Sedimentation in Our Reservoirs: Solutions and Causes Sedimentation in Our Reservoirs: Causes and Solutions

Home , Cheney Reservoir, Hillsdale Lake, Kanopolis Lake, Perry Lake (Kansas), Tuttle Creek Lake, Waconda Lake

This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Kansas Water Office Kansas Water Resources Institute Kansas Center for Agricultural Resources and the Environment Kansas State University Agricultural Experiment Station and Cooperative Extension Service This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Table of Contents

Reservoirs: Infrastructure for Our Future 3 Tracy Streeter

Sedimentation and the Future of Reservoirs in Kansas 5 W. L. Hargrove

Reservoirs in Kansas 7 Current State, Trend, and Spatial Variability of Sediment in Kansas Reservoirs 9 Frank deNoyelles, Mark Jakubauskas

Methods for Assessing Sedimentation in Reservoirs 25 Mark Jakubauskas, Frank deNoyelles

Effects of Sedimentation on Biological Resources 35 Donald G. Huggins, Robert C. Everhart, Andrew Dzialowski, James Kriz, Debra S. Baker

Management Practices to Control Sediment Loading From Agricultural Landscapes in Kansas 47 Daniel Devlin, Philip Barnes

Can Reservoir Management Reduce Sediment Deposition? 57 Debra Baker, Frank deNoyelles

Economic Issues of Watershed Protection and Reservoir Rehabilitation 71 Jeff Williams, Craig Smith

Reusing Dredged Sediment: Geochemical and Ecological Considerations 103 Margaret A. Townsend, Nathan O. Nelson, Deborah Goard, DeAnn Presley

Photo Credits Dan Devlin, K-State Research and Extension: Susan Brown, K-State Research and Extension: Pages 25, 35, 51, 55, 67 Pages 18, 143

Jennifer Anderson, USDA NRCS PLANTS Database: U.S. Army Corps of Engineers: Pages 21, 33, 57, 70 Page 127 USDA NRCS: Pages 6, 9, 10, 15, 24, 26, 44, 46, 47, 58, John Charlton, Kansas Geological Survey: Back Cover 61, 64, 71, 73, 74, 79, 83, 84, 90, 93, 96, 97, 100, 107, 110, 119, 123, 137, 138 Kansas Water Office: Page 3 USDA NRCS PLANTS Database: Page 124 NOAA Restoration Center: Page 38 All other photos from K-State Research and Extension Scott Bauer, USDA ARS: Page 116 files. This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu. This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Reservoirs: Infrastructure for Our Future

Federal reservoirs in Kansas serve as the source of municipal and industrial water for more than two-thirds of the state’s population. They are recreational destina- tions and provide a reserve to supplement streamflow for water quality, aquatic life, and related activities. These reservoirs were built from the 1940s through the 1980s by the U.S. Army Corps of Engineers and the Bureau of Reclamation primarily for flood control. State and local users saw value in adding water supply storage to the purpose of those reservoirs.

Reservoirs are integral to Kansas’ water supply infrastructure, but like all infrastructure, reservoirs age. By their nature, reservoirs act as settling basins; they gradually fill with sediment, which reduces their capacity to store water to meet our needs. Although erosion is natural, our actions often accelerate this process. Human activities such as urbanization, agriculture, and alteration of riparian and wetland habitats have changed flow regimes, increasing the concentrations and rates at which sediment enters streams and rivers.

Kansas’ economic landscape is changing. A viable economy depends on well-managed natural resources. Too often we take for granted that the foundation of our lives and livelihoods will be there forever. Future demand for water supply from federal reservoirs is projected to increase. Increasing demands coupled with decreasing supplies will eventually result in water supply shortages during severe drought conditions. Preliminary studies indicate that if a multi-year, severe drought occurred in the foreseeable future, water supply shortages could occur because of diminished storage in several basins. Models are currently being developed to more effectively use available storage and optimize use of reservoir water to meet current and future needs.

At the same time, study and research should be directed toward determining sources and movement of sediment in our streams and rivers. This knowledge will allow resource managers to improve the effectiveness of programs and practices to reduce sedimentation rates, improve riparian and aquatic habitats, and derive the most value from dollars spent and resources invested.

Protecting and making the best use of reservoirs and the streams and rivers that feed them requires an investment today to assure they will be sustained for future generations. The Kansas Water Office is committed to that investment.

Tracy Streeter Director, Kansas Water Office

Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

4 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Sedimentation and the Future of Reservoirs in Kansas

The U.S. government made significant investments in building reservoirs in the 1950s and 1960s, which changed much of the rural environment in Kansas. Although many reservoirs were built with a projected lifespan of 150 to 200 years, current projections indicate these lifespans could be cut short by 50 to 100 years. Sedimentation is reducing water-storage capacity of these reservoirs, and deposited sediments containing nutrients, trace metals, and endocrine disrupting compounds are significantly affecting reservoir water quality. Scientists have documented changes in sediment load and water quality, and citizens have watched reservoirs “shrink” over past decades. Bridges that once spanned water now sit above a “mud flat” of sediment.

The Dust Bowl of the early 1900s had dramatic social, biological, and physical consequences in Texas, Oklahoma, and Kansas and resulted in dramatic technological changes in land management. The “Mud Bowl” resulting from reservoir sedimentation poses an even larger threat that demands corrective action based on sound science and practical, afford- able technologies.

Protecting reservoirs from sedimentation will: • result in overall water conservation (i.e., maximize reservoir water storage, minimize water loss during storm events, and improve water conservation management); • require widespread implementation of conservation measures; this requires us to evaluate, understand, and influence producer management behaviors that affect implementation of conservation measures as well as sedimentation and future functioning of reservoirs; • involve participants from a variety of disciplines including agriculture, engineering, hydrology, sociology, economics, and others; • affect water savings on a large scale not only by conserving and protecting existing reservoir resources but also by retaining more soil and water on land; and • be crucial to agriculture and rural life, especially in Kansas, and encompass a variety of community, economic, environmental, health, and social issues.

This publication brings together leading scientific knowledge from many academic disciplines and identifies technological solutions that will protect and conserve federal reservoirs. The following white papers evaluate threats to sustainability of federal reservoirs, causative factors behind these threats, and technological solutions along with their scientific underpinnings and propose future research needed to improve sustainability of these vital water resources and landscapes to which they are connected. Our aim is to advance interdisciplinary science, research, collaboration, and problem solving to achieve a key goal: sustaining supplies of abundant, clean water in Kansas.

W.L. Hargrove Director, Kansas Center for Agricultural Resources and the Environment (KCARE)

6 Sedimentation in Our Reservoirs: Causes and Solutions CK CR Cedar BB WY Hillsdale LN JO MI Empire Bronson Olathe LV DP LB Crystal AL FR NO AN DG County AT Gardner Atchison JF Big Hill Big Mission Hiawatha BR Pomona Perry Pony MG Creek CF Clinton WL OS WO SN Melvern Toronto JA Creek Banner Elk City John NM Redmond LY Fall CQ EK River WB GW PT Wabaunsee Centralia Otis Creek Otis MS CS MR GE El Dorado Grove Council CL RL BU Creek Tuttle WS MN DK CY Milford Marion HV SU SG A on MP SA RP OT CD Cheney HP RN KM LC RC MC EW JW Lovewell Kanopolis Wilson Waconda BA SF PR SM BT RS OB PN EL CM PL ED RH KW RO Harlan County Harlan Kirwin Webster CA TR NT GH HG Cedar Blu NS FO Reservoirs in Kansas Keith Sebelius ME DC SD GY LE GO This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu. FI HS SW SC TH RA LG Swanson KE GT SV WH SH CN WA GL ST HM MT Map from USGS; Kansas Geological Survey. Adapted with permission. Kansas has more than 120,000 impoundments ranging in size from small farm ponds to large reservoirs. The 2 4 federal reservoirs range 1,200 1 5 , 3 surface acres; 21 of these provide drinking water for more than half the state’s population. Smaller, state- and locally owned reservoirs are vital resources water, flood control, recreation are distributed across nearly every county in the state. This map shows the 2 4 federal reservoirs in Kansas and several smaller basins referenced throughout this publication.

8 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu. Current State, Trend, and Spatial Variability of Sediment in Kansas Reservoirs

Frank deNoyelles, Deputy Director and Professor Mark Jakubauskas, Research Associate Professor Applied Science and Technology for Reservoir Assessment (ASTRA) Initiative Kansas Biological Survey, University of Kansas

Introduction half of the mid-continental United States, particularly the central states of The more than 300,000 acres of public and Kansas, Missouri, Oklahoma, Arkansas, private reservoirs and ponds constructed in and Texas, has the greatest number of Kansas during the past century are steadily reservoirs. The National Recreation Lakes filling with silt. These water resources were Study Commission (1999) determined that constructed at great expense. For example, the 490 federal reservoirs larger than 1,000 cost of a typical Kansas reservoir (≈7000 acres had an annual economic impact of acres in size) constructed in the 1970s was $44 billion and provided employment for $50 million to $60 million ($200 million to 637,000 persons. Several thousand smaller $250 million in 2007 dollars). Yet, reser- reservoirs provide recreation opportuni- voirs provide significant economic value to ties, and all reservoirs provide flood control the state through flood control, irrigation, that protects lives and property; economic recreation, wildlife support, power genera- impacts of these benefits are incalculable. tion, and high-quality water for human and livestock consumption. More than half the Reservoirs and lakes are basins of stand- U.S. and Kansas population receives some ing water; flow of water through them is drinking water from reservoirs. slower than that in entering streams and rivers. Reservoirs are constructed by human It is becoming increasingly complicated means, but lakes form naturally. Both and costly to manage these crucial water range greatly in size, function similarly, resources; inevitably, silt will fill these water are affected by the same environmental bodies entirely unless removed periodi- conditions, and provide similar resources. cally. Silt removal will be an enormous task, Most reservoirs have a normal operation even more so than original construction, depth and pool volume for recreation but there is still time to prepare. Although and water supply with additional flood a number of state agencies are beginning control depth and pool volume above to examine this long term management the normal pool and below the spillway problem, new efforts must be directed at to temporarily absorb floodwaters (i.e., controlling the currently declining quality minimize prolonged added pressure on the of aging reservoirs. dam). Reservoirs and lakes require similar management and renovation practices, but The Reservoir as a Resource these efforts often are focused on reservoirs, During the 20th century, more than 2 mil- which typically are constructed to serve lion reservoirs of all sizes, including smaller particular continuing needs. ponds, were constructed in the United States, and many more were constructed Reservoir problems requiring particular worldwide. Nearly 1,000 U.S. reservoirs management actions usually involve quality are larger than 1,000 acres, and about half of drinking water and recreation and water of these are federally operated. The lower

storage capacity for flood control level or build new reservoirs nearby. Obvi- and power generation. We build ously, we must develop and implement new reservoirs in areas with few natural management strategies to maintain cur- lakes, but we also recognize that rent reservoirs for their intended uses and these environments do not support extend their life expectancy. reservoirs’ continued existence. Soils in these areas are very erodible and can be Kansas Reservoirs: disturbed even more by human activities. Number, Size, Distribution, In the lower half of the mid-continental Ownership, Uses United States, where many reservoirs have Kansas has more than 120,000 impound- been constructed, surface soils and clays are ments, although most (> 80%) are farm deep. For thousands of years, these materi- ponds smaller than 1 acre. Nearly 6,000 als moved naturally into valleys and stream reservoirs are large enough to be regulated channels; now they move into reservoirs. by the state (Figure 1). Approximately Thus, reservoirs act as settling basins in 585 reservoirs are owned by state or local which the sedimentation process deposits governments; these average 30 years in age. soil, clay, and smaller rock particles. The The 93 Kansas reservoirs used as water upper regions of reservoirs, where streams supplies are an average of 51 years old; 63 enter, fill with sediment three to five times of these are state or locally owned. The 21 more rapidly than deeper areas. Expanding federal reservoirs used for drinking water shallow zones reduce quality of water and in Kansas have watersheds that cover 23% wildlife habitat as well as operation storage of the state and contain more than 4,000 capacity for drinking water and recreation. miles of stream channels. Many reservoirs Sediment can fill the basin in 100 to 200 serve multiple purposes (e.g., domestic years, the projected life expectancy of most water supply, flood control, recreation, and reservoirs. In contrast, most natural lakes irrigation). exist for tens of thousands of years. Responding to increasing occurrences of Two hundred of the largest reservoirs in the water quality problems affecting use of United States are now more than 40 years Kansas reservoirs is an enormous challenge. old. What will we do when most of our The most pressing issue is ensuring the existing reservoirs are filled enough to end quality of water received by drinking water their useful life? We already built reservoirs suppliers, who provide treated water to in nearly all of the best places. Excavating more than 60% of Kansas residents. Flood old reservoirs will require moving 15 to 30, control, recreation, irrigation, and other even up to 100, times more material than uses also must be protected. Sediment originally was moved to construct the dam. accumulation and other factors continue We also need to find a location for the to create immediate problems for water removed material, ideally one that is nearby and habitat quality. But, siltation is just and will withstand this environmental dis- one part of the problem; reservoirs experi- turbance. Further, because urban and rural ence many problems long before they are development steadily surrounded our reser- completely filled (deNoyelleys et al., 1999). voirs, we cannot continually raise the height For example, sedimentation produces of the original dam and the contained water

10 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

shallow water zones. This leads to increased north end of Perry Lake (Figure 3) led to cyanobacteria (blue-green algae) produc- abandoned recreation areas and boat ramps tion, which, in turn, often causes taste and and loss of fish habitat. odor problems in drinking water (Figure 2). Numerous Kansas reservoirs are already Particular Challenges of experiencing problems. Cheney Reservoir Smaller Reservoirs (Smith et al., 2002; Wang et al., 2005b), Smaller, state- and locally owned reservoirs Clinton Lake (deNoyelles et al., 1999; are vital resources for drinking water, flood Mankin et al., 2003; Wang et al., 1999, control, and recreation and are distributed 2005a), and Marion Lake (Linkov et al., across nearly every county in the state 2007) all experienced massive algae blooms (Figure 4). Small reservoirs are more likely that triggered shutdowns of drinking water than large reservoirs to exhibit serious intakes. The near-complete siltation of the

Figure 1. Reservoirs and impoundments in Kansas Data analysis and map preparation: Kansas Biological Survey Data source: USACE (200

Nutrients and light

Siltation Shallow areas Algal blooms Taste and odor events

Figure 2. Sedimentation triggers a series of problems

Sedimentation in Our Reservoirs: Causes and Solutions 11 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

April 24, 1974

Figure 3. Siltation in Perry Lake, 1974-2001 An estimated 91.5 million cubic yards of sediment have accumulated leading to loss of more than 1,000 acres of surface area Images courtesy of Kansas Biological Survey

October 25, 2001

Figure 4. Reservoirs owned by the state of Kansas or local governments Average age: 30 years; Average normal storage: 639 acre-feet Data analysis and map preparation: Kansas Biological Survey Data source: USACE (2005)

12 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

impairments in water quality and quantity supply impairment. Water managers lack and wildlife habitat due to siltation. For basic physical and biological data that can example, Cedar Lake in Johnson County help identify impaired reservoirs, prioritize (54-acre surface area) lost 50% of its vol- reservoirs in terms of impairment and need ume since its construction in 1938. Cedar for renovation, or assess the current state of Lake is upstream from Lake Olathe, a water a reservoir. supply for Johnson County, and intercepts much of its sediment load. Current State, Trend, and Conditions of Kansas currently is losing value, resources, and benefits from all its impoundments Sedimentation in Kansas to varying degrees and will experience Reservoirs more rapid losses in the future, but the Large Reservoirs vast number of small reservoirs in Kansas Current information on sedimentation is a challenge for state agencies charged is not available for most large, federal with managing them. Unfortunately, most reservoirs in Kansas. In most cases, these nonfederal reservoirs are not mapped and reservoirs have not been surveyed for 10 to monitored for changes that could signal 20 years (Table 1). Available information the onset of conditions that lead to water (projected through 2005) indicates that

Table 1. Bathymetric surveys of 18 federal reservoirs in Kansas Year of most Years since most Reservoir Year of closure recent survey recent surveya Kanopolis 1948 1982 25 Marion 1968 1982 25 Wilson 1964 1984 23 Council Grove 1964 1985 22 Melvern 1972 1985 22 Pomona 1963 1989 18 Fall River 1949 1990 17 Toronto 1960 1990 17 Clinton 1977 1991 16 Big Hill 1981 1992 15 Elk City 1966 1992 15 Milford 1967 1994 13 Hillsdale 1981 1996 11 Cheney 1964 1998 9 Tuttle Creek 1962 2000 7 Perry 1969 2001 6 El Dorado 1981 2005 2 John Redmond 1964 2007 0 a As of 2007

Sedimentation in Our Reservoirs: Causes and Solutions 13 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

100%

90%

80%

70%

60%

50%

Percent Loss Percent 40%

30%

20%

10%

Perry Tuttle Big Hill Webster Melvern Cheney Clinton Marion Milford Pomona Elk City Toronto Hillsdale Waconda Fall River Kanolopis El Dorado Cedar Blu Council Grove John Redmond Figure 5. Loss of multipurpose pool water-storage capacity in Kansas federal reservoirs Data source: KWO (2008)

Table 2. Mean annual sediment yield and mean annual precipitation for selected reservoir basins in Kansasa Sediment yield (acre-feet/ Mean annual Reservoir basin square mile per year) precipitation (in.) Small reservoir basins Mound City Lake 2.03 40 Crystal Lake 1.72 40 Mission Lake 1.42 35 Gardner City Lake .85 39 Otis Creek Reservoir .71 33 Lake Afton .66 30

Large reservoir basins Perry Lake 1.59 37 Hillsdale Lake .97 41 Tuttle Creek Lake .40 30 Cheney Reservoir .22 27 Webster Reservoir .03 21 a Data source: Juracek (2004)

14 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

multipurpose pool water-storage capacity generalized map of sediment yield lost because of sedimentation ranges from in Kansas using available informa- less than 10% for Cheney Reservoir, Hills- tion on areal geology, topography, dale Lake, and Webster Reservoir to more soil characteristics, precipitation, than 40% for the Tuttle Creek, Kanopolis, runoff, reservoir sedimentation, and Toronto, and John Redmond Reservoirs measured suspended-sediment loads (Figure 5; KWO, 2008). Approximately in streams (Figure 6). In the Collins 18% of the original multipurpose pool of map, mean annual sediment yields ranged Perry Reservoir, one of the largest reservoirs from less than 50 tons/square mile in parts in Kansas, which was constructed in 1969 of southwestern and south-central Kansas with a 12,200-acre operation pool and a to more than 5,000 tons/square mile in 25,300-acre flood control pool, has been the extreme northeastern part of the state. lost to sediment deposition (Figure 5). More than 4,000 of the nearly 6,000 major Mean annual sediment yields from basins reservoirs in the state are located in areas of five large reservoirs range from 0.03 with the three highest sediment yield acre-feet/square mile for Webster Reservoir classes. A recent comparison of basin-spe- to 1.59 acre-feet/square mile for Perry Lake cific sediment yields for eight reservoirs (Table 2; Juracek, 2004). using regional estimates provided by Collins (1965) indicated that basin-specific Small Reservoirs yields tended to be smaller. This difference Current information on sedimentation could be due to implemented conservation also is lacking for most small reservoirs in practices and information used to estimate Kansas. However, the U.S. Army Corps of yields (Juracek, 2004). Engineers recently completed a resurvey of 34 small reservoirs (KWA, 2001). Results To explain differences in sediment yields indicated that water-storage capacity lost among reservoir basins in Kansas, Juracek because of sedimentation ranged from (2004) compared estimated mean annual negligible for Wellington New City Lake sediment yields for 11 reservoirs with fac- (4 years old at the time of the resurvey) tors that affect soil erosion—precipitation, to 62% for Alma City Lake (34 years old soil permeability, slope, and land use. Only at the time of the resurvey) (Table 3). In the relationship between mean annual another study, Juracek (2004) determined sediment yield and mean annual precipita- that mean annual sediment yields from six tion (Table 2) was statistically significant. small reservoirs ranged from 0.66 acre- As mean annual precipitation increased, feet/square mile for Lake Afton to 2.03 mean annual sediment yield also increased. acre-feet/square mile for Mound City Lake For the 11 reservoirs studied, mean annual (Table 2). precipitation was the best predictor of sediment yield. Given the pronounced decrease Statewide Variability in in precipitation from east to west across Reservoir Sedimentation Kansas, a similar east to west decrease in reservoir sedimentation rates is likely. The combined influence of several factors determines the sedimentation rate for a given reservoir. Collins (1965) created a

Sedimentation in Our Reservoirs: Causes and Solutions 15 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Table 3. Characteristics of small municipal reservoirs in Kansasa Original 2000 Community Reservoir Year built capacity capacity served (acre-feet) (acre-feet) Alma City Lake Alma 1966 1,013 383 Augusta City Lake Augusta 1940 2,358 2,100 Blue Mound City Lake Blue Mound 1957 --- 165 Buffalo City Reservoir Buffalo 1960 --- 1,631 Council Grove City Lake Council Grove 1942 8,416 7,346 Crystal Lake Garnett 1879b 229 104 Eureka Reservoir Eureka 1939 3,690 3,125 Fort Scott City Lake Fort Scott 1959 --- 7,200 Gardner Lake Gardner 1940 2,301 2,020 Harveyville City Lake Harveyville 1960 235 222 Herington Reservoir Herington 1982 5,759 5,750 Lake Kahola Emporia 1936 6,600 5,500 Lake Miola Paola 1957 2,960 2,760 Louisburg City Lake Louisburg 1984 --- 3,750 Lyndon City Lake Lyndon 1966 948 930 Madison City Lake Madison 1970 1,445 1,333 Mission Lake Horton 1924 1,866 940 Moline Reservoir Moline 1937 --- 1,590 Mound City Lake Mound City 1979 1,773 1,525 Olathe Lake Olathe 1957 3,330 3,300 Parsons Lake Parsons 1938 10,050 8,500 Pleasanton Reservoir Pleasanton 1968 --- 1,180 Polk Daniels Lake Howard 1935 777 640 Prairie Lake Holton 1948 --- 495 Prescott City Lake Prescott 1964 138 --- Richmond City Lake Richmond 1955 --- 220 Sedan City South Lake Sedan 1965 780 770 Severy City Lake Severy 1938 --- 115 Strowbridge Reservoir Carbondale 1966 3,371 2,902 Thayer New City Lake Thayer 1960 --- 560 Winfield City Lake Winfield 1970 19,800 19,500 Wabaunsee Lake Eskridge 1937 4,175 3,600 Wellington New City Lake Wellington 1996 3,250 3,250 Westphalia Lake Anderson RWDc 1963 278 130 Yates Center City Lake Yates Center 1990 2,720 2,241 a Data source: KWA (2001) b Date incorrectly listed as 1940 in KWA (2001) c RWD = rural water district 16 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Mean annual sediment yield, tons/sq. mile < 50 50 - 300 300 - 750 750 - 2000 2000 - 5000 > 5000 Figure 6. Sediment yield regions in Kansas and 5,847 major Kansas reservoirs Data analysis and map preparation: Kansas Biological Survey Sediment map: Collins (1965); Reservoir data: USACE (2005)

Information Needs for regulated reservoirs in Kansas do not have Reservoir Management bathymetric (lake bottom contour) data. and Restoration Data for state and local reservoirs in Kansas are even rarer, collected on an as-needed or Estimates of Sediment ad-hoc basis, and often incomplete. Volume, Mass, Load, and Yield Estimates of Reservoir Effective reservoir sedimentation manage- Sediment Trap Efficiency ment requires knowing the amount of Reservoir sediment trap efficiency is a sediment deposited (i.e., volume and mass) measure of the effectiveness of a reservoir as well as the rate (i.e., load and yield) at for trapping and permanently storing the which sediment deposition is occurring. inflowing sediment load. Trap efficiency This information provides a baseline to typically is greater than 90% for large reser- assess changes in sedimentation and the voirs (Brune, 1953; Vanoni, 2006), less for effectiveness of implemented sediment smaller reservoirs. For example, estimated reduction management practices. Federal trap efficiency of Perry Lake is 99% (Jura- reservoirs are surveyed most frequently, cek, 2003). Trap efficiency declines with typically along range lines, and an increas- increasing sedimentation (Morris and Fan, ing number of federal reservoirs have been 1998); therefore, obtaining trap efficiency mapped using acoustic echosounding to estimates is crucial, especially for reservoirs produce whole-reservoir maps of water that are rapidly filling with sediment. depth. However, most of the nearly 6,000

Sedimentation in Our Reservoirs: Causes and Solutions 17 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Sediment Quality within a basin. Using a combination of Sediment quality is an environ- several chemical tracers, Juracek and Ziegler mental concern because sediment (2007) determined that the majority of can act as a sink for various sediment now being deposited in Perry contaminants and, under certain Lake originated from channel-bank sources. conditions, a source of contaminants for the overlying water column and biota Sedimentation Dynamics (Baudo et al., 1990; Zoumis et al., 2001). Repeated bathymetric surveys can pro- Examples of sediment-associated contami- vide significant insight into the nature of nants include phosphorus, trace elements, sedimentation within a reservoir (e.g., is certain pesticides, and polychlorinated the rate of sedimentation a continuous or biphenyls. Once in the food chain, some episodic process?). Changes in reservoir sediment-derived contaminants pose a bottom topography can be monitored over greater concern because of bioaccumula- time to provide an overall estimate of the tion. Even after the source of a particular sediment accumulation rate and a spatially contaminant is eliminated from a basin, explicit representation of sediment accu- it could take several decades before newly mulation and movement across a reservoir. deposited sediment recovers to baseline Similarly, bathymetric surveys before and contaminant concentrations (Van Metre after major rain events can provide infor- et al., 1998; Juracek and Ziegler, 2006). mation on whether significant sediment When considering dredging as a sediment movement occurred. management strategy, it is important to ascertain the quality of reservoir bottom Sedimentation Patterns sediment before determining where to store Similar to bathymetric data, sediment dredged material (Morris and Fan, 1998). thickness information for Kansas reservoirs Sediment quality information is available is limited. Federal reservoirs have the most for several large and small Kansas reservoirs complete data sets, state and local reservoirs (Juracek and Mau, 2002; Juracek, 2003, have the poorest. Sediment thickness and 2004, 2006). volume can be estimated by several direct or indirect approaches (e.g., topographic and Sediment Sources acoustic differencing and sediment coring). Nationally, billions of dollars have been But even in the best cases, sediment thick- spent over the past several decades to ness and distribution data likely are limited control erosion and mitigate its effects to a few point samples or transects across (Pimentel et al., 1995; Morris and Fan, a reservoir, which provides a very limited 1998). Determining sediment sources representation of actual sediment accumu- is essential for designing cost-effective lation patterns and rates. sediment management strategies that will achieve meaningful reductions in sediment Statewide Suspended- loads and yields (Walling, 2005). A funda- Sediment Monitoring mental question is whether the sediment Network load in streams originates mostly from erosion of channel banks or surface soils A suspended-sediment monitoring network can provide valuable information

18 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

for managing sediment loads in streams. chemical impairment; and existing data and Information could include instantaneous information are of little use unless acces- concentrations, long-term variability, sible to a wide variety of users. Therefore, a seasonality, and relation to streamflow reservoir decision-support system should be and turbidity. Moreover, data from the developed as a resource for Kansans. This monitoring network could be used to system should incorporate a suite of physi- document and explain differences among cal, chemical, geospatial, and other data sites and provide baseline information to gathered from a variety of sources. assess effectiveness of implemented erosion control practices. A USGS suspended-sedi- Reservoir Restoration: ment monitoring network provided data Issues Related to for several sites from the 1950s through the Sediment Removal 1980s (Jordan, 1985). However, at present, few if any suspended-sediment data are Unique Aspects of Sediment being collected routinely. Removal Projects Removing sediment from a reservoir typi- Reservoir Information cally is performed by dredging. Unique Systems for Decision Support among earthmoving projects, dredging Multiple constituencies in Kansas need requires removing material from beneath or desire information from state agencies a water surface. Excavated material is out on water depth, sediment accumulation, of sight of both the contractor and stake- and related conditions affecting reservoirs. holders until deposited on land. Generally, This need is expressed in many ways: a dredging projects in Kansas involve pump- fisherman desiring a reservoir depth map, ing sediment from the reservoir bottom as a a neighborhood association faced with the slurry and placing it on land behind levees, difficult decision of whether to dredge their which allow water to drain back to the res- reservoir, and state officials grappling with ervoir. It is difficult to quantify the amount major issues of drinking water quality and of excavated sediment and impossible to quantity in reservoirs. determine if removal achieved the desired reconfiguration of the reservoir bottom. Critical decisions about reservoir manage- The end product of dredging is out of view ment must be made at numerous times with only the spoils as evidence of progress and places across the state, yet information and completion. on the current status and trends of Kansas reservoirs is not readily accessible and is Also unique to dredging is a basin of water dispersed among federal, state, and local (with more water flowing in and out) entities. This prevents timely and efficient that is highly disturbed by the excavation identification of currently impaired res- process. Observers, particularly those living ervoirs and reservoirs that could become nearby, expect to see sediment deposits impaired. No comprehensive database on land. However, they will also witness exists to identify these water bodies changes in the reservoir—waters becoming and determine their size, age, location, increasingly cloudy, heavier than normal proximity to urban areas, current level of growth of aquatic plants, and impaired impairment, or potential future physical or fishing and other activities. Failing to Sedimentation in Our Reservoirs: Causes and Solutions 19 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

identify or address these effects and issues expected needs? Was the investment can hinder satisfactory project completion. worth it? Examples of potential problems include: • Dissatisfaction of stakeholders and • Inability of stakeholders to adequately contractors leading to discouraging develop project goals because they can- projections for the future with no other not accurately identify the extent and restoration options available location of sediment • Higher bids from contractors to cover Managing These Issues contingencies because they are not able To address the above-mentioned issues and to adequately assess sediment condi- resulting effects, a management plan should tions beneath the water surface be developed based on accurate mapping • Stakeholder concerns including unex- of the reservoir bottom before, during, and pected project costs, difficult-to-view after the sediment removal project. The progress, and unexpected appearance of Kansas Biological Survey, a state agency, site disturbances can provide this mapping service through a newly developed bathymetric mapping • Impeded progress or equipment dam- capability. Simultaneously measuring water age as unexpected rocks, tree stumps, quality conditions can help address other compacted sediment, or other impedi- related issues. State and federal agencies ments are encountered with expertise in measuring particular • Uncertainty between contractors and water and sediment quality conditions of stakeholders regarding the new bot- interest can work together to provide this tom configuration as each area of the information. reservoir bottom is completed Before sediment removal. Of • Disenchantment among financial primary importance are high-resolution investors, particularly citizen stakehold- (less than 1 square meter) contour maps ers, due to continuing site disturbances of the bottom configuration for the entire and perceived slow progress reservoir and for specific sites. Comparing • Disagreements between contractors this information with pre-impoundment and stakeholders regarding project contours and selected sediment coring to completion resulting from contractors verify thickness in certain locations will judging contract commitments only by enable stakeholders to develop well-defined rough estimates of removed materials project goals and work plans to support the bidding process. All interested contrac- • Diminished credibility between con- tors can receive clear project goals and an tractors and stakeholders, whether accurate view and quantification of the justified or not, leading to contentious reservoir bottom contour conditions to be final contract completion settlement reconfigured. This will minimize unknown • Lingering questions among stakehold- factors and encourage preparation of the ers: Will the reservoir meet future most accurate, cost-effective bids and most mutually acceptable work plan.

20 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

During sediment removal. Excavated Summary sediment can be quantified most accurately Many reservoirs have been con- with mapped contour changes at each structed in locations where their bottom site before and after excavation. lifespans are threatened by natural During the sediment removal process, conditions as well as human land use bottom configuration information should activities. It is impossible to expect that be available immediately before the dredge we could someday restore or replace all moves into a new area and immediately these reservoirs. Hundreds of reservoirs in after the new area is completed. Such data Kansas and thousands more throughout the allows contractors to more accurately quan- United States already require restoration or tify sediment removal continually during replacement. Eventually, all reservoirs will the project, a determination that is difficult, require some action to maintain, restore, if not impossible, to make based only on or replace their ability to provide resources excavated slurry on land that might still be as intended. Most reservoirs worldwide combined with an undetermined volume were constructed at about the same time of water. Quantifying excavated sediment (post-1930s) and have similar lifespans. will improve contractors’ sediment removal This creates a time period for renovation or efficiency and provides contractors and replacement that is similarly condensed and stakeholders an ongoing measure of prog- too short to ensure successful rehabilitation ress related to the original goals and work of all reservoirs. Replacement is difficult plan. because reservoirs have already been Keeping Stakeholders Informed. constructed in most of the best locations. Raising dam height to compensate for lost Other issues can be addressed by dissemi- water storage is structurally impossible for nating useful information (e.g., excavation many reservoirs, and it is not feasible to lose progress and changing water quality) to all of the urban development surrounding stakeholders. State agencies should main- many reservoirs. Renovation by dredging tain an information network to continually requires moving material and will cost document progress and changing water 15 to 100 times more than original dam quality conditions resulting from excava- construction. Dredging one 7,000-acre tion or water returning from the spoils reservoir nearly filled with sediment would area. Periodic stakeholder meetings, some cost about $1 billion today. We must on site, should be convened. However, continue to preserve quality of reservoirs this level of oversight and communication and watersheds with better management among all parties, particularly dredging until renovation or replacement is feasible. contractors who might not have previously It is imperative that we protect these vital worked with this level of stakeholder input, public resources, first by responding to requires conscientious management to immediate problems affecting water quality ensure continued progress. and wildlife habitat and then by addressing progressive siltation.

Sedimentation in Our Reservoirs: Causes and Solutions 21 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Recommendations Reservoir management is an enormous task requiring considerable investment. Our actions and procedures must be successful. Therefore, both now and in the future, we should: • Determine rates of sedimentation by bathymetric mapping, coring, and isotopic dating • Manage reservoirs, their watersheds, and stream channels more effectively to delay filling • Address declining environmental quality of water and habitat in reservoirs • Identify and refine renovation or replacement strategies for particular reservoir situations • Prioritize particular reservoirs for types of eventual treatments • Explore alternative water collection, holding, and distribution systems • Accept that all reservoirs eventually will fill with sediment and prepare to address the consequences

References Juracek, K.E. 2003. Sediment deposition and occurrence of selected nutrients, other chemical constituents, and Baudo, R., Giesy, J.P., and Muntau, H. (Eds.). 1990. Sedi- diatoms in bottom sediment, Perry Lake, northeast ments—Chemistry and toxicity of in-place pollutants. Kansas, 1969-2001. USGS Water-Resources Investiga- Ann Arbor, MI: Lewis. tions Report 03-4025.

Brune, G.M. 1953. Trap efficiency of reservoirs. Transac- Juracek, K.E. 2004. Sedimentation and occurrence and tions of the American Geophysical Union, 34:407-448. trends of selected chemical constituents in bottom sediment of 10 small reservoirs, eastern Kansas. USGS Collins, D.L. 1965, June. A general classification of source Scientific Investigations Report 2004-5228. areas of fluvial sediment in Kansas. Kansas Water Resources Board Bulletin No. 8. Juracek, K.E. 2006. Sedimentation and occurrence and trends of selected chemical constituents in bottom deNoyelles, F., Wang, S.H., Meyer, J.O., Huggins, D.G., sediment, Empire Lake, Cherokee County, Kansas, Lennon, J.T., Kolln, W.S., et al. 1999. Water quality 1905-2005. USGS Scientific Investigations Report issues in reservoirs: Some considerations from a study 2006-5307. of a large reservoir in Kansas. Proceedings of the 49th Annual Environmental Engineering Conference. Juracek, K.E. and Mau, D.P. 2002. Sediment deposition Lawrence, KS. pp. 83-119. and occurrence of selected nutrients and other chemical constituents in bottom sediment, Tuttle Creek Jordan, P.R. 1985. Design of a sediment data-collection Lake, northeast Kansas, 1962-1999. USGS Water- program in Kansas as affected by time trends. USGS Resources Investigations Report 02-4048. Water-Resources Investigations Report 85-4204. Juracek, K.E. and Ziegler, A.C. 2006. The legacy of leaded gasoline in bottom sediment of small rural reservoirs. Journal of Environmental Quality, 35:2092-2102.

22 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Juracek, K.E. and Ziegler, A.C. 2007. Estimation of Vanoni, V.A. (Ed.). 2006. Sedimentation engineering. sediment sources using selected chemical tracers in Reston, VA: American Society of Civil Engineers. the Perry Lake and Lake Wabaunsee Basins, northeast Kansas. USGS Scientific Investigations Report Walling, D.E. 2005. Tracing suspended sediment sources 2007-5020. in catchments and river systems. The Science of the Total Environment, 344:159-184. [KWA] Kansas Water Authority. 2001. Executive summary for House substitute for Senate Bill 287 man- Wang, S.H., Huggins, D.G., deNoyelles, Jr., F., Feng, C. dates. Submitted to the Kansas Legislature on January 1999. Public internet access for selected water quality 8. Topeka, KS. p. 3-14. Available at: http://www.kwo. data in surface water of Clinton Lake, east-central org/Reports%20%26%20Publications/HB287_execu- Kansas. Proceedings of the 24th Annual National tive_summary.pdf. Accessed April 2008. Association of Environmental Professionals Confer- ence. June 20-24. Kansas City, MO. pp. 89-102. [KWO] Kansas Water Office. 2008. Reservoir information: Reservoir fact sheets. Available at: Wang, S-H., Dzialowski, A.R., Meyer, J.O., deNoyelles, http://www.kwo.org/ReservoirInformation/ Jr., F., Lim, N-C, Spotts, W., et al. 2005a. Relation- Reservoir%20Information.htm. Accessed April 2008. ships between cyanobacterial production and the physical and chemical properties of a Midwestern Linkov, I., Fristachi, A., Satterstrom, F.K., Shilfrin, A., Reservoir, USA. Hydrobiologia, 541:29-43. Steevens, J., Clyde, Jr., G.A., et al. 2007. Harmful cyanobacteria blooms: Identifying data gaps and the need Wang, S.H., Huggins, D.G., Frees, L., Volkman, C.G., for a management framework. Chapter 12 in I. Linkov, Lim, N.C., Baker, D.S., et al. 2005b. An integrated G.A. Kiker, and R.J. Wenning (Eds.). Managing criti- modeling approach to watershed management: Water cal infrastructure risks. New York: Springer-Verlag. and watershed assessment of Cheney Reservoir, Kan- sas, USA. Journal of Water, Air, and Soil Pollution, Mankin, K.L., Wang, S.H., Koelliker, J.K., Huggins, D.G., 164:1-19. and deNoyelles, Jr., F. 2003. Water quality modeling: Verification and application. Journal of Soil and Water Zoumis, T., Schmidt, A., Grigorova, L., and Calmano, W. Conservation, 58:188-197. 2001. Contaminants in sediments—Remobilisation and demobilization. The Science of the Total Environ- Morris, G.L. and Fan, J. 1998. Reservoir sedimentation ment, 266:195-202. handbook. New York, NY: McGraw-Hill.

National Recreation Lakes Study Commission. 1999, June. Reservoirs of opportunity. Final report of the Additional Resources National Recreation Lakes Study. Washington, DC: ASTRA Initiative, Kansas Biological Survey: http://www. National Recreation Lakes Study Commission. kars.ku.edu/astra

Pimentel, D., Harvey, C., Resosudarmo, P., Sinclair, K., USGS Reservoir Sediment Studies: http://ks.water.usgs. Kurz, D., McNair, M., et al. 1995. Environmental gov/Kansas/studies/ressed/ and economic costs of soil erosion and conservation benefits. Science, 267:1117-1123.

Smith, V.H., Sieber-Denlinger, J., deNoyelles, Jr., F., Campbell, S., Pan, S., Randtke, S.J., et al. 2002. Manag- ing taste and odor problems in a eutrophic drinking water reservoir. Lake and Reservoir Management, 18:318-322.

[USACE] U.S. Army Corps of Engineers. 2005. National inventory of dams. Available at: http://crunch.tec. army.mil/nidpublic/webpages/nid.cfm. Accessed April 2008.

Van Metre, P.C., Wilson, J.T., Callender, E., and Fuller, C.C. 1998. Similar rates of decrease of persistent, hydrophobic and particle-reactive contaminants in riverine systems. Environmental Science and Technol- ogy, 32:3312-3317.

Sedimentation in Our Reservoirs: Causes and Solutions 23 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu. This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Methods for Assessing Sedimentation in Reservoirs

Mark Jakubauskas, Research Associate Professor Frank deNoyelles, Deputy Director and Professor Applied Science and Technology for Reservoir Assessment (ASTRA) Initiative Kansas Biological Survey, University of Kansas

Introduction Current State of the Sediment accumulation and other factors Science: Bathymetric continue to create water quality problems Mapping that affect the many uses of Kansas reser- Traditional Approaches to voirs. The most pressing issue is ensuring the quality of drinking water supplies. Water Depth Measurement Flood control, recreation, irrigation, and Information on water depth has been other reservoir uses also must be protected, important for thousands of years. Until the and renovation to ensure reservoirs’ long- 20th century, water depth measurements term viability is becoming increasingly were obtained manually from the side of a necessary. Solving these problems is an boat with a sounding line and lead weight enormous challenge that requires gathering (Figure 1) or, in shallower waters, a pole crucial information about physical, chemi- with depth markings. Sounding weights cal, and biological conditions in reservoirs and poles often were tipped with an and watersheds. Bathymetric (lake bottom adhesive substance, such as wax or lard, to contour) mapping and reservoir assess- capture a sample of sediment. The location ments are becoming particularly important of each sounding (depth measurement) was as federal, state, and local agencies contem- determined by estimation or direct mea- plate and initiate sediment management surement in smaller water bodies or harbors projects to renovate Kansas reservoirs. and by celestial navigation (sextant or astro- labe) in oceans. Thus, horizontal accuracy

Figure 1. A 19th century sounding boat Image from NOAA Central Library

Sedimentation in Our Reservoirs: Causes and Solutions 25 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

of these ad-hoc spot positions a target (e.g., a submarine or the bottom generally was low. A measure of a water body) is measured. The distance of control could be imposed in between sensor and target can be calculated areas where range lines could be using the following equation: established between identifiable landmarks on shore. This permitted D = ½ (S × T) repeat visits to sounding positions over time to monitor sedimentation or erosion. Where D = distance between sensor and target, S = speed of sound in water, and T = Manual approaches to depth measure- round-trip time. ment are labor intensive, have relatively low accuracy and precision, and have To acquire information about the nature of considerable limitations, particularly the target, intensity and characteristics of for mapping detailed bottom contours the received signal also are measured. The or estimating whole-lake sedimentation echosounder has four major components: volumes, rates, and changes. Development a transducer, which transmits and receives of acoustic echosounding systems that the acoustic signal; a signal generation com- use global positioning systems technology puter, which creates the electrical pulse; the for horizontal position location enabled global positioning system, which provides “whole-lake” approaches that build detailed precise latitude/longitude coordinates; and representations of depth contours based the control and logging computer. Typical on mathematical interpolation of thou- acoustic frequencies for environmental sands of geographically referenced depth work are: measurements. • 420 kHz – plankton, submerged aquatic vegetation Whole-Lake Acoustic • 200 kHz – bathymetry, bottom classi- Echosounding for Lake Depth fication, submerged aquatic vegetation, (Bathymetric) Mapping fish By the 20th century, advances in acoustic • 120 kHz – fish, bathymetry, bottom science and technology permitted develop- classification ment of sonar systems, originally used for military purposes but adapted for civil- • 70 kHz – fish ian mapping operations. During the past • 38 kHz – fish (marine), sediment decade, acoustic echosounding systems penetration became sufficiently self-contained and portable, allowing for use even on small lakes and ponds. Prior to conducting a bathymetric survey, geospatial data (including georeferenced Acoustic echosounding relies on accurate aerial photography) of the target lake are measurement of time and voltage. A sound acquired, and the lake boundary is digitized pulse of known frequency and duration is as a polygon shapefile. Transect lines are transmitted into the water, and the time predetermined based on project needs and required for the pulse to travel to and from reservoir size. Immediately before or after the bathymetric survey, elevation of the

26 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

lake surface is determined. For large reser- points are interpolated to a continuous voirs (e.g., U.S. Army Corps of Engineers surface by generation of a triangulated, or Bureau of Reclamation lakes), elevation irregular network or simple raster inter- is determined using local gages. For smaller polation. Elevation of the digitized lake reservoirs that are not gaged, a laser line is perimeter is set to the predetermined established from a surveyed benchmark to value and used in the interpolation as the the water surface at the edge of the lake. defining boundary of the lake. Then, area- volume-elevation tables can be computed System parameters are set after boat launch from the lake bottom surface model. and echosounder initialization. Water temperature at a depth of 1 to 2 meters Current State of the is recorded (°C) and used to calculate Science: Sediment the speed of sound in water for the given Classification and temperature and depth. A ball check is performed using a tungsten-carbide sphere, Thickness Assessment which is supplied specifically for this Acoustic Characterization of purpose with each transducer. The ball is Sediment Types lowered to a known distance below the The acoustic echosounding system has a transducer face. The position of the ball in proprietary software suite that classifies the water column (distance from the trans- reservoir bottom sediment (e.g., rock, sand, ducer face to the ball) is clearly visible on silt, or mud) based on characteristics of the echogram, and the echogram distance the acoustic return signal (Figure 2). Ide- is compared with the known distance to ally, this process would be used to collect ensure parameters are set properly. acoustic data from known bottom types to provide a “library” of Kansas-specific A typical survey procedure for smaller lakes classification data. Sediment sampling is to run the perimeter of the lake, maneu- and coring also provide bottom composi- vering as close to shore as permitted by tion data for calibration and accuracy boat draft, transducer depth, and shoreline assessment. obstructions to establish near-shore lake bottom dropoff. Then, predetermined transect patterns are followed, and data are automatically logged by the echosounding system.

Raw acoustic data are processed through proprietary software to generate ASCII point files of latitude, longitude, and depth. Point files are ingested to ArcGIS and merged into a master point file, and bad points and data dropouts are deleted. Figure 2. Acoustic signal classification for Depths are converted to elevations of the bottom type mapping lake bottom based on the predetermined Image courtesy of Mark Jakubauskas, Kansas Biological lake elevation value. Lake bottom elevation Survey

Sedimentation in Our Reservoirs: Causes and Solutions 27 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Approaches for Estimating the tube, allowing for sediment thick- Sediment Thickness ness measurement and sample collection. Estimating thickness of accumulated sedi- The interface between pre-impoundment ment in a reservoir is not a simple process. substrate and post-impoundment sediment Three techniques—sediment coring, is fairly distinct in Kansas lake sediment topographic differencing, and acoustic esti- samples (Figure 3). mation—show promise for estimating the spatial distribution, thickness, and volume Several companies manufacture and of accumulated sediment in Kansas res- distribute sediment coring systems. How- ervoirs. Each technique has strengths and ever, most systems are intended for deep limitations, and an ideal methodology uses water marine use in the ocean and are all three approaches in concert to calibrate not suitable for smaller, shallower lakes and cross-check results. and reservoirs. Sampling inland reservoirs requires a portable, self-contained unit with Sediment Coring. Sediment cores typi- an independent power supply that is small cally are taken from a boat using a gravity enough to fit on an outboard motorboat corer or vibrational coring system. In either or pontoon boat, which disqualifies pneu- case, an aluminum, plastic, or steel tube matic, hydraulic, or high-voltage systems is forced into the sediment, ideally until commonly used on larger marine vessels. pre-impoundment substrate is reached. The Smaller systems have been developed and tube is withdrawn and sliced longitudinally, are used in Kansas (e.g., the VibeCore or the sample is carefully removed from System, Specialty Devices Inc., Texas).

Figure 3. Sediment core from Mission Lake in Brown County, Kansas, showing pre- impoundment substrate (left) and post-impoundment sediment (right) Photo courtesy of Kansas Biological Survey

28 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

A benefit of the sediment coring approach used to create a pre-impoundment surface, is that cored material can be preserved and data from new bathymetric surveys are and analyzed for sediment classification used to create a map of current reservoir or chemical composition. However, core bottom topography. Unlike spot measure- sampling is time and labor intensive; only a ments of sediment thickness, topographic small number (≈10 to 25) of point samples differencing can display a “whole-lake” can be taken per day. Although sediment representation of sediment accumulations, core data are likely highly accurate for facilitating estimates of sediment volume a given location, the overall result is an (Figure 5). incomplete and fragmentary representation of sediment thickness and volume across However, quality of sediment thickness the reservoir. data produced by this approach depends on quality of data used to create pre-impound- Topographic Differencing. The ment maps. Archival topographic data can topographical approach computes the have one or more of the following limita- difference between pre-impoundment tions: no information on horizontal or and present-day lake bottom topographic vertical projection of data used, referenced data and uses that information to create to an arbitrary local elevation (i.e., non- a spatially-explicit, three-dimensional standard/nongeodetic vertical control), or representation of sediment accumulation of inappropriate spatial scale to produce (Figure 4). Data from archived topographic meaningful comparisons with present-day maps, reservoir blueprints, or “as-built” topographic data. pre-impoundment topographic surveys are

Figure 4. Topographic differencing of pre-impoundment and present-day reservoir topography Left: 1923 engineering contour map of Mission Lake in Brown County, Kansas; Center: Digital elevation model created from 1923 map; Right: Present-day lake bottom topography created from analysis of acoustic echosounder data. Images courtesy of Kansas Biological Survey

Sedimentation in Our Reservoirs: Causes and Solutions 29 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Figure 5. Elevation map of John Redmond Reservoir showing the difference between 2007 bathymetric survey data and a 1957 U.S. Army Corps of Engineers topographic map Negative numbers indicate loss of material during the 50-year period; positive numbers indicate accumulated material (siltation). Image courtesy of Kansas Biological Survey

Acoustic Estimation. In the acoustic the dam towards the backwater and approach, high-frequency and low-fre- no delta forms at the tributary inlet. quency transducers (200 kHz and 38 kHz) As long as the water depth is greater are operated simultaneously during a lake than the sediment thickness, the base survey. Differencing acoustic returns from of sediment can be mapped without high and low frequencies (reflecting off interference from the water-bottom the current reservoir bottom and the pre- multiple reflection, and the entire impoundment bottom, respectively) have reservoir can be surveyed from a boat. shown considerable promise for successful Coarse-grained dominated reservoirs sediment thickness mapping in inland fill from the backwater towards the reservoirs (Figure 6; Dunbar et al., 2000). dam and form deltas in the backwater. Our results indicate that mapping the In the time [sic] the backwater region base of sediment acoustically works cannot be surveyed, because it is dry best in reservoirs that are dominated by land. In these cases, the only option is fine-grained deposition (clay and silt, differing the bathymetry. (John Dun- rather than silt and sand). Reservoirs bar, personal communication, 2007) with fined-grained-deposition fill from

30 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

a) 200 kHz 7

9 Depth (m) Depth

b) 48 kHz 7

9 Depth (m) Depth

10 c) 24 kHz 7

9 Depth (m) Depth

d) 12 kHz 7

9 Depth (m) Depth

10 e) 3.5 kHz 7

9 Depth (m) Depth

0 400300200100 500 m

Figure 6. Echograms of acoustic reflectance at multiple frequencies for reservoir sediments: a) High frequency, showing strong discrimination of sediment-water interface; b through e) Increasing penetration of post-impoundment sediments and increasing return from pre- impoundment substrate with progressively lower frequencies. Figure reprinted from Dunbar et al. (2000) with permission

Sedimentation in Our Reservoirs: Causes and Solutions 31 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Information Needs What is the rate of sedimentation, and is sedimentation continuous Information needs related to lake bathym- or episodic? Repeated bathymetric etry and reservoir assessment can be divided surveys provide significant insight into into two broad categories: 1) reservoir-scale the nature of sedimentation in a reservoir. information needs, which can be satisfied Changes in reservoir bottom topography by applying bathymetric technology in an can be monitored over time, allowing an integrated reservoir assessment program, overall estimate of the rate of sediment and 2) technology-specific information accumulation and a spatially explicit needs that explore strengths and limita- representation of sediment accumulation tions of bathymetric technology. Crucial and movement across a reservoir. Bathy- information is lacking, and many questions metric surveys before and after major rain remain. events can provide information on whether significant sediment movement occurred. Reservoir-Scale Information Needs Technology-Specific What is the current depth and Information Needs volume of the state’s reservoirs? To better understand data produced by Bathymetric data are not available for a bathymetric surveying, research should majority of the more than 5,000 regulated be conducted to explore strengths and reservoirs in Kansas. A review of 18 federal limitations of this technology. Answering reservoirs in Kansas showed that average the following questions can help improve time since last bathymetric survey was 15 speed, accuracy, and precision of data years (USGS, 2008), but an increasing acquisition, which is necessary for making number of federal reservoirs have been informed decisions about reservoir manage- mapped using acoustic echosounding to ment and renovation. produce whole-lake maps of water depth.

Bathymetric data for state and local lakes Topographic and acoustic in Kansas are even more rare, collected on sediment thickness estimation an as-needed or ad-hoc basis, and often techniques incomplete. • What are the possible sources of error How much and where has sedi- of this approach? ment accumulated in a given • What are the effects of sediment reservoir? Like bathymetric data, sedi- composition on estimating sediment ment thickness information is limited in thickness? Kansas. Federal reservoirs have the most complete data sets, state and local reservoirs • What are the limitations to identifying have the poorest. Even in the best cases, the pre-impoundment bottom contour sediment thickness and distribution data in acoustic data? likely are limited to a few point samples or • What are the effects of scale (horizontal transects and thus provide a very limited and vertical resolution) on accuracy? representation of actual sediment accumulation patterns and rates.

32 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

• What spatial error results from dif- Sustained Reservoir- ferences between pre-impoundment Mapping Program published topographic data and “as- These surveys will provide a set built” topographic conditions? of baseline bathymetric elevations and sediment data. One advantage Processing acoustic data for is that water quality and bathymetric bathymetric and sediment data can be measured simultaneously surveying from the same boat. Also, because surveys • What are the optimal interpolation will be conducted with the same equipment algorithms, in terms of speed, accuracy, and methods, it will be possible to compare and precision, for bathymetry and sedi- results among reservoirs and from the same ment thickness estimation? reservoir over time. • Can advanced signal processing of Change Detection Studies acoustic echosounder data accurately These studies would involve revisiting pre- identify pre-impoundment lake bottom viously mapped reservoirs, re-mapping the traces? bathymetry and cores, and comparing past • Can advanced signal processing of and present maps to identify sedimentation acoustic echosounder data coupled locations and rates. This element likely with an “acoustic library” of Kansas will not occur during the first few years reservoir substrate signatures improve of the program but eventually could grow bottom type classification? into a major focus as baseline bathymetric and sediment data are accumulated for Mapping and Assessment comparison. Program Before/After Mapping, A long-range bathymetric mapping and Coring, and Sediment reservoir assessment program for Kansas Estimation will have numerous benefits. Decision Comparing high-resolution contours of makers will be able to easily assess current bottom topography with pre-impound- conditions of a given reservoir and identify ment topography and selected sediment and prioritize reservoirs based on sediment coring to verify thickness in certain loca- load and need for renovation. Enhanced tions will enable stakeholders to develop knowledge of sediment deposition in well-defined project goals and work plans. reservoirs will help determine effectiveness Dredging contractors can receive an of watershed protection practices. When accurate representation of reservoir bot- dredging appears to be the best alternative tom contours to be reconfigured. This will to extend the life of a reservoir, sediment minimize unknown factors and encourage deposition data will indicate how much preparation of the most accurate and cost- sediment needs to be removed and can help effective bids and the most mutually accept- determine how much was removed by the able work plan. dredger. Such a program should contain the following elements:

Sedimentation in Our Reservoirs: Causes and Solutions 33 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Ad-hoc Mapping of Small Reservoir Information Reservoirs System In this capacity, the program can provide Multiple constituencies in Kansas need or timely, unbiased, impartial bathymetric desire information on water depth, sedi- data and sediment estimates to help local ment type, sediment accumulation, and stakeholders make management decisions related conditions affecting reservoirs. relating to water quality, watershed man- However, data and information are of little agement, and reservoir renovation. use unless readily and easily accessible to a wide variety of users. Large-Scale Mapping and Sediment Studies References

Because of the intensive effort required and Dunbar, J.A., Allen, P.M., and Higley, P.D. 2000. large amount of data generated, we envision Color-encoding multifrequency acoustic data for near- this program mapping four to six federal- bottom studies. Geophysics, 65:994-1002. size reservoirs per year. [USGS]. United States Geological Survey. 2008. Reservoir sediment studies in Kansas. Available at: http:// ks.water.usgs.gov/Kansas/studies/ressed/. Accessed March 31, 2008.

Concept for a Long-Range Bathymetric Mapping and Reservoir Assessment Program • Sustained reservoir-mapping program that includes a number (≈10 to 20) of bathymetric and coring surveys per year • Change detection studies to estimate rates and locations of sediment accumulation • Before/after bathymetric mapping, coring, and sediment volume estimation for reservoir dredging projects • Ad-hoc bathymetric mapping of small reservoirs for state, local, and private entities • Large-scale federal reservoir bathymetric mapping and sediment studies • Development of a reservoir information system

34 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Effects of Sedimentation on Biological Resources

Donald G. Huggins, Senior Aquatic Ecologist and Director Robert C. Everhart, Graduate Research Assistant Andrew Dzialowski, Post Doctoral Researcher James Kriz, Graduate Research Assistant Debra S. Baker, Assistant Director Central Plains Center for BioAssessment, Kansas Biological Survey, University of Kansas

Summary In-stream sediments come from two sources: runoff from surrounding areas Sedimentation is a natural process, but and erosion from both the sides and bed too much sediment in aquatic ecosystems of the channel. The complex interaction can cause loss or impairment of fish, of streams and the surrounding landscape macroinvertebrates, and other aquatic can be characterized to a large extent by organisms. Our current ability to quantify describing sediment movements. Ero- relationships among aquatic sediment sion and sediment deposition affect many variables and aquatic biota in the Central stream characteristics including channel Plains is limited by available data and the depth, channel shape, substrate, flow complexity of direct and indirect linkages patterns, dissolved oxygen concentrations, between resource components. At present, adjacent vegetation, and aquatic communi- turbidity appears to be the best indicator of ties (Leopold et al., 1964; ASCE, 1992; suspended sediment for defining biologi- OMNR, 1994; Rosgen, 2006). cal impairment in flowing water systems. Better coordination of existing and new Sedimentation is a natural process that research, use and analysis of well-selected occurs in most aquatic ecosystems, and indicators of suspended and deposited sediment-borne organic materials provide sediment and ecosystem function, and the primary food source for a number of advanced statistical analyses will allow us filtering macroinvertebrates (Waters, 1995; to more accurately identify and quantify Wood and Armitage, 1997). However, effects of sediment on aquatic ecosystems in human activities such as urbanization, Kansas. agriculture, and alteration of riparian habitat and flow regimes have increased Introduction the concentrations and rates at which Water from streams and rivers is used sediment enters streams and rivers (Wood for drinking, irrigation, waste dilution, and Armitage, 1997; USEPA, 2000; Zweig power generation, transportation, and and Rabeni, 2001; Angelo et al., 2002); recreation and provides habitat for fish and losses of habitat, biota, and ecosystem and other aquatic organisms (Allan, 1995). services due to sediment have caused severe This water also contains sediment (e.g., socioeconomic impacts (Duda, 1985). As eroded soil particles), which can be either a result, sedimentation is listed as one of suspended in the water or deposited on the the most common stream impairments in bottom. Sedimentation is the process by the United States (USEPA, 2000, 2004), which sediment is transported and depos- occurring in almost one-third of the river ited in aquatic ecosystems. and stream miles recently assessed by the U.S. Environmental Protection Agency (USEPA; 2004). Sedimentation in Our Reservoirs: Causes and Solutions 35 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Increased sedimentation and sediment Both “clean” and “dirty” sediment directly loading are also threatening the ecologi- and indirectly affect the structure and cal integrity of other aquatic systems. For function of all aquatic ecosystems (Figure example, sedimentation at higher than nor- 1). Clean sediment is free from additional mal rates can reduce or impair habitat and contaminants (e.g., volatile organics, primary production in wetlands (Gleason metals, or other toxic compounds), and and Euliss Jr., 1998; USEPA, 2002; Glea- dirty sediment harbors these materials. son et al., 2003). Similar habitat reduction Effects of dirty sediment are due to the has been observed in lakes; several Kansas nature and concentration of both sedi- reservoirs are experiencing 10% to 40% ment and contaminants, whereas effects of decreases in conservation-pool water-stor- clean sediment are due to the nature and age capacity. If sedimentation continues concentration of sediment particles alone. at current rates, sediment pools of these Duration of exposure is also important. In reservoirs will be filled by the 2020s (Jura- the environment, clean and dirty sediments cek, 2006). In other reservoirs (e.g., Perry, constantly interact as contaminants are Tuttle Creek), increased sedimentation is added, broken down, and removed. Because occurring primarily in the riverine upper both sediment types occur simultaneously, reaches, reducing both quality and quantity clean and dirty sediment effects are difficult of habitat. to separate. To begin understanding sediment interactions, this white paper focuses on effects of clean sediment.

WATER QUALITY FLOW (Chemical and some (Low ows, oods, physical parameters) wet years, duration)

“CLEAN” SEDIMENT “DIRTY” SEDIMENT (Sediment transport curves, total suspended solids, bedload, related variables) (Media for contaminants)

GEOMORPHOLOGY (Large and moderate scale factors like sinuosity and channel shape) BIOTA (Fish, macroinvertebrates, primary producers) HABITAT (Moderate to small scale factors or units like rie embeddedness and debris jams)

Figure 1. Conceptual framework showing interactions of sediment in aquatic ecosystems Boxes illustrate important ecosystem units with examples, and arrows represent functional directions and links between those units. Ultimate goals are to understand the links and quantify sediment effects on biota.

36 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Although effects of sedimentation are tions, or damage ecosystem capacity for widespread, a comprehensive theory of production these effects on benthic communities does • Sublethal effects, which injure organ- not currently exist (Zweig and Rabeni, ism tissues or cause physiological stress, 2001). Appropriate management of aquatic both without causing mortality ecosystems in Kansas requires improving our ability both to more accurately quan- • Behavioral effects, which alter the activ- tify relationships among aquatic sediment ity of affected organisms variables and aquatic biota and to distinguish between natural and anthropogenic Both suspended and deposited sediment sediment loading in this region. As a first particles can affect aquatic ecosystems step in that process, this white paper sum- (Waters, 1995; Zweig and Rabeni, marizes current knowledge and provides 2001; Richardson and Jowett, 2002). recommendations for future research. For example, increased suspended solid concentrations can reduce primary produc- State of the Art: Review tion (Van Nieuwenhuyse and LaPerriere, of Science to Date 1986), disrupt feeding and respiration rates of macroinvertebrates (Lemly, 1982), Brief Literature Review and reduce growth and feeding rates of Most sedimentation research focuses on many stream fish (Wood and Armitage, cold water systems. Representative works 1997). Both intensity (concentration) and include basic research studies (Luedtke duration (time of exposure) of suspended and Brusven, 1976; Erman and Ligon, sediment loading contribute to biological 1988; Lisle and Lewis, 1992; Goodin et impairment, and models that consider both al., 1993; Maund et al., 1997; Simon et al., are better predictors of impairment than 2003; Dodds and Whiles, 2004), literature models that use either intensity or duration reviews (Cordone and Kelley, 1961; Foess, alone (Newcombe and MacDonald, 1991). 1972; Newcombe and MacDonald, 1991; Increased sediment deposition can reduce Doisy and Rabeni, 2004), and books (Ford the complexity of stream habitat (Allan, et al., 1990; Waters, 1995). Previous stud- 1995) and smother aquatic organisms ies report both direct and indirect effects including macroinvertebrates, fish, and of sedimentation. Direct physical effects macrophytes (Waters, 1995; Wood and include light interruption; smothering of Armitage, 1997). organisms; and coverage of sites used for germination, feeding, spawning, and other In addition to the abundance of studies on activities. Biotic effects include direct mor- cold water systems, the majority of stream tality; reduced fecundity; reduced disease sediment research has been conducted resistance; and inhibited feeding, growth, in systems with either a naturally high and reproduction. Reviews by Newcombe gradient (i.e., steep downhill slope) or and MacDonald (1991) and Doisy and naturally low turbidity (Dodds et al. 2004). Rabeni (2004) have also grouped direct However, aquatic systems in the Central biotic effects into three categories: Plains—especially those in agriculturally • Lethal effects, which cause direct dominated areas like the Central Great mortality of organisms, reduce popula- Plains, Western Corn Belt Plains, and, Sedimentation in Our Reservoirs: Causes and Solutions 37 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

to a lesser extent, the Central Recent Regional Findings Irregular Plains—generally are To analyze complex systems, it often is characterized as warm water, low- necessary to construct linked individual gradient (i.e., mild downhill slope), relationships to depict indirect effects. Sta- high-turbidity systems, though early tistically significant relationships between reports suggest that many Central indicators (i.e., representative, measurable Plains streams that have been turbid for components of the ecosystem) form the the past 100 years might have been clear links. For example, effects of clean sediment prior to widespread plowing in the region (i.e., sediment only, without associated (Matthews, 1988). Compounding the nutrient or chemical loading consider- issue, many systems in the Central Plains ations) on biology can be modeled by have sand as the natural substrate (Angelo relating a sediment loading indicator (e.g., et al., 2002). In biological terms, sand-bot- total suspended solids) to a water quality tom streams are different than streams indicator (e.g., turbidity) then relating that with either large substrates (e.g., bedrock, water quality indicator to a biological one cobble, gravel) or fine substrates (e.g., silt, (e.g., number of fish species) (Figure 2). mud, muck) because they provide different Additional indirect effects are modeled in a structural and chemical characteristics that similar fashion. affect aquatic life. Sand-bottom systems can have significant movement of sand in the A variety of potential sediment and erosion channel bed (i.e., high bedload) under natu- indicators exist. USEPA uses water column ral conditions. However, induced loading indicators (e.g., suspended sediment, bed- of silt or mud can still impair sand-bottom load sediment, and turbidity), streambed streams (Angelo et al., 2002). Distinguish- indicators (e.g., streambed particle size and ing between natural sediment loading and embeddedness), and riparian indicators induced sediment loading in these systems (e.g., buffer size and vegetation community can be very difficult; significant regional composition) to set criteria for allowable testing is required to understand how loading of induced sediment (i.e., Total anthropogenically altered sediment loading Maximum Daily Loads for sediment; can affect aquatic ecosystems. USEPA, 1998). Several biological indicator groups such as macroinvertebrates and fish Because of the need for regional testing and also respond to sediment-related effects current lack of a comprehensive theory of (Luedtke and Brusven, 1976; Culp et al., sediment effects, a sediment workgroup 1986; Richards and Bacon, 1994; Rier and sponsored by USEPA Region VII developed King, 1996; Birtwell, 1999). However, a conceptual framework for interactions of except for a study by Whiles and Dodds sediment in lotic (i.e., flowing water) eco- (2002), linkages between sediment indica- systems (Figure 1). This framework provides tors and biological indicators both within hypothesized direct and indirect linkages and between streams in the Central Plains among both clean and dirty sediments, remain largely undocumented. geomorphology, flow regimes, chemical and physical water quality parameters, habitat Sediment–Water Quality Links. effects, and biotic components including pri- Using data from more than 500 samples in mary producers, macroinvertebrates, and fish. 16 small watersheds throughout the West-

38 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

300 350

240 280

180 210 n = 560 R2 = 0.81 120 140 p < 0.0001

n = 580 (NTU) Turbidity 60 R2 = 0.99 70 p < 0.0001 Total Suspended Solids (mg/L) Suspended Total 0 0 0 30024018012060 0 35028021014070 Inorganic Suspended Solids (mg/L) Total Suspended Solids (mg/L) (A) (B)

22 100 20 n = 386 n = 978 86 18 R2 = 0.298 R2 = 0.145 16 p < 0.0001 71 p < 0.0001 14 12 57 10 43 8 6 29 4 14

2 Species Fish Sensitive Percent 0 0

Sediment Sensitive Macroinvert. Richness Macroinvert. Sensitive Sediment -0.5 0.50.0 1.51.0 3.02.52.0 -0.5 0.50.0 1.51.0 3.02.52.0 log (Average Turbidity) log (Average Turbidity) (C) (D)

Figure 2. An example of relating sediment effects to biological responses using indirect effects (A) Inorganic suspended solids, a measurement of the amount of mineral sediment particles floating in the water column, is related to total suspended solids, a measure of the amount of all particles (both inorganic and organic) floating in the water column. (B) Total suspended solids is related to turbidity, and turbidity is related both (C) to the number of macroinvertebrate taxa that are known to be sensitive to sediment and (D) to the percentage of fish species that are known to be sensitive to sediment. In this example, we relate “clean” sediment (e.g., inorganic suspended solids and total suspended solids) to biological responses (e.g., sediment sensitive macroinvertebrate richness and percentage of sensitive fish species) via the indirect effects of water quality (e.g., turbidity). Additional and more complicated analyses follow this general concept. ern Corn Belt Plains, the Central Plains throughout the Central Plains and across Center for BioAssessment (CPCB; 1994) ecoregions (RTAG, 2006); and Dodds found that inorganic suspended solids and Whiles (2004), using nationwide data, (ISS) explained 99% of the variation in found that TSS explained 89% of the varia- total suspended solids (TSS) and that TSS tion in turbidity. Because turbidity is highly explained 81% of the variation in turbidity. correlated with TSS and, by extension, ISS, The USEPA Region VII Regional Tech- turbidity measurements can be used as a nical Assistance Group (RTAG) found surrogate indicator for suspended clean that TSS explained 98% of the variation sediment in streams in the Central Plains. in turbidity for more than 13,800 sites

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Sediment/Water Quality–Biota of sediment-sensitive fish also declined Links. In most biological systems, greater with increasing turbidity. Data collected diversity of organisms implies better or during the National Wadeable Streams “healthier” environmental conditions. Assessment (USEPA, 2004) from 125 sites Models developed using RTAG (2006) in Kansas, Nebraska, Iowa, Missouri, and data suggest that macroinvertebrate rich- Oklahoma showed similar trends. Total ness (i.e., number of unique taxonomic macroinvertebrate and EPT taxa richness groups of macroinvertebrates) significantly both decreased with increasing TSS. Rich- declines with increasing turbidity. Such ness of EPT taxa and macroinvertebrate declines usually are associated with impair- scrapers (i.e., macroinvertebrates that ment or decreasing environmental quality. scrape their food off substrates) decreased However, statistical analysis and modeling as the percentage of fine substrates (i.e., silt determined a “threshold range” of turbid- or mud but not sand) increased, but taxa ity levels between 10 and 25 NTU above richness of macroinvertebrate shredders which macroinvertebrate richness drops (i.e., macroinvertebrates that shred larger very little. Even though turbidity can, and particles for food) and macroinvertebrate often does, increase significantly beyond predators (i.e., macroinvertebrates that eat this threshold range (the average turbid- other macroinvertebrates) were generally ity level of 125 Central Plains streams unaffected by changes in the percentage of is 42 NTU), relatively few taxa are lost, fine substrates. Three things are important presumably because some ecological limit to note about these relationships. First, of turbidity impairment has already been evidence for impairment is consistent reached. In other words, increased turbidity across many ecological and taxonomic has changed ecosystem function or struc- groups because increasing sediment loading ture (or both) such that more turbidity correlates with decreasing diversity. Second, does not elicit a biological response. Lack though the relationships are significant, the of response could be because the sensi- amount of variance in biological indicators tive species are gone because of death or explained by changes in sediment indica- emigration or because the ecology has been tors alone is relatively low (10% to 30%). altered to a new state that cannot be further Advanced statistical techniques might degraded by turbidity. As a corollary, allow us to better understand the complex- reduction of turbidity might not result in a ity of these relationships. Third, some significant increase of taxa unless turbidity groups (e.g., macroinvertebrates as a whole, is reduced below the threshold range. Such EPT taxa, scrapers) are more impaired by threshold ranges often are used as the basis increased sediment loads than others (e.g., for developing benchmarks and criteria for shredders and predators); this is consistent other types of impairments (e.g., nutrient with a priori expectations based on known loading). ecology of the organisms.

Regional RTAG (2006) data also revealed Habitat–Sediment/Biota Links. that the taxa richness of three typically Current data and quantification of interac- habitat-sensitive orders of aquatic insects tions between small-scale habitat indicators (i.e., Ephemeroptera, Plecoptera, and and both sediment and biology are limited. Trichoptera [EPT]) and the percentage One commonly measured habitat indicator,

40 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

“percent embeddedness,” is the degree to and Ozark Highland areas of which sediments fill spaces around rocks, eastern Oklahoma, which are gravel, and other substrates at the bottom not representative of the majority of water bodies. When these spaces fill of streams in the Central Plains. with sediment, they can no longer provide Analysis of 53 geomorphic variables habitat or shelter for fish and macro- from 16 stream reaches throughout invertebrates. Data from the National Kansas showed no statistical correlation Wadeable Streams Assessment (USEPA, with any indicators of sediment, habitat, 2004) revealed that percent embedded- or biota. Better understanding of scale (i.e., ness explained about 12% of the variation reach-scale vs. channel-scale vs. site-scale in turbidity and 26% of the variation in measurements) and advanced statistical percentage of fine substrates present. As techniques (e.g., principal components expected, total macroinvertebrate richness analysis, regression trees) are required for and EPT taxa richness declined as percent regional explanations of sediment links embeddedness increased (USEPA, 2004), with geomorphology, habitat, and biology. but the amount of explained variation in richness was limited (13% and 10%, Conclusions respectively). Effects of sedimentation in low-gradient Geomorphology–Sediment/Habi- aquatic systems are complex and difficult to measure directly. Often, surrogate variables tat/Biota Links. Geomorphology are required to relate different ecosystem is the measure of the physical structure components such as habitat, biota, water and geometry of streams and rivers. Geo- quality, clean and dirty sediment, geomor- morphic variables include reach-scale phology, and flow. Based on Kansas and indicators (e.g., reach length, number and regional data, turbidity appears to be a length of riffles, sinuosity or “curviness”) reliable and easily measurable indicator for and channel-scale indicators (e.g., channel clean sediment in lotic systems throughout depth, channel width, cross-sectional area). the Central Plains. Differences in scale make it difficult to relate some ecosystem units (e.g., geomor- Although data indicate that increased phology) to others (e.g., habitat, biota) (see sediment has a negative effect on many bio- Fausch et al., 2002, for a general overview). logical variables, regional data are limited, Although geomorphology can be important direct relationships are statistically weak, for describing particular aspects of streams and indirect relationships are difficult to and rivers, more research is required to quantify (Figure 3). In addition, factors relate these aspects to smaller-scale indica- other than sediment might contribute to tors of sediment, habitat, and biota in these relationships. Therefore, depiction the Central Plains. For example, though of direct and indirect sediment effects Dauwalter et al. (2007) found that sub- via a hypothetical framework coupled strate type and geomorphology were related with advanced statistical analyses such as to increased smallmouth bass density, the multiple linear regression, principal compo- streams they examined were cold water, nents analysis, regression trees, and quartile high-gradient, low-turbidity streams in the regression (Koenker, 1995, 2005; Cade Boston Mountain, Ouachita Mountain,

Sedimentation in Our Reservoirs: Causes and Solutions 41 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

WATER QUALITY FLOW Turbidity Few concurrent data

“DIRTY” SEDIMENT To be considered “CLEAN” SEDIMENT in future studies Inorganic suspended solids, total suspended solids

GEOMORPHOLOGY Few concurrent data, little BIOTA correlation, issues of scale Macroinvertebrate total richness, EPT richness, % sensitive sh species, sediment sensitive taxa richness HABITAT Mean embeddedness, % ne substrates

Figure 3. Conceptual framework showing observed effects of sediment on aquatic biota Boxes illustrate important ecosystem units, and arrows represent functional directions and links observed in this study. Specific indicators used for each ecosystem unit are listed. Relative weights of the arrows indicate relative strengths of relationships observed in this study.

and Noon, 2003) might lead to a better Funding for portions of the unpublished understanding and quantification of com- data used in this report was provided by the plex sediment-biota relationships. Better following USEPA grants: understanding leads to better management, • Developing Regional Nutrient Bench- including more effective interventions and mark Values for Streams, Rivers, and better estimates of socioeconomic losses Wetlands Occurring in USEPA Region associated with sediment impairment of 7. FED35840, X7-987401001. aquatic ecosystems. • Acquisition and assessment of nutrient Acknowledgments data and biological criteria methods gathered from historical sources, new This white paper is based on Report no. collections, and literature reviews. 146 of the Kansas Biological Survey, FED23582, X7-98718201. “Effects of Sedimentation on Biological Resources” (Huggins et al., in press), which • Defining Relationships Among Indica- contains detailed descriptions of recent tors of Sediment, Erosion & Ecosystem regional findings including additional Health in Low Gradient Streams. figures, tables, and analyses. Kansas Bio- FED39410, X7-98749701. logical Survey reports and other technical publications are available at: http://www. kbs.ku.edu/larc/tech/html/default.htm.

42 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Recommendations for Future Research We offer the following recommendations, based on reviews of available literature and recent research results, to guide future research on the effects of sedimentation on biological resources:

• Adopt a multidisciplinary approach. The complex nature of sedimentation spans topics including hydrology, geomorphology, aquatic ecology, water chemistry, soil and sediment chemistry, and landscape-level phenomena (e.g., urban development and agriculture). Usually, sediment studies are approached from only one or two of these points of view. • Observe both sediment loading and biological response. Surprisingly, little overlap exists between datasets on sediment loading and biological indicators. Future studies should emphasize concurrent collection of physical, chemical, geomorphic, and biological data to gain a more comprehensive understanding of complex and integrated relationships. • Begin with gaged locations. Often, sediment loading rates are the limiting factor in a multidisciplinary suite of sediment data. To better estimate effects of sediment on biological resources, those resources should be evaluated at locations where sediment loading data is available. Typically, stream gaging stations provide available loading data or opportunities to calculate sediment loads. • Determine reference conditions for sedimentation. To evaluate the extent of sedimentation effects on biological resources (i.e., how “good” or “bad” a site is), a condition of high quality must be established for comparison. Currently, there is little agreement among hydrologic, geomorphic, and biological definitions of this reference condition, making assessment of sediment-biological quality interactions problematic. • Consider the regional context. In many cases, the full range of geomorphic, hydrologic, and biological characteristics of certain aquatic systems are not present in Kansas. However, such a range might be observable at a regional or multi-state scale. Study of related systems in other states is appropriate. • Record both intensity and duration of sedimentation events. Research shows that an ecotoxicological model (i.e., one that considers both amount of sediment and length of sediment exposure) better predicts effects of sedimentation. However, most

Sedimentation in Our Reservoirs: Causes and Solutions 43 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

current studies report only sediment concentration (intensity). Temporal cycling of sediment could be important for biological systems. • Distinguish between natural and induced sedimentation. Some low-gradient, high turbidity systems in the Central Plains have elevated natural sediment loads as an ambient condition. Discerning impairment in these systems could require significant study. • Use advanced statistical techniques. Interactions between response and predictor variables in ecological systems are complex. Statistical procedures used to analyze response data must be robust to account for variation, and techniques such as multiple linear regression, principal components analysis, regression trees, analysis of covariance, quantile regression, and structural equation modeling might be appropriate.

44 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

References Doisy, K.E. and Rabeni, C.F. 2004. Effects of suspended sediment on native Missouri fishes: A literature review Allan, J.D. 1995. Stream ecology: Structure and function and synthesis. Columbia, MO: University of Missouri, of running waters. New York: Chapman & Hall. Missouri Cooperative Fish and Wildlife Research Unit. [ASCE] American Society of Civil Engineers. 1992. Sedi- ment and aquatic habitat in river systems. Journal of Duda, A.M. 1985. Environmental and economic damage Hydraulic Engineering, 188(5):669-687. caused by sediment from agricultural nonpoint sources. Journal of the American Water Resources Association, Angelo, R.T., Cringan, M.S., and Haslouer, S.G. 2002. 21(2):225-234. Response of stream biological communities to agricultural disturbances in Kansas: An historical overview Erman, D.C. and Ligon, F.K. 1988. Effects of discharge with comments on the potential for aquatic ecosystem fluctuation and the addition of fine sediment on restoration. Proceedings of the Plains Aquatic Bioas- stream fish and macroinvertebrates below a water- sessment and Biocriteria Symposium. Sept. 18-19. filtration facility. Environmental Management, Lawrence, KS. 12(1):85-97.

Birtwell, I.K. 1999. The effects of sediment on fish and Fausch, K.D., Torgersen, C.E., Baxter, C.V., and Li, H.W. their habitat. Research Document 99/139. West 2002. Landscapes to riverscapes: Bridging the gap Vancouver, British Columbia: Fisheries and Oceans between research and conservation of stream fishes. Canada, Canadian Stock Assessment Secretariat. BioScience, 52(6):483-498.

Cade, B.S. and Noon, B.R. 2003. A gentle introduction to Foess, G.W. 1972. Influence of aquatic sediments on quantile regression for ecologists. Frontiers in Ecology water quality. Journal of the Water Pollution Control and the Environment, 1(8):412-420. Federation, Literature Review, 44(6):1211-1218.

Cordone, A.J. and Kelley, D.W. 1961. The influences Ford, D.E., Thornton, K.W., Cole, T.M., Hannan, H.H., of inorganic sediment on the aquatic life of streams. Kennedy, R.H., and Walker, W.W. 1990. Chapters California Fish and Game, 47(2):189-228. 2-5: 2. Reservoir Transport Processes, 3. Sedimentary Processes, 4. Dissolved Oxygen Dynamics, 5. Reservoir [CPCB] Central Plains Center for Bioassessment. 1994. Nutrient Dynamics. In K.W. Thornton, B.L. Kimmel, 1992-1994 tristate nonpoint source pollution study. and F.E. Payne (Eds.). Reservoir limnology: Ecological Lawrence, KS: Kansas Biological Survey, Central Plains perspectives. New York: Wiley-Interscience Publica- Center for BioAssessment. tion John Wiley & Sons.

Culp, J.M., Wrona, F.J., and Davies, R.W. 1986. Response Gleason, R.A. and Euliss, Jr., N.H. 1998. Sedimentation of of stream benthos and drift to sediment deposition prairie wetlands. Great Plains Research, 8(1):97-112. versus transport. Canadian Journal of Zoology, 64:1345-1351. Gleason, R.A., Euliss, Jr., N.H., Hubbard, D.E., and Duffy, W.G. 2003. Effects of sediment load on emergence of Dauwalter, D.C., Splinter, D.K., Fisher, W.L, and aquatic invertebrates and plants from wetland soil egg Marston, R.A. 2007. Geomorphology and stream and seed banks. Wetlands, 23(1):26-34. habitat relationships with smallmouth bass (Microp- terus dolomieu) abundance at multiple spatial scales in Goodin, D.G., Han, L., Fraser, R.N., Rundquist, D.C., eastern Oklahoma. Canadian Journal of Fisheries and and Stebbins, W.A. 1993. Analysis of suspended Aquatic Sciences, 64(8):1116-1129. solids in water using remotely sensed high resolution derivative spectra. Photogrammetric Engineering and Dodds, W.K., Gido, K., Whiles, M.R., Fritz, K., and Remote Sensing, 59:505-510. Matthews, W.J. 2004. Life on the edge: The ecology of Great Plains prairie streams. BioScience, Huggins, D.G., Everhart, R.C., Dzialowski, A.R., Kriz, 54(3):205-216. J., and Baker, D.S. In press. Effects of sedimentation on biological resources. Open-file Report No. 146. Dodds, W.K. and Whiles, M.R. 2004. Quality and Lawrence, KS: Kansas Biological Survey. quantity of suspended particles in rivers: Continent- scale patterns in the United States. Environmental Juracek, K.E. (2006). A comparison of approaches for Management, 33(3):355-367. estimating bottom-sediment mass in large reservoirs. Scientific Investigations Report 2006-5168. Reston, VA: USGS.

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Koenker, R. 1995. Quantile regression soft- Rosgen, D. 2006. Watershed assessment of river stability ware. Available at: http://www.econ.uiuc. and sediment supply (WARSSS). Fort Collins, CO: edu/~roger/research/rq/rq.html. Accessed Wildland Hydrology. July 21, 2007. Simon, A., Dickerson, W., and Heins, A. 2003. Sus- Koenker, R. 2005. Quantile regression. New pended-sediment transport rates at the 1.5-year York: Cambridge University Press. recurrence interval for ecoregions of the United States: Transport conditions at the bankfull and effective Leopold, L.B., Wolman, M.G., and Miller, J.P. 1964. discharge? Geomorphology, 58(1-4):243-262. Fluvial processes in geomorphology. San Francisco: W.H. Freeman & Company. [USEPA] U.S. Environmental Protection Agency. 1998. Protocol for developing sediment TMDL’s. EPA-841- Lemly, A.D. 1982. Modification of benthic insect com- B-99-004. Washington, DC: USEPA, Office of Water. munities in polluted streams: Combined effects of sedimentation and nutrient enrichment. Hydrobiolo- [USEPA] U.S. Environmental Protection Agency. 2000. gia, 87:229-245. National water quality inventory. EPA-841-R-02-001. Washington, DC: USEPA, Office of Water. Lisle, T.E. and Lewis, J. 1992. Effects of sediment transport on survival of salmonid embryos in a natural [USEPA] U.S. Environmental Protection Agency. 2002. stream: A simulation approach. Canadian Journal of Methods for evaluating wetland condition: Land-use Fisheries and Aquatic Sciences, 49:2337-2344. characterization for nutrient and sediment risk assessment. EPA-822-R-02-025. Washington, DC: USEPA, Luedtke, R.J. and Brusven, M.A. 1976. Effects of sand Office of Water. sedimentation on colonization of stream insects. Journal of the Fisheries Research Board of Canada, [USEPA] U.S. Environmental Protection Agency. 2004. 33:1881-1996. Wadeable streams assessment: A collaborative survey of the nation’s streams. Washington, DC: USEPA, Matthews, W.J. 1988. North American prairie streams Office of Water. as systems for ecological study. Journal of the North American Benthological Society, 7(4):387-409. [RTAG] USEPA Region VII Regional Technical Assistance Group. 2006. Dataset for nutrient criteria Maund, S., Barber, I., Dulka, J., Gonzalez-Valero, J., development, Lawrence, KS: Kansas Biological Survey, Hamer, M., Heimbach, F., et al. 1997. Development Central Plains Center for BioAssessment. and evaluation of triggers for sediment toxicity testing of pesticides with benthic macroinvertebrates. Envi- Van Nieuwenhuyse, E.E. and LaPerriere, J.D. 1986. ronmental Toxicology and Chemistry, 16:2590-2596. Effects of placer gold mining on primary production in subarctic streams of Alaska. Water Research Bulletin, Newcombe, C.P. and MacDonald, D.D. 1991. Effects of 22:91-99. suspended sediments on aquatic ecosystems. North American Journal of Fisheries Management, 11:72-82. Waters, T.F. 1995. Sediment in streams: Sources, biological effects and control. Monograph 7. 0-913235-97-0. [OMNR] Ontario Ministry of Natural Resources. 1994. Bethesda, MD: American Fisheries Society. Natural channel systems: An approach to management and design. Toronto, Ontario: Ontario Ministry of Whiles, M.R. and Dodds, W.K. 2002. Relationships Natural Resources. between stream size, suspended particles, and filter-feeding macroinvertebrates in a Great Plains Richards, C. and Bacon, K.L. 1994. Influence of fine sedi- drainage network. Journal of Environmental Quality, ment on macroinvertebrate colonization of surface and 31(5):1589-1600. hyporheic stream substrates. Great Basin Naturalist, 54:106-113. Wood, P.J. and Armitage, P.D. 1997. Biological effects of fine sediment in the lotic environment. Environmental Richardson, J. and Jowett, I.G. 2002. Effects of sediment Management, 21:203-217. on fish communities in east cape streams, North Island, New Zealand. New Zealand Journal of Marine Zweig, L.D. and Rabeni, C.F. 2001. Biomonitoring for and Freshwater Research, 36:431-442. deposited sediment using benthic invertebrates: A test on 4 Missouri streams. Journal of the North American Rier, S.T. and King, D.K. 1996. Effects of inorganic Benthological Society, 20(4):643-657. sedimentation and riparian clearing on benthic community metabolism in an agriculturally-disturbed system. Hydrobiologia, 339:111-121.

46 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu. Management Practices to Control Sediment Loading From Agricultural Landscapes in Kansas

Daniel Devlin, Professor, Department of Agronomy Philip Barnes, Associate Professor, Department of Biological and Agricultural Engineering Kansas State University

Introduction • Gully erosion: accumulated water repeatedly fills narrow Suspended solids are the largest category channels and, over short periods, of water pollutants in Kansas (Devlin and removes soil from this narrow area to Powell, 1996). Almost all Kansas lakes considerable depths resulting in chan- and streams contain undesirable levels of nels that are too deep to correct easily suspended solids in the water and sediment with farm tillage machinery deposits in lake beds and stream channels. Suspended solids typically consist of solid organic or mineral particles in water Implementing best management practices suspension that have been detached and (BMPs) to minimize erosion can improve transported (eroded) from their original water quality. However, some studies site. Sedimentation occurs when water showed that despite implementation of slows enough to allow particles to settle conservation practices, sediment yield in out. The terms “suspended solids” and many of our nation’s streams and lakes “sediment” (or sedimentation) often are remained constant for several decades used interchangeably. However, “sediment” (Trimble, 1999). In many cases, this actually refers to particles that have settled continuing sediment yield comes from out of suspension to the bottom of streams, additional erosion that occurs in streams rivers, or lakes. and lakes as channels and banks are eroded by varying velocities of flowing water Major sources of suspended solids in (Simon and Rinaldi, 2006). This form of agricultural landscapes include cropland, erosion can be accelerated by channeliza- grazing lands, livestock confinement operation or modification of stream banks. tions, forest lands, roads and ditches, rural homesites, and unstable stream beds and Sediment Sources from channels. Several types of erosion occur Agricultural Lands from these sites: In Kansas, main sources of sediment from • Sheet erosion: a relatively uniform thin agricultural landscapes are cropland fields, layer of soil is removed by rainfall and grazing lands, streambeds and streambanks. largely unchanneled surface runoff Runoff also occurs from livestock con- • Rill erosion: numerous and randomly finement operations, roads and roadway occurring small channels only a few ditches, forest lands, and rural homesites. inches deep with steep sides form on Previous research includes field measure- sloping fields ments and modeled estimates of erosion from crop fields, but few studies discuss • Ephemeral erosion: small channels other sediment sources (Schnepf and Cox, eroded by concentrated flow that can 2006a, 2006b). Data from the National be filled easily by normal tillage re-form Resources Inventory (NRI), a nationwide in the same location during subsequent survey conducted by the Natural Resources runoff events Conservation Service (NRCS, 2007),

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indicate that erosion from cropland and erosion or amount of sediment leaving the pasturelands in Kansas declined over the field. Further, few studies have examined last 20 years (Table 1). relationships between in-field or edge-of- field sediment losses and actual sediment Table 1. Estimated erosion on nonfederal delivery into Kansas rivers and lakes. lands in Kansas, 1982 to 2003a Land Use Two terms, “sediment delivery ratio” Cultivated Pasture- CRP and “sediment yield,” are important for Year Cropland land Landb determining the effect of erosion on tons/acre per year sedimentation of Kansas lakes. Sediment 1982 2.7 0.8 --- delivery ratio is defined as the extent to 1987 2.6 0.8 2.3 which eroded soil (sediment) is delivered 1992 2.3 0.7 0.4 from the erosion source to the watershed outlet and accounts for sediment deposi- 1997 2.2 0.7 0.3 tion along the path from source to outlet. 2003 2.1 ------Deposition areas include buffers, water- a Data source: NRCS (2007) b CRP = Conservation Reserve Program ways, ponds, road ditches, fence rows, edges of fields, and terraces. Sediment delivery Another NRCS (1992) study in north- ratio is calculated using the following east Kansas quantified sediment yields equation: from different sources for two watersheds SDR = sediment yield at outlet (Figure 1). In both the Missouri River and total erosion Kansas River basins, unprotected croplands contributed the majority of sediment The larger the watershed, the smaller the loads, more than 20 tons/acre per year in sediment delivery ratio (Figure 3). For the Kansas River basin. The second-largest example, a watershed with a drainage area contributor was unprotected pasture, with of 1 square mile has a predicted delivery values near 5 tons/acre per year. Sheet and ratio of 37%, but a watershed with a drain- rill erosion contributed more than 60% of age area of 100 square miles has a predicted sediment loads, and ephemeral and classic delivery ratio of 11%. A large reservoir with gullies each contributed around 10% to a large drainage area, such as the Tuttle 20% (Figure 2). Creek Reservoir, might have a delivery ratio as low as 3% or 4%. Limitations in Determining Agricultural Practices to Reduce Contributions to Erosion and Reservoir Sedimentation Sedimentation Erosion by water from croplands and Erosion Process grazing lands is estimated with the Revised The first step in developing an erosion Universal Soil Loss Equation (RUSLE), management strategy is to understand the which estimates sheet and rill erosion three-stage erosion process. Implementing occurring in an individual field, but the BMPs can reduce erosion and sediment model does not estimate ephemeral gully yield at any or all of these stages: 48 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Missouri Basin 20 Kansas Basin

Tons/Acre 10

0 Crop Crop Pasture Pasture Range Range Forest Forest (P) (U) (P) (UP) (P) (UP) (P) (UP) Figure 1. Sediment load contribution from various sources in two northeast Kansas watersheds P = protected, UP = unprotected Data source: NRCS (1992) Figure adapted from McVay et al. (2005) with permission

70 Missouri Basin Kansas Basin 60

% Contribution 30

0 Sheet & Rill Ephemeral Gully Classic Gully Streambank Figure 2. Sediment load contribution from various types of erosion in two northeast Kansas watersheds Data source: NRCS (1992) Figure adapted from McVay et al. (2005) with permission

Sedimentation in Our Reservoirs: Causes and Solutions 49 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

100

Sediment Delivery RatioSediment (%) 20

0 0.01 0.1 1 10 100 1000 Drainage Area (Square Miles) Figure 3. Relationship between sediment delivery ratio and drainage area Data source: NRCS (1992)

Detachment. Erosion starts with the Best Management Practices impact of a raindrop. Raindrops’ collisions Although any soil surface left unprotected with the soil break the soil aggregate into is vulnerable to erosion, this paper focuses its component parts of sand, silt, and clay. on BMPs that reduce erosion from crop Moving water picks up smaller particles of fields and grazing lands, major sources of silt and clay. The force of flowing water also sediment in Kansas. Strategies for reducing detaches soil particles. erosion and sedimentation can be divided into two categories: conservation structures Transport. As initial water movement and management practices. into the soil slows, smaller particles settle out, and finer particles start to plug pores Conservation Structures. Con- at the soil surface. Runoff occurs if rain servation structures typically include an continues to fall at rates greater than what engineering design and often have been the soil can absorb, and soil particles move cost-shared through conservation districts with runoff water. and the NRCS using state and federal funds. Generally, these long-term practices Deposition. Soil particles are deposited have an expected useful life span of at least when water velocity slows enough that it 15 to 20 years. Examples of conservation can no longer support them. structures include: • Terraces—gradient, level, tile outlet • Grassed waterways • Vegetative and riparian buffers/filters • Grade stabilization structures • Water and sediment control structures

50 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Management Practices. These different soil series in central practices generally are related to agronomic Kansas. In a field with a 6% practices and typically do not require an slope and 150-foot slope length, engineering design. Examples of manage- soil erosion would be reduced ment practices include: approximately 54% by using one • No-till terrace and approximately 90% by installing two terraces (Table 2). Field • Reduced or minimum tillage studies in Kansas showed that terraces with • Contour farming tile outlets or those draining into grassed waterways reduced soil erosion approxi- • Crop rotations mately 30% (Devlin et al., 2003; Tables 3 and 4). McVay et al. (2005) used the Soil Some strategies reduce soil erosion; others and Water Assessment Tool (SWAT), a trap sediment in the field. A system that watershed model, to examine the effect of combines conservation structures and terraces and other management practices management practices will be most effec- in the Little Blue River watershed located tive at reducing soil erosion and sediment in Kansas and Nebraska and estimated that yield. Several methods including in-field terraces would reduce sediment loss by 89% and edge-of-field measurements, in-field and 98% on conventional and no-till fields, models, and watershed models have been respectively (Table 5). used to evaluate effectiveness of conservation structures and management practices. Table 2. Predicted terrace effectiveness for reducing soil loss from four soil types Effectiveness of Selected in a field with 6% slope and 150-foot slope length in central Kansasa Practices Silty Sandy Ter- Clay Terraces (gradient, level, or tile outlet) are clay Loam clay races loam the backbone of conservation practices loam loam in many Kansas fields. Although terraces tons/acre per year can be somewhat expensive, with onetime None 16.8 13.9 14.4 14.3 installation costs of $30/acre to $40/acre plus an annual cost of $13.60/acre (Devlin 1 7.75 6.69 6.62 6.65 et al., 2003), they also can be quite effective. 2 1.75 1.52 1.36 1.42 a Terraces reduce erosion by breaking slopes Data source: Kent McVay, personal communication, 2005 into segments, which reduces the speed of runoff and amount of soil and adsorbed pollutants that can be transported, and reduce ephemeral and gully erosion by safely transporting surface runoff to a stable outlet. Some sediment deposition will occur in the terrace channel. Kent McVay (personal communication, Sep- tember 1, 2005) used the RUSLE equation to estimate soil erosion losses from four

Sedimentation in Our Reservoirs: Causes and Solutions 51 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Table 3. Effectiveness of BMPs for reducing and allows for sediment deposition before edge-of-field soil losses in conventionally runoff water leaves the field. Grassed water- a tilled fields ways can reduce sediment loss from crop Best Management Reduction in fields by 15% to 35% (Devlin et al., 2003). Practice runoff (%) Placing vegetative buffers on the downhill Crop rotations 25 slopes of crop fields or riparian buffers Establish vegetative buffer next to streams are recommended practices 50 strips for removing sediment from runoff water Conservation tillage prior to the runoff water leaving the crop (>30% residue cover fol- 30 field. Well-designed buffers can reduce lowing planting) sediment loss by 50% (Tables 3 and 4), and No-till farming 75 the SWAT model predicted that installing Contour farming (without a 20-meter buffer on the downhill side of 35 terraces) every field in the Little Blue River water- Terraces with tile outlets 30 shed would reduce sediment loss by 89% to Terraces with grass 97% (Table 5). waterways (with contour 30 farming) No-till and minimum/reduced tillage a Data source: Devlin et al. (2003) farming practices are being adopted rapidly in Kansas (Figure 4) and, when adopted, Table 4. Effectiveness of BMPs for reducing will significantly reduce sediment loss from soil losses in no-till fieldsa crop fields. In a continuous corn field in Best Management Reduction in Brown County, Kansas, converting from Practice runoff (%) conventional tillage with <10% residue Crop rotations 25 to no-till or minimum/reduced tillage Establish vegetative buffer reduced sediment loss from 10.5 tons/acre 50 strips per year to 0.20 tons/acre per year and 0.53 Contour farming (without tons/acre per year, respectively (B. Marsh, 20 terraces) personal communication, November 23, Terraces with tile outlets 30 1992). In a Franklin County, Kansas, field Terraces with grass with a grain sorghum/soybean rotation, waterways (with contour 30 adopting no-till reduced sediment loss from farming) 0.85 tons/acre per year to 0.23 tons/acre a Data source: Devlin et al. (2003) per year (K. Janssen, personal communication, May 22, 2000). Devlin et al. (2003) Grassed waterways are also used widely in reported that adopting reduced/minimum Kansas. They serve as an outlet for excess tillage (>30% residue cover following plant- field runoff water and sediment, reducing ing) and no-till reduced erosion by 30% and the potential for gully erosion and excessive 75%, respectively (Table 3). The SWAT sedimentation. Grassed waterways often model predicted that adopting no-till on all are used as outlets for water from gradient crop fields in the Little Blue River water- terraces or diversions. Vegetative cover in shed would reduce sediment loss from crop the grassed waterways slows runoff water fields by 77% (Table 5).

52 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Table 5. Estimated reductions in water flow and sediment loss due to BMP implementation compared with a conventional tillage scenarioab Water Sediment Tillage System Best Management Practice Discharge Loss % Reduction Conventional None 0.0 .0 10-m buffer 0.0 72 20-m buffer 0.0 89 contour 0.9 50 effective terraces 0.9 89.4 10-m buffer + contour 0.8 86 10-m buffer + contour + terraces 0.8 97 Conservation tillage None 0.4 47 with 20% residue Conservation tillage None 0.8 63 with 50% residue No-till None 13 77 10-m buffer 13 93 20-m buffer 13 97 contour 20 90 effective terraces 20 98 10-m buffer + contour 20 97 10-m buffer + contour + terraces 20 99 Mixed grass None 42 99 prairie/range a Table adapted from McVay et al. (2005) with permission b Based on SWAT model results in the Little Blue River basin of Kansas and Nebraska averaged over 22 years

Tilling and planting along the contour of field slopes can reduce soil erosion. Con- tour farming is a recommended practice for all sloping, erosive fields and is the only acceptable method of farming in terraced fields. Conducting tillage and planting operations on the contour without terraces reduced soil erosion by 35% (Devlin et al., 2003; Table 3), and computer modeling with SWAT in the Little Blue River watershed predicted contour farming could reduce sediment loss by 50% to 90% depending on tillage system (Table 5).

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70 Corn Double-Crop 60 Oat Soybean Winter Wheat Cotton 50 Soybean Grain Sorghum

20 Percent of Planted Acres of Planted Percent 10

0 1990 1992 1994 1996 1998 2000 2002 2004 Figure 4. Rate of no-till adoption for various crops in Kansas Data source: CTIC (2005) Figure adapted from McVay et al. (2005) with permission

Recommendations Because erosion is a natural process, there always will be some suspended solids in streams. However, excessive soil erosion and sedimentation are negatively affecting nearly all lakes and streams in Kansas. It is difficult to determine to what extent measured and predicted erosion actually affects sedimentation in rivers and lakes, but minimizing erosion can improve water quality. A variety of BMPs, used separately or together, can reduce erosion and sediment loss from agricultural lands, and the most effective erosion reduction strategies include a combination of conservation structures and management practices.

We offer the following recommendations: • Determine sediment sources and methods of sediment delivery from agricultural lands to surface waters • Determine effectiveness of cropland and grazing land erosion control practices at both the field and watershed scale • Develop an understanding of the lag period between implementation of erosion control practices and sediment delivery to surface water bodies • Develop methods that link changes in land cover with hydrologic response, sediment-load response, and stream channel changes • Determine the sediment load contributions of roads, urban sprawl, and other nonagricultural activities in the rural landscape

54 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

References Schnepf, M. and Cox, C. (Eds.). 2006a. Environmental benefits of conservation practices on cropland: The [CTIC] Conservation Technology Information Center. status of our knowledge. Ankeny, IA: Soil and Water 2005. 2004 National crop residue management survey. Conservation Society. Available at: http://www2.ctic.purdue.edu/CTIC/ Schnepf, M. and Cox, C. (Eds.). 2006b. Managing CRM.html. Accessed March 24, 2008. agricultural landscapes for environmental quality: Devlin, D. and Powell, M. 1996, March. Nonpoint source Strengthening the science base. Ankeny, IA: Soil and pollution in Kansas. Publication MF-2204. Manhat- Water Conservation Society. tan, KS: Kansas State University. Simon, A. and Rinaldi, M. 2006. Disturbance, stream Devlin, D., Dhuyvetter, K., McVay, K., Kastens, T., incision, and channel evolution: The roles of excess Rice, C., Janssen, K., et al. 2003, February. Water transport capacity and boundary materials in control- quality best management practices, effectiveness and ling channel response. Geomorphology, 79:361-383. cost for reducing contaminant losses from cropland. Trimble, S. 1999. Decreased rates of alluvial sediment Publication MF-2572. Manhattan, KS: Kansas State storage in the Coon Creek Basin, Wisconsin, 1975-93. University. Science, 285(5431):1244-1246. McVay, K., Devlin, D., and Neel, J. 2005, July. Effects of conservation practices on water quality: Sediment. Publication MF-2682. Manhattan, KS: Kansas State University.

[NRCS] Natural Resources Conservation Service. 1992. Northeast Kansas erosion and sediment yield report. 1992. Salina, KS: USDA-Soil Conservation Service.

[NRCS] Natural Resources and Conservation Service. 2007. National resources inventory: 2003 annual NRI – soil erosion. Washington, DC: NRCS.

Sedimentation in Our Reservoirs: Causes and Solutions 55 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu. This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Can Reservoir Management Reduce Sediment Deposition?

Debra Baker, Environmental Scientist, Kansas Water Office Frank deNoyelles, Deputy Director and Professor, Applied Science and Technology for Reservoir Assessment (ASTRA) Initiative, Kansas Biological Survey, University of Kansas

Introduction are needed for long-term protection and maintenance of reservoirs. This white paper describes why sedimentation in public water supply reservoirs is cause for concern about both water Reservoir Construction quantity and quality, proposes manage- Natural lakes form through geologic pro- ment options for reducing sedimentation cesses, such as glacial melting or scouring. and strategies for implementing these Although often referred to as lakes, res- options, identifies needed resources, and ervoirs do not occur naturally; they are recommends assessment methods. We created by transforming part of a flowing focus on federal reservoirs because of their water body (lentic) into a still water body large storage capacity, but similar problems (lotic) by building a dam to hold back the and solutions also apply to smaller, locally water. Sediment transport occurs naturally owned reservoirs, commonly referred to as through streamflow, and reservoirs act as lakes. settling basins for soil, clay, and smaller rock particles deposited through sedi- Thirteen federal reservoirs in Kansas are in mentation. Eventually, sediment will fill the state public water supply marketing and all reservoirs unless removed or properly assurance programs, both managed by the redistributed. Reservoirs commonly are Kansas Water Office (KWO). The market- constructed in areas with few natural lakes, ing program allows public water suppliers particularly locations south of the glaciated to purchase and withdraw state-owned area in middle latitudes. Soils in these areas water stored in federal reservoirs. The assur- are inherently very erodible and can be ance program allows public water suppliers disturbed further by human activities. In who draw water from streams downstream addition to receiving sediment deposited from reservoirs to purchase stored water through streamflow, most federal reservoirs that can be released during low flow condi- in Kansas experience shoreline erosion, due tions to supplement natural flows. About to erodible soils, and constant maintenance 50 smaller, mostly city-owned reservoirs is required to stabilize shorelines. provide additional localized public water supplies to municipalities and industries. Federal reservoirs were built and are owned All these reservoirs are vital resources by either the U.S. Army Corps of Engineers because they provide regional sources of (USACE) or the Bureau of Reclamation stored, untreated water to public water and were constructed at the direction and suppliers in Kansas for use in surrounding authorization of Congress. Authoriza- communities and industries. Many Kansans tions for use vary, but most reservoirs were rely on the long-term availability of water constructed primarily for flood control, supplies. However, long-term planning to irrigation, water supply storage, aquatic ensure sustained water availability is lack- habitat, low flow supplementation, and ing. Plans similar to those created for public water quality maintenance. The USACE infrastructures, such as roads and bridges, also uses some reservoirs to maintain flows

Sedimentation in Our Reservoirs: Causes and Solutions 57 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

for navigation in the Missouri 2004). Historically, the prairie ecosystem River. Congress has the final produced steady, prolonged runoff from authority to authorize reservoir storms. Over hundreds of thousands of use or propose operational changes. years and long periods of climate change, stream channels formed to accommodate Many reservoirs were designed and runoff during normal and extreme rainfall built based on a 100-year planning events. framework. During this time, reservoirs were expected to remain fully functional Watersheds gradually transformed from and satisfy the needs and purposes for expansive tallgrass prairie to a checkerboard which they were constructed. Now, nearly of rural communities, cropland, urban land, half that time has passed. Federal reservoirs and managed pastureland. Native prairie in Kansas were built between 1946 and and riparian woodlands were removed for 1976. The oldest, Kanopolis, is 60 years old, crop cultivation and building materials, the youngest, Hillsdale, is 30 years old, and resulting in increased soil erosion from the the average age is about 44 years. Reservoir disturbed landscape. Land gradually became designers assumed future stakeholders less fertile as soil was lost, and maintaining would be better equipped, with new tech- desired production levels required applying nologies and enhanced perspectives, to deal additional nutrients. As erosion continued with future water resource problems. But, on steeper slopes, added nutrients washed management strategies to ensure longer into tributaries and rivers. reservoir lifespans have not been adequately considered. Runoff from cultivated and grazed land occurs quickly, frequently, and intensely, Sedimentation in accelerating natural bank and channel Reservoirs erosion. Other alterations, such as levees that contain flood waters and prevent sedi- Erosion ment from settling out on the floodplain, Reservoir sedimentation begins with runoff constrictions due to road crossings, and and soil erosion. Various types of land hundreds of dams forming small ponds, cover produce different runoff character- affect stream channel stability and will istics that, in turn, transform hydrology of take many years to fully manifest. Urban streams, and watersheds across the country development results in increased impervi- are dynamically adapting to continuous ous cover, further exacerbating erosion land use changes. Original land cover in the and decreasing stability of watersheds and uplands of most watersheds draining into stream systems. federal reservoirs in Kansas was grassland, the native, pre-settlement condition. Ripar- Sedimentation ian forests occurred along most streams and Soil particles eroded from land surfaces rivers, especially in floodplains. Prior to (e.g., uplands, prairie, pasture, agricultural human settlement, Kansas forests covered fields, and streambanks) by wind and rain about 8% of the landscape; today they become suspended in water that flows into cover about 4% (Bob Atchison, Kansas streams. Streamflow slows as it enters a Forest Service, personal communication, reservoir, and suspended particles begin 58 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

to settle out. Eventually, all sediment will Webster Reservoir (north-central Kansas), settle to the bottom of a still pool of water, to about 25% to 40% for Perry Lake and but heavier sediment particles are depos- Tuttle Creek Lake (northeast Kansas). If ited first. Sedimentation does not occur sedimentation continues at historical rates, uniformly; it is affected by many factors designed sediment pools in Perry Lake and including flow and volume of water pro- Tuttle Creek Lake will be filled by 2021 duced by the incoming stream and size and and 2023, respectively, and further sedi- weight of sediment particles. ment accumulation will encroach on water supply storage intended for other purposes Regardless of rate or location, sediment (Juracek, 2006). Yet, KWO population accumulation reduces reservoirs’ water projections indicate that many communi- storage capacity. Therefore, reservoirs ties that currently use these reservoirs were built larger than necessary for their continue to grow and have increased intended purposes, allowing sediment to demand for municipal and industrial water be collected behind the dam. Most Kansas supplies. When reserve pools of existing reservoirs were designed with a reserve reservoirs fill with sediment, few viable sediment storage pool that was projected to options will exist for maintaining resources fill with sediment over a 100-year period. provided by reservoirs. Designers expected that although sediment would continue to accumulate beyond Eutrophication this point, occupying space previously Although this paper focuses primarily on available for water storage, aquatic habitat, preservation of public water supply stor- recreation, or other uses, reservoirs would age capacity, a related and more imminent maintain flood control capacity for an concern is the effect of sedimentation on extended period of time and wetland and water quality. The main water quality issue marsh habitats would slowly form. Design- is eutrophication, the process that both ers expected other forms of recreation, such natural lakes and constructed reservoirs as waterfowl hunting and bird watching, undergo as they age. Eutrophic conditions to develop but did not anticipate how occur as sediment and nutrients attached to much communities and the state would sediment or suspended in water gradually rely on reservoirs for public water supplies. accumulate, leading to excessive aquatic Although water supply is an authorized plant growth, especially algae. Most federal reservoir use, designers gave the effects of reservoirs in Kansas already are in some reduced water storage capacity little con- stage of eutrophication, and some are in sideration and did not anticipate a need for advanced stages. operating procedures or funding to address this situation. Originally, most sediment was expected to accumulate at the bottom of reservoirs Recent USGS studies indicate that near dams. However, large quantities of decreases in conservation-pool water-stor- sediment are settling out in upper arms of age capacity of federal reservoirs due to reservoirs, creating shallow flats and deltas. sedimentation range from less than 10% for Because inflow waters typically are nutri- Cheney Reservoir (south-central Kansas), ent rich, these shallow areas of still water Hillsdale Lake (northeast Kansas), and provide ideal conditions for algal growth Sedimentation in Our Reservoirs: Causes and Solutions 59 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

and dense growth of rooted aquatic plants. debris dams, sediment basins, and wetlands; When nutrient ratios are favorable, much reservoir bypass, and off-channel storage. of the algal biomass is composed of blue- green algae that produce geosmin. This Watershed Management. Ero- compound causes taste and odor problems sion is a natural, geologic process but can in drinking water, issues that can be dif- accelerate when the soil surface is exposed. ficult and expensive to treat. Additionally, Implementing best management practices aquatic plant growth produces living and (BMPs) that minimize soil exposure and decaying biomass that restricts boat access soil particle detachment can reduce soil and adds to taste and odor problems. loss. Watershed BMPs are categorized as rural/agricultural or urban/suburban Managing Sedimentation practices. Agricultural BMPs include conservation crop rotations, cover crops, and Current state and federal management conservation tillage. These BMPs improve efforts focus on reducing sediment inputs soil structure and increase soil organic mat- from the watershed landscape, including ter content and surface roughness. Other streambanks and streambeds. However, beneficial agricultural practices include it also is necessary to manage sediment terraces that trap sediments and pond and already deposited in reservoirs. Reducing infiltrate water, waterways and filter strips sedimentation will extend the useful life that slow water flow and trap sediment, of reservoirs, particularly for water stor- and buffers along streambanks that reduce age capacity, and reduce the amount of streambank erosion and trap nutrients and nutrients entering reservoirs, slowing the sediment. Each farm enterprise is unique, eutrophication process and reducing taste and encouraging widespread adoption of and odor problems and associated treat- appropriate BMPs requires one-on-one ment expenses. interaction with producers (Birr and Mulla, 2006). Reservoir sedimentation management strategies can include one or more of the Urban/suburban BMPs include settling following techniques (Palmieri et al., 2003; basins, construction erosion control, WOTS, 2004): construction timing, buffers, and on-site • Reducing sediment inflows detention. These practices focus on pre- • Managing sediment in the reservoir venting soils from leaving construction sites. Other practices include swales, open • Removing sediment from the reservoir space detention, streambank protec- • Replacing lost storage tion, and on-site infiltration. These are applicable in developed areas and focus • De-commissioning the reservoir on preventing increased runoff and flows; many are included as recommended prac- Reducing Sediment Inflows tices in Phase 1 and 2 stormwater permits. Techniques applied to the watershed system before water enters the reservoir Agricultural BMPs are designed to be include watershed management; upstream effective for 24-hour storm events ranging from 10- to 25- year recurrence intervals,

60 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

but available data indicate that the greatest processes and sediment transport sediment loads occur during storm events in rivers and how these relate does that exceed these parameters. During not allow modeling to consistently flows of this magnitude, watershed BMPs or adequately predict effects of have reduced effectiveness for containing watershed management techniques sediment. However, stable streambanks are on sediment discharge in rivers. No beneficial during flood events. During the simple solution exists, and assessing 1993 flood in northeast Kansas, forested potential effects of optional watershed riparian buffers along the main stem of management approaches requires detailed the Kansas River were considerably less study of watersheds under consideration impacted (amount of bank loss) than areas and thorough analysis of available data and with streamside land cover of cropland or local knowledge. grass (Geyer et al., 2003). Additionally, streambank stabilization projects with Currently, the USGS is investigating sedi- associated riparian buffer establishment are ment sources in the Perry Reservoir and effective at minimizing streambank erosion Lake Wabaunsee watersheds in Kansas. and reducing sediment loads. The objective of this study is to determine, by comparing composition of reservoir Where properly designed, installed, and bottom sediments and sources materials, maintained, watershed landscape-level whether the majority of deposited sedi- BMPs (e.g., terraces, waterways, and filter ment originated from surface soil erosion strips) are effective at reducing soil ero- or streambeds and streambanks. Under- sion on specific sites, which, theoretically, standing sediment sources will help target should reduce reservoir sedimentation future management efforts to achieve rates. Unfortunately, research does not meaningful reductions in sediment yield. support this. Studies estimate that reduc- Preliminary results indicate that sediment ing sediment yields by 10% to 20% might source is watershed specific and cannot be require intensive conservation efforts generalized. spanning several decades. Furthermore, conservation measures often are considered Good upland watershed management can ineffective, from a reservoir sedimentation reduce sediment yields and produce many management point of view, because of associated benefits for agriculture, rural the large time lag between when erosion and urban environments, food production, control measures are implemented and forestry, and water availability. But during when their effects on sediment reduction the next 25 to 50 years, upland BMPs likely are realized (Birr and Mulla, 2006). will not have a large effect on reservoir sedimentation. A paired watershed study on effects of agricultural BMPs revealed that many factors, Upstream Debris Dams, Sediment including lag time, rate of BMP adoption, Basins, and Wetlands. Debris dams mechanisms of nutrient transport, and are used for streams in steep watersheds climatic variability, influence BMP evalua- and those with coarse-grained sediments. tion at the watershed scale (Birr and Mulla, Debris dams usually are located on one 2006). Current knowledge of watershed or more tributaries upstream from the

Sedimentation in Our Reservoirs: Causes and Solutions 61 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

reservoir, and sediments are removed Managing Sediment in the periodically from behind the dam. Ease of Reservoir access to remove sediment from the debris Techniques for preventing sediment from dams and potential to reuse sediment make settling once water enters the reservoir debris dams a feasible option. Sediment include multilevel selective withdrawal, basins and constructed or enhanced wet- changes in lake level management plans lands in upstream tributaries use the same (LLMPs), inflow routing, sluicing, and den- concepts. sity current venting. These techniques are most applicable in reservoirs that stratify Reservoir Bypass. Installing convey- thermally. Because of their large size and ance structures (i.e., closing gates) upstream prevailing windy conditions that promote from the reservoir diverts sediment-laden mixing, most federal reservoirs in Kansas flows around the reservoir, carrying away do not thermally stratify for long periods of large volumes of sediment that otherwise time during the summer, which limits the would accumulate in the reservoir. This applicability of these methods. technique limits flood control capability of the reservoir, and floodplain development Multilevel Selective Withdrawal. might already have occurred downstream. Operating a multilevel withdrawal struc- Often, bypassing is feasible only when ture to manage sedimentation requires favorable hydrological and morphological considering numerous conditions and conditions exist. Operating costs of convey- constraints, most important of which is ance structures and benefits lost by not thermal stratification. Selective withdrawal, capturing flood flows must be considered, the capability to identify the vertical and this technique might require a change distribution of withdrawal from a stratified in congressional authorization. reservoir and use that capability to selec- tively release the desired quality of water, Off-Channel Storage. Off-channel can be used to determine the appropriate storage reservoirs are built adjacent to the or best available operation of a release main river channel (e.g., a small tributary structure, design multilevel withdrawal or on the floodplain). Water from the structures, or modify existing projects. main river is routed into the reservoir when sediment concentrations are low. This Lake Level Management Plans. option does not manage sediment in exist- Many reservoir projects operate under some ing reservoirs but could be considered for type of LLMP that incorporates seasonal new projects. A variation of this technique changes in elevation. Modifying LLMPs that can be applied in existing reservoirs is can enhance water quality and reduce construction of settling basins in tributar- sedimentation. By changing the hydraulic ies; sediment can be periodically removed residence time of the reservoir, inflows can from these basins. be retained or routed quickly through the reservoir. This allows the reservoir to retain high quality water for later release or retain poor quality water for treatment by in-reservoir processes.

62 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

The KWO, in consultation with the Kan- inflow constituents can settle and become sas Department of Wildlife and Parks, the trapped in the reservoir, contributing to USACE, and the Bureau of Reclamation, eutrophication and increasing sediment is responsible for annual development and accumulation. If inflow quality is a concern, oversight of LLMPs. Planned variations in it might be possible to route inflow through operating level of each reservoir are pub- the reservoir for downstream release with- lished each year and cover the period from out significantly affecting reservoir water October through September of the follow- quality. Because inflow will seek its layer of ing year. Stakeholders can submit concerns neutral density in a thermally or density- through a public input process. stratified reservoir, a density current will develop and proceed through the reservoir. Depending on project authorization, the Using the existing release structure and management plan might include large, operating within the existing water control pool-level fluctuations on an annual basis. plan, undesirable water is routed through For example, operation of a flood control the pool as quickly as possible. project usually involves drawing down the reservoir level during fall and winter and Sluicing. Sluicing is an operational tech- filling during spring and early summer, nique in which a substantial portion of the resulting in a stable pool through summer incoming sediment load moves through the and early fall. Water quality might be a reservoir and dam before sediment particles concern when summer pool elevation is can settle, reducing the reservoir’s trap kept relatively stable. Water quality compo- efficiency. In most cases, sluicing is accom- nents that could be affected include inflow plished by operating the reservoir at a lower with undesirable qualities, nutrient loading level during the flood season to maintain of the reservoir (and associated effects on higher flow velocity and sufficient sedi- algal growth and fisheries), turbidity, and ment transport capacity of water flowing sedimentation. For example, inflows with a through the reservoir. Increased sediment high sediment load might be delayed in the transport capacity reduces the volume of upper reaches of a reservoir and settle out deposited sediment. After flood season, before reaching the outlet works. Addition- the pool level in the reservoir is raised to ally, shoreline erosion can accelerate when store relatively clear water. Effectiveness of high elevations are maintained for long sluicing operations depends on availability periods of time. This results in sediment of excess runoff, grain size of sediment, and accumulation around the edges of the reservoir morphology. In many cases, sluic- reservoir and contributes to formation of ing and flushing are used in combination. flats and deltas, promoting unwanted algal If flood control is an authorized purpose of growth. a reservoir, use of sluicing might require a change in congressional authorization. Inflow Routing. Poor inflow water quality (e.g., high concentrations of nutri- Density Current Venting. Density ents, suspended solids, or other undesirable currents occur because the density of constituents) can result in poor reservoir sediment-carrying water flowing into a water quality. Depending on volume of reservoir is greater than the density of inflow and retention time of the reservoir, clearer water impounded in a reservoir.

Sedimentation in Our Reservoirs: Causes and Solutions 63 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

The increased density, increased Partial draw-down flushing occurs when viscosity, and concomitant the reservoir level is partially reduced. reduction in turbulence intensity Sediment transport capacity in the reservoir result in a uniform current with increases only enough to allow sediment high sediment concentration that from upstream locations to move farther dives underneath the clear water and downstream, closer to the dam. Partial moves toward the dam. In reservoirs with draw-down flushing can clear more water known density currents, installation and storage space upstream and transport operation of low-level gates allows sediment sediment to a more favorable location for currents to pass through the dam for down- future complete draw-down flushing. stream discharge. Density current venting is an attractive option because, unlike flush- Artificial Lake Stirring and ing operations, it does not require lowering Aeration. Dissolved oxygen (DO) is the reservoir level. However, this approach an important component of reservoir results in increased downstream sediment water quality and can affect drinking loads that can degrade stream habitats. In water taste and odor, especially during addition, dispersing sediment across large lake turnover events or when a fish die-off areas makes it more difficult to eventu- occurs because of eutrophication and low ally remove sediment from the watershed DO levels. In surface waters, DO occurs system. naturally through two primary sources: surface exchange with atmospheric oxygen Removing Sediment from the (adsorption) and algae that create oxygen Reservoir as a by-product of photosynthesis; DO is Techniques for removing accumulated removed from the water column by fish sediment include flushing, aeration, and respiration and decomposition of organic mechanical removal (e.g., dredging, dry matter by aerobic bacteria. An oxygen excavation, and hydro-suction). shortage or depletion can occur when photosynthesis ceases or is substantially Flushing. Flushing increases flow reduced during snow and ice cover or when velocities in a reservoir to the extent that excessive biomass is present (e.g., in eutro- deposited sediments are resuspended and phic lakes). transported through low-level outlets in the dam. Flushing occurs in two ways: complete Several methods can supply DO artificially: draw-down flushing and partial draw-down mechanical stirring by fountains, pumps, flushing. Complete draw-down flush- and electric or wind-driven stirrers; com- ing occurs when the reservoir is emptied pressed air supplied by oilless compressors during flood season; this creates river-like or blowers and diffusers; and chemical flow conditions in the reservoir. Deposited oxidizers such as potassium permanga- sediment is remobilized and transported nate. Each method varies in effectiveness. through low-level gates to the river reach Compressed air likely provides the best downstream from the dam. Low-level gates long-term treatment, and potassium are closed toward the end of flood season to permanganate provides the most immediate capture clearer water for use during the dry results. The compressed air method also season. promotes long-term organic matter decom- 64 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

position and nutrient recycling that can by flushing. The pipe venturi might be use- help correct eutrophication-related taste ful for dredging and redistributing organic and odor problems. matter, clay particles, and nutrients in eutrophic lakes. However, type and quality Compressed air is more efficient than of sediment must be quantified prior to mechanical stirring or a water fountain using this technique. Some sediment might system at moving the oxygen-deprived contain contaminants or unusually high water column located in the bottom, or levels of nutrients that could have deleteri- hypolimnion, region of a lake (i.e., lake ous effects on water in the reservoir and turnover). Stirrers usually cannot reach the receiving stream. lake bottom, and fountain intakes can plug if mounted too close to bottom sediments. Mechanical Removal. Mechanical Chemical oxidizers might be the best solu- removal of deposited sediment occurs tion for providing DO immediately, but through conventional dredging techniques, this is a short-lived, temporary solution. In dry excavation, and hydro-suction. addition to providing supplemental oxygen, an aeration system can: The process of excavating deposited • Suspend organic matter in the water sediments from under water is termed column, allowing better oxidation and dredging. This is a highly specialized activ- fertilization of phytoplankton and zoo- ity used mostly used for clearing navigation plankton in the epilimnion, the upper channels in ports, rivers, and estuaries. portion of water in the reservoir Dredging also can be used to reclaim reservoir storage capacity lost to sedi- • Resuspend and transfer sediment dur- ment deposition. However, conventional ing water exchange events hydraulic dredging often is much more • Partially restore lake depth and volume expensive than the cost of storage replacement and generally is not economically viable or necessary. Excavating sediment One type of aeration system, the pipe ven- from existing reservoirs will require mov- turi, can perform a specific type of dredging ing 20 to 50, even up to 100, times more called “air dredging” (Haag, 2006) and has material than originally moved to construct been used in wastewater lagoon systems to the dam. Costs of dredging larger reservoirs move and aerate sludge. The pipe venturi is in Kansas in their latter stages of filling approximately 3 feet in length and 6 inches could be more than 100 times the original in diameter with holes cut in the bottom construction cost, billions of dollars in and sides. It is placed vertically on the bot- some cases. In addition, it will be necessary tom of the reservoir in loosely compacted to find a disposal location for the excavated sediments. Air is released at the bottom of material, preferably close to the reservoir the pipe, and bubbles rise through the pipe to reduce transportation costs. Spreading creating a suction, or venturi, effect. The sediment uniformly over one square mile venturi disturbs the loosely compacted, in a one-foot-thick layer would dispose of unconsolidated sediment, which becomes 640 acre-feet of sediment, but sediment resuspended in the epilimnion and then accumulation in a reservoir can total tens of moves out of the lake through the spillway thousands of acre-feet.

Sedimentation in Our Reservoirs: Causes and Solutions 65 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Disposing dredged material can cause controlled without interfering with exca- environmental problems, and solutions, vation work. Sediment is excavated and which can be quite expensive, have to be transported using traditional earth-moving developed on a case-by-case basis. Dis- equipment. Excavation and disposal costs charging high sediment concentrations are high; therefore, this technique generally generally associated with dredging directly is used in relatively small reservoirs. Sedi- downstream from the dam can be envi- ment from some reservoirs excavated using ronmentally unacceptable. However, it this method has been used as engineered might be possible to reduce the sediment landfill in hills adjacent to the reservoirs. concentration of water flowing in the river It can be difficult to dry the bottom of by concurrently releasing clean water and the reservoir thoroughly enough for heavy dredged material from the reservoir. If excavating equipment to operate on it. dredged material is not deposited downstream, large expanses of landfill might be A hydro-suction removal system is a varia- required. Although dredged material can tion of traditional dredging. Traditional be a liability, it also can be seen as an asset dredging uses pumps powered by electricity (WOTS, 2004). Uses for dredged sediment or diesel. Hydro-suction uses energy from include habitat development, soil improve- the hydraulic head available at the dam. ment for agriculture and forestry, and Where sufficient head is available, operat- construction (e.g., brick making). ing costs for hydro-suction are substantially lower than for traditional dredging. Most Kansas reservoirs are about the same age and fill at about the same rate. Excavat- Replacing Lost Storage ing sediment-filled basins and finding a Lost storage can be replaced by construct- place for the excavated material from all ing a new dam (upstream, downstream, these reservoirs is currently beyond our or on another river) or raising the existing means. Fortunately, we likely will not need dam, but neither option can be accom- to dredge entire basins of most reservoirs. plished easily. Raising the dam requires Tactical dredging of upper arms of the conducting reallocation studies and reservoir removes sediment from where it mitigation of additional flooded land and is accumulating most rapidly. Excavating recreational structures. A single realloca- upper basins deeper than their original tion study can cost more than $1 million. contour creates settling basins that serve as Few good locations for large-scale new sediment traps. Preserving an infrastructure dam development remain, and construc- that allows access to these settling basins tion costs can be prohibitive. Urban and will allow convenient redredging every 20 rural development steadily surrounded to 30 years, a possible long-term manage- reservoirs, limiting our ability to raise dam ment strategy. heights and flood additional land. Also, environmental effects of large-scale dam Dry excavation (i.e., trucking) requires low- projects would be difficult to overcome ering the reservoir during the dry season, because of enhanced environmental protec- when reduced river flows can be adequately tion regulations.

66 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Decommissioning the • Does most sediment deliv- Reservoir ery occur during high-flow Decommissioning should be regarded events, or are cumulative as the last possible option. There are no low-flow delivery ratios more reported cases of decommissioning dams important? higher than 40 meters. Decommissioning • What are the stratification charac- large dams is problematic and needs careful teristics of the reservoir? consideration, particularly when the reservoir behind the dam is full of sediment. • How will dredging affect the usefulness Other options to explore before decom- of the reservoir for water supply during missioning include maintaining the dam the dredging process? Would alterna- at a lower level or using the silted reservoir tive water supplies be necessary for a for ecological enhancement (e.g., wetland period of time? Does the infrastructure habitat, farming, or recreation). However, exist to manage this? these options are site specific and still result • Which reservoirs have multilevel release in lost water storage capacity. structures? Which could be modified to incorporate these structures? Implementing Sediment Management Strategies • What are the effects of discontinuing flood control benefits in favor of water Implementing sediment management supply capacity preservation? What is strategies requires collecting various data, the economic effect on properties that securing financial resources, and developing would no longer be protected from a comprehensive plan with input from all flooding? What is the cost to buy land stakeholders. for floodplain preservation? What other options for flood control are Information available? Sedimentation rate is the fundamental • What is the sediment quality? problem in all reservoirs; all other reservoir problems are linked, by various degrees, • What are the costs and benefits of to this issue. Therefore, determining a various management techniques or reservoir’s sedimentation rate is necessary combinations of techniques? for developing both short- and long-term • What is the true cost of providing management strategies and will help deter- water via a reservoir if costs for long- mine the flow regimes under which most term storage capacity maintenance are sediment is delivered and deposited. This, included? in turn, can guide design and placement of appropriate BMPs. • Which reservoirs should be decommissioned first if this becomes necessary? If To determine appropriate sediment man- a reservoir is decommissioned, how will agement strategies for Kansas reservoirs, the water storage, flood control, and other following questions should be answered: needs be satisfied? • What are the sediment delivery ratios for all watersheds above federal reservoirs? Sedimentation in Our Reservoirs: Causes and Solutions 67 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Resources of their lifespan or how benefits could be At typical dredging costs of $5,000/acre- replaced. Future generations were left to foot to $6,000/acre-foot ($3/cubic yard deal with substantial environmental, social, to $5/cubic yard) (deNoyelles et al, 2004) economic, and safety issues. The conven- and assuming a constant rate of sediment tional wisdom is to assume dams have a deposition, removing the annual sediment finite ability to store water and accept that load deposited in Kansas reservoirs is cost this ability will diminish gradually because prohibitive. Estimated annual costs for four of sedimentation. An alternative approach reservoirs are (KWO, 2005): is to view dams and reservoirs as sustainable • Clinton: $1.6 million structures.

• John Redmond: $4.5 million Sustainability requires that resources be • Perry: $5.6 million developed and used in a way that accounts for interests of all stakeholders, includ- • Tuttle: $22.4 million ing future generations. For infrastructure projects, this means that future generations These costs alone are more than two should not be burdened with emergency times the annual State Water Plan Fund. maintenance or decommissioning of assets Although BMPs can reduce sedimentation built to benefit their predecessors. The and, ultimately, dredging costs, implement- ultimate goal of developing sustainable res- ing these practices can be cost prohibitive. ervoirs is to maintain the major functions To help defray costs of BMP implemen- of the dam through appropriate manage- tation, landowners can participate in ment and maintenance in perpetuity. government cost-share programs such When this is not possible, decommission- as the Natural Resources Conservation ing can be used as a last resort, provided Service (NRCS) Environmental Quality that this action is funded by an accumu- Incentive Program. A recent report evaluat- lating dam retirement fund. Sustainable ing natural resource cost-share programs reservoir management will ensure that summarized expenditures during recent current and future generations enjoy the years for the two voluntary government benefits of the facility and spread owner- cost-share programs with greatest participa- ship, operation, and maintenance costs over tion. The NRCS cost shared $89,450,451 many generations. to private landowners in Kansas from 2003 through 2005 for BMPs including terraces, With reservoir capacity and water quality livestock production improvements, and concerns looming, it is time to change the wetlands. The State Conservation Com- paradigm of viewing reservoirs as projects mission cost shared $12,972,721 from 2004 with a defined life span. We must develop to 2006 for similar practices. and implement sustainable strategies to maintain and extend reservoirs’ useful life, Planning beginning by taking action to preserve The original “design life” approach to reservoir water supply infrastructures with reservoir construction did not consider a phased plan that first address the most what would happen to dams at the end crucial problems in the most important reservoirs.

68 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Developing a Comprehensive Plan We offer the following suggestions as a guide for developing comprehensive sediment management plans for Kansas reservoirs: • Establish goals or targets for reductions in sediment deposition for each reservoir. • Stabilize watersheds. Continue Watershed Restoration and Protec- tion Strategy efforts and other watershed conservation work with focus on public water supply (PWS) reservoirs and erosion control. • Increase acres of cropland managed with no-till. Prioritize streams for buffer installation and streambank stabilization. Provide cost- share payments or cover the entire cost to ensure implementation and maintenance. Develop means of monitoring and enforcing BMP implementation. • Prioritize reservoirs for maintenance and infrastructure development and upgrades. Determine which developments will have the greatest effect on water supply infrastructure considering population served, water quality problems, demand, and location of alternative supplies. • Develop a dedicated state dredging/infrastructure upgrade and maintenance fund. • Complete a reservoir dredging pilot study. During the pilot study, excavate deeper sedimentation basins in reservoir arms or tributaries and establish maintenance infrastructures. • Consider establishing critical water quality management areas above PWS reservoirs, and direct funds to establish widespread erosion control practices and streambank stabilization. • Determine viable management options for in-reservoir water manipulation. • Establish maintenance infrastructures in priority reservoirs. • Identify sediment disposal areas. • Establish wetlands and riparian areas for use in conjunction with sediment disposal sites. • Increase number and size of wetlands to store flood waters and filter sediment. • Protect sites that have potential for new dam construction.

Sedimentation in Our Reservoirs: Causes and Solutions 69 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

References Juracek, K.E. 2006. Sedimentation in Kansas reservoirs. Abstract from the 23rd Annual Water and the Future Birr, A. and Mulla, D. 2006. Using paired watersheds to of Kansas Conference. March 16. Topeka, KS. evaluate the effects of agricultural best management [KWO] Kansas Water Office, Evaluation and Assessment practices on water quality in south-central Minnesota. Unit. 2005. Unpublished data. Presentation at the Managing Agricultural Landscapes for Environmental Quality Conference. Oct. 11-13. Palmieri, A., Shah, F., Annandale, G., and Dinar, A. 2003. Kansas City, MO. Reservoir conservation volume I: The RESCON approach. Washington, DC: World Bank. deNoyelles, J., Jakubauskas, M., and Randke, S. 2004. Reservoir management and restoration. Addressing [WOTS] Water Operations Technical Support problems in multipurpose reservoir systems. Lawrence, Program. 2004. The WES handbook on water quality KS: Kansas Biological Survey. enhancement techniques for reservoirs and tailwaters. Vicksburg, MS: U.S. Army Engineer Research and Geyer, W., Brooks, K., and Neppl, T. 2003. Streambank Development Center. Waterways Experiment Station. stability of two Kansas river systems during the 1993 flood in Kansas, USA. Transactions of the Kansas Academy of Science, 106(1/2):48-53.

Haag, D.A. 2006. Supplemental aeration and oxidation systems. Unpublished manuscript.

70 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu. Economic Issues of Watershed Protection and Reservoir Rehabilitation

Jeff Williams, Professor, Department of Agricultural Economics Craig Smith, Watershed Economist, Department of Agricultural Economics Kansas State University

Summary fulness, it could be more economical for the government to fund expen- Comprehensively analyzing economic ditures for management practices that issues of watershed protection and reser- reduce further erosion and sedimenta- voir rehabilitation projects is a somewhat tion in a watershed than to rely on dredging daunting task because of the extensive in the future. However, our economic effects of the costs and benefits of alterna- analysis is not complete because critical tive management strategies. In addition, data are not available. We do not know, data on economics of sediment control at among other things, the source of sediment, a watershed scale are lacking, and previous how suitable management practices are studies have not evaluated whether dredg- for various locations in a watershed, or the ing sediment or preventing sedimentation number of acres that, from a technical and is more economical. Many questions economic perspective, actually need these remain unaddressed and unanswered. practices applied. We also do not know Nevertheless, the economics of watershed the benefits of reduced sedimentation. protection and reservoir rehabilitation is an Evaluating the best approach for reducing important topic. Although this white paper additional sedimentation in watersheds is not a complete, comprehensive analysis, with reservoirs for which dredging is being it provides valuable insight into potential considered is a demanding task. A team watershed/reservoir management strategies, approach that integrates expertise from the magnitude of costs, preferred analysis various disciplines is essential for analyzing approaches, and research needs. sediment prevention, erosion management, and reservoir rehabilitation. Ultimately, In this white paper, we provide an overview a variety of models that incorporate both of costs of soil erosion and sedimentation physical and economic watershed charac- based on existing literature and review fea- teristics are needed. tures and costs of common soil erosion and sediment control methods. Appropriate in-field soil erosion management practices Soil Erosion and and their costs vary by site. Thus, we limit Sedimentation Costs our analysis to estimating potential savings Erosion of cropland and streambanks of from implementing individual, in-field Kansas rivers increases sediment loads erosion control methods in a watershed to deposited in downstream reservoirs, alters reduce future costs of dredging sediment fish and wildlife habits, and can cause from a reservoir. Then, we compare poten- significant damage to fields bordering tial savings with the cost of management streams, resulting in direct economic losses practices. for landowners and Kansas citizens. Soil erosion causes loss of cropland, particularly Our brief analysis indicates that in situa- along streambanks and riverbanks, and tions where the amount of accumulated loss of soil productivity in crop fields and sediment has not reduced a reservoir’s use- pastures. Cropland erosion from high-flow

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events in floodplains can disrupt farming calcium, sodium, magnesium bicarbonate, operations. Soil erosion also has several off- and chloride ions (Clark et al., 1985). site consequences (Figure 1); it can reduce reservoirs’ water storage capacity, which Sedimentation caused by soil erosion can affects public water supplies, flood control create significant societal costs (Mooney capability, and water availability for down- and Williams, 2007). For example, sedi- stream navigation. mentation can affect the enjoyment people derive from using waterways for recreation. Suspended soil particles can affect viability MacGregor (1988) estimated that increased of aquatic life, reduce recreational value of sedimentation at Ohio state park lakes lakes and waterways, and increase opera- reduces the economic benefit of recreation tional costs for power plants, city water to out-of-state boaters by an average of supplies, and navigation. Deposited sedi- $0.49/ton of sediment. Bejranonda et al. ment causes extensive damage to aquatic (1999) examined effects of sedimentation life, shortens reservoirs’ useful life, and on lakeside property values at 15 Ohio state clogs navigation channels (Clark et al., park lakes and found that homeowners 1985). Sediment can fill drainage channels, are willing to pay more for properties on such as ditches and culverts, causing local- lakes with less sedimentation. A broader, ized flooding if not removed. Sediment national estimate of the value of recre- also includes nutrients such as nitrogen ation loss attributable to sedimentation and phosphorus that alter water quality is between $612 million and $3.6 billion and affect aquatic life. Other potential (2006$) (Tegtmeier and Duffy, 2004). contaminants in sediment include agricul- Amounts reported in 2006 dollars (2006$) or tural pesticides and dissolved solids such as 2005 dollars (2005$) as indicated.

Resources Leave the Physical Environmental Quality Landscape E ects and Economic E ects

Recreation Water Quality Drinking Water

Wildlife Habitat

Soil Property Values Nutrients Runo Reservoir Pesticides and Life Bacteria Erosion Flood Control

Water Supply

Fix or Replace On-site Crop Reservoir Productivity Yield Loss

Figure 1. General effects of soil erosion

72 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Hansen et al. (2002) examined costs of soil National Estimates erosion and sedimentation to downstream of Total Damage navigation across different areas of the from Water Erosion United States. Their results suggest that Mooney and Williams (2007) eroded soil poses no costs to navigation in reviewed literature on water erosion areas with no downstream shipping chan- damages. They summarized work by nels or harbors but can create costs up to Clark et al. (1985), Ribaudo (1986), and $5.67/ton of soil erosion (2006$) in areas Tegtmeier and Duffy (2004), who provided where navigation is affected (Hansen et national estimates of total annual damages al., 2002). Tegtmeier and Duffy (2004) attributable to water-based soil erosion estimated that costs of sedimentation ranging from $2 billion to $31 billion to shipping range from $345 million to (2006$). These analyses included costs $383 million (2006$). Moore and McCarl related to recreation, navigation, water stor- (1987) estimated effects of sediment on age facilities, municipal and industrial water municipal water treatment, road drainage users, water conveyance systems, and flood- system maintenance, navigation channel ing. Estimated damages did not include all maintenance, reservoir capacity deteriora- sectors of the economy or all possible activi- tion, and hydroelectric power plant costs in ties and thus represent a partial estimate of Oregon. In this state alone, the total aver- the value of reduced soil erosion. age cost of erosion for navigation channel maintenance, municipal water treatment, No comprehensive studies examining and country road and state highway main- damages attributable to water-based soil tenance is approximately $5.5 million erosion have been conducted since 1986 annually (Moore and McCarl, 1987). Tegt- when Ribaudo calculated the value to meier and Duffy (2004) updated figures society of reducing soil erosion by one ton from Ribaudo (1986); they estimated that based on potential annual damages from annual costs of sediment removal from erosion in 1983. Per-ton values ranged roadside ditches and irrigation channels from a low of $0.98/ton in the northern throughout the United States range from Plains to $11.29/ton in the Northeast $304 million to $895 million (2006$) and (2006$). However, erosion of cropland annual costs of flood damage attributable to and other agricultural soil declined con- erosion range from $215 million and $622 siderably during the past 20 years (NRCS, million (2006$). Nationally, estimates of 2007b), partly because improved farming annual costs of dredging inland waterways practices and government programs such as range from $282 million to $291 million, the Conservation Reserve Program (CRP) and reservoir siltation costs range from retired highly erodible lands. According $274 million to $851 million (Clark et al., to the 2003 National Resources Inven- 1985; Ribaudo, 1986; Hansen et al., 2002; tory (NRCS, 2007b), the average rate for Tegtmeier and Duffy, 2004). sheet and rill erosion on cropland declined from 4.0 tons/acre per year in 1982 to 2.6 tons/acre per year in 2003. Wind erosion rates dropped from 3.3 tons/acre per year in 1982 to 2.1 tons/acre per year in 2003.

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Damages created by soil erosion negatively affecting water bodies even if probably changed over time, and sediment loads from new sources decline? previous estimates likely are inac- It is likely that reducing sedimentation will curate now. Today, actual per-ton require a multi-strategy approach. damages depend on the value and cost of downstream activities affected Strategies and Costs for by soil erosion. Reducing Soil Erosion and Controlling Sediment Sediment Control Costs Sediment reduction strategies include Sediment source as well as type and effec- keeping sediment in place on upland land- tiveness of erosion management strategies scapes, flood plain management, upstream affect costs of reducing sedimentation. sediment traps, and dredging reservoirs Sediment sources include upland land- once sedimentation occurs. Landscape scape areas (e.g., cultivated fields, poorly management encompasses a variety of soil maintained pastures, construction sites, conservation measures. For example, no-till and streambanks), sediment previously systems leave crop residue on fields to deposited in floodplains, and in-stream reduce soil disturbance and erosion dur- sources. Knowing the distribution of ing wind and rainfall events. Alternatives sediment sources can help determine what include cropping rotations that increase management strategies to use. For example, crop and residue cover, vegetative buf- if sediment occurs mainly from high-flow fers and CRP land, contour farming, and events causing streambank erosion, it terraces. might be economically efficient to target streambanks rather than cultivated fields. According to the 2003 National Resources However, if most erosion and sedimenta- Inventory (NRCS, 2007b), soil erosion in tion occurs during infrequent but heavy Kansas declined from 1987 to 1997 (Figure precipitation and water flow events, tar- 2). Cultivated cropland remains the largest geting erosion control strategies to these erosion source; but, like other land use cate- events rather than to average rainfall events gories, erosion from this source is declining. might be useful. Presence of contaminants, This decline likely is due to increased use such as phosphorous or other chemicals, in of conservation practices and enrollment sediment also could influence source target- of land in the CRP. Still, we must ask: Has ing decisions. reduced soil erosion decreased reservoir sedimentation? Stakeholders must consider several questions regarding effectiveness of soil erosion Putnam and Pope (2003) reported results management strategies. How effective of time-trend tests from 1970 to 2002 for are the variety of in-field management sediment sampling sites in Kansas. Most strategies at reducing soil erosion? If we of the 14 sampling sites, including five implement practices to reduce field erosion, of the six sites upstream from reservoirs, what is the effect on reservoir sedimenta- exhibited decreasing suspended sediment tion? Will sediment already accumulated concentrations, but only two sites had in streambeds or low-lying areas continue trends that were statistically significant.

74 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Cropland 5 Pastureland CRP Land 4 Total

3 Tons/Acre/Year 2

0 1982 1987 1992 1997 2003 Year Figure 2. Soil erosion trends in Kansas Data source: NRCS (2007b). Erosion rates for pastureland and CRP land were not reported in 2003.

Increasing suspended sediment concentra- location. The ultimate decision to adopt a tions occurred at three sites but were not specific management strategy depends on statistically significant. Both sites that several factors including physical, biologi- exhibited statistically significant decreasing cal, and economic characteristics of a site suspended sediment concentrations have a and land managers’ capabilities and risk large number of watershed impoundments preferences. (i.e., structures designed to trap sediment) in their respective drainage basins. The In-Field Strategies relationship between percentage of the Altering Residue Cover with Crop watershed affected by impoundments and Rotations. Plant residue management suspended sediment concentration for is one strategy used to reduce soil erosion. 11 sites indicated that suspended sedi- Crop rotations and tillage methods affect ment concentration decreases as number the amount of plant residue left on the soil of watershed impoundments increases. surface. Al-Kaisi (2000) provided a relative Implementing other conservation practices, ranking of erosion from selected cropping such as terracing and contour farming, systems in Iowa. Fallow ground had the could further reduce suspended sediment highest rate of erosion followed by a corn- concentrations. soybean rotation. Increasing the amount of corn relative to beans in the cropping The following sections contain rough cost rotation reduced erosion as did adding a estimates of various erosion management permanent cover crop or small grain crop, strategies; applicability and economic such as oat. Devlin et al. (2003) reported viability of these strategies vary greatly by that the cost of using soil-conserving crop

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rotations is $0.00/acre (Table 1). However, Contour Farming. Contour farming actual costs of crop rotations vary by site, uses field operations that follow the con- and changes in commodity prices cause the tour of the field rather than move straight relative profitability of rotations to change up and down field slopes. This method from year to year. requires additional labor and time and

Table 1. Cost for implementing sediment management practices Practice Cost Altered crop rotations $0.00/acre/yearb Contour farming without terraces $6.80/acre/yearb Land retirement $30 to more than $82/acre/yearf No-till $0.00/acreb -$37.00 to more than $37.00/acreg -$3.81 to $1.51/acred Riparian forest buffer $585/acre establishment plus annual loss of annual income (land rent)h Sediment trap $1,300 establishment cost per acre of construction area drainage to trapa Streambank stabilization $5,381 establishment cost per acre of CRP ($12.31/linear foot)g $3,252/acre of CRP after accounting for preserved land value and incomeh Terraces $0.66 to $3.30/linear foot depending upon slopee Terraces with tile outlet $40 establishment cost per acre plus annual cost of $13.60/acreb $1.05/linear foote Terraces with grassed waterways $30 establishment per acre plus annual cost of $13.60/ and contour acre in field plus loss of annual income (land rent)b Vegetative buffers $100 establishment cost per acre plus annual loss of land rentb $73 establishment cost per acre plus loss of annual income (land rent) – Annualized cost $63.29/acrec $104 establishment cost per acre plus annual loss of annual income (land rent)j Waterways (grass) including $870 establishment cost per acre plus loss of annual topsoiling income (land rent)e a California Stormwater Quality Association (2003) b Devlin et al. (2003) c KSU-VegetativeBuffer estimate; Smith and Williams (2007) d Langemeier and Nelson (2006) e NRCS (2007a) f Taylor et al. (2004) g Williams et al. (2007) h Williams et al. (2004)

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might necessitate using equipment with Previous research shows that profitability reduced widths, which reduces efficiency. of no-till systems varies. Dhuyvetter et al. Clark et al. (1985) reported that contour (1996) reviewed nine studies including 23 farming practices reduced suspended comparisons between no-till and other till- residue by 25% to 50%. Contour farming age systems for various crops and rotations costs a few dollars per acre on fields with in the Great Plains and found that no-till consistent contours and is significantly had higher returns than conventional more expensive on farms with variable field tillage in eight comparisons. Most of these topography; Devlin et al. (2003) reported comparisons were either wheat-fallow or contour farming costs approximately wheat-sorghum-fallow rotations. Williams $6.80/acre (Table 1). et al. (1990) found that net returns from no-till for continuous corn and corn- Land Retirement. The CRP and soybean rotations were higher than from other programs that retire land from crop conventional tillage in several government production and require establishment commodity program designs. In contrast, of permanent cover can reduce soil ero- no-till had lower average net returns than sion. The major cost of the CRP to land conventional tillage for continuous soy- managers is the value of lost production. bean. Similarly, average net returns from Therefore, the CRP pays an annual rental no-till were less than from conventional rate to those who enroll land. Kansas tillage for wheat and grain sorghum in CRP payments range from $30/acre to the central Plains (Williams et al., 2004). $82/acre (Table 1; Taylor et al., 2004). In Texas, no-till had higher net returns Land not currently enrolled in CRP likely than conventional tillage for three crop- is more profitable in crop production and ping rotations: sorghum-wheat-soybean, will require a larger incentive payment wheat-soybean, and continuous wheat, but than land currently enrolled. Cash rental conventional tillage had higher net returns payments landlords received for renting for continuous sorghum and soybean nonirrigated land in northeast Kansas in (Ribera et al., 2004). 2006 averaged $69/acre. The statewide average is $39/acre and ranges from $26/ Pendell et al. (2005) reported that net acre to $69/acre (Dhuyvetter and Kastens, returns for no-till were higher than for 2006). conventional tillage for continuous corn in northeast Kansas. A recent study (Wil- No-Till. No-till is a form of conservation liams et al., 2007) of five cropping systems tillage in which chemicals are used in place in northeast Kansas showed that returns of tillage for weed control and seedbed from no-till compared with conventional preparation. In a 100% no-till system, the tillage ranged from a negative $37.25/acre soil surface is never disturbed except for to a positive $37.12/acre; compared with planting or drilling operations. Two other reduced tillage, returns from no-till ranged forms of tillage, reduced tillage and rota- from a negative $40.10/acre to a positive tional no-till, involve light to moderate use $21.14/acre depending on crop rotation of tillage equipment. These methods also (Table 1). Langemeier and Nelson (2006) control erosion and nutrient runoff but are reported that reducing tillage had a small not as effective as 100% no-till. effect on production costs in northeast

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Kansas but significantly reduced soil ero- Riparian Forest Buffers. Riparian sion. Changing from conservation tillage forest buffers are areas of forested land to no-till for a corn-soybean rotation could adjacent to streams, rivers, or other water reduce production costs by $3.81/acre, bodies. Shrubs and grasses often are located assuming no yield change, and soil erosion upslope from the trees to reduce nutrient by 15% to 42% depending on soil type; and sediment losses from agricultural fields, changing to no-till in a sorghum-soybean- improve runoff water quality, and provide wheat rotation could increase production wildlife habitat (Goard, 2006). Because of costs by $1.51/acre and reduce soil erosion these societal benefits, several federal and by 2.1% to 26.9% (Langemeier and Nelson, state programs encourage installation and 2006). maintenance of riparian forest buffers. Establishment costs for a riparian forest Nationally, the percentage of planted buffers with trees, shrubs, and grass range cropland in a no-till system increased from from $243/acre to $970/acre with an aver- 6% in 1990 to 22% in 2004 (CTIC, 2005). age of $585/acre (Table 1; Williams et al., However, these data are just a snapshot of 2004). Annual income is lost from land in the total no-till acres in a given year. The the buffer that can no longer be cropped, number of continuous no-till acres, which but the cash rental rate for land in the area are important for soil erosion control, is is approximately the same as the amount of less than the total. Dhuyvetter and Kastens lost income. (2005) summarized no-till adoption data for Midwest crop production. In 2004, Sediment Traps. Sediment traps, or no-till use was highest in soybean at 36.9%, basins, are excavated areas designed to up from 26% in 1994, and next highest in temporarily impound runoff water long grain sorghum at 33.2%, up from 13.6%. enough for suspended sediment to settle No-till use in corn and fall small grains was out. Typically, these structures are tem- 17.8% and 18.5%, respectively. Overall porary and used to control erosion from adoption of no-till in Kansas (21.2%) was construction sites. Sediment traps can be slightly less than in the Midwest region constructed along a watercourse or between (24.8%). In central and eastern Kansas, a field and an outlet to a stream by excavat- no-till use is increasing primarily because of ing or forming an earthen embankment lower costs, but higher yields and the associ- across a drainage area or waterway. Limited ated revenue provide incentives for no-till information is available on cost and effec- adoption in western Kansas (Dhuyvetter tiveness of these structures in agricultural and Kastens, 2005). watersheds; however, the California Storm- water Quality Association (2003) reported Large-scale adoption of no-till is relatively costs of $1,300/acre of drainage (Table 1). slow, indicating many farm managers Costs for sediment traps or impoundments regard it as unprofitable or that changing for agricultural erosion control vary by site tillage practices has high transaction costs. because of differences in area and character- We need to learn more about the types and istics of land from which runoff is collected; magnitude of incentives that could encour- removal and disposal of accumulated sedi- age farm managers not already using no-till ment add to the cost. to adopt this practice.

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Terraces. Terraces are embankments Vegetative Buffers. Veg- constructed perpendicular to the slope of a etative buffers are land areas field; they reduce the length of a field slope, maintained in permanent veg- catch water flowing off the slope, reduce etation that reduce nutrient and the rate of runoff, and allow soil particles sediment losses from agricultural to settle out. Terraces can increase the time fields, improve runoff water quality, needed complete field operations because and provide wildlife habitat. Several farm managers are unable to use larger or federal and state programs encourage wider equipment, and loss of some farm- installation and maintenance of vegetative able land might occur depending on slope buffers. Establishment costs for vegeta- and whether part of the terrace must be tive buffers average $104/acre (Table 1; seeded with grass. Terrace construction Williams et al., 2004) plus annual loss of costs include earth work for regrading land income from land in the buffer that can no and can be several hundred dollars per acre. longer be cropped. We used the K-State Carman (2006) reported construction costs Vegetative Buffer Decision-Making Tool ranging from $1/linear foot to $6/linear (Smith and Williams, 2007) to estimate foot, and the NRCS (2007a) reported costs annualized costs. Establishment costs for of $.66/linear foot to $3.30/linear foot a buffer using native grass are $73.12/acre depending on slope (Table 1). without any cost-share or incentive payments, and annualized costs including loss Terraces with Grassed Waterways of income are $63.29/acre (Table 1). and Contour Farming. Grassed waterways are used to prevent erosion and gully In-Stream Strategies formation and also function as outlets for Streambank Stabilization and water from terraces. Vegetative cover slows Bendway Weirs. Various strategies are water flow and minimizes channel surface used to reduce streambank degradation, erosion (Green and Haney, 2006). Grassed and several can be combined for effective waterways might require removing land streambank stabilization. Willow posts can from production, which reduces potential be planted on the outer bend of smaller income, and also affect efficiency of field of streams to create a natural riparian zone equipment, which increases time and cost that slows water flow and dissipates energy of field operations. Maintenance includes that will erode the bank toe. Posts usually harvesting and marketing forage, repairing are 3 to 4 inches in diameter and 10 to 14 rills and gullies, and removing accumulated feet tall. Depending on bank height, three sediment. Establishment costs include to five rows are planted 4 feet apart. Other field grading and vegetation establishment strategies include bendway weirs, stone and usually are less than costs for terraces. toes, pools and riffles, and stream barbs. Devlin et al. (2003) estimated that grassed These methods use rock structures to slow waterway costs include a onetime $30/acre or divert water flow and protect the bank cost, $13.60/acre for all acres in the field, toe. Bendway weirs are jetties constructed and the annual loss of income from land in at an upstream angle of 10 to 25 degrees the waterway (Table 1). that directs water toward the center of the stream. Typically, they are less than half the

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stream width in length and slightly higher the bank toe. The trees slow stream flow than low water. Sediment tends to collect and trap sediment from the eroding bank. on the downstream side of weirs. Bend- Eventually, willow and cottonwood seed- way weirs generally are suitable for larger lings will sprout and grow, re-establishing a watercourses, such as sections of the Little riparian zone. Riprap is large rocks placed Blue River in Washington County, Kansas. on the face of a bank to resist scouring from A stone toe is a row of large rocks along the water flow. toe of the outside bank of a bend. Perpen- dicular “keys” are constructed at intervals Williams et al. (2004) analyzed costs of along the bank to protect against undercut- streambank stabilization based on actual ting. In the pool and riffle method, a series construction and establishment costs at of riffles (i.e., rock and sand bars) are con- 13 sites on a 35-mile stretch of the Little structed across a stream. These slow stream Blue River in Washington County, Kansas flow by breaking a steeply sloping stretch of (Table 2). Each site required establishing a streambank into a series of gently sloping 125-foot-wide riparian buffer consisting sections (Johnson, 2003). Other methods of trees, shrubs, and grass; 100 feet of the include placing tree revetments or riprap on width was CRP land (Figure 3). Land area the outer bank of a bend. Tree revetment enrolled in the CRP ranged from .8 acres involves securing cut trees, often cedars, at to 4.6 acres with an average size of 3 acres.

Table 2. Construction and establishment costs of streambank stabilization by sitea Percent Cost per Length in CRP Total Percent Cost per Site Equipment Linear feet Acres Costs Materialsc Acred & Laborb foot 1 1,250 2.9 $18,261 32.5% 67.5% $6,364 $14.61 2 925 2.1 16,524 32.0% 68.0% 7,781 17.86 3 1,140 2.6 23,988 20.3% 79.7% 9,166 21.04 4 882 2.0 17,410 29.5% 70.5% 8,598 19.74 5 2,016 4.6 12,552 19.3% 80.7% 2,712 6.23 6 336 0.8 3,019 82.9% 17.1% 3,914 8.99 7 1,049 2.4 8,392 72.3% 27.7% 3,485 8.00 8 1,255 2.9 20,814 65.3% 34.7% 7,225 16.58 9 1,188 2.7 14,488 61.5% 38.5% 5,312 12.20 10 1,150 2.6 10,395 61.6% 38.4% 3,937 9.04 11 1,983 4.6 35,073 23.0% 77.0% 7,704 17.69 12 1,980 4.5 16,937 75.6% 24.4% 3,726 8.55 13 1,888 4.3 12,008 54.2% 45.8% 2,771 6.36 Average 1,311 3.0 $16,143 42.2% 57.8% $5,592 $12.31 a Table adapted from Williams et al. (2004) with permission b Percentage of total costs for engineering and design, equipment, and labor to prepare the site including planting grass seed c Percentage of total costs for material including rock, trees, shrubs, grass seed, tree shelters, and chemicals d Cost per acre in the CRP stabilization area

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CRP Area

C D Cropland B 50 . 25 . River A 25 .

25 .

Figure 3. Streambank stabilization profile A. Willow (4-foot spacing) and cottonwood (6-foot spacing) B. Cottonwood, silver maple, and/or sycamore trees (8-foot spacing) C. One row each of green ash, black walnut, and burr oak trees (10-foot by 12-foot spacing) and one row each of choke cherry, fragrant sumac, and American plum shrubs (6-foot by 6-foot spacing) D. Native grass mixtures of big bluestem, Indiangrass, switchgrass, sideoats grama, and western wheatgrass Figure adapted from Williams et al. (2004) with permission

Construction equipment reshaped the erosion. Streambank stabilization projects streambank so it rose 1 foot from stream typically require that cropland be taken level to field level for every 3 feet of distance out of production to install the vegetative from stream to field. Bank width from buffer but result in long-term net savings stream level to field level was approximately of land. If the project can be enrolled in the 55 feet. Approximately every 175 feet, CRP, landowners will receive annual rental bendway weirs were constructed from rock payments. Cost-share payments, subsidies, boulders one-eighth ton to 1 ton in size or other incentives also might be provided. (Oertal, 2002). A typical weir was one- For purpose of cost calculations, the value third the width of the stream at low water of CRP, cost-share, and other incentive and about 2 feet high, 18 feet wide at the payments are not included in our analysis. base, and 10 feet wide on top. The present value of CRP payments over 15 years ranges from $724 to $3,602 with Per-site construction and establishment an average of $1,907. Present value of rental costs ranged from $3,019 to $35,073 with income not lost because of erosion over an average of $16,143. Cost per linear foot 15 years ranges from negative $1,211 to of streambank ranged from $6.23 to $21.04 $4,805 with an average of $474. Present with an average of $12.31. Cost per acre, market value of cropland preserved after 15 based on acres in the 100-foot-wide sta- years ranges from $990 to $16,985 with an bilization portion, ranged from $2,712 to average of $6,121 (Table 3). $9,166 with an average of $5,592 (Table 2). The annualized cost, using a 15-year period In-Reservoir Management and 6% interest rate, ranged from $279/acre Dredging. Dredging is the removal of per year to $944/acre per year with an aver- accumulated sediment from bottoms of age of $576/acre per year. Landowners also lakes, reservoirs, or other water bodies by incurred some annual maintenance costs. mechanical, hydraulic, or pneumatic means (Hudson, 1998). Sediments often are Landowners receive several benefits from removed from rivers and ports for naviga- streambank stabilization including income tion and boating purposes. Less frequently, or rental payments from preserved crop- dredging is used in lakes and reservoirs to land and market value of land saved from reclaim water storage capacity. Dredging

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Table 3. Present value and annualized present value of streambank stabilization costs Average Site $/acrea Costs without potential landowner benefits: – Total construction and establishment cost –$16,143 –$5,381 – PV of annual maintenance costs over 15 years –$206 –$69 = Present value of costs of project to land owner –$16,349 –$5,450 Annualized present value of costsb –$1,670 –$557

Costs with potential landowner benefits: – Total construction and establishment cost –$16,143 –$5,381 – PV of annual maintenance costs over 15 years –$206 –$69 + PV of rental income effect over 15 years +$474 +$158 + PV of net land conserved in the terminal year (year 15) +$6,121 +$2,040 = NPV of costs of project to land owner –$9,754 –$3,252 Annualized present value of costs –$997 –$332 a Cost per acre in the CRP stabilization area b Annualized using a 5.81% discount rate

Table 4. Dredging costsa Tuttle Creek Dredging and Cost to remove Cost per sediment depos- Data Source disposal cost per sediment depos- cubic yard ited as of 2005 acre-foot ited by 2005 (acre-feet) Corps of Engineersb $3.75 $6,049.99 165,000 $998,247,938 Iowa Minimumc $2.55 $4,115.58 165,000 $679,070,469 Iowa Maximumc $5.31 $8,574.48 165,000 $1,414,789,093 Kansas Minimumd $3.00 $4,839.99 165,000 $798,598,350 Kansas Maximumd $8.67 $13,983.22 165,000 $2,307,230,768 a Costs provided in 2005 dollars b USACE (2005) c Iowa Department of Natural Resources (K. Jackson, personal communication, Nov. 1, 2006) d Kansas Water Office (2004)

costs provided by the Iowa Department of ects. Other organizations and companies Natural Resources (K. Jackson, personal report hydraulic dredging costs ranging communication, Nov. 1, 2006), U.S. Army from $4.00/cubic yard to $14/cubic yard Corps of Engineers (USACE; 2005), and (Illinois Environmental Protection Agency, Kansas Water Office (2004) range from 2005; Kansas Biological Survey, 2005; $2.55/cubic yard to $8.67/cubic yard Dredging Specialists, 2007). (Table 4) and include dredging, equipment mobilization, and sediment disposal. Other In-Reservoir. Information on Mobilization costs represent a higher options for and economics of in-reservoir percentage of overall costs in smaller proj- sediment management strategies other

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than dredging is limited. Baker (2007) and Hotchkiss, 2006). In hydro reviewed some options for managing suction dredging, one end of a sediment within a reservoir. However, pipeline is located at the reservoir in-reservoir management strategies have bottom upstream from a dam. The limited effectiveness for reducing sediment pipeline extends through the dam loads introduced from the watershed and to a downstream discharge point and transported via major tributaries. In some draws sediment-entrained water into areas, shoreline erosion control techniques the pipe for transport downstream. This reduce sediment loading in reservoirs, but sluicing process relies on the availability of sedimentation from shoreline erosion likely “surplus” water that drives suspended sedi- is quite small compared with sedimentation ment beyond the reservoir. The “surplus” is from off-site erosion. annual inflow beyond storage capacity that is involuntarily spilled. One dredging alternative does not involve sediment management; rather, it raises the Targeting Best legal level of water storage elevation in the Management Practice lake. This approach is a temporary measure. Implementation Costs for this strategy are very site specific and can include purchasing additional land, Identifying land in a watershed that should loss of income from cropland or other uses, be treated is crucial for reducing sedi- habitat loss on environmentally sensitive mentation. Because limited resources are sites, and relocation of roads, walks, ramps, available to fund implementation of best or other structures. management practices (BMPs), it is most cost-effective to target areas that contribute Huffaker and Hotchkiss (2006) grouped most to sedimentation. Targeting attempts sediment control strategies into three broad to identify BMPs and land that have the approaches: greatest sediment reduction benefits rela- 1. Reducing inflow by controlling erosion tive to cost. in the catchment area (i.e., watershed) Khanna et al. (2003) developed a frame- 2. Diverting sediment by routing it to off- work that includes a hydrological model stream reservoirs or sluicing it through that uses geographic information system a dam before it can settle (GIS) data and an economic model to 3. Removing accumulated sediment by determine cost-effectiveness of retiring land hydraulic flushing, hydraulic dredging, using the Conservation Reserve Enhance- or dry excavation. ment Program (CREP) to reduce sediment. They applied the model to a 61,717-acre They also examined another sediment Illinois watershed and assumed that sloping removal strategy called hydro suction cropland adjacent to a stream or ripar- dredging, but their research was limited to ian buffers within 900 feet of a stream developing a theoretical economic model of were eligible for land retirement using the this process and determining the optimal CREP. Model results revealed that 8,172 volume of reservoir water to allocate to acres could be targeted. To achieve 20% this sediment removal strategy. (Huffaker sediment reduction for a 5-year storm, 11%

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of the acres in this area needed bodies, more sloping, more erosive, and to be in the CREP; this had an more likely to receive larger volumes of average cost of $31/ton. With a upland sediment flows than the crop- 30% reduction goal, average cost land not selected for retirement. (Yang was $47/ton. Marginal costs rose et al., 2003, p. 261) from $29/ton at a 10% reduction goal This study focused on one management to $117/ton at a 30% reduction goal. To practice and did not consider sediment achieve a 20% sediment reduction goal, the reduction benefits, optimal amount of sedi- cost-effective land rental payment is $54/ ment reduction, or dredging costs. ton times the tonnage of reduction per acre. Results also showed that most land selected To extend research by Khanna et al. (2003) for enrollment was from highly sloping and and Yang et al. (2003), Yang and Weersink highly erodible areas rather than less erod- (2004) examined cost-effectiveness of ible flat floodplains. targeting riparian buffers in a 36,077-acre …it is preferable to capture the sedi- agricultural watershed in Ontario by com- ment at the end of the flow channel by bining economic and hydrologic models retiring parcels adjacent to the water with GIS data. Their model minimizes the body rather than reduce sediment loss of economic return from crop produc- generated by retiring upslope parcels tion, which varies by watershed location that are farther from the water body. subject to fixed levels of sediment reduction Those parcels with high on-site erosion goals for a variety of buffer strip widths and high sediment trapping effective- in each sub-catchment of the watershed. ness are also given priority. (Khanna et The model selects appropriate buffer strip al., 2003, p. 547-548) widths and locations for five separate sedi- Yang et al. (2003) used a similar approach ment reduction goals but does not estimate to examine CREP use across 12 contiguous benefits of sediment reduction, determine Illinois watersheds to reduce sedimentation the optimal level of sediment to control, in the Illinois River by 20%. For a 5-year suggest an optimal combination of manage- storm event, a 20% reduction goal trans- ment practices other than buffer strips, or lated into a 32,000-ton sediment reduction consider dredging. Results indicated that in the 617,763-acre region. However, only cost-effective targeting results in buffer a 900-foot-wide area along all streams and strip locations that vary across the water- tributaries was eligible for CREP establish- shed and are not necessarily located on sites ment. To achieve 20% reduction at the adjacent to streams or having the greatest aggregate level (i.e., total watershed) at slopes. Marginal costs of sediment control least cost, sediment reduction in the 12 increase as amount of land used for buf- watersheds ranged from 4.1% to 33.3%. A fer strips and desired sediment reduction uniform standard applied to all 12 water- increase. sheds was more costly and required that more cropland be placed in CREP. Yang et al. (2005) used a similar approach to examine spatial targeting of no-till to Regardless of the variability across improve water quality and carbon reten- watersheds, cropland selected for retire- tion benefits in a 90,470-acre agricultural ment in all watersheds is closer to water

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watershed in Ontario. They reported that Dredging Versus Best 9.7%, 16.5%, 25.2%, and 39.6% of the Management Practices land must be in no-till to achieve 20%, 25%, 30%, and 35% sediment reduction, We use Tuttle Creek Lake and its water- respectively. Their study assumed a corn- shed as a preliminary case study to examine soybean-wheat cropping system. Average the economics of watershed protection and costs ranged from $10.89/acre per year reservoir rehabilitation. Tuttle Creek Lake to $12.26/acre per year. As the sediment is a 14,000-acre impoundment in northeast reduction goal increased, additional no-till Kansas at the lower end of the Big Blue acreage needed and costs also increased. As River. The 9,628-square-mile watershed expected, the percentage of land in no-till supplying the lake is largely agricultural. varied across subwatersheds because of the The majority of the watershed extends cost relative to amount of reduced sedi- north into Nebraska, and the lower quarter mentation. Subwatersheds that required is in Kansas. The USACE built Tuttle a higher percentage of no-till cropland to Creek Lake in 1962 for flood control, achieve the least-cost solution generally had irrigation, water supply, recreation, fish higher land slope and more erosive soils; and wildlife, low-flow augmentation, and costs for using no-till were relatively lower navigation-flow supplementation for Mis- in these areas. souri River barge traffic. The lake provides up to 50% of the Kansas River flow; this Within a watershed, the number of sub- river is a public water source for Topeka, watersheds that might need to be modeled Lawrence, and Kansas City. Table 5 pro- affects the number of regions that can be vides additional information about the lake used to determine a cost-effective targeting and watershed. approach for sediment reduction. Using data from Soil and Water Assessment Tool As of 2005, which was 43 years since the (SWAT) models of four Iowa watersheds, reservoir was completed, Tuttle Creek Lake Jha et al. (2004) developed preliminary contained 266,199,450 cubic yards of sedi- guidelines for subdividing a watershed into ment. Although Table 4 shows a range of subwatersheds for modeling purposes. They dredging costs, we assume the cost of dredg- found that predicted sediment yields are ing is $5.00/cubic yard for the remainder related to subwatershed size and delinea- of our discussion. Total estimated cost of tion and suggested modeling studies should removing sediment from Tuttle Creek include sensitivity analyses with various Lake at $5.00/cubic yard is $1,330,997,250 subwatershed delineations to determine the (which translates to $301/watershed- appropriate level for actual analysis. acre). Calculating the annual payment on a loan for the total dredging cost provides These spatial targeting studies reveal an perspective; assuming a 7% interest rate important policy issue: How should BMPs and 43-year period, the loan payment is for sediment control be spatially distributed $98,541,573/year or $22.28/acre of crop- to achieve optimal results (i.e., additional land in the watershed. Clearly, dredging is costs of sediment control equal the addi- an expensive option. tional benefits)?

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Table 5. Tuttle Creek Lake and watershed characteristics, dredging costs, and equivalent per-acre expenditures Characteristics Original conservation storage pool (acre-feet) 425,000 Sediment deposited as of 2005 (acre-feet) 165,000 Sediment deposited as of 2005 (cubic yards)a 266,199,450 Drainage area (square miles) 9,600 Drainage area (acres) 6,144,000 Pastureland (%) 16% Pastureland (acres) 983,040 Cropland (%) 72% Cropland (acres) 4,423,680 Other (%) 12% Other (acres) 737,280

Dredging Cost in 2005 Cost per cubic yard $5.00 Dredging and disposal cost per acre foot $8,066.65 Sediment deposited as of 2005 (acre-feet)a 165,000 Cost to remove sediment deposited until 2005 $1,330,997,250

Onetime Equivalent Costs Cost per acre of cropland $301 a Projected based on average annual sedimentation rate to 1999

Although dredging is effective at removing A detailed analysis of this decision for sediment, it does not prevent sedimenta- Tuttle Creek Lake or other reservoirs is tion. If accumulated sediment has not beyond the scope of this paper. A complete significantly reduced reservoir functions study should consider costs, benefits, and and benefits, it might be reasonable to forgo the optimal level of sediment control, and dredging and instead implement manage- determining the best approach to man- ment practices that significantly reduce the age erosion and sediment requires a more need for future dredging. This decision will detailed economic analysis of the number depend on sediment source, sedimentation of acres within a watershed that can be rate with and without management prac- treated with a variety of practices. The fol- tices, effectiveness and cost of management lowing analysis does not consider all costs practices, dredging cost inflation, the plan- and benefits. However, given a number of ning horizon, and the discount rate used to assumptions, we estimate how many acres calculate present values. of land can be treated with four individual management practices: vegetative buffers, no-till, terraces, and streambank stabilization.

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Our analysis examines how many acres a the current rate of sedimentation versus management practice can be applied to if a reduced rate of sedimentation that will savings generated from reduced dredging result from implementing management finance the management practice (Figure practices. Because we do not know the 4). Estimated future savings from dredg- specific effectiveness, cost, or combina- ing costs avoided because of implementing tion of management practices that will be sediment reduction management practices appropriate for each area in the watershed, are a key component of this analysis. To we apply general assumptions to the entire determine these values, we estimate the watershed. Our analysis is limited to costs; reservoir sedimentation rate with and with- therefore, we do not consider any benefits out management practices over a 20-year resulting from reduced erosion and sedi- planning period. We also estimate the cost mentation (Smith et al., 2007). of dredging 20 years in the future based on In the following scenarios, we use characteristics of the Tuttle Creek Watershed Select Management Practice listed in Table 5. We examine four management strategies (i.e., vegetative buffers, no-till, terraces, and streambank stabiliza- Determine E ectiveness of Erosion and Sediment Reduction tion) to determine how many acres they can potentially be applied to based on cost savings from reduced dredging. Cost sav- Select Time Period for Analysis ings for all strategies, summarized in Table 6, are based on a 2005 dredging cost of $5.00/cubic yard inflated at a 5.81% annual Estimate Cost of Dredging in a Future Year for Do Nothing inflation rate over the next 20 years and versus Management Practice a 7% annual discount rate for the present value calculations (Appendix A). Dredging cost inflation rate is based on historical data Calculate Future Savings in Dredging Costs Due to (Figure 5). Management Practices In the first scenario, we assume vegeta-

Adjust Savings to tive buffers are 50% effective at reducing Present Value and Annualize erosion and the sedimentation rate (Devlin et al., 2003). Compared with applying no management practices, installing vegeta- Estimate Annualized Compare Savings to Cost of Management Annualized Cost of tive buffers will result in 61,906,849 fewer Practice Management Practice cubic yards to dredge in 20 years. Estimated dredging cost savings are $247,495,574 Calculate Number (2005$), equivalent to $55.95/cropland of Acres Potentially acre. Average annual savings over the Applied 20-year period are $5.28/cropland acre. The interpretation of this value is that Figure 4. Method for comparing dredging spending $5.28/acre per year on every acre with management practices of cropland in the watershed over the next

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Table 6. Estimation of dredging cost savings from erosion reduction Management Practice Do Vegetative Streambank No-Till Terrace Nothing Buffera Stabilizationab Dredging inflation 5.81% 5.81% 5.81% 5.81% 5.81% Initial dredge cost ($/cubic yard) $5.00 $5.00 $5.00 $5.00 $5.00 Sediment rate based on 1962 to 2005 6,190,685 6,190,685 6,190,685 6,190,685 6,190,685 (cubic yards per year) Reduction in sediment rate due to 0.00% 50.00% 75.00% 30.00% 90.00% management practice New sediment rate (cubic yards per 6,190,685 3,095,342 1,547,671 4,333,479 619,068 year) Number of years at this new sediment 20 20 20 20 20 rate Accumulated sediment over 20-year 123,813,698 61,906,849 30,953,424 86,669,588 12,381,370 period (cubic yards) Reduction in sediment to dredge 61,906,849 92,860,273 37,144,109 111,432,328 compared with do nothing Future dredging cost ($/cubic yard) $15.47 $15.47 $15.47 $15.47 $15.47 Future dredge cost of 20-year $1,915,459,554 $957,729,777 $478,864,888 $1,340,821,688 $191,545,955 accumulation Future savings in dredging cost $957,729,777 $1,436,594,665 $574,637,866 $1,723,913,598 Discount rate for present value 7.00% 7.00% 7.00% 7.00% 7.00% calculations Present value of future dredging costc $494,991,148 $247,495,574 $123,747,787 $346,493,803 $49,499,115 Present value of dredging savings $247,495,574 $371,243,361 $148,497,344 $445,492,033 compared with do nothingc Annualized savings $23,361,831 $35,042,747 $14,017,099 $42,051,296

Onetime savings per acre Savings per acre of cropland $55.95 $83.92 $33.57 $100.71 Savings per acre of 50% of cropland $111.90 $167.84 $67.14 $201.41

Annualized savings per acre over selected year period Savings per acre of cropland $5.28 $7.92 $3.17 $9.51 Savings per acre of 50% of cropland $10.56 $15.84 $6.34 $19.01

Management practice cost $/acre/year $65.00 $10.00 $20.00 $332.04 Potential crop acres applied 8,985,320 3,504,275 700,855 3,166,132 Percentage of cropland in watershed 203.12% 79.22% 15.84% 71.57%

Management practice cost $/stream- $4,024.73 bank mile/year Potential streambank miles 10,448 a We assume 1 acre of buffer treats 25 aces of cropland b Cost for streambank stabilization includes an adjustment for landowner benefits (Refer to Table 3) c Amounts reported in 2005 dollars

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$4.00

$3.50

$3.00

$2.50

$2.00

Cost/Cubic Yard Cost/Cubic $1.50

$1.00

$0.50

$0.00 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 Year Figure 5. Historical dredging costs in nominal dollars Data source: USACE (2005). Average annual increase is 5.8%.

20 years will equal savings from reduced yards to dredge in 20 years. Estimated dredging due to implementing buffer strips dredging cost savings are $371,243,361 that are considered 50% effective. If only (2005$), equivalent to $83.92/cropland 50% of crop acres actually need manage- acre. Average annual savings over the 20- ment practices, $10.56/acre can be spent year period are $7.92/cropland acre. If only each year. If we assume the annualized cost 50% of crop acres actually need manage- of a vegetative buffer is $65/acre per year ment practices, $15.84/acre can be spent and each acre of vegetative buffer treats each year. At $10/acre per year, no-till can 25 acres (Smith, 2004), savings will cover be used on 3,504,275 acres (79% of crop costs when buffers are applied on up to acres) in addition to any acres already under 8,985,320 acres. This is more than twice no-till. If no-till needs to be applied to less (203%) the number of cropland acres in the than 79% of cropland acres, savings from watershed. Under these assumptions, using reduced dredging will pay for the cost of a vegetative buffers appears more economical program that provides $10/acre per year to than dredging. use no-till.

The second scenario examines no-till, The third scenario examines farmable ter- which is considered 75% effective at races, which are considered 30% effective reducing erosion and the sedimentation at reducing erosion and the sedimenta- rate (Devlin et al., 2003). Compared with tion rate (Devlin et al., 2003). Compared applying no management practices, using with applying no management practices, no-till will result in 92,860,273 fewer cubic installing farmable terraces will result in

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37,144,109 fewer cubic yards bank stabilization are very site specific, but to dredge in 20 years. Esti- given the average costs reported in Table mated dredging cost savings are 3, annualized cost for a 15-year period is $148,497,344 (2005$), equivalent $332/acre excluding any cost-share and to $33.57/cropland acre. Average annual incentive payments but including annual savings over the 20-year period benefits to the landowner in the form of are $3.17/cropland acre. If only 50% of annual income from and asset value of crop acres actually need management prac- preserved land (Williams et al, 2004). At tices, $6.34/acre can be spent each year. We this cost, streambank stabilization can be assume 223 linear feet of terrace are applied used on 10,448 streambank miles. Assum- to each acre requiring terracing. Using ing each acre of vegetative buffer in the the lowest establishment cost reported in stabilization area treats 25 acres (Smith, Table 1 ($.66/linear foot), terrace establish- 2004), the stabilization project can treat ment costs $147.18/acre. Annualizing this 3,166,132 acres (71.6% of crop acres). If cost using a 10-year life and 6% interest each stabilization acre treated only 10 acres, rate results in a $20/acre per year cost. At dredging cost savings could be used to treat this cost, terraces can be used on 700,855 1,266,453 acres (29.6% of crop acres). Fully acres (15.8% of crop acres) in addition to evaluating whether streambank stabiliza- any acres that already have terraces. Fully tion is more economical than dredging evaluating whether establishing terraces is requires determining how many stream- more economical than dredging requires bank miles need to be stabilized to reduce determining how many acres of terraces are sedimentation. needed to reduce sedimentation. Our calculations do not reflect the In the final scenario, we assume stream- optimum number of acres to which man- banks are stabilized as described previously agement practices should be applied. We do (Williams et al., 2004) and include buffer not know, from a technical and economic strips that are 90% effective at reduc- perspective, how suitable no-till, terraces, ing erosion and the sedimentation rate. vegetative buffers, or streambank stabiliza- Compared with applying no management tion might be for various locations in the practices, streambank stabilization will watershed or the number of acres or miles result in 111,432,328 fewer cubic yards to that actually need these practices applied. dredge in 20 years. Estimated dredging cost Numbers presented represent only the savings are $445,492,033 (2005$), equiva- potential area to which these management lent to $100.71/cropland acre. Average practices can be applied based solely on annual savings over the 20-year period are cost savings from reduced dredging. The $9.51/cropland acre. If only 50% of crop more expensive or less effective the practice, acres actually need management practices, the fewer acres to which it can be applied. $19.01/acre can be spent each year. We Estimates provide some perspective on assume that 100 linear feet of buffer width dredging versus use of soil erosion manage- are required for each linear foot of stream- ment practices. Our brief analysis indicates bank requiring stabilization. Therefore, 1 that in situations where the amount of acre of land is required for every 436 feet accumulated sediment has not reduced of streambank stabilized. Costs for stream- a reservoir’s usefulness, it could be more

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economical for the government to fund strategy comparison. For example, if an expenditures for management practices that in-field strategy keeps more soil on a field, reduce further erosion and sedimentation productivity of that field will be greater in a watershed than to rely on dredging in over time; this benefit is not realized as the future. much through in-reservoir strategies. Other benefits associated with in-field strategies From an economic perspective, the optimal include reduced nutrient and pesticide level of sedimentation control is when the loads entering the reservoir and increased marginal (additional) benefits of control wildlife habitat. practices equal the marginal costs of implementing those practices. Because data on Sensitivity Analysis costs and benefits of sediment management Although many variables in our analysis are practices are significantly limited, this paper unknown, we perform sensitivity analy- provides only a rough analysis and does not ses on three variables that can affect the consider benefits of BMPs versus dredging. analysis: sedimentation rate, dredging cost, Further, none of the articles we reviewed and discount rate. Because BMPs such as presented a model for or attempted a CRP land, terraces, and no-till have been comprehensive analysis. In previous litera- established over time in the watershed, ture, alternative levels of sedimentation simply averaging sedimentation rates over reduction simply are assumed. Although the time period since the impoundment we do not attempt to quantify benefits was constructed might overstate the future of BMPs or dredging, we recognize that sedimentation rate. Therefore, we use in-field BMPs might provide benefits, in alternative sedimentation rates (110%, addition to reduced sediment loads, that 100%, 90%, 80%, and 70% of the original) need to be accounted for in a comprehen- in a sensitivity analysis (Figure 6). The sive in-field versus in-reservoir management

$50,000,000 Streambank Stabilization No-Till $45,000,000 Vegetative Bu er $40,000,000 Terrace $35,000,000 $30,000,000 $25,000,000 $20,000,000

Annualized Savings Annualized $15,000,000 $10,000,000 $5,000,000 $0 70% 80% 90% 100% 110% % of estimated sedimentation rate Figure 6. Annualized savings as a function of sedimentation rate Annualized savings are avoided dredging costs that can be spent on BMPs. Annualized cost savings from reduced dredging at the original sedimentation rate for each management practice are reported in Table 7 and range from $14 million for terraces to $42 million for streambank stabilization. These values are represented at the 100% level in this figure. Sedimentation in Our Reservoirs: Causes and Solutions 91 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

original rate is 6,190,685 cubic yards/year. Original dredging cost is $5.00/cubic If the expected sedimentation rate without yard (2005$). Future dredging costs are management practices is lower than the unknown and could be lower because of original rate, annualized savings decline. technological improvements. Therefore, we A lower sedimentation rate means fewer performed a sensitivity analysis using vari- dredging costs are avoided by using BMPs. ous dredging costs inflated at an annual rate As a result, savings from reduced dredging of 5.81% (Figure 7). If dredging costs less in costs cover application of BMPs on fewer the future, annualized savings from reduced acres or stream miles (Table 7). dredging decline and will cover application of BMPs on fewer acres or stream miles (Table 7). Alternatively, if dredging costs are higher than expected, annualized savings increase.

Table 7. Sensitivity of percentage of acres or potential streambank miles to which BMPs could be applied based on dredging savings for various sedimentation rates, dredging costs, and discount rates Sedimentation rate (% of original) 70% 80% 90% 100% 110% Percentage of cropland in watershed Vegetative buffer 142.2% 162.5% 182.8% 203.1% 223.4% No-till 55.4% 63.4% 71.3% 79.2% 87.1% Terrace 11.1% 12.7% 14.3% 15.8% 17.4% Potential streambank miles Streambank stabilization 7,314 8,359 9,403 10,448 11,493

Dredging cost $3.00 $4.00 $5.00 $6.00 $7.00 Percentage of cropland in watershed Vegetative buffer 121.9% 162.5% 203.1% 243.7% 284.4% No-till 47.5% 63.4% 79.2% 95.1% 110.9% Terrace 9.5% 12.7% 15.8% 19.0% 22.2% Potential streambank miles Streambank stabilization 6,269 8,359 10,448 12,538 14,628

Discount rate 4% 5% 6% 7% 8% Percentage of cropland in watershed Vegetative buffer 279.6% 251.8% 226.4% 203.1% 182.0% No-Till 109.1% 98.2% 88.3% 79.2% 71.0% Terrace 21.8% 19.6% 17.7% 15.8% 14.2% Potential streambank miles Streambank stabilization 14,384 12,954 11,644 10,448 9,360

92 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Discount rate also affects the analysis. The discount rate, the larger the original discount rate is 7% per year. A annualized savings from reduced lower discount rate discounts future values future dredging. These larger less. Therefore, future values discounted savings can be used to implement to the present are worth more (in 2005$) BMPs on more acres or streambank or are larger (Figure 8). The lower the miles (Table 7).

$70,000,000 Streambank Stabilization No-Till $60,000,000 Vegetative Bu er Terrace $50,000,000

$40,000,000

$30,000,000

Annualized Savings Annualized $20,000,000

$10,000,000

$0 $3.00 $4.00 $5.00 $6.00 $7.00 Dredging Cost per cubic yard Figure 7. Annualized savings as a function of dredging cost Annualized savings are avoided dredging costs that can be spent on BMPs. Annualized cost savings from reduced dredging at the original dredging cost for each management practice are reported in Table 7 and correspond to the $5.00 level in this figure.

$70,000,000 Streambank Stabilization No-Till $60,000,000 Vegetative Bu er Terrace $50,000,000

$40,000,000

$30,000,000

Annualized Savings Annualized $20,000,000

$10,000,000

$0 4% 5% 6% 7% 8% Discount Rate Figure 8. Annualized savings as a function of discount rate Annualized savings are avoided dredging costs that can be spent on BMPs.

Sedimentation in Our Reservoirs: Causes and Solutions 93 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

A Potential Process 1. Sediment Source Identification for Evaluating the Best 2. Data Collection Approach for Sediment - Watershed characteristics Reduction and Reservoir - Rates of sedimentation and erosion Rehabilitation - Extent and types of management practices currently in place Evaluating the best approach for reducing - Potential management practices additional sedimentation in watersheds with reservoirs for which dredging is being 3. Modeling considered is a large and demanding task - Develop baseline watershed model that is beyond the scope of this paper. - Evaluate erosion and sedimentation Many issues require discussion and analysis: changes under alternative manage- determining important sediment sources, ment scenarios effectiveness of management practices for 4. Economic Analysis these sources, effectiveness of manage- - Evaluate effects of erosion and ment practices under heavy rainfall and sedimentation on stakeholders high stream flow events, and location and - Determine costs of alternative amount of and appropriate management practices modeled at field and practices for acres needing treatment. watershed scale Many questions remain: Is there an accept- - Evaluate sediment reduction cost- able level of sedimentation? What levels effectiveness using spatial targeting of sedimentation are acceptable before approaches dredging is the only option? What is the - Estimate benefits of alternative appropriate combination of management scenarios for land managers, practices and dredging? What are the producers, and watershed users environmental, flood control, irrigation, water supply, recreation, fish and wildlife, low-flow augmentation, and navigation- Available Tools and Tool flow supplementation costs and benefits of Development alternative management approaches? What Livestock and cropland BMPs can benefit time period should be considered? What society as a whole, but it also is important is the quality of sediment and is any of it to consider how these BPMs affect produc- marketable? ers and land managers who decide whether to adopt the practices and are responsible We need to know more about management for implementing them. To facilitate this practice costs, which vary by site and with analysis, several spreadsheet-based deci- commodity price changes. The follow- sion-assistance tools are currently under ing outline provides a general research development in the Department of Agricul- approach for a more detailed analysis of tural Economics at Kansas State University. these issues and questions; it is not inclusive These tools are designed to analyze BMPs of the entire decision-making process. Fig- based on economic benefits and costs at ure 9 provides an overview of this approach. the individual field or farm level (societal benefits and costs are not included in the

94 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

analysis) and will allow producers or land managers to identify sediment- and nutri- Establish Watershed Characteristics ent-reducing BMPs, determine costs and and Management Practices benefits of BMPs for their operations, and identify available cost-share funding.

Identify Erosion Rates and Sources The K-State Vegetative Buffer Decision- Making Tool (Smith and Williams, 2007) is designed to answer the following ques- Develop Baseline Watershed Model tions: What are the benefits and costs of vegetative buffers, and does it make sense to install a buffer on my operation? This Identify Alternative BMPs spreadsheet tool provides information, for Each Erosion Problem specific to vegetative buffers, about three factors: economic benefits, costs, and avail- Determine E ectiveness of able financial programs and incentives. The Erosion and Sediment Reduction tool also compares net benefits of buffers with net benefits from cropping. Other decision-making tools currently under Select Time Period for Analysis consideration will focus on economics of alternative tillage (e.g., reduced tillage or no-till), riparian forest buffers, streambank Evaluate Erosion and Sedimentation stabilization projects, and various livestock Change under Alternative BMPs and rangeland management strategies.

Research Issues Estimate Costs and Benets of Each BMP Combination at Watershed Level and Opportunities Predicting effects of management practices on erosion and sedimentation requires Estimate Cost of Dredging in a development of detailed watershed models. Future Year for Do Nothing Scenario These models must include information about sediment source because source location will influence the type of management Compare Alternatives practices used to reduce the sedimentation rate. Type of management practices selected influences the cost of sediment Figure 9. Preferred approach for comparing dredging with sedimentation BMPs reduction and overall costs and benefits of sediment reduction versus dredging. Even if watershed models can be designed to determine the technically best sediment reduction management practices, site-specific costs will influence selection

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of the most economical manage- active sulfur dioxide market for air emis- ment practices. Currently, we can sions, the emissions target was achieved for assign only a general cost to each less than half its originally estimated cost management practice even though (NCEE, 2001). different managers can have different costs for implementing the same Although current programs target nutri- practice. Two possible approaches for ent reduction, WQT programs for erosion gaining additional information about costs control can be structured similarly. Eligible of implementing management practices are BMPs in nutrient trading programs also Water Quality Trading (WQT) programs reduce sedimentation because a large por- and BMP auctions. tion of discharged nutrients are dissolved in soil particles. In an erosion control WQT Water Quality Trading programs create a program, each credit represents a specified market for “water quality credits.” Farmers amount of erosion reduction (e.g., one ton generate income by selling these credits and of soil loss). A schedule delineating the then are obligated to implement certain number of credits generated by each BMP BMPs on their farms. A recent report will need to be developed from watershed (Breetz et al., 2004) identified more than modeling simulations, which already are 70 WQT programs operating in the United being developed for various watersheds in States, and additional WQT programs are Kansas (Mankin, 2005). Credits generated being adopted rapidly to manage a variety by a particular BMP can vary across differ- of water quality problems. Most existing ent subwatersheds depending on soil and WQT programs aim to reduce nutrient topographic features. Landowners across concentrations, primarily nitrogen and the watershed will be eligible to sell credits, phosphorous, in streams and lakes. In a and likely buyers include state agencies, typical program, point source polluters local municipalities, recreation entities, and (mainly municipal wastewater treatment concerned environmental groups. Buyers plants) buy water quality credits from will set prices based on financial gain from nonpoint source polluters (farmers). Point reduced dredging, improved recreation sources polluters use credits to offset some opportunities, and other benefits. Essen- of their current nutrient discharges to meet tially, sellers will be providing cost estimates regulatory discharge limits. In essence, they for controlling erosion and sediment to purchase nutrient reductions from farmers various degrees, allowing more accurate instead of installing potentially costly treat- identification of erosion and sediment ment technologies. reduction costs.

Economists often favor market approaches A BMP auction is another market-based to environmental management because program with potential to accurately iden- these approaches ensure cost-effectiveness. tify sediment reduction costs. In a BMP If certain conditions are met, active mar- auction, agricultural producers compete kets ensure the environmental quality by submitting bids to supply the buyer target is met at the lowest possible cost for (i.e., project sponsor) with water quality the watershed as a whole (Atkinson and improvements through BMP implementa- Tietenberg, 1991). For example, in the tion. Bids are ranked by amount of water

96 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

quality improvement generated per dollar. Buyers contract first with the producer Research Needs who can offer water quality improvement Additional research should be con- at the lowest price. This process is repeated ducted to determine: until a predetermined point is reached (e.g., funds are exhausted or bids no longer meet 1. Sources of sediment and rates of a certain water quality improvement/price sedimentation ratio target). These auctions allow buyers to 2. Effectiveness of sediment- identify and purchase the most cost-effec- reducing BMPs in high- and tive water quality improvements with a low-runoff events specified budget. 3. Costs and returns of alternative A unique characteristic of BMP auctions BMPs is that if existing incentives (e.g., cost-share 4. Future dredging costs or incentive payments) are insufficient to induce cooperation for high-priority, 5. Environmental and economic high-impact improvements, a producer can effects of alternative watershed “reveal” the price required to undertake the protection and reservoir rehabili- desired action. In the marketplace, numer- tation strategies ous producers provide such information, and project sponsors can select among competing bids to purchase the most cost-effective bundle of pollution reduction investments. Further, the totality of information provides valuable insight into the incentive levels required to induce producers to adopt various desirable practices.

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Appendix A: Selecting a Discount Rate Selecting an appropriate discount rate reflects the time value of money. A dollar received today is valued more than a guarantee today of a dollar to be received in the future because the future payment implies forgone consumption or investment opportunities today. Many agree that a discount rate should be based on the minimum acceptable rate of return or the opportunity cost of dollars invested in private investments. Raising taxes to pay for public projects removes dollars from private investments that earn a rate of return for investors. Selecting a discount rate can be difficult and controversial because higher discount rates place less emphasis on future benefits and costs. Choice of discount rate is further complicated if both private and public funds are involved in projects because of the nature of who pays and benefits from the projects over time.

Discounting is necessary for economic analysis of projects that have benefits and costs over many years. Discounting benefits, savings, and costs transforms dollar flows occurring in different time periods to a common measure of time value for analysis and comparison, but discount rate affects results. In this study, present values are calculated in 2005 dollars.

One alternative is to calculate a discount rate according to the following formula: i = (r + 1)(1 + f) - 1 where: i = nominal discount rate or minimum acceptable rate of return on the investment of dollars, r = real rate of return or discount rate, and f = inflation rate.

A reasonable real rate of return for a risk-free investment is 2.0% to 3.5% (AAEA, 2000). Inflation rate can be measured by the average rate of change in the Personal Consumption Expenditure Index. The long-run average annual rate from 1960 to 2007 was approximately 3.6% (Bureau of Economic Analysis, 2007). Thus, the real rate of return (r) at the midpoint of the suggested range is 2.75%, and an inflation rate (f) of 3.6% gives a resulting discount rate (i) of 6.45%.

The Office of Management and Budget suggests using a 7% rate for benefit-cost analysis of projects (National Center for Environmental Decision-Making Research, 2007), but those who place more emphasis on the future and are in favor of larger government investments in public projects will argue for a lower discount rate. Those who favor less government expenditures and place more emphasis on the present will favor a higher discount rate. The USACE (2002) recently used 6.875% and 3.5% discount rates. The NRCS provides discount rates used for projects since 1957 at: http://www.economics.nrcs.usda.gov/cost/discountrates.html. Since 1990, rates ranged from 4.875% to 8.875%. We used a 7% rate to calculate present values and amortized or annualized present values.

98 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Acknowledgments Breetz, H.L., Fisher-Vanden, K., Garzon, L., Jacobs, H., Kroetz, K., and Terry, R. 2004. Water quality trading We thank the following individuals for contributing and offset initiatives in the United States: A compre- knowledge, data, references, or reviews: hensive survey. Report for the USEPA. Hanover, NH: Dartmouth College Rockefeller Center. Phil Balch, Watershed Institute, Topeka, KS Bureau of Economic Analysis. 2007. Personal con- Nick Brozović, Department of Agricultural and Con- sumption expenditures: Chain-type price index. sumer Economics, University of Illinois Washington, DC: U.S. Department of Commerce.

Dan Devlin, Department of Agronomy, Kansas State California Stormwater Quality Association. 2003, University January. Sediment trap. California stormwater BMP handbook fact sheet SE-3. Menlo Park, CA. Available Allen Featherstone, John Leatherman, Richard Llewe- at: http://www.cabmphandbooks.com/Construction. lyn, and Jeff Peterson, Department of Agricultural asp. Accessed Dec. 2006. Economics, Kansas State University Carman, D. 2006. Terraces. Little Rock, AR: Paul Gallagher and Larry Kuder, National Resources USDA-NRCS. Available at: www.sera17.ext.vt.edu/ Conservation Service, Salina, KS Documents/BMP_Terraces.pdf. Accessed Nov. 2006. Kyle Juracek, United States Geological Survey, Lawrence, Clark, E.H., Haverkamp, J.A., and Chapman, W. 1985. KS Eroding soils: The off-farm impacts. Washington, DC: Steve Nolen, Chief Environmental Branch, Planning The Conservation Foundation. Division, U.S. Army Corps of Engineers [CTIC] Conservation Technology Information Center. Waite Osterkamp, United States Department of the Inte- 2005. 2004 National crop residue management rior—United States Geological Survey, Tucson, AZ survey. Available at: www.ctic.purdue.edu/ctic/ crm2004/1990-2004data.pdf. Accessed April 6, 2005. Thomas Roth, National Resources Conservation Service, Clay Center, KS Devlin, D., Dhuyvetter, K., McVay, K., Kastens, T., Rice, C., Janssen, K., et al. 2003, February. Water Kerry Wedel, Kansas Water Office, Topeka, KS quality best management practices, effectiveness and cost for reducing contaminant losses from cropland. Publication MF-2572. Manhattan, KS: Kansas State References University. Dhuyvetter, K.C. and Kastens, T. 2005. Economics [AAEA] American Agricultural Economics Association. of no-till in Kansas. Available at: www.agmanager. 2000, February. Commodity costs and returns estima- info/dhuyvetter/presentations/default.asp. Accessed tion handbook. Report of the AAEA Task Force on April 11, 2005. Commodity Costs and Returns. Ames, IA: AAEA. Dhuyvetter, K. and Kastens, T. 2006, October. Kansas Al-Kaisi, M. 2000. Soil erosion: An agricultural produc- land prices and cash rental rates. Publication MF-1100. tion challenge. Iowa State University, Department of Manhattan, KS: Kansas State University. Agronomy. Available at: www.ent.iastate.edu/Ipm/ Icm/2000/7-24-2000/erosion.html. Accessed Dec. Dhuyvetter, K.C., Thompson, C.R., Norwood, C.A., and 2006. Halvorson, A.D. 1996. Economics of dryland cropping systems in the Great Plains: A review. Journal of Atkinson, S. and Tietenberg, T. 1991. Market failure Production Agriculture, 9:216-222. in incentive-based regulation: The case of emissions trading. Journal of Environmental Economics and Dredging Specialists. 2007. Dredging 101. Available at: Management, 21:17-31. http://www.dredgingspecialists.com/Dredging101. htm. Accessed Jan. 2007 Baker, D. 2007. Can reservoir management reduce sediment deposition? Presentation at the Water in the Feather, P., Hellerstein, D., and Hansen, L. 1999. Future of Kansas Conference. March 15. Topeka, KS. Economic valuation of environmental benefits and the targeting of conservation programs: The case of Bejranonda, S., Hitzhusen, F.J., and Hite, D. 1999. Agri- the CRP. Agricultural Economics Report No. 778. cultural sedimentation impacts on lakeside property Washington, DC: USDA Economic Research Service, values. Agricultural and Resource Economics Review, Resource Economics Division. October:208-218.

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Sedimentation in Our Reservoirs: Causes and Solutions 101 This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu. This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu. Reusing Dredged Sediment: Geochemical and Ecological Considerations

Margaret A. Townsend, Kansas Geological Survey, University of Kansas Nathan O. Nelson, Department of Agronomy, Kansas State University Deborah Goard, Kansas Forest Service DeAnn Presley, Department of Agronomy, Kansas State University

Introduction Estimates of chemicals deposited in sediments from eight Kansas reservoirs Options for rehabilitating federal reservoirs range from approximately 9,720 to 3 and water-supply lakes filling because of million lb/year of phosphorus; 19,000 to excess sedimentation include controlling 7.6 million lb/year of nitrogen; 96 to 2,700 pollutant and sediment inputs, decommis- lb/year of selenium; 620 to 58,000 lb/year sioning dams, renovating dams or building of arsenic; 330 to 85,000 lb/year of lead; them higher, and dredging (Peterson, 1982; 1,400 to 366,000 lb/year of zinc; and 340 Caldwell, 2007). In Kansas, dredging to 100,000 lb/year of copper (Appendix sediments is one of several methods being A-1). These trace elements and nutrients considered for reservoir restoration. How- may be mobile or immobile when sediment ever, many issues need to be addressed prior is moved from reservoirs to land. However, to pursuing this option: dredging cost, these estimates imply that large quantities finding sites on which to apply dredged of trace elements and nutrients are associ- sediments, transporting sediments to ated with reservoir sediment and may cause those sites, effects on aquatic biota due to problems if land application is used as a sediment resuspension, effects on reservoir sediment disposal method (see Appendix water quality due to release of trace ele- A-2 for estimates of total sediment and ments from sediment during the dredging chemical loads in eight reservoirs). process, and effects on aquatic and land biota due to chemical changes in land- applied sediment. In this white paper, we Overview of Dredging focus on the last issue and provide an over- and Sediment Disposal view of possible sediment chemistry effects Options associated with dredging Kansas reservoirs. Dredging is used to remove sediments from lakes or reservoirs to restore storage area, Chemistry of reservoir sediment is of reduce eutrophication, remove aquatic concern because of 1) effects on reservoir plants and algae buildup along lake edges, water quality during the dredging process, and improve water quality by reducing particularly if the reservoir is a primary nutrient sources, especially phosphorus drinking-water source, and 2) effects of (Ryding, 1982; Darmody et al., 2004; Sigua, remobilized metals, trace elements, or 2005). Most literature on dredging deals nutrients on aquatic and land biota and with harbor or canal remediation in areas water resources. If large quantities of chem- of high shipping traffic, such as the Great ical constituents of concern are present, Lakes or oceanic ports, and many stud- potential chemical effects of land-applied ies involve toxic chemical concentrations sediment can be important for elements higher than those found in Kansas envi- such as lead, zinc, chromium, cadmium, ronments. The keys to removing polluted arsenic, or selenium and nutrients such as sediments are minimizing disruption of nitrogen and phosphorus.

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the sediment-water interface, containing can seal the diked area, preventing draining polluted, dredged materials until they are and delaying remediation (Dunst, 1987). remediated, and treating water accompany- Lack of storage space can cause flooding ing the sediment (Peterson, 1982). Prior to overflow from the CDF, and excess nutri- dredging, sediment should be characterized ents, sediment, and other contaminants for deposited thickness, particle size, bulk could return to the lake if the CDF is density, organic and nutrient content, and located nearby. potential contaminant concentrations. Land Application Typically, dredged sediment is disposed of Issues associated with land application of by either placement in a confined disposal dredged sediment include compatibility facility (CDF) or application to agricultural of sediment with the host soil with respect land, grasslands, brownfields, strip mines, to leaching, stability of the land for use of highway borders, and other areas, provided heavy machinery, and overland flow of sedi- that the chemistry of the sediment will not ments and contaminants back to the lake harm the soil or environment (Skogerboe (Cooke et al., 1986). Land application of et al., 1987; Darmody et al, 2004; Kelly et dredged sediments is frequently used when al., 2007). CDFs are used for contaminated chemistry of the sediments is not poten- sediments, those with metal concentrations tially toxic to aquatic or plant life and areas above environmental toxicity levels recom- are located away from the dredged lake. mended by the USEPA (1997), and in Dredged material that has low metal or areas with river or lake contamination from contaminant toxicities generally is suitable mining or industrial waste (Darmody et al., for various land uses including strip mine 2004). reclamation, brownfields, construction areas, agriculture, forestry, wetland areas, Confined Disposal Facilities parks, beaches, and landscaping (Darmody (CDFs) and Marlin, 2002; Machesky et al., 2005). CDFs are diked enclosures in which sediment or sediment slurries are deposited Work by Kelly et al. (2007) showed that to permit water mixed with the sediment mixing dredged sediment from the Illinois to leach or evaporate. Disposing dredged River with wastewater biosolids increased sediment in a CDF can be problematic organic and nutrient content of the sedi- if the facility is too small. Factors such ments, had a positive effect on microbial as sediment volume, water content, and biomass of the soil, and resulted in usable underlying soil type need to be considered farmland. In another study, using manure in the CDF design phase (Myers, 1996). as an amendment to dredged sediments Freshwater sediments have a high water-to- helped retain metals in the sediment and sediment ratio and are slow to settle. Slow enhanced removal of metals by plants (i.e., settling can cause diked areas to fill faster phytoremediation; Skogerboe et al., 1987). because of the volume of water accumulating with the sediment; usable retention area Work by Sigua et al. (2004a, 2004b) decreases until water has either evaporated showed that sediments from Lake Pan- or drained from the sediment (Peterson, asoffkee, FL, had 82% calcium carbonate 1982). Settling of fine-grained sediments content. When combined with agricultural 104 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

soil, these sediments had the same favor- elements currently stored in and annually able effects as liming, including enhanced moving into Kansas lakes are large (Appen- phosphorus and micronutrient availabil- dices A-1, A-2). Chemistry, soil physical ity, nitrification, nitrogen fixation, and properties, and potential contaminant haz- soil physical conditions (Nelson, 1981). ards of dredged material must be evaluated All trace element contents of reservoir prior to land disposal (Cooke et al., 1986; sediments were below USEPA sediment USACE, 1987). toxicity values (USEPA, 1997); therefore, agricultural or livestock industries could Environmental Effects of use the sediments to produce forages. In Dredging Sediment addition, sediment properties improved the level of local soil compaction and structure. Much of the sediment in freshwater lakes One Sigua et al. (2004b) study showed that is fine grained, generally silt and/or clay. grass yield from amended fields was greater Dredging this type of material, regardless than that from control sites, and forage of the depth of sediment removed, results from amended fields had increased crude in resuspension of some sediment. Resus- protein content. These studies show that pended sediment can interfere with light freshwater sediments with low levels of and food needs of benthic communities and trace elements can be used by agricultural is a major concern associated with reservoir industries with no obvious side effects. dredging.

A study by Darmody and Marlin (2002) Resuspension also can cause water-quality indicated that dredged, fine-grained lake problems, particularly in Kansas where sediment is suitable for agriculture if many rivers, streams, and lakes have Total allowed to drain sufficiently to support Maximum Daily Loads (TMDLs) of sus- heavy machinery. In that study, dredged pended sediments and nutrients above the sediment was applied to nearby agricultural recommended limits adopted by the Kansas land. Heavy metal composition of the soil Department of Health and Environment was below USEPA toxicity values (USEPA, (2008). Chemical effects associated with 1997), and nutrient values were sufficient fine-grained sediment include: 1) adsorp- to encourage plant growth and survival. tion of phosphorus species to fine sediment Bramley and Rimmer (1988) showed that particles and subsequent transport into with proper remediation by drainage, lakes, 2) recycling of phosphorus in water mixing with manure or biosolids, and use with potential increased eutrophication if of phytoremediation and other methods, sediment is disturbed, 3) increased total contaminated Rhine River sediments were inorganic nitrogen concentrations in water usable for landscaping, agriculture, and from conversion of ammonium-nitrogen in other material-fill situations. the sediment to nitrate-nitrogen in water, and 4) release of adsorbed trace elements Economics of dredged sediment trans- because of an environmental change from portation and availability of sufficient an anaerobic (low oxygen) to an aerobic land for disposal must be addressed before (oxygenated) environment (Barnard, 1978; land application can be used in Kansas. Cooke et al., 1986). Estimated volumes of sediment and trace

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Physical Effects of ness. However, organic matter content can Reusing Dredged be improved by adding amendments such Sediment on Land as compost, waste-treatment biosolids, or manure. Soil physical properties determine how liquids, gases, and heat move through a soil Applied sediment should have a texture profile, thereby affecting internal drainage similar to that of the original underlying and aeration of the soil profile. However, material; a layered system of contrast- sediment that is dredged from reservoirs ing textures is undesirable. The different is not soil and lacks many of the proper- textures affect sediment-soil permeability ties present in natural soils (SSSA, 2001). and movement of water vertically and hori- Vermuelen et al. (2003) estimated that 70% zontally in both unsaturated and saturated (by volume) of recently dredged sediment conditions (Hillel, 1998). Incorporating is water. To use dredged sediment on land organic amendments such as compost for growing vegetation, several physical decreases textural differences and improves properties must be modified. This section overall permeability (Burden and Sims, provides a brief review of selected physical 1999). properties that should be considered prior to land application of dredged, dewatered sediments. Soil Strength Soil strength is the measure of the capac- Particle-Size Distribution ity of a soil mass to withstand stresses. Soil strength is most affected by changes Particle-size distribution, also referred to in soil-water content and bulk density, as texture, influences sediment use. For although other factors including texture, example, sandy sediments can be used in mineralogy, cementation, cation composi- beach construction, whereas clayey mate- tion, and organic matter content also affect rial might make a liner material for ponds soil strength (SSSA, 2001). In agricultural or lagoons. Sediment with a loamy texture settings, increases in strength and bulk often is the best choice for supporting density usually result in decreased plant vegetation, whether in cropland, residential emergence, decreased soil aeration, and areas, or reclamation of degraded land. increased compaction (Unger and Kaspar, Reservoir sediment reflects local geography 1994). In Florida pastures, incorporating and soils but generally is composed of finer- carbonate-rich, dredged sediment increased grained sizes such as silt and clay (Darmody overall soil permeability and reduced soil and Marlin, 2002). compaction (Sigua et al., 2006). Freshly deposited, dredged sediments usually have Organic matter is important for supporting low soil strength and need modification by vegetation; it provides nutrient storage and amendments, plants, and/or drainage to cycling (cation exchange capacity), water- facilitate their future use (Darmody and holding capacity (important in coarser Marlin, 2002). At sites in Illinois, sediment sediments), and increased aggregation soil strength increased after addition of (ability for particles to combine; Tisdall amendments, use of water-loving plants, and Oades, 1982). Sediment with minimal and drainage of excess water (Darmody and organic matter content has reduced useful- Marlin, 2002). 106 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Structural Properties the development of sediments Structure is the arrangement of individual into soil into three processes: soil particles into aggregates, groups of physical, biological, and chemical. primary soil particles that cohere more The physical process of forming strongly to each other than to other sur- structure occurs through desiccation rounding particles (SSSA, 2001). Soil and the resulting formation of cracks. structure can be difficult to assess and During this process, sediment bulk quantify. However, soil structural charac- density decreases and void space increases, teristics are important because they control thereby increasing internal drainage of the movement of gases and solutes as well as a sediments. However, physical formation of variety of other biological, chemical, and structure occurs only in sediments with clay physical processes (for specific examples, see content greater than 8% and/or organic Diaz-Zorita et al., 2002, p. 5). Immediately matter content greater than 3% (Verm- after dewatering, dredged sediment con- uelen et al., 2003). tains no structure or aggregation. Growing aquatic plants in draining Soil aggregation is a function of organic sediment aids development of physical matter content, clay mineralogy, concen- properties by creating root cavities. These tration and ratio of ions, vegetation type cavities allow oxygen to penetrate soil, and abundance, and soil biology (Bronick leading to microbe growth and increased and Lal, 2005). Soil aggregates develop as aggregation and permeability (Loser and a function of five soil-forming factors: cli- Zehnsdorf, 2002). Terrestrial plants are mate, organisms, parent material, relief, and introduced naturally from seeds trans- time (Jenny, 1941). Aggregate stability is ported by wind and birds (Vermuelen et the ability of an aggregate to retain its shape al., 2003). Soil fauna such as bacteria, fungi, when wetted. The degree of both structure and earthworms decompose fresh organic and aggregate development affect entry matter and produce humus, a more stable and movement of water and air through form of organic matter that increases bind- soil. Plants cause changes in soil structure ing of soil particles into aggregates. through penetration of roots, modification of the soil-water regime, enmeshment of Surface soils containing stable aggregates soil particles and micro-aggregates by roots, resist formation of a surface soil crust and and deposition of carbon below ground; allow water to enter (infiltration) and move microbes alter soil structure by increasing through (permeability) the soil profile. soil stability (Angers and Caron, 1998). Darmody and Marlin (2002) showed that Soil aggregates and soil structure develop the rate of aggregate formation in dredged with time, vegetative growth, and wetting- sediments used for agriculture became drying and freeze-thaw cycles. Presence of similar to that of native soils over a 10-year water-stable aggregates decreases soil erod- period. ibility (Tisdall and Oades, 1982). Exposure of dredged sediments to air is Initial development of internal drainage termed chemical ripening. Exposure to oxy- is referred to as conditioning or ripen- gen results in oxidation of metals occurring ing. Vermuelen et al. (2003) categorized as reduced species such as iron or selenium

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and either decreased or increased mobility polychlorinated biphenyls and several pes- of these elements. Also, mineral weather- ticides (Smith et al., 1996; USEPA, 1997; ing of primary soil minerals can increase USEPA, 2004). Two such level-of-concern secondary (clay) minerals and change the concentrations are the threshold-effects cation exchange capacity, thereby affecting level (TEL) and the probable-effects level soil solution concentrations (Vermuelen (PEL). The TEL represents the concentra- et al., 2003). Chemical changes affecting tion below which toxic biological effects selected trace elements and nutrients are rarely occur. In the range between the TEL described in more detail in the remainder of and PEL, toxic effects occasionally occur. this paper. The PEL represents the concentration above which toxic effects usually or fre- Sediment Chemistry quently occur. These guidelines are used by Studies in Kansas the USEPA as screening tools and are not Reservoirs enforceable (Sigua et al., 2004a; USEPA, 2004). Studies of sediment chemistry in Kansas reservoirs are mainly limited to studies As of 2006, the USGS used a combination performed by the USGS (2008a). These of the USEPA level-of-concern concentra- studies assessed a variety of nutrients tions and the consensus-based sediment and trace elements to determine which quality guidelines developed by MacDonald reservoirs have potential contamination et al. (2000), which consist of a threshold- problems. Information obtained from these effect concentration and a probable-effect studies provides a background database that concentration. Much of the USGS can be used for future comparison of trace sediment work prior to 2006 reported level- elements if reservoirs are dredged and sedi- of-concern concentrations using TELs and ment is disposed of by land application. PELs; thus, those levels are reported in this paper to provide a level of comparison. The USGS sediment data presented in this review are from eight of 24 federal reser- Of the trace elements and pesticides voirs and 14 of the many freshwater lakes in evaluated in Kansas lakes, six contaminants Kansas. The studies provide information on typically exceeded TELs: arsenic, chro- measured concentrations, potential nutri- mium, copper, lead, nickel, and zinc (Table ent sources, trace elements, and pesticides 1). No TEL is established for selenium. In and the volume of sediment, trace elements, addition, DDE, a daughter product of the and nutrients deposited at selected lakes pesticide DDT, was measured in a number (USGS, 2008a). Results are summarized of the tested reservoirs and lakes. Typically, in Appendices A-1, A-2, A-3, B-1, and B-2 pesticides concentrations are less than and cited throughout this paper. the TELs (USGS, 2008a). Most national studies had similar results, with variation Sediment quality guidelines adopted by occurring because of different metal sources the USEPA allow assessment of reservoir and varying depths of collected samples. sediment with respect to level-of-concern concentrations of various trace elements Christensen and Juracek (2001) observed and organochlorine compounds, including an increase in arsenic, selenium, and stron-

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Table 1. Kansas reservoirs with trace elements above USEPA TELsa Trace Elements and TELs Reservoir Arsenic Chromium Copper Lead Nickel Zinc (7.24 mg/kg) (52.3 mg/kg) (18.7 mg/kg) (30.2 mg/kg) (15.9 mg/kg) (124 mg/kg) Swanson x x x Harlan County x x x Milford x x x Kirwin x x Webster x x Waconda x x Tuttle Creek x x x x x Perry x x x o Centralia x x x x Mission x x x x x Pony Creek x x x x Cheney x x x x Lake Afton x x x x x x Hillsdale x x x x x x Cedar Lake x x x x x x Lake Olathe x x x x x x Gardner x x o x o x Bronson x x o x x x Crystal x x o x x x Otis Creek x x x x a Data source: USGS (2008a) ο = Value above USEPA PEL TEL = threshold-effects level PEL = probable-effects level tium in several reservoirs in the Republican lead and zinc mining that occurred in the and Solomon River basins. The increase tri-state area of Missouri and Kansas begin- might be related to increased irrigation ning in 1870 (Brosius and Sawin, 2001). throughout the two basins. Arsenic and Concentrations of lead, zinc, and cadmium, copper values often exceeded TELs, but an element that occurs with lead and zinc, overall, other trace elements (i.e., cadmium, are above PELs (Appendix B-1). Concen- nickel, lead, zinc, and chromium) tested in trations decreased over time, but present the basins did not. surface sediment concentrations are still above PELs of concern for aquatic life. Empire Lake in Cherokee County in southeastern Kansas is the most contaminated Other Kansas reservoirs have various lake examined by the USGS in Kansas metals above TELs but not PELs. In most (Juracek, 2006). This lake is affected by Kansas reservoirs and lakes studied by the

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USGS, arsenic, copper, and nickel who also found that post-cultural sediment were measured above TELs; at (from 1818-1970) showed increased levels a few of the lakes and reservoirs, of chromium, copper (related to the use of chromium, lead, and zinc were copper sulfate for algal control in the lakes), measured above TELs; and at all lead, and cadmium in the more recent the reservoirs and lakes, cadmium sediments (1970s) of five hard-water and and mercury were below TELs (USGS, five soft-water Wisconsin lakes. Sources for 2008a). Use of total concentrations implies these metals were sewage effluent, chemical the amount of constituent measured in the treatment for algae, and vehicular traffic; sediment. It does not imply that this total trace-element concentrations increased quantity is available for mobility or use by overall because of human activities. plants if sediment is dredged. However, total quantity does report the amount of Chemical results from selected USGS stud- the constituent that is stored and could be ies conducted in Kansas (USGS, 2008a) mobilized under certain chemical condi- are summarized in Appendices A-1 and tions or change when sediment is dredged A-2. Appendix A-3 shows the mercury and removed from the lake environment. concentration in the few lakes where it was detected, and ranges of concentrations Chemical Changes in observed in cores from selected lakes are Dredged Sediment presented in Appendices B-1 and B-2. Much literature on dredged-sediment Reduction-Oxidation disposal on upland areas describes chemical Chemistry changes that occur when sediment from the bottom of a lake is brought into an oxidiz- Reduction-oxidation (redox) poten- ing situation. Many studies focused on tial describes the chemical reactions in one or more trace elements, nutrients, and sedimentary environments that occur organic matter. This section of the paper with changes in dissolved oxygen levels. focuses on trace elements typically found When dissolved oxygen in reservoir sedi- in Kansas reservoirs above TELs: arsenic, ments decreases to a very small amount, chromium, copper, lead, nickel, and zinc redox potential decreases and the system (Table 1). Potential sources and effects of is described as anoxic or anaerobic. Some mercury, methylmercury, and selenium are elements such as arsenic, iron, manganese, also included because of possible biogeo- and phosphorus are more mobile in an chemical effects of these compounds on fish anaerobic environment and can move with and other aquatic life. pore water. If sediments become exposed to oxygen, these elements can become Work by Delfino et al. (1969) and Nrigau oxidized and coprecipitate with other ele- (1968) showed a strong relationship ments, forming compounds such as iron- or between water depth and increased concen- manganese-hydroxides or oxides (Forstner, trations of nitrogen, phosphorus, iron, and 1977). Coprecipitated oxides and hydrox- total- and sulfide-sulfur in Lake Mendota, ides also can serve as adsorptive surfaces, WI. This trend was mirrored in observa- thereby increasing adsorption of other tions made by Iskandar and Keeney (1974), potential contaminants (e.g., phosphorus).

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Increased redox potential (i.e., more oxygen profile, suggesting rapid sedimentation is available) can result in decomposition with few chemical or biological changes of organic material and transformation of with depth (Callender, 2000; Mahler et al., redox-sensitive elements, such as copper, 2006; Juracek, personal communication, zinc, cadmium, and nickel, to oxidized 2007). states. These dissolved metals can coprecipitate as oxides or oxyhydroxides (DeLaune Estimated total organic carbon loads and Smith, 1985; Brannon et al., 1994; from the Kansas lake studies included in Rognerud and Fjeld, 2001; Davidson et this literature survey range from 19,300 al., 2005). Increased aeration of silt/clay to 928,000 tons (Appendix A-2). Total sediment in a Mississippi reservoir resulted organic carbon measured from specific in decreased concentrations of copper, zinc, cores ranged from 0.7 to 3.9 mg/kg in cadmium, and nickel in water and increased many of the lakes; Webster, Kirwin, and coprecipitation of these elements with iron, Waconda had unusually high values rang- forming solid amorphous oxides (Davidson ing from 3,440 to 16,200 mg/kg (Appendix et al., 2005). Oxidizing conditions gener- B-1). This large volume of organic carbon ally favor metal insolubility, and reducing suggests that microbial transformations of conditions favor metal solubility or mobil- trace elements are likely if dredging is used ity (Miao et al., 2006). as a remediation method in Kansas. Because availability of organic carbon and oxygen Organic Carbon Cycling affects mobility of trace elements and nutri- Rate and extent of organic matter cycling ents, potential changes that could occur in in a lake help determine oxygen levels and Kansas require further study. redox-potential levels in the water column and sediments (Avnimelech et al., 1984). Contaminants of Interest Lake sediments generally contain greater Final use of land where dredged sedi- concentrations of organic matter and ment is applied depends on the amount nutrients than the overlying water. Organic of contamination in the sediment. When matter decomposition also contributes to contaminants are present at high levels, veg- nutrient recycling in sediment and water. etative growth on the deposited sediment During dredging, microbial transforma- can be harmed or completely restricted. tions of nutrients to more mobile forms Sediment in a number of Kansas reservoirs and trace elements to less mobile forms is contaminated with trace elements and occurs if sufficient organic carbon is pres- nutrients, but contaminant levels are ent and the sediment environment changes relatively low compared with other parts of from anaerobic to aerobic. the country.

In cores, organic carbon often decreases Lead, zinc, copper, cadmium, arsenic, with increasing depth, indicating organic selenium, nickel, dissolved salts, DDE, and matter degradation and changes in sedi- nutrients are the contaminants of most ment chemistry with depth. However, the interest in Kansas lake sediments. Lead, organic-carbon concentration in several zinc, copper, cadmium, arsenic, and nickel Kansas lakes is uniform throughout the are found above TELs for sediment qual-

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ity in Kansas (USGS, 2008a). These trace toxic to fish; it also bioaccumulates, which elements, DDE, and the nutrient content can affect human health. of sediment are of concern because of resuspension of sediment (Peterson, 1982), Methylmercury is formed by sulfate-reduc- effects on drinking water quality, and ing bacteria in anaerobic environments, ecological effects if sediment is applied on particularly lake sediments and wetlands. agricultural land (Skogerboe et al., 1987; Bacteria metabolize mercury into meth- Darmody et al., 2004; Kelly et al., 2007). ylmercury. Sources of methylmercury Mercury is also of concern because it has include mercury sources mentioned previ- potentially deleterious biological effects if ously as well as terrestrial runoff and direct resuspended with sediment or dissolved in atmospheric deposition onto a lake surface lake water during dredging. (Rudd, 1995).

Mercury. Atmospheric deposition, Organic carbon has a strong connection agricultural chemicals, power-plant and to presence of mercury or methylmercury waste-incineration emissions, and decom- in the environment. Several studies show position of terrestrial litter are potential that water movement through wetlands sources of mercury in Kansas. Forest fires as and peat bogs, which have relatively high well as industrial sources such as mining or dissolved organic carbon concentrations, coal-fired power plants can also add mer- increases methylmercury formation and cury to the environment (Wiedinmyer and transport (Jackson, 1989; Kelly et al., 1995; Friedli, 2007). Krabbenhoft et al, 1995; Rudd, 1995). Methylation increases when sulfate and Total mercury was measured in only a few salinity levels are low and concentrations of the Kansas lakes and reservoirs evaluated of organic fermentation products are high by the USGS (Appendix A-3). All mean (Kongchum et al., 2006). Jackson (1989) and median values were below the USEPA demonstrated that quantity and type of TEL of 0.13 mg/kg, except Empire Lake clay minerals, oxides, and humic matter in southeast Kansas, which had one core also affects methylmercury production in with values above the TEL (Juracek, 2003, sediments. 2004). Several lakes in northeast Kansas had mean annual net loads for mercury Land uses such as agriculture, forestry, or ranging from 0.39 to 317 lb/year (Juracek, mining also affect occurrence of meth- 2003, 2004; Juracek and Mau, 2002). ylmercury in surface water, sediments, Although the majority of lakes studied and fish (Brumbaugh et al., 2001). The had mercury values below USEPA TELs, increased quantities of plant matter, because of mercury’s potential ecological organic carbon, and sediment transported effects and the presence of measurable to rivers or lakes during storms enhance mercury in some lakes, sediment should be the potential formation of methylmercury tested for mercury prior to dredging. within a lake or river system (Rudd, 1995). Most sampled lakes in Kansas had mercury Methylmercury. Methylmercury is a values below the TEL, but methylmercury neurotoxin that is harmful to both aquatic sediment-core pore waters were not evalu- and terrestrial biota. This compound is ated. Because a large volume of organic

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carbon and sediment enters Kansas lakes drainage. Lead needs to be evalu- and reservoirs, it is likely that methylmer- ated prior to dredging because cury could form in the sediment or mercury it has potential environmental could dissolve in lake water if sediment is effects and occurs, sometimes at resuspended during dredging. This issue high levels, in most lakes studied in warrants further research. Kansas.

Lead. Lead concentrations in lake and Zinc. Zinc is present at levels between river sediment cores are directly related TELs and PELs in Kansas lakes (Table 1, to exhaust from vehicles that use leaded Appendices A-1, A-2, B-2). At high con- gasoline (Callender and Van Metre, 1997; centrations, zinc causes a range of biological Machesky et al., 2005). A study of 10 and toxic responses in a variety of aquatic small lakes in Kansas (Juracek and Ziegler, organisms (Mullis et al., 1996; Lefcort et 2006) showed strong relationships between al., 1998). Atmospheric deposition of zinc observed lead concentration and traffic occurs from metal production, waste-incin- volume, reservoir size, and basin size. Lead eration and fossil fuel emissions, phosphate profiles showed an increasing concentra- fertilizer use, and cement production. tion trend related to leaded gasoline use Water-contamination sources include de- from 1940 to 1970 and a decreasing trend icing salts; automotive exhaust; and wear after lead was removed from gasoline in and tear of rubber tires, brake linings, 1972. Over time, lead concentrations in and galvanized metal parts (Councell et sediment might return to baseline condi- al., 2004). There is a strong relationship tions. However, the buried, high lead between traffic density and zinc concen- concentrations (often above both TELs trations in sediment cores in Georgia and and PELs) could cause future concerns if Florida lakes (Callender and Rice, 2000). reservoirs are dredged, dams are removed, or dams fail. Estimated annual zinc loads for the Kansas lakes studied range from 1,363 to 366,000 The estimated mean annual net lead load lb/year, and estimated total chemical loads of lead for Empire Lake is 6,500 lb/year, of zinc range from 84,506 to 11.7 million lb and approximately 650,000 lb of lead have (Appendices A-1, A-2). Ecological effects of been deposited in the lake since the dam and phytoremediation possibilities for zinc was closed (Appendices A-1, A-2). Lead should be evaluated prior to dredging. concentrations in younger sediments have decreased over time, but the present surface Arsenic. Arsenic is of environmental con- sediment concentrations are still above cern in freshwater lakes, surface water, and PELs of concern for aquatic and plant groundwater (Huang et al., 1982). Poten- life (Appendix B-2). Lead concentrations tial sources of arsenic include past use of in lake sediments can remobilize if pH arsenical pesticides (banned in the 1970s), and oxygen levels change (Telmer et al., smelters, coal-fired power plants, erosion 2006). If Empire Lake is dredged, lead in caused by intensive land use, leaching from sediments could affect the environment lumber pressure treated with chromated because of chemical changes in the sedi- copper arsenate, mineral weathering, high ment caused by exposure to oxygen and evaporation rates in arid environments,

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and irrigation-return flows (Huang et al., (Appendices A-1, A-2). Arsenic should be 1982; Welch et al., 2000; Rice et al., 2002; evaluated prior to using land application of Smedley and Kinniburgh, 2002). Arsenic dredged material for remediation. is strongly sorbed to surfaces of aluminum and iron oxides and edges of clay minerals Selenium. Selenium is derived primarily under oxidizing conditions (Kneebone and from weathering of rocks. In the northern Hering, 2000). Great Plains, Cretaceous-aged Pierre Shale is a primary source of seleniferous soils. Arsenic in solution exists as either arsenite Other sources include volcanic activity (As+3, toxic form) or arsenate (As+5, non- and fossil fuel combustion. Selenium often toxic form). In a laboratory experiment occurs in colloid- and sulfide-rich lake and conducted by Oscarson et al. (1980), river sediments and in organic- and iron- manganese and iron compounds of clay rich soil layers. Selenium is more likely to particle size (0.002 mm) in sediment leach in sediments with low organic matter affected oxidation of arsenite (As+3) to and clay content and an alkaline pH (above arsenate (As+5). This suggests that pres- 7) and in calcareous soils (Sarma and Singh, ence of manganese and iron compounds in 1983). Processes that affect selenium trans- freshwater sediments could help detoxify port include soil leaching, groundwater arsenic concentrations. transport, metabolic uptake and release by plants and animals, sorption and desorp- Arsenic in lake-sediment pore water is tion, chemical or bacterial reduction and generally present as arsenite, which is toxic oxidation, and mineral formation (Juracek in anaerobic conditions. Dredging permits and Ziegler, 1998). mixing of arsenite in the water column until oxidation or sorption remove it or Selenium is generally inert under reducing render it nontoxic (Brannon and Patrick, conditions. In an oxidized environment, 1987). Disposal of arsenic-rich sediment several forms of selenium exist: selenate (Se+6), in a CDF could result in pulses of toxic selenite (Se+4), and an organic form of sele- (arsenite) and nontoxic (arsenate) forms of nium (Se-2) (USEPA, 1996). Because sele- arsenic in leachate depending on whether nium can coexist in several forms, the USEPA oxidizing or anaerobic conditions are pres- set the toxicity limit for total selenium and ent. Precipitation reactions occurring at the not separate forms of the element. Selenium site could result in pH changes at both the concentrations equal to or greater than 4.0 surface and at depth, which could affect the mg/kg in sediment are of concern for fish form of arsenic present in sediment (Bran- and wildlife because of food-chain bioaccu- non and Patrick, 1987; Kneebone and mulation (Lemly and Smith, 1987). Hering, 2000). Selenium is of particular concern in rivers Arsenic is an issue in Kansas lakes where it and lakes in western Kansas because of is present above TELs (Table 1, Appendix geologic sources from the Pierre Shale and B-2). In lakes where arsenic was measured, other Upper Cretaceous strata and from annual chemical loads ranged from 619 to evapoconcentration of irrigation water. 57,800 lb/year with total chemical loads Estimated mean annual net chemical loads ranging from 24,760 to 1.8 million lb deposited in the few Kansas lakes where

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selenium was measured range from 96 to In a number of Kansas lakes, copper values 2,730 lb/year with estimated total loads in exceeded the TEL; in a few lakes, cores bottom sediments ranging from 3,856 to showed copper values above the PEL (Table 87,360 lb (Appendices A-1, A-2, B-2). 1, Appendix B-2). Estimated mean annual net loads of copper in Kansas lakes range If selenium-containing dredged soils are from 336 to 100,000 lb/year; estimated land applied, selenium likely will be immo- total loads range from 19,845 to 3.2 million bilized in soils amended with manure or lb (Appendices A-1, A-2, B). Copper can compost because it binds well with organic pose disposal problems because changes matter and clays (Geering et al., 1968). The from an anaerobic to aerobic environment potential for selenium to become remo- during dredging or when sediment is depos- bilized in lake water during the dredging ited on land can permit remobilization process is of more concern. If dredging (Baccini and Joller, 1981). occurs in lakes used for public drinking- water supply, the USEPA drinking-water Cadmium. Sources of cadmium are gen- limit of 0.05 mg/L selenium will need to be erally associated with industrial processes, carefully monitored. wastewater, or emissions. Atmospheric sources include waste incineration, fossil Copper. Copper is a micronutrient and fuel combustion, mining, and smelting of toxin. It strongly adsorbs to organic mat- zinc ore for galvanized roofing (Mahler ter, carbonates, and clay, which reduces et al., 2006). Additional sources include its bioavailability. Copper is highly toxic application of phosphate fertilizers, bio- in aquatic environments and affects fish, solids, or manure on fields; weathering of invertebrates, and amphibians; all three rocks and soils; and leaching from landfills. groups are equally sensitive to chronic Major factors governing cadmium specia- toxicity (USEPA, 2007a). Cu+2 is the oxidation, adsorption, and distribution in soils tion state of copper generally encountered are pH, soluble organic matter content, in water. When Cu+2 occurs in the environ- hydrous metal oxide content, clay content ment, the ion typically binds to inorganic and type, presence of organic and inorganic and organic materials contained in water, ligands, and competition from other metal soil, and sediments (ATSDR, 2004). ions (UN, 2006).

The most obvious copper source, particu- Relative to more industrialized areas of larly in Kansas lakes, is use of copper sulfate the country, Kansas lakes have minimal to control algal blooms. The compound is cadmium concentrations that generally are used in smaller ponds and lakes, where algae below the TEL (Appendix B-2). Estimated problems are most severe (Peterson and mean annual net loads of cadmium in Lee, 2005; D.E. Peterson, KSU Agronomy selected Kansas reservoirs range from 3.2 Dept., personal communication, 2007). to 1,520 lb/year, and stored quantity Copper in lake sediments also comes from estimates range from 171 to 48,640 lb leaching from animal waste and pressure- (Appendices A-1, A-2). However, remobili- treated lumber, atmospheric deposition zation of cadmium from sediments in lakes by precipitation, and road wear of brake with higher concentrations, such as Empire linings (Rice et al., 2002). Lake in southeastern Kansas, can affect

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aquatic life and plants (USEPA, streambank erosion is high (Whittemore 2001). and Switek, 1977; ATSDR, 2001).

Chromium. Chromium is found Chromium was detected at concentrations in rocks, animals, plants, soil, and exceeding the TEL at some Kansas reser- volcanic dust and gases. The concen- voirs (Table 1; Appendix B-2). Estimated tration of naturally occurring chromium mean annual net loads of chromium for in U.S. soils ranges from 1 ppm to 2,000 selected Kansas lakes range from 864 to ppm (USEPA, 2007b). Chromium is pres- 302,000 lb/year; estimated total chemical ent in the environment in several different loads range from 52,740 to 9.6 million forms. Its valence states range from +2 to +6, lb (Appendices A-1, A-2). Because of the but in natural environments, it is gener- potential for environmental and human ally found as trivalent chromium (Cr+3) harm, chromium in lake sediment needs or hexavalent chromium (Cr+6). Triva- to be evaluated prior to dredging and land lent chromium occurs naturally in many application. fresh vegetables, fruits, meat, grains, and yeast and is added to vitamins as a dietary Nickel. Some anthropogenic sources of supplement. However, release of Cr+3 to nickel include oil combustion, oil-burning the environment can be toxic because of and coal-fired power plants, trash incin- conversion to Cr+6. Hexavalent chromium erators, treated wastewater, car exhaust, is most often produced from industrial abrasion of nickel-containing automobile sources such as coal-fired power plants, steel parts, and animal waste (Lagerwerff and making, leather tanning, chrome plating, Specht, 1970; ATSDR, 2005). Because of dyes and pigments, and wood preservation the density of agricultural land use near and can indicate environmental contami- lakes and reservoirs, the most likely anthro- nation. This form of chromium exists in pogenic sources of nickel for Kansas lakes oxidizing conditions and can move through are wastewater and animal waste. soil to underlying groundwater. Hexavalent chromium is the more toxic form and is a Nickel strongly adsorbs to soil or sediment threat to aquatic life and human health if containing iron or manganese. However, ingested (ATSDR, 2001). nickel becomes more mobile if water or sediment pH becomes more acidic, such as Chromium enters air, water, and soil in an anaerobic environment. Nickel does mostly in the trivalent (Cr+3) and hexava- not appear to accumulate in fish or other lent (Cr+6) forms. In air, chromium animals used as food but is a known car- compounds are present mostly as fine dust cinogen and toxic to humans and animals particles that eventually settle over land and when maximum tolerable amounts are water. Chromium concentrations are gen- exceeded (ATSDR, 2005; LENNTECH, erally low, but the metal often concentrates 2008). in hydrous manganese and iron oxides or adsorbs to clay-size particles in sediment. Nickel occurs at levels between TELs and The clay-size fraction is the particle size PELs in Kansas lakes (Table 1; Appendices most likely to be transported to lakes, A-1, A-2, B-2). Estimated mean annual net particularly during floods or in areas where loads range from 355 to 152,000 lb/year;

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estimated total net loads range from 22,000 Nutrient to 4.8 million lb. Phytoremediation possi- Transformations bilities for nickel should be evaluated prior and Salinity Effects to dredging. Land application of dredged sediments has potential benefits. Even if minimally DDE and DDD. DDE and DDD are contaminated with trace elements or toxic degradation products from the pesticide organic compounds, lake sediments can DDT, which was used extensively in agri- support crop growth and even improve culture during the 1950s and 1960s until agricultural soils. Woodard (1999) found it was banned in 1972 (USGS, 2008a). that amending soil with dredged sedi- Sources of DDT, DDE, and DDD include ment had minimal effects on growth of runoff from agricultural fields and deposi- soybean, corn, and sunflower but increased tion on lakes, streams, and land of soil growth and nutrient concentrations in big particles carried by wind (Rapaport et al., bluestem. Sigua et al. (2004b) reported 1985). increased growth and nutrient uptake of bahiagrass forage when grown on soils Detection of DDE and DDD in recently amended with dredged lake sediment. deposited sediments of eight Kansas reservoirs (Appendix B-1) indicates that Dredged lake sediments can have higher DDT use was widespread in eastern Kansas nutrient concentrations than the originat- (Juracek, 2004). DDT, with a half-life of 2 ing soil. This phenomenon, known as to 15 years, lasts for years in soil (ATSDR, sediment enrichment, is caused by selective 2002). Detection of the daughter products transport and deposition of fine particles DDD and DDE in upper parts of cores (silt and clay) to which nutrients are indicates that DDT breakdown products attached (Sigua, 2005). Studies by Mau are continuing to enter Kansas lakes, (2001), Pope et al. (2002), and Juracek probably from eroding soils in upstream and Ziegler (2007) showed that sediments watersheds. from several Kansas lakes have higher total phosphorus concentrations than Salinity. Salinity affects both mobiliza- soils in contributing watersheds (Table 2). tion and biological availability of metal Furthermore, sediment transport from an contaminants. Lakes in semi-arid or arid anaerobic lake bottom to aerobic surface environments can have increased salinity soils can result in nutrient transformations in both water and sediments because of associated with changes in redox potential. evaporation or inflow of soils affected by Therefore, sediment properties and nutri- evapotranspiration upgradient. Disposing ent transformations should be considered of saline sediments in upland, unconfined when evaluating agronomic and environ- areas could result in increased remobiliza- mental sustainability of land application of tion of many metals; subsequently, these dredged sediments. metals could be taken up by plants, leach into groundwater, or run off to surface water (Francingues et al., 1985). Additional information on salinity is presented in the next section.

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Nitrogen environmental standpoint because nitrate is Total nitrogen concentrations of lake subject to leaching loss. Moore et al. (1992) sediments are generally similar to those of found that pore-water nitrate-nitrogen contributing watershed soils (Juracek and concentrations increased to greater than 30 Ziegler, 2007). Although the majority of mg/L of nitrogen during the first 15 days in nitrogen in lake sediments likely is organic- an aerobic environment. This indicates that nitrogen (non-plant available), various there can be a sudden flush of nitrate fol- forms of nitrogen in sediment samples are lowing land application of lake sediments; rarely determined. Nitrogen transforma- however, nitrate leaching from dredged tions in soils and sediments are dynamic sediments has not been studied. Aerobic and highly influenced by oxygen supply conditions followed by anaerobic condi- (Figure 1). These transformations influence tions could convert much of the nitrate to plant availability, transport, and potential nitrogen gas through denitrification (Figure environmental effects of nitrogen. 1). Soil-water content, water flux, and plant uptake influence nitrate losses. Proper man- Organic-nitrogen forms must be mineral- agement could minimize nitrate losses, but ized before they are available to plants. additional research is needed to confirm Nitrogen mineralization occurs in anaero- this supposition. bic sediments, but the rate nearly doubles when sediments are subjected to an aerobic Measured nitrogen in sediment cores environment (Moore et al., 1992). Nitri- ranges from 30 to 5,200 mg/kg depending fication, conversion of nitrogen from on the lake (Appendix B-1). This variation + - ammonium (NH4 ) to nitrate (NO3 ), is in nitrogen availability reflects different strictly an aerobic process (Figure 1). Nitri- source areas and land uses near the sampled fication is particularly important from an lakes. Estimated mean annual net loads

N2 FIXATION

NH3(g) N2O

VOLATILIZATION DENITRIFICATION

UPTAKE

NO ANAEROBIC NH3 PROCESS NO2 MINERALIZATION Plant available N Root - Organic N NO NO - NH + Zone 3 3 NITRIFICATION 4 IMMOBILIZATION

AEROBIC PROCESS LEACHING

- NO3 Figure 1. General nitrogen cycle in soils Red lines emphasize aerobic or anaerobic processes

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of nitrogen available in sediments from eroded sediment before it reaches selected Kansas lakes range from 19,200 to surface water bodies is an impor- 7.6 million lb/year; estimated stored chemi- tant component of plans for land cal loads range from 1.2 million to 243 application of dredged sediments. million lb (Appendices A-1, A-2). In Kan- sas lakes, the volume of nitrogen available Loss of dissolved phosphorus can for transformation when sediment redox have environmental effects even when conditions change is large and needs to be erosion is controlled. Phosphorus cycling considered when selecting a disposal area in soils is generally governed by inorganic and plants for use in phytoremediation. phosphorus reactions, such as adsorption and precipitation. Phosphorus desorption Phosphorus and dissolution release sediment-bound Total phosphorus concentrations in lake phosphorus into soil solution or runoff sediment generally are higher than average water (Figure 2). Changes in redox status phosphorus concentrations in soils in con- of the soil, which occur during dredging tributing watersheds (Table 2). Although and land application of sediment, affect elevated phosphorus concentrations in adsorption/desorption and precipitation/ sediment are not a concern for crop pro- dissolution reactions (Sharpley, 1995; Miao duction, high phosphorus concentrations et al., 2006). are an environmental concern. Increases in lake sediment phosphorus content are The majority of research on redox effects correlated to increased phosphorus loss on phosphorus sorption reactions has through erosion and runoff (Sharpley, been conducted on either agricultural soils 1995). Implementing best management that are flooded or in situ lake-bottom practices to control erosion and capture sediments. Under reduced conditions,

Table 2. Total phosphorus concentrations in lake sediments and corresponding watershed soils for several Kansas lakes Upstream Downstream Watershed Lake/Watershed sediments sediments soils Mean Total Phosphorus Concentration (mg/kg) Atchison County Lakea 800 1000 520 Banner Creek Reservoira 770 860 740 Mission Lakea 670 1100 620 Perry Lakea 810 930 610 Lake Wabaunseea 620 870 550

Nonagricultural Out-of-channel In-channel (cemetery) Cheney Lakebc 430 630 245 a Juracek and Ziegler (2007) b Pope et al. (2002) c Mau (2001)

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UPTAKE Adsorbed P Organic P ADSORPTION MINERALIZATION DESORPTION IMMOBILIZATION Root Plant available P - 2- Zone H2PO4 / HPO4

PRECIPITATION Secondary DISSOLUTION DISSOLUTION Primary Mineral P LEACHING Mineral P

Figure 2. Phosphorus transformations and reactions in soil environments

phosphorus sorption is greater at high on the lake (Appendix B-1). This variation phosphorus concentrations and lower at in phosphorus availability reflects different low phosphorus concentrations compared source areas and land uses near the sampled with oxidized soils (Khalid et al., 1977; lakes. Estimated mean annual net loads of Vadas and Sims, 1998). Therefore, pre- phosphorus available in sediments from dicted phosphorus release patterns resulting selected Kansas lakes range from 9,720 to from oxidizing reduced sediments depend 3.4 million lb/year; estimated stored chemi- on the phosphorus status of soils. cal loads range from 437,400 to 109 million lb (Appendices A-1, A-2). In Kansas lakes, Oxidizing sediments with low phosphorus the volume of phosphorus available for concentrations would decrease soluble transformation when sediment redox phosphorus, but oxidizing sediments with conditions change is large (Appendix B-1) high phosphorus concentrations could and needs to be considered when selecting a increase soluble phosphorus release. Reac- disposal area. Because of the complex redox tions can be further complicated if soils effects on phosphorus sorption and lack of undergo repeated cycles of oxidation and phosphorus-loss data from soils amended reduction. A general increase in phos- with dredged sediments, additional research phorus release has been observed in soils is needed to fully characterize phosphorus that are reduced, oxidized, and reduced loss risks from land application of dredged again (Young and Ross, 2001; Shenker et sediments. al., 2005). Chen et al. (2003) found that pore-water phosphate concentrations did Salinity not increase following initial application Salinity of land-applied dredged sediments of dredged sediment to soil surface but is a concern (USACE, 1987); however, increased 10-fold over the control follow- most salinity problems cited are due to ing the first drying and wetting cycle. sediments taken from brackish or saltwater waterways (Winger et al., 2000; Novak and Measured phosphorus in sediment cores Trapp, 2005). Data on potential salinity ranges from 422 to 1,300 mg/kg depending issues in land-applied sediments dredged

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from freshwater Kansas reservoirs are lack- salts. Effects of salinity on crop growth are

ing; therefore, the following information is evaluated by comparing ECse with crop- based on reservoir water analyses. specific threshold values. Yield loss or plant

growth problems occur when ECse exceeds Salinity of Kansas reservoirs varies because threshold values. Most major Kansas crops of the precipitation gradient and variety will tolerate low levels of salinity (Table 4). of drainage-basin geology found across the state (Table 3). In general, reservoir Salinity is not an issue for land application salinity increases from east to west in the of sediment dredged from the majority of state, as indicated by increases in electri- Kansas lakes. Some lakes in western Kansas, cal conductivity of the water. Soil salinity such as Wilson Lake, probably have sedi- is determined by measuring electrical ment with a high dissolved salt content,

conductivity of a saturated paste extract but the predicted ECse of sediments from

(ECse); ECse is an approximation or rela- these lakes is less than threshold values tive index of the electrical conductivity of for sorghum, soybean, and wheat. Corn soil water (Zhang et al., 2005). Assuming production, however, could be limited on that sediment pore water is in equilibrium dredged sediments from Wilson Lake. Cor-

with reservoir water, sediment ECse can be recting soil-salinity problems can be costly. approximated by determining electrical Therefore, salinity of material dredged conductivity of reservoir water. from lakes with electrical conductivities greater than 1 dS/m should be confirmed

Soils with ECse greater than 1 dS/m are with sediment analysis before land-applica- referred to as having high salts, and soils tion. Field or greenhouse research trials with ECse greater than 4 dS/m are classified can help quantify effects of saline sediment as “saline,” or severely limited because of applications on crop growth.

Table 3. Electrical conductivity of lake water in Kansas reservoirsa Mean Number First Last electrical Standard Reservoirb of sampling sampling Longitude conductivity deviation samples date date (dS/cm) Olathe Lake 0.539 0.105 103 6/21/00 9/30/05 94°50´ W Perry Lake 0.308 0.034 15 5/1/92 8/30/93 95°27´ W Tuttle Creek Lake 0.348 0.131 9 5/5/92 9/1/93 96°38´ W Milford Lake 0.518 0.086 9 5/5/92 9/1/93 96°55´ W Cheney Reservoir 0.835 0.056 148 10/7/70 6/13/07 97°50´ W Kanopolis Lake 1.097 0.339 39 12/28/49 9/3/93 98°00´ W Waconda Lake 0.766 0.104 8 5/6/92 9/2/93 98°21´ W Wilson Lake 2.649 0.428 258 8/16/66 9/2/93 98°33´ W Cedar Bluff Reservoir 1.317 0.255 27 10/23/75 8/9/82 99°47´ W a Data source: USGS (2008b) b Reservoirs sorted from east to west

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Table 4. Salt Tolerance Ratings for Various Field and Forage Cropsa Sensitive Moderately Tolerant Tolerant Highly Tolerant (0-4 dS/m)b (4-6 dS/m) (6-8 dS/m) (8-12 dS/m) Field beans (dry) Corn Wheat Barley Red clover Grain sorghum Oat Rye Ladino clover Soybean Triticale Bermudagrass Alsike clover Bromegrass Sunflower Crested Wheatgrass Sudangrass Alfalfa Sorghum-Sudans Tall fescue Sweet clovers a Table adapted from Lamond and Whitney (1992) with permission b dS/m = deciSiemens per meter, a measure of electrical conductivity of a soil solution. Soils with electrical conductivity of 4 dS/m or greater are considered saline.

Phytoremediation 5 meters recommended by Schnoor et al., Processes and Methods 1995) available in the state for treatment of different contaminants. Contamination in land-applied dredged sediment is a concern. However, some Metal Uptake contaminants can be contained, degraded, One part of the phytoremediation process or removed through phytoremediation, is uptake of metals through plant roots. a process in which plants remediate con- Heavy metals can be taken up without tamination by taking up contaminated negatively affecting plant growth, but the water (USGS, 2008c). Phytoremediation is quantity taken up depends on several fac- useful because plants survive higher con- tors including soil characteristics and plant centrations of hazardous wastes than most species. Only some forms of metals in the microorganisms used for bioremediation. soil are available for uptake, and availability Phytoremediation works best when soil of different metals is affected by soil pH, contaminants are less than 5 meters deep organic matter, soil water content, and (Schnoor et al., 1995). presence of other metals (Madejon and Lepp, 2006). As water drains out of soil, Types of phytoremediation include oxidation can lower soil pH. Lower pH phytoextraction, phytostabilization, levels increase availability, solubility, and rhizofiltration, phytodegradation, phyto- mobility of most metals, which increases volatilization, rhizosphere degradation, and their availability to plants (Borgegard phytorestoration (Salt et al., 1998; Peer et and Rydin, 1989; Turner and Dickinson, al., 2005). In Kansas, phytostabilization 1993). Arsenic is an exception; its mobility and phytoextraction are most applicable is lower at lower pH levels (Madejon and because of generally low trace-element Lepp, 2006). Plant-available arsenic could concentrations in lake sediments, the decrease as soil acidity increases with plant likelihood of dredged sediments being land growth. This requires further research, applied, and the variety of plant species especially for Kansas lake sediments with (many with rooting depths less than the arsenic concentrations that exceed the TELs.

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Usually, dredged material is anaerobic, has a are either poorly bioavailable in pH around 7.0, and has a moisture content soil or not translocated out of greater than 40%. In these conditions, roots. heavy metals are tightly bound to sediment and not available to vegetation (Skogerboe Phytostabilization et al., 1987). As dredged material dries and According to Raskin and Ensley is oxidized, heavy metals become more (2000), the purposes of phytostabiliza- soluble and are of concern to the environ- tion are to: 1) stabilize waste so no wind ment because they are more mobile in or water erosion occurs, 2) stop leaching surface runoff and more available to vegeta- of contaminants to groundwater, and 3) tion (Skogerboe et al., 1987). immobilize contaminants both physically and chemically by making them bind to Contaminated soil becomes less so as plant roots and organic matter. Phytostabi- roots take up metals and translocate them lization is best used on soils with low to other parts of the plant. After uptake, contaminant levels (Raskin and Ensley, many metals are immobilized in roots 2000; McCutcheon and Schnoor, 2003). and not translocated to other plant parts (Cunningham and Lee, 1995). Metals that Vegetation reduces wind and water ero- immobilize in tree roots include chromium, sion in several ways. Accumulation of leaf mercury, lead, aluminum, tin, and vana- litter forms a barrier over the surface of dium. Metals that are translocated include contaminated soil, which provides physical boron, cadmium, cobalt, copper, molybde- stabilization by reducing splash erosion. num, nickel, selenium, arsenic, manganese, Roots of grasses, shrubs, and trees bind and zinc (Pulford and Dickinson, 2005). and stabilize soil as water runs over it. The litter layer and binding of soil by roots also Not every heavy metal is mobilized the help reduce wind erosion. Reducing wind same way. Uptake and retention of many erosion with vegetation also lowers human heavy metals available to trees follows the exposure because of reduced potential for pattern of roots > leaves > bark > wood inhalation of contaminated soil and inges- (Pulford and Dickinson, 2005). Copper tion of contaminated foods (Schnoor et al., uptake by weeping willow (Salix spp.) 1995). occurred in the roots > wood > new stems > leaves (Punshon and Dickinson 1997). Vegetation also takes up large amounts Sycamore maple (Acer pseudoplatanus L.) of water that are lost from leaf surfaces concentrated lead and zinc in roots, then through transpiration. Tree species such as lead translocated to stems, and zinc moved poplar, willow, and cottonwood are good at to leaves (Turner and Dickinson, 1993). taking up water from the top 2 to 3 meters Only cadmium and zinc accumulate in of soil (Raskin and Ensley, 2000). This above-ground tree tissues at concentrations large amount of water moving through the sufficiently high enough for phytoremedia- plant from the soil to the atmosphere can tion to be useful (Pulford and Dickinson, decrease the potential for metals to leach 2005). Other commonly studied metals from the soil (Schnoor et al., 1995). (e.g., chromium, copper, nickel, and lead)

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Madejon and Lepp (2006) Phytoextraction studied three contaminated sites Phytoextraction removes contaminants that were naturally revegetated from the system by immobilizing them in with mosses, ferns, and herbaceous soil or biomass (Peer et al., 2005; Pulford and woody plant species suitable for and Dickinson, 2005). Vegetation such as phytostabilization. They found that grasses and trees can be harvested, which arsenic was taken up and immobilized helps permanently remove contaminants in roots with little transfer to stems and from soil. Dried, ashed, and composted leaves. Root uptake of arsenic in herbaceous plant material can be isolated as hazardous and woody plants ranged from 0.66 to 18.3 waste or recycled as a metal ore (Kumar mg/kg and 1.37 to 5.54 mg/kg, respectively. Nanda et al., 1995). Amount of arsenic translocated to stems and leaves in herbaceous and woody species Hyperaccumulator plants are good for was less than 2 mg/kg. These data show phytoextraction of metals and include that the species tested would work well for herbs, shrubs, and trees. To be labeled a phytostabilization because little arsenic was hyperaccumulator, a plant must take up translocated out of roots. more than 10,000 µg/g (ppm) of zinc and 1,000 µg/g of copper, nickel, chromium, Another study in the southern United and lead (Baker and Brooks, 1989). More States noted successful use of Bermudagrass than 300 of the approximately 400 species for phytostabilization on dredged material of hyperaccumulators accumulate nickel containing low amounts of zinc (Best et (Brown, 1995). Table 5 compares amounts al., 2003). Bermudagrass responded to an of selected metals taken up by hyperaccu- increase in zinc levels by increasing bioac- mulators with amounts normally found in cumulation of zinc until a decrease of plant plant leaves and soil. mass occurred at a zinc phytotoxicity level of 324 mg/kg. Red fescue (Festuca rubra) Metals present in Kansas reservoir sedi- also is metal tolerant and has been used in ments at concentrations greater than TELs grazing-management strategies on highly include arsenic, chromium, copper, lead, contaminated soils (Cunningham and Lee, nickel, selenium, and zinc (Appendix B-2). 1995). Examples of hyperaccumulator species that take up these metals are shown in Table Species native to a particular area are best 6. Most plants that accumulate metals are for phytostabilization because they are slow-growing, small, weedy plants that have most likely adapted to the climate, insects, a low biomass, but some herbaceous hyper- and diseases present (Peer et al., 2005). The accumulators such as Brassica juncea have a U.S. Army Corps of Engineers (1987) pub- high biomass (Kumar Nanda et al., 1995). lished a list of vegetation that can be used Plants with higher biomass can remove on dredged material; Appendix C contains greater amounts of contamination and a condensed version that lists 161 species have more uses when harvested (Pulford found in the mid-Plains. and Dickinson, 2005). For a more complete list of hyperaccumulators, see Baker and Brooks (1989) and McCutcheon and Schnoor (2003).

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Compared with herbaceous hyperaccumu- stabilize substrate and their leaves pro- lators, trees are advantageous for several duce organic matter when they drop. reasons (Pulford and Dickinson, 2005): • Uptake of water and transpiration • Certain tree species have high-yielding through leaves helps limit leaching of biomass that would only need to take heavy metals from soils and protects up moderate amounts of metal to be groundwater and surface waters from effective. contamination. • Trees have more uses when harvested than most hyperaccumulators. Sites most favorable for timber growth include marginal land or abandoned • A greater genetic diversity of fast grow- disposal sites on which dredged, dewatered ing, short-rotational trees such as Salix material has been deposited (Best et al., spp. and Populus spp. are available. This 2003). An additional benefit of using trees allows for selection of traits for resis- is that dredged materials can be applied in tance to high metal concentrations as thicker layers because tree roots descend well as genotypes that have high or low farther than herbaceous plant roots. This metal uptake. allows marginal land to be made more pro- • Woody plant biomass use is well ductive. And, trees can be used to produce a established. variety of beneficial products. Tree species suitable for use on dredged material include • Short-rotation, fast growing coppice eastern cottonwood, American sycamore, trees have a high economic value. eucalyptus, green ash, water oak, and sweet • Trees on highly contaminated land are gum on periodically flooded sites; and long- visually aesthetic. leaf pine, slash pine, loblolly pine, black walnut, white ash, pecan, and several oak • Trees protect soil surfaces from wind and hickory species on upland sites (Best et and water erosion because their roots Table 5. Comparison of amounts of heavy metals normally found in plant leaves and soil with the minimum amounts required for plants to be considered hyperaccumulators Normal Range of Normal Range of Metal Minimum Amount of Metal Element Concentrations Concentration in Soil Metal Taken up to be a in Dried Plant Leavesa (United States)b Hyperaccumulatorc (mg/kg) Arsenic --- 3.6-8.8 --- Chromium 0.2-5 14-29 1,000 Copper 5-25 20-85 1,000 Nickel 1-10 13-30 1,000 Lead 0.1-5 17-26 1,000 Selenium 0.05-1 ------Zinc 20-400 34-84 10,000 a Raskin and Ensley (2000) b Sandia National Laboratory (2007) c Baker and Brooks (1989)

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Table 6. Hyperaccumulator species used to remove metals present in Kansas reservoir sediments

Metal Scientific Name Common Name Family Location

Pteris vittataa Ladder brake Pteridadeae USA Pteris creticaa Cretan brake Pteridadeae USA Arsenic Pteris longifoliab Long-Leaved brake Pteridadeae USA Pteris umbrosab Jungle brake Pteridadeae USA Holcus lanatusb Common velvetgrass Poaceae USA* Salix spp.b Willow species Salicaceae USA* Brassica junceaac Indian mustard Brassicaceae USA* Copper Helianthus annuusd Common sunflower Asteraceae USA* Avena sativae Oat Poaceae USA* Hordeum vulgaree Barley Poaceae USA* Salix spp.a Willow species Salicaceae USA* Betula spp.a Birch species Betulaceae USA* Chromium Salsola kalia Russian thistle Chenopodiaceae USA Brassica junceac Indian mustard Brassicaceae USA* Brassica junceacd Indian mustard Brassicaceae USA* Nickel Helianthus annuuse Common sunflower Asteraceae USA* Brassica junceaacd Indian mustard Brassicaceae USA* Lead Brassica spp. (others)a --- Brassicaceae USA Helianthus annuusd Common sunflower Asteraceae USA* Astragalus bisulcatusa Two-grooved milk vetch Fabaceae USA* Selenium Brassica junceaa Indian mustard Brassicaceae USA* Thlaspi caerulescensad Alpine pennycress Brassicaceae USA Brassica junceaacd Indian mustard Brassicaceae USA* Zinc Helianthus annuusd Common sunflower Asteraceae USA* Avena sativae Oat Poaceae USA* Hordeum vulgaree Barley Poaceae USA* a Peer et al. (2005) b Baker and Brooks (1989) c Kumar Nanda et al. (1995) d McCutcheon and Schnoor (2003) e Ebbs and Kochian (1998) *Natural or introduced to Kansas

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al., 2003). However, not all are suitable for Summary Kansas. Dredging and land-applying sediments pose a variety of con- Using trees for phytoextraction also has cerns including costs, locations disadvantages. Because trees take longer to of disposal sites, economics, and mature, the time period between sediment transportation. From a chemical stand- disposals is longer than if herbaceous plants point, dredging and subsequent disposal are used (Best et al., 2003). Disposing addi- of sediments as a means to renovate Kansas tional dredged sediment around planted reservoirs appears viable. Contaminants trees limits the quantity of oxygen available of concern in most Kansas reservoir sedi- to the roots and can result in death of the ments evaluated in USGS studies are not trees. Trees also tend to acidify soil, which analytically detectable or are present at could cause increased bioavailability of concentrations below USEPA TELs. metals. A few metals (e.g., lead, arsenic, selenium, Phytoextraction and phytostablization have copper, nickel, chromium, and zinc) will be method-specific advantages and disadvan- issues in some parts of the state. Whether tages (PRC, 1997). Phytoextraction by lead will create problems depends on depth trees has high biomass production but is of sediment dredged, lake location, and disadvantageous because of the potential source of lead. Sediments from Empire for off-site migration and transportation Lake in southeastern Kansas are most likely of metals to the leaf surface. Phytoextra- to have disposal-related problems because tion by grasses has high accumulation but of high concentrations of cadmium, lead, low biomass production and a slow growth and zinc. Other reservoirs have higher rate. A disadvantage for both methods is concentrations of lead in deeper sediments that metals concentrated in plant biomass because of past use of leaded gasoline and must eventually be disposed of. Phyto- will need to be evaluated if dredging is stabilization does not require disposal of considered as a remediation option. contaminated biomass but does necessitate long-term maintenance. Phytoremediation is a natural process that can be beneficial, especially on sediments The main disadvantage of all phytoreme- with low contamination levels, such as diation methods is that they are cyclical those found in many Kansas reservoirs. and occur only during the growing season. Many vegetation species, including some Some sites might require additional soil native to Kansas, are appropriate for amendments such as manure, sawdust, phytoremediation. Although phytoreme- and lime or the addition of chemicals to diation requires further research, it is viable increase solubility of metals (Brown, 1995; for Kansas and should be considered along Murray, 2003). An additional concern is with land application of dredged sediment whether plants take up enough contami- as part of an overall reservoir dredging nants to make a difference or if it will take evaluation. thousands of years to clean soil to acceptable contaminant levels (Pulford and Dickinson, 2005).

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Questions and Research Needs Chemical Issues Although contaminants in Kansas reservoir sediments generally are below TELs, changes that could occur when sediment is removed and placed on land have not been evaluated. Research should examine: • Redox potential and pH of sediment • Potential changes in concentrations of metals and nutrients due to land disposal • Leaching of lake sediment in combination with disposal site soil: Are contaminants of interest mobile or retained in the soil matrix? • Retention of trace elements in soil: Do amendments (biosolids and liming) prevent trace-element mobility and/or uptake by plants? • Quantity of manganese- and iron-oxides and hydroxides and content and type of clay present in combined soils at disposal sites: What combination will optimize retention of metals? • Leaching of nitrate and other contaminants from land-applied dredged sediments • Management of dredged sediment to minimize nitrate losses • Phosphorus loss risks from land-applied dredged sediments due to complex redox effects on phosphorus sorption • Sediment from lakes with high electrical conductivity (field or greenhouse research trials) prior to dredging; correcting soil-salinity problems can be costly • Methylmercury content in sediment pore-water

Phytoremediation Successful establishment of vegetation for phytoremediation depends on physical qualities of dredged materials, contaminants present, soil water, soil structure, and salinity. Questions to ask prior to using phytoremediation on dredged sediments include: • What are the risks of metal uptake by plants and potential transmis- sion up the food chain? • What can or should be done with material after it accumulates in plant tissue? Can woody material be used if it contains heavy metals? What other disposal possibilities exist?

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• What volume of metals is removed by phytoremediation, and what is the rate of uptake? • What are the economic effects of phytoremediation compared with other remediation methods? • Will species currently used for phytostabilization and phytoextraction be successful in Kansas? Many species used for phytoremediation are short-rotation, hybrid, fast-growing woody species; are they feasible here? • Should controlled, pre-trial experiments be conducted to determine likelihood of success before various plant species are used on dredged materials?

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Appendix A-1. Estimated annual sediment deposition and chemical loads for selected Kansas reservoirs Reservoir (year completed) Tuttle Perry Hillsdale Cheney Webster Empire Lake Cedar Creek Lake Lake Reservoir Reservoir Lake Olathe Lake Lake (1969)a (1981)bc (1964)e (1956)fc (1906)g (1956)h (1938)h (1962)d

Drainage areai, mi2 1,117 144 9,628 933 1,150 2,500 16.9* 16.9*

Years since dam 32 15 37 33 40 100 45 62 closurei Total deposition, 56,700 2,100 142,000 7,100 1,267 1,000 317 338 acre-ft Mean Annual 3,040 265 1,633 453 7.8 24 12.6 9.6 Sediment Reservoir characteristics million million million million million million million million Deposition, lb/yr

3.4 2.5 Phosphorus 154,000 226,000 29,400 --- 9,720 14,700 million million Nitrogen 7.6 (Total organic-N --- 672,000 840,000 129,000 --- 29,610 19,200 + Ammonia-N) million Total organic 58 33 ------966,000 ------carbon million million

Selenium 2,730 --- 1,324 190 96 ------

Arsenic 57,800 --- 22,861 15,800 619 ------

Lead 85,100 --- 40,824 8,640 --- 6,500 416 326

Zinc 366,000 --- 196,000 37,500 --- 120,000 1,966 1,363

Copper 100,000 --- 55,000 7,940 --- 830 441 336

Chromium 302,000 --- 132,450 31,740 --- 1,591 1,172 864

Cadmium 1,520 --- 717 146 --- 780 3.8 3.2

Mean net load (lb/year) based on values reported for period of study Mean net load (lb/year) based on values reported for period Nickel 152,000 --- 62,143 13,830 --- 840 441 355

a Juracek (2003) f Christensen (1999) b Juracek (1997) g Juracek (2006) c Mau and Christensen (2000) h Mau (2002) d Juracek and Mau (2002) i USGS (2008a) e Mau (2001) *Watershed includes both Lake Olathe and Cedar Lake

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Appendix A-2. Estimated total sediment deposition and chemical loads for selected Kansas reservoirs Reservoir (year completed) Tuttle Perry Hillsdale Cheney Webster Empire Lake Cedar Creek Lake Lake Reservoir Reservoir Lake Olathe Lake Lake (1969)a (1981)bc (1964)e (1956)fc (1906)g (1956)h (1938)h (1962)d

Drainage areai, mi2 1,117 144 9,628 933 1,150 2,500 16.9* 16.9*

Years since dam 32 15 37 33 40 100 45 62 closurei Total deposition, 56,700 2,100 142,000 7,100 1,267 1,000 317 338 acre-ft Total estimated sediment deposi- 48.6 1.9 30.2 7.5 1.2 156,000 283,500 297,500 Reservoir characteristics tion since dam million million million million million closure, tons

109 2.3 93 7.5 1.1 Phosphorus --- 437,400 911,400 million million million million million Nitrogen 243 24.8 27.7 1.3 1.2 (Total organic-N --- 5 million --- + Ammonia-N) million million million million million Total organic 928,000 --- 610,000 --- 19,300 ------carbon

Selenium 87,360 --- 48,988 6,270 3,856 ------

1.8 Arsenic --- 845,868 521,400 24,760 ------million 2.7 1.5 Lead --- 285,120 --- 650,000 18,720 20,212 million million 11.7 7.25 1.2 12 Zinc ------88,470 84,506 million million million million 3.2 Copper --- 825,000 262,020 --- 83,040 19,845 20,832 million 9.6 4.9 Chromium --- 1 million --- 159,110 52,740 53,568 million million

Cadmium 48,640 --- 26,517 4,818 --- 78,000 171 198

4.8 2.3 Total estimated load (lb) based on values reported for period of study Total estimated load (lb) based on values reported for period Nickel --- 456,390 --- 84,000 19,845 22,010 million million a Juracek (2003) f Christensen (1999) b Juracek (1997) g Juracek (2006) c Mau and Christensen (2000) h Mau (2002) d Juracek and Mau (2002) i USGS (2008a) e Mau (2001) *Watershed includes both Lake Olathe and Cedar Lake

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Appendix A-3. Mercury values from sediment cores at selected Kansas reservoirs and estimated mean annual net loads Reservoir Gardner e Lake Mission Perry Tuttle Cedar Hiawatha Lake Empire Lake (one core) City Aftona Lakea Lakeb Creekc Laked Lakea Olathed Lakea Top Middle Bottom Number of ------19/19 41/41 ------samples Measured ------0.12 .029 .022 value Minimum, 0.03 0.05 0.02 0.01 <0.02 0.05 0.1 ------mg/kg Mean, 0.04 0.06 0.02 ------0.07 0.04 0.06 ------mg/kg Median, 0.04 0.06 0.04 0.05 0.04 ------mg/kg Maximum, 0.04 0.07 0.04 0.07 1.4 0.14 0.06 ------mg/kg

TEL 0.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13

PEL 0.696 0.696 0.696 0.696 0.696 0.696 0.696 0.696 0.696 0.696 0.696

Mean annual net 0.46 0.39 0.93 69 144 ------load, kg/yrf Mean annual net 0.35 0.33 0.93 152 317 ------load, lb/yrf TEL = threshold-effects level d Mau (2002) PEL = probable-effects level; values given for comparison e Juracek (2006) a Juracek (2004) f Values calculated using median concentration, bulk densities, b Juracek (2003) and annual sediment loads reported in studies cited c Juracek and Mau (2002)

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Appendix B-1. Nutrient and pesticide concentrations in sediment cores from selected Kansas reservoirs Nutrients Pesticides Organic Total Total Total carbon DDD DDE DDT nitrogen phosphorus carbon (TOC) μg/kg μg/kg μg/kg mg/kg mg/kg % mg/kg

US EPA TELs and PELsa TEL ------1.22 2.07 1.19 PEL ------7.81 374 4.77

Reservoir Values from Sampled Sediment Cores Websterb Range 30-1,910 251-692 10,600-16,200 --- <0.2 <0.2 <0.2 Kirwinb Range 1,200-1,980 422-795 8,310-13,600 --- <0.2 <0.2 <0.2 Waconda Lakeb Range 704-3,210 281-904 3,440-19,900 ------Tuttle Creekc Range 600-5,200 198-952 0.84-2 0.93-2.2 <0.50 <0.2 <0.50 Range 2,000-2,700 1,370-1,810 ------Cedar Laked Median 2,350 1,540 --- 1,540 <0.2 <0.2 <0.2 Range 1,300-2,700 588-1,030 ------Lake Olathed Median 2,000 774 ------<0.50 0.2 <0.50 Pony Creeke Range 3,000- 3,400 1,100-1,200 2.6-2.8 3.2-3.5 ------Otis Creeke Range 2,200-2,400 600-640 2-2.3 3.5-3.7 ------Mission Lakee Range 1,900-2,400 750-1,200 2.1-2.6 1.9-2.3 <0.50 1.86 <0.50 Lake Aftone Range 2,200-2,600 740-840 1.9-2.4 2-2.5 <1.25 0.22 <1.25 Hiawathae Range 1,000-1,700 400-680 1.1-2.4 1.1-2.6 1.19 1.99 <0.50 Gardner Lakee Range 1,600-3,100 1,100-1,300 3.2-3.4 3-3.9 0.46 <0.50 --- Edgerton Citye Range 1,000-2,200 480-610 0.7-2.1 0.6-2 <0.50 0.22 <0.50 Crystal Lakee Range 2,600-4,300 690-1,300 2.6-3.9 2.7-6.1 <0.50 4.76 <0.50 Centraliae Median 2,400 1,300 2.7 2.7 <0.50 0.27 <0.50 Bronsone Median 3,700 1,100 3.6 3.9 <0.50 0.52 <0.50 Perry Lakef Range 1,300-2,800 630-1,300 1-2.1 1-2.3 <0.5-0.55 <0.2-0.8 <0.50 Empire Lakeg Mean 1,250 610 1.35 1.7 ------Cheney Lakeh Range 1,400-2,400 495-647 ------Hillsdale Lakei Range --- 410-810 ------Milford Lakej Range ------TEL = threshold-effects level c Juracek and Mau (2002) g Juracek (2006) PEL = probable-effects level d Mau (2002) h Mau (2001) a USEPA (2004) e Juracek (2004) i Juracek (1997) b Christensen (1999) f Juracek (2003) j Christensen and Juracek (2001)

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Appendix B-2. Trace element concentrations in sediment cores from selected Kansas reservoirs Trace Elements Arsenic Cadmium Chromium Copper Lead Nickel Selenium Zinc mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

USEPA TELs and PELsa TEL 7.24 0.676 52.3 18.7 30.2 15.9 --- 124 PEL 41.6 4.21 160 108 112 42.8 --- 271

Reservoir Values from Sampled Sediment Cores Websterb Range 8-15 <3.0 <6-26 19-29 16-32 <12-30 0.5-2.7 --- Kirwinb Range 4.6-10 <2.7-3.7 9-33 17-28 14-26 <11-24 <0.5-2.2 --- Waconda Lakeb Range 5.4-13.1 <5.1 <10 - 17 7-27 <14-25 <21 <0.6 - 3.6 35-137 Tuttle Creekc Range 6.9-18 0.26-0.6 48-120 20-44 16-160 19-77 0.34-1.5 65-150 Range 13-16 0.23-0.36 90-98 32-45 32-35 32-39 0.86-1.1 150-170 Cedar Laked Median 14 0.31 90 32 33 34 0.99 150 Range 15-18 0.27-0.41 88-94 32-38 28-40 35-39 0.95-1.2 140-150 Lake Olathed Median 16 0.33 89 36 36 37 0.99 140 Pony Creeke Range 13-17 0.4-0.5 70-77 26-29 24-25 35-38 0.8-0.9 170-200 Otis Creeke Range 10-13 0.4-0.6 76-82 21-22 23-24 35-39 1-1.2 66-74 Mission Lakee Range 12-16 0.3 74-84 28-35 24-31 37-41 0.8-0.9 120-140 Lake Aftone Range 9.9-15 0.6-0.8 69-74 32-35 34-54 37-40 0.7 120-140 Hiawathae Range 8.2-12 0.5-0.9 43-54 14-20 21-58 21-26 0.4-0.6 58-250 Gardner Lakee Range 7.3-15 0.6-1 83-100 39-210 1,300-1,600 1.3-1.6 130-150 <.50 Edgerton Citye Range 7.3-15 0.1-0.4 48-61 14-19 21-24 19-24 0.7-1.1 58-76 Crystal Lakee Range 14-21 0.5-1.4 67-93 25-1600 28-65 32-43 0.8-1.2 130-250 Centraliae Median 18 0.8 77 30 19 40 0.8 110 Bronsone Median 15 0.7 74 200 34 37 0.9 150 Perry Lakef Range 8-25 0.2-0.6 59-100 18-35 18-30 22-54 0.4-1 58-140 Empire Lakeg Mean 4.6 29 66.3 34.6 270 25 0.8 4,900 Cheney Lakeh Range 5.9-10 0.24-0.40 55-100 12-24 14-24 18-43 0.31-0.52 58-120 Hillsdale Lakei Range ------Milford Lakej Range 6.1-9.9 ≈0.9-1.5 34-46 21-30 <33-53 29-38 0.2-2.2 29-38 TEL = threshold-effects level c Juracek and Mau (2002) g Juracek (2006) PEL = probable-effects level d Mau (2002) h Mau (2001) a USEPA (2004) e Juracek (2004) i Juracek (1997) b Christensen (1999) f Juracek (2003) j Christensen and Juracek (2001)

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Appendix C. Vegetation used to remediate dredged materialsa Plant Name Natural Planted Plant Name Natural Planted Grasses Herbs Barley x x Alfalfa Barnyard grass x Alsike clover Beaked panic grass x Arrow-leafed tearthumb x Big bluestem x Black medic x Bromegrass x Black nightshade x Bromesedge x Blackseed plantain x Corn x x Bracted plantain x Deertongue x Broadleaf plantain x Fall panic grass x Chufa x x Foxtail millet Common chickweed x Goose grass x Common lambsquarters x Green bristlegrass x Common mullein x Johnson grass x Common purslane x Jungle rice x Common ragweed x Large crabgrass x Common spikerush x Oat Common threesquare x Orchardgrass x Cow pea x Panic grass x Crimson clover Prairie cordgrass x x Curly dock x Quackgrass x Dwarf spikerush x Red fescue x Flowering spurge x Redtop x Giant ragweed x Red canary grass x Goosefoot x Rice cutgrass x Hairy vetch Rye Hardstem bulrush x x Sand dropseed x Hop clover Sixweeks fescue Horseweed x Smooth crabgrass x Japanese clover Sorghum Jerusalem artichoke Sudan grass Korean clover x Switchgrass x Ladino clover Timothy x x Ladysthumb x Wheat Lespedeza Wild rye x Malta starthistle x Yellow bristlegrass Mapleleaf goosefoot x Marsh pea x

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Plant Name Natural Planted Plant Name Natural Planted Marsh pepper x Vines Maximillian’s sunflower Common greenbrier x Mexican tea x Fringed catbrier x Narrowleaf vetch x Japanese honeysuckle x Nodding smartweed x Kudzu Nutsedge x Muscadine grape x Pennsylvania smartweed x Peppervine x Pokeberry x Virginia creeper x Prostrate knotweed x Prostrate spurge Purple nutsedge x Plant Name Natural Planted Purple vetch x Shrubs and small trees Red clover x American elderberry x Redroot pigweed x American hornbeam Schweinitz’s nutsedge x American plum x Sea blite x Black raspberry x Seaside dock x Carolina ash Sericea lespedeza Carolina rose x Sheep sorrel x Eastern hophornbeam x Soybean x x Gray dogwood x Spotted burclover Halberd-leaved willow x Spotted spurge x Multiflora rose x Squarestem spikerush x Poison ivy x Sunflower x Possumhaw x Tansy mustard Rough-leafed dogwood x Tumbleweed x Russian olive x x Virginia pepperweed x Sandbar willow x Western ragweed x Shining sumac x White clover x x Silky dogwood x Wild bean x Smooth sumac x Wild buckwheat x Squaw huckleberry Wild sensitive pea Staghorn sumac x Wild strawberry Tartarian honeysuckle x Wooly croton x Thorny eleagnus x Wooly indianwheat x Wild apple x Witch hazel Shining sumac x

136 Sedimentation in Our Reservoirs: Causes and Solutions This publication from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service has been archived. Current information is available from http://www.ksre.ksu.edu.

Plant Name Natural Planted References

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