon to identify potential linkages between geomorphological and ecological conditions at each of these scales. The conceptual framework is useful for guiding integrated ecogeomorphological research at specific scales and across different scales. It also is helpful for illustrating how widespread human modification of streams has catastrophically altered the scalar structure of fluvial systems in East Central Illinois. Knowledge emerging from the integrated research provides a basis for environmental-management schemes directed toward stream naturalization.

Low‐flow frequency exacerbation by irrigation withdrawals in the agricultural midwest under various climate change scenarios

As a possible outcome of global climate change, reductions in precipitation, while directly decreasing surface water streamflows and reserves, can also initiate or exacerbate the surface water demand by regional agriculture. Driven by the desire to maintain consistent yields and hedge the risk of drought, farmers may implement or increase supplemental irrigation applications, obtaining water from either surface sources or aquifers. This paper presents results of an investigation of the impact of these effects on streamflows in the midwestern United States. The investigation examines the direct effect of precipitation reduction and the indirect effects of riparian and nonriparian irrigation. The crop‐growth and farm‐scale hydrologie model erosion‐productivity impact calculator is used in conjunction with the routing features of the basin‐scale hydrologic model soil water analysis tool to simulate direct and indirect effects of global change on streamflows. The analysis shows that the coupled effects of decreases in runoff and increases in irrigation may be devastating to the streams of Illinois and other midwestern states. For the example basin a 25% decrease in mean precipitation under optimal irrigation practices by both riparian and nonriparian farmers yields an increase in the annual (mean) occurrence of the historical 7Q10 from 3 days/year to 13 days/year, despite the streamflow accretion from groundwater‐supplied irrigators.

Logistic Model of Nitrate in Streams of the Upper‐Midwestern United States

AbstractNitrate in surface water can have adverse effects on aquatic life and, in drinking‐water supplies, can be a risk to human health. As part of a regional study, nitrate as N (NO3‐N) was analyzed in water samples collected from streams throughout 10 Midwestern states during synoptic surveys in 1989, 1990, and 1994. Data from the period immediately following crop planting at 124 sites were analyzed using logistic regression to relate discrete categories of NO3‐N concentrations to characteristics of the basins upstream from the sites. The NO3‐N data were divided into three categories representing probable background concentrations (&lt;3 mg L−1), elevated concentrations (3–10 mg L−1), and concentrations that exceeded the U.S. Environmental Protection Agency maximum contaminant level (MCL) for drinking water (&gt;10 mg L−1). Nitrate‐N concentrations were positively correlated to streamflow, upstream area planted in corn (Zea mays L.), and upstream N‐fertilizer application rates. Elevated NO3‐N concentrations were associated with poorly drained soils and were weakly correlated with population density. Nitrate‐N and streamflow data collected during 1989 and 1990 were used to calibrate the model, and data collected during 1994 were used for verification. The model correctly estimated NO3‐N concentration categories for 79% of the samples in the calibration data set and 60% of the samples in the verification data set. The model was used to indicate where NO3‐N concentrations might be elevated or exceed the NO3‐N MCL in streams throughout the study area. The potential for elevated NO3‐N concentrations was predicted to be greatest for streams in Illinois, Indiana, Iowa, and western Ohio.

River Channel Restoration: Guiding Principles for Sustainable Projects.

Perspectives on River Channel Restoration (A. Brookes & F. Shields). GUIDING PRINCIPLES AND METHODS FOR RESTORATION. Hydraulic and Hydrologic Stability (F. Shields). Geomorphological Principles for Restoring Channels (A. Brookes & D. Sear). Habitat Enhancement (A. Brookes, et al.). CATCHMENT AND FLOODPLAIN CONTEXTS. Catchment Approach to Planning Channel Restoration (G. Kondolf & P. Downs). The Sediment System and Channel Stability (D. Sear). Water Quality Issues in River Channel Restoration (E. Herricks). Floodplain Restoration and Riparian Zone Management (A. Brookes, et al.). CASE STUDIES. River Restoration Experience in Northern Europe (A. Brookes). Lowland Stream Restoration in Denmark (M. Nielsen). Restoration Approaches in California (J. Haltiner, et al.). Naturalization of Headwater Streams in Illinois: Challenges and Possibilities (B. Rhoads & E. Herricks). Restoring the Hydrogeomorphology of the Channelized Kissimmee River (L. Toth). Towards an Approach to Sustainable River Restoration (A. Brookes & F. Shields). Indexes.

Effects of Sampling Area and Subsampling Procedure on Comparisons of Taxa Richness among Streams

the biotic integrity of communities. In all cases, we make the implicit and sometimes brash assumption that we can really measure the number of taxa in a community. Although measuring taxa richness might appear straightforward, accurate measurement has been extraordinarily difficult; and despite years of effort, no universally accepted methods for its measurement have emerged. The essential problem is that we can never completely census a taxonomic assemblage or entire community; we rely instead on estimates that describe some portion of the real taxa richness of an assemblage. The problem of knowing what percent of the taxa present have been collected is exacerbated when investigators fail to explicitly define their universe of interest (i.e., the spatial bounds of the community or communities in question). Comparisons of taxa richness among studies that used different sampling and subsampling methods are especially difficult and should be viewed skeptically. The difficulty of obtaining accurate measurements of richness is due to the collector's curve

Sediment Load during Flood Events for Illinois Streams

ABSTRACT A large percentage of the annual sediment yield from a watershed is transported by a stream during a small number of floods that occur in a relatively short period of time in a year The sediment load during flood events is examined and relations between the annual sediment yield and the sediment load during the major floods in a given year are developed based on available stream sediment data from the state of Illinois. On the average, the annual flood transports from 20 per cent (for large rivers) to 23 per cent (for small streams) of the annual sediment load, while the two highest floods in a year transport from 32 to 43 per cent of the annual sediment load. The average duration of the annual flood is only 9.2 days, which is 2.5 per cent of the whole year The average duration of the two highest floods is 17 days, which represents only 4.7 per cent of time in a year

Floodplain Mapping Using Continuous Hydrologic and Hydraulic Simulation Models

A new approach for estimating floodplain limits using continuous-simulation modeling is proposed. A hydraulic model with flood-routing capabilities is coupled with a continuous-simulation hydrologic model to compute river stages. Simulations are made using historical precipitation data to produce long, continuous flow records. Simulations are also made using precipitation data for extreme storms to gain additional information on overbank flooding. A new statistical approach is then directly applied to the simulated peak stages to estimate peak stage exceedence probabilities. To illustrate the benefits of this approach, floodplain limits for an Illinois stream are estimated with the new method and compared to estimates based on a design storm approach and conventional frequency analysis applied to the peak stages.

Non-native Fishes Inhabiting the Streams and Lakes of Illinois

At the turn of the century, only one non-native species of fish, the common carp, was established in Illinois (Forbes and Richardson 1908). In contrast, by 1979, six non-native fishes were reproducing in Illinois (Smith 1979) and, in 1996, only 17 years later, seven more nonnative fishes have become established (Table 1). In addition to these 13 species, 9 non-native fishes are periodically stocked in Illinois or stray into the state from nearby states where they are stocked (Table 1). Because several of these fishes only recently have become introduced or are expanding their ranges in Illinois, they are not familiar to most residents of the state. The keys and descriptions in this publication are intended to assist in the identification and monitoring of the impacts of these 22 species. Also included for each species is a brief summary of its ecological and life history characteristics, and a discussion of its Illinois distribution. Additional information can be found in accounts by Smith (1979) and by Burr (1991), who reviewed various aspects of recent changes in the fish fauna of Illinois.