DRAFT
THE CONTROL OF POLLUTION FROM
CONSTRUCTION ACTIVITIES
CAUSING CHANGES IN THE CIRCULATION OF WTEP
Office of Mater Proqram Operations
uater Duality and Non-Point
Source Control Division
Toon 1035, Fast Tower
Auaust 2, 1973
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CONTENTS
Introduction 1
Guidance for Identification
and Evaluation of the Effects of
Channelization 5
Methods, Processes, and Procedures to
Control Pollution Resulting from Channel
Modification Projects 46
Guidance for the Identification and
Evaluation of the Effects of
Reservoirs 66
Methods, Processes, and Procedures to
Control Pollution from the Impoundment
of Water 116
Guidance for the Identification and
Evaluation of the Effects of Urbanization 145
Processes, Procedures, and Methods to
Control Pollution Resulting from
Urbanization 161
Guidance for the Identification and
Evaluation of the Effects of Dredging 167
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INTRODUCTION
This report will discuss processes, procedures and 11
methods to control pollution resulting from changes in the
imovement, flow or circulation of any navigable waters or 12
ground waters caused by construction activities in or in 13
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conjunction with a stream channel which includes 14
construction of dams, levees, channels or flow diversion 15
facilities. This report is mandated in Section 16
304 (e) (1)6(2) part (F) of PL 92-500. 17
The initial step in such a study is to endeavor to 19
determine exactly what the congress intended to accomplished 20
by this Section of the Federal Water Pollution Control Act 21
Amendments of 1972. Examination of the Senate Committee on 23
Public Works Report which accompanied S. 2770 and the Report 2H
of committee on Public works of the U.S. House of 25
Representatives which accompanied H.R. 11896 was made to 26
make this determination in conjunction with the specific 27
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language contained in the law as finally passed (P.L. 92- 28
500).
A
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The information, gu,
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of hydrographic modification work,..." (p.49). The term 33
water quality is defined by the Committee as "...to refer to 34
the biological, chemical and physical parameters of aquatic 35
ecosystems, and is intended to include reference to key f
species, natural temperature and current flow patterns,..." 36
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Jp.51). Thus, changes in flow patterns through channel 38 *
modification which must be identified and if possible, 39
methods to reverse or alleviate damages described. Another 41
problem cited by the committee is the effects of H...the •
temporary or permanent obstruction or diversion of fresh 42
water flows in the construction of a dam or other facility, 43
which may also cause salt water intrusion from estuaries" 44 9
(p.54).
The descriptions in the House of Representatives 46 ^
Committee were not as expansive as the senate Committee's 47
discussion for this section. The report directs the 49
Administrator to be "...diligent in gathering and
distribution of the guidelines for the identification and 50
the information or processes, procedures, and methods for 51
control of pollution from such non-point sources 52 A
as...natural and manmade changes in the normal flow of 53
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surface and ground waters."
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With these comments in mind, the specific language of 55
the bill i_s clarified. The pertinent part of the Act reads 57
as follows: sec 30U(e)
Administrator. . .shall issue. ..within one 59
•
year. . .information including (1) guidelines for 60
identifying and evaluating the nature and extent of 61
non-ooint sources of pollutants, and (2) processes, 62
1 procedures, and methods to control pollution resulting 63
from--... (F) changes in the movement, flow or 64
circulation of any navigable waters or ground waters, 65
i including changes caused by the construction of dams, 66
levees, channels, causeways, or flow diversion 67
facilities. "
i
Part. (1) calls for guidelines for identification and 69
evaluation; this does not reguire EPA to identify and 70
evaluate rather only to provide yardsticks for such. Part 72
(2) reguires identification of available processes,
procedures and methods for relieving or ameliorating the 73
• pollution resulting from changes in flow induced by stream 7U
bed modification. It does not reguire evaluation of these 76
4
methods, only identification. 77
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Basically the assigned task is to develop informational 79
guidelines for evaluating the pollution caused by flow and 80
circulation changes through stream bed modifications; and to 81
describe known processes to control pollution resulting from 82
such changes. Although not mandated in the legislation, the 84
pollution problems themselves must also be identified and 86
highlighted in order for the mandated requirements to be
meaningful. This is not to say evaluated, but only 88
identified.
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Guidance for the Identification 93
and Evaluation of Channelization 9U
Introduction 99
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This discussion will be limited to aspects of 102
channelization where actual in-channel modifications occur. 103
consideration of other aspects of channelization will be 105
covered under senarate headings such as reservoirs. 106
The type of channel envisaged in this discussion is the 108
relatively small stream which frequently floods either urban 110
or rural areas causing significant damage. Also included 111
are those drainage projects used to render low-lying
wetlands usable for agriculture or construction of suburban 112
developments.
Cur r ent_Government al,_I nvol ve ment 116
The initial step in identifying and subsequently 119
evaluating channelization projects is to determine those 120
governmental agencies, grivate groups and individuals 122
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involved in desiqninq and constructing projects, Zor 124
Federal Agencies the list is quite short, perhaps even
shorter for State Aoencies hut conceivably quite extensive 125
for local aqroups and individuals constructing such 126
projects.
The Federal Aqencies principally concerned with 128
channelization projects on a whole basin scale or major 129
portions of basins are the Soil Conservation Service of the 130
Department of Aqriculture, U.S. Army Corps of Engineers of 131
the Defense Department, the Bureau of Reclamation of the 132
Interior Department and the Tennessee Valley Authority. 133
Other Agencies may be indirectly involved in smaller 134
projects because drainage or flood protection may be 135
included as part of a project. These Agencies would include 137
the Federal Housing Administration in the Department of 138
Housing and Urban Development, Veterans Administration and 139
Federal Highway Administration of the Department of 140
Transportation. These smaller incidental projects will not 141
be discussed in this section. 142
Contacts with the major Federal Construction Agencies 144
should yield listings of projects completed, under planning 145
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and/or design and those being requested by various local 146
governments or private interest groups. Such contacts would 148
provide the major projects in a given state or planning 149
area.
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state and local agencies involved in channelization 151
projects are more difficult to identify in this type of 152
report bocause of the various names of such organizations 153
used from State to State and locality to locality. Often 154
these Agencies will be identified in project reports 155
prepared by the Federal Agencies as participants in a given 156
* project. Organization names frequently used include a State 157
Soil and Water conservation Committee, Soil Conservation 159
Districts, Conservancy District, Flood Control District or 160
• Irrigation District. These organizations provide local 161
support and frequently partial funding of projects 162
constructed under the auspices of a federal grogram. 163
4) State and local governments frequently are directly 164
involved in the financing of projects either on a partial 165
basis conjunctively with Federal Agencies or totally for 166
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£ Federally ineligible projects. 167
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Privately constructed projects are even more difficult 169
to identify. Usually, these projects are small and limited 170
to an individual's or at most a few individual's property. 171
These projects would generally be for drainage purposes to 172
make land usable for agriculture or housing developments. 173
However, the effects of such projects may cause significant 174
water quantity and quality changes in a given area. These 176
projects may be identified by examination of Department of
Agriculture aerial photographs, examination of construction 178
permits issued, examination of recently constructed housing 179
subdivisions or contact with large housing or heavy 180
equipment contractors in a local area.
Current_Practices 184
Current practices can generally be subdivided into 188
those principally flood control oriented or those
principally drainage oriented. In combined projects, design 191
is frequently controlled by flood control requirements. 192
Several alternatives are generally available to accomplish 194
the goals of a given project. Current practice is generally 195
to use the method with the highest benefit-cost ratio unless 196
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some compelling reason overrides the economic justification. 197
DP"4 & F*TP
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CLEARING AND SNAGGING 200
Clearing and snaqqinq operations may be used as an 202
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independent technique for increasing channel hydraulic 203
capacity or it may in essence be a maintenance technique for 205
maintaininq a previously imoroved channel. The basic 207
operation is the removal cf obstructions from the channel
which may impede flow directly, increase hydraulic friction, 208
or present obstructions which accumulate debris carried by 209
the stream during hiqh water conditions and reduce the 210
available area of flow.
Clearing and snaaqing operations are frequently used 212
following high water to remove accumulated debris, logs, 213
rocks, etc. and restore the hydraulic capacity of the 21U
channel. Equipment used consists of bulldozers and front 215
loaders to ghysically remove the obstructions. 216
Although the least expensive means for increasinq the 218
hydraulic capacity, clearinq and snagqing is also the least 219
effective. Only modest improvements can be anticipated and 221
these frequently short lived. In certain types of basins 222
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channel obstructions re-occur within relatively short spans 223
of time.
CHANNEL EXCAVATIONS 226
Channel excavating is principally of two types. In 229
many cases the existing channel is enlarged and reshaped to 230
increase hydraulic capacity. In other cases the existing 232
channel is abandoned with a new channel being excavated. 233
New channel construction has also frequently been used for 234
irrigation canals where no previous channel existed. In 236
these irrigation channels, design is more precise because 237
flow rates are predetermined and not subject to the whims of 238
nature.
The design configuration and construction of the 240
channel excavations depends on the purpose and setting of 241
the new channel. In urban areas where land values are high 242
and flood damage losses high, channels are frequently 243
designed with a rectangular configuration and are concrete 244
lined to achieve maximum hydraulic efficiency and require a 245
minimum of right-of-way. .In rural settings channels may be 246
designed wider with a trapezodal shape. Side slopes are 247
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determined by soil stability or by the final coverinq used 2U7
such as grass or rip-rap. In situations where channel 249
straightening has resulted in excessively steep hydraulic 250
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slopes with resulting excessively high water velocities
which erode the channel bottom or side slopes, drop 251
structures are used to dissipate energy at frequent points 252
along the channel.
The method selected for excavation varies with the 25 U
project size, whether "wet" or "dry" techniques are possible 255
and the method of disposing of the spoil. In dry situations 257
conventional drag lines, power shovels or front end loaders 258
are used; in wet situations generally some method of
dredging is employed. The dredging method used also depends 260
on the material to be dredged.
CHANNEL REALIGNMENT 263
The purpose of channel realignment is principally to 265
eliminate the meandering of the stream over the flood plain. 266
"Such meanders frequently result in instabilities which cause 268
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shifting of the channel and poor hydraulic efficiency. By 270
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realigning the channel into a straighter and therefore
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shorter length, costs of a channel improvement may be 271
reduced.
Restraints on realignment are existing roads and 273
bridges and the existence of available land for right of 274
way. Channel realignment is complicated by the problem of 275
excavated material disposal and the abandonment of the fish 276
and wildlife habitat available in the old channel. 277
Frequently, these "oxbows" are maintained with sufficient 278
flow or backwater to maintain the habitat. 279
FLOODWAYS 282
Floodways are channels which are constructed to convey 285
floodwaters around a protected area. These channels may be 286
constructed in lieu of modification of the existing channel 288
or in conjunction with channel hydraulic improvements.
Such channels are constructed to be dry until the water 290
stage in the stream reaches a predetermined level and then 291
to convey (in conjunction with the existing channel) flows 293
greater than this amount. When flood flows recede, water is 294
diverted from the floodway back into the principal channel. 295
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Floodways are generally shorter than the natural 297
channel and have greater hydraulic efficiency. Flood stages 299
up-and-downstream may be affected by such a project.
<
Since floodways are normally dry, they may be used for 301
other purposes such as pasture or as parkland. Maintence is 303
required to remove new growths of trees and brush and to
maintain grass cover to minimize erosion during flood 304
periods.
This type of flood control project requires more land 306
then a channel modification project and is therefore more 307
expensive. Maintenance costs are also high especially if 308
non-permanent overflow devices are used such as a narrow 309
earthen levee which must be replaced following each period 310
of high water.
The principal benefits as related to water quality are 312
the non-destruction of the nataral fish and wildlife habitat 314
and aesthetically by maintaining the natural appearance of 315
*the stream.
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RESERVOIRS 318
The type of reservoir considered in this discussion of 320
channelization is basically a retarding basin. These basins 322
contain a dam with an unqated outlet which discharges water
proportional to the height of water stored in the reservoir. 32U
The purpose of these structures to hold large volumes 326
of storm water initially with a subsequent gradual release 327
when the channel capacity exists to pass the flow. The 329
hydrograph thus reflects a reduced stage and is lengthened 330
time-wise consequently reducing flooding downstream.
Consideration of such structures as part of a project 332
is influenced by actual construction costs, land acquisition 333
costs and the existence of acceptable terrain. 334
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DRAINAGE DITCHES 337
Drainage ditches, although included in a channelization 339
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scheme as part of the justification, seldom dictate channel 341
capacity. Channel capacity normally is dictated by flood 342
1 flow conditions. Drainage ditches usually involve deepening 343
natural channels or in constructing new ditches where none 344
previously existed.
I
The major effect on the hydrology is to lower the water 346
table and perhaps reduce dry weather stream flows in the 347
main channel if ditching is sufficiently extensive, some 349
increase in main channel peak flows may occur as a result of 350
better interception of surface run-off and more efficient
hydraulic conveyance than previously existed. 351
Depletion of ground waters and subseguent reduction of 353
stream flows can adversely affect water guality in both the 355
surface and subsurface. in addition to adverse effects on 356
fish and wildlife habitat, there is decreases dilution water 357
* and higher water temperatures.
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Sources_Qf Pollution 361
Following stabilization after the various 364
channelization schemes, both direct and indirect sources of 365
pollution are identifiable. Realizing that the main purpose 367
of channelization projects is either to increase hydraulic 368
capacity to convey flood waters thus protecting adjacent 369
property; or to provide drainage of land to increase its 370
economic usefulness, the attributes in terms of 371
environmental pollution are readily apparent.
SCOUR FROM BOTTOM AND BANKS 374
In order to enhance the hydraulic efficiency of 376
channels by excavation, realignment or even clearing and 377
snagging, the channel roughness is reduced. Such a 380
reduction in roughness decreases friction losses and thereby 381
increases the velocity of flow. Increased flow velocities 382
may exceed the stability velocities of the bottom or bank 383
materials and cause erosion or scour. This in turn degrades 38U
the channel and furnishes sediment for stream transport, 395
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destroys natural habitats and detracts from the aesthetics 386
of the stream.
Perhaps the worst offender in this regard is channel 388
_jstraightening and realignment. This process reduces channel 390
lengths but not the decrease in elevation over which the 391
water is lowered in traversing a stream section. The net 393
result is a substantial increase in the stream gradient with 394
resulting substantial increases in stream velocities. 395
Without extensive control measures for stabilization or the 397
use in-channel drop structures, channel degradation can be 398
extensive.
INCREASE USE OF FLOOD PROTECTED AND DRAINED LAND 401
Following the implementation of both flood control and 403
drainage projects, extensive amounts of land become 404
available for higher economic production. Land formerly 407
used for pasture or low return agricultural crops can be
converted to high yield agricultural crops. Within 409
municipal areas, property values are increased and uses with
more economic return can be developed. With such economic 411
gains generally there follows environmental degradation.
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Enhanced agricultural uses is accompained by increased 413
fertilizer, herbicide and pesticide use and by increased 414
.land tillage which increases erosional soil losses. The by- 416
products of this agricultural use drains to the stream and 417
causes various amounts and kinds of water quality
impairment.
Channelization projects which provide flood protection 420
within urban areas frequently include the provision of lined 421
channels. The effects on the water environment of these 423
channels is both the destruction of fish and wildlife 424
habitat and to destroy aesthetic gualities. 425
GROUND WATER DEPLETION 428
Provision of protection against overbank flooding by 430
various channel modification schemes and the provisions of 431
drainage channels through wetland areas both contribute to 433
the deterioration of ground water quality and the reduction 434
in ground water quantity.
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Many flood plain aquifers receive recharqe during 436
overbank flooding periods. Such recharqe provides in 438
addition to the quantity of available qround water, low 439
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mineral content water which serves to dilute mineral
concentrations in existing ground waters. Removal of this 441
recharqe will thus result in both reduced quantity and
quality of these qround waters. 442
Additionally, since qround waters frequently furnish 445
the dry weather base flow of many streams, the effects of 446
the removal of recharqe and resultinq lowered water table is 447
to reduce this base flow. The annual hydroqraph of a stream 448
may become more extreme between wet and dry weather periods 449
of the year if the channelization project is sufficiently
extensive.
Drainage ditches also lower water tables substantially 451
and reduce the base flow of streams which is provided by 452
qround water infiltration. Since swampy or wet areas which 454
are in hydraulic contact with the qround water are 455
frequently drained and converted to other uses, this
reservioir of water is also made unavailable for providing 456
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infiltration to streams.
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ELIMINATION OF FISH AND WILDLIFE HABITAT AND AESTHETIC 459
QUALITIES
The various channelization practices have varying 461
effects on fish and wildlife habitats. In general, the more 463
extensive the modification structurally the more damage that 465
is caused to habitat areas. For example, concrete lining of 466
channels eliminates habitat areas for practical purposes 467
whereas at the other extreme, clearing and snagging may not 468
have a detectable effect. The effects of the project can 469
only be determined by the use of before and after surveys 470
designed to detect both drastic and subtle changes. 471
Aesthetic values for streams depends a great deal on 473
the beholder. swamp habitats may be quite disagreeable to a 474
non-naturalist whereas parkland or pasture beside an 475
improved channel may appear quite pleasing. To this extent 477
aesthetics may be somewhat acquired in conjunction with 478
strictly innate appreciation. Perhaps aesthetics is the 479
most difficult environmental factor to quantify and may 480
require the opinion of a representative cross section of the 481
population before classification of a project is acceptable. 482
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o f _Poi l.u t ant s 186
Depending on the location of a project, perhaps almost U89
^
any conceivable pollutant could be introduced by a 490
channelization project. This discussion will be limited to 193
the common pollutants both contributed directly and U91
indirectly. Such pollutants are the common denominators to 195
be anticipated from the majority of projects. 196
gIRECT EFFECTS 199
Sediment 501
Sediment is perhaps the most ubiquitous of all 503
pollutants associated with channelization. The most 505
pronounced effect on sediment occurrence and concentration
is during the construction phase of the project. With bare 508
soil banks and a non-stabilized channel, the natural stream 509
flow itself and any rain that occurs flushes sediment into 510
the stream discoloring the water and making it turbid and 511
'non-transparent. Following stabilization however, the 512
stream frequently remains more turbid than before the 513
project was constructed
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Every stream has an ability to naturally transmit 515
certain amounts of sediment. The amount transmitted is 517
termed bedload and is a definable stream characteristic. 518
When channel hydraulic characteristics are changed by 519
constraininq the channel to a fixed location, by
realignment, or by other ireans, the velocity of water flow 520
in increased and consequently the ability to transmit 521
sediment is likewise increased.
The effects of increased sediment or water quality are 523
to reduce light penetration, to blanket fish spawning areas, 524
to blanket and suffocate aquatic insect larvae used by fish 525
as J-ood, to create shoaling and instabilities in the channel 526
itself, and to cause problems with sedimentation in 527
unimproved channel sections downstream from the project 528
section, ^n addition to these problems which directly 529
affect water quality instream, increased costs are realized 530
by water users including water suppliers and irrigators, 531
Additionally, aesthetic quality is reduced to a substantial 532
degree.
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Jhermal 535
The design of channelization projects in terms of flood 537
* prevention requires increased channel dimensions. Because 539
of enlarged channels, the dry weather flow is directed near 511
the center of the channel and is thus exposed to solar 542
radiation which heats the water. Previously in the natural 543
channel, the presence of trees along the banks provided 544
shade and helped moderate stream temperatures. The purpose 545
of channelization being to increase the hydraulic efficiency
of the channel, those trees are removed as they impede flows 546
during high water. 547
In addition to reducing temperatures during daylight 549
hours, the insulating effect of these trees is removed and 550
night time temperatures are reduced to a greater extent than 551
previously. Thus, a greater diel variation in temperature 552
can result from a channelization project. 553
The effects on fish and aguatic life are caused by both 555
* the absolute temperature itself and the temperature 556
variation. Both increased maximum temperatures and 557
increased variation can have detrimental effects on fish and 558
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aquatic life during various stages of their life cycle. 559
Specie selection, availability of food, attendant life cycle 560
chemistry and water quality changes are all phenomene that 562
are temperature affected.
Water quality is affected by the increased respiration 56<»
rates caused by increased temperatures so that dissolved 565
oxygen is removed more rapidly by bacterial oxidation of 566
soluble and suspended organic materials. This problem is / 568
compounded by reduced oxygen solubility at higher
temperatures so that a resultinq decline in stream dissolved 569
oxygen concentrations results. Decreased dissolved oxygen 571
concentrations decreases water quality and stresses aquatic 572
life dependent on this constituent.
Movement of Pollution Effects Downstream 575
Because one result of channel improvement projects is 578
to improve hydraulic conveyance of channels, frequently 579
velocities of flow are increased. Jn channel relocation or 582
realignment projects where channel lengths are substantially 583
reduced, the effect of increased velocity can be pronounced. 58U
Jhe effects of increased velocities on surface water quality 585
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is to move the effects of pollutants which are time 586
dependant downstream. Discharges of organic wastes or 587
drainage of natural organics from swampy areas along the 588
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stream, both of which are bacterially degraded and oxidized 589
, in the course of moving downstream, move much farther in 590
distance for the equivalent period of time required for
completion of the reaction. Thus the effects of reduced 592
dissolved oxygen levels extends farther downstream than 593
previously.
increased water velocities also are capable of 595
transporting increased sediment loads which are deposited in 596
non-channelized areas downstream. Such deposition effects 598
tend to migrate upstream clogging channels and defeating the 599
channelization improvement unless removed during maintenance 600
operations.
In addition to simply transporting more sediment, 602
increased velocities make streams more aggressive in eroding 603
channels and stream banks which destroys much of they 604
A
usefulness of the stream for other purposes. 605
Fish and wildlife Habitat Alteration 607
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Almost any modification of a channel alters the 609
existing habitat for fish and wildlife. Not all such 612
changes are detrimental however, provision of water storage 613
for example may provide increased habitat areas but perhaps 614
for a different than pre-project biological assemblage.
Most in-channel modifications do remove obstructions 616
that are used by fish for protection from predators, for 618
fish food habitats and for backwater breeding areas.
Removal of trees and brush along stream banks removes 619
protective cover and food sources for various water related 620
wildlife.
Many of these effects can be mitigated by incorporating 622
proper factors into project design. For example, 621
maintenance of water in cut-off oxbows helps retain 625
available fish and wildlife habitats.
INDIRECT EFFECTS 628
Destruction of Aesthetics 630
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Channelization projects have frequently been criticized 633
for the destruction of aesthetic values of natural streams. 634
The creation of geometrical shaped channels with highway- 636
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type alignment is not conducive to aesthetic appreciation by 637
.naturalists or the general public. It is possible to 639
mitigate much of the aesthetic destruction by use of proper 610
design techniques. For example, those techniques which only 611
alter one stream bank or which provide a replanting program 612
similar to that existing £rior to construction can be used. 613
Other similar measures can be included to minimize the 615
reduction of aesthetic values.
It should be mentioned also that aesthetic values can 617
be enhanced for many people by various channelization- 618
related projects. In many instances public accessibility to 619
water courses is improved and parks or other recrection 650
facilities can be incorporated into the right of way 651
acquired for the project.
In-stream techniques can also be applied to maintain 653
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fish and wildlife habitat. Construction of pool and riffle 655
areas is one technique available. Use of more natural 656
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alignment, and other design features are available to project 657
planners.
Hydrology 660
Considering the major function of channelization 662
projects as either flood control or drainage or a 663
combination of both, many of the effects on basin hydrology 665
can be anticipated. The major effect of these changes is to 666
increase the hydraulic capacity of the principal channel and 667
the smaller channels which drain into the principal channel. 668
The effect of this change is to move water more rapidly 669
through the channel. Downstream from the channelization 671
project these increased flows may cause increased flooding. 672
Drainage projects may aggravate this problem by 674
allowing higher valued operations on the drained land. If 676
the higher valued use is urbanization, then the paved areas
including roof areas drain water to storm drains which 677
convey water to the water course even more quickly and 678
increase peak flow rates and subsequent flooding. 679
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Drainage facilities also tend to lower the water table 681
during wet periods of the year and deprive streams of the 682
critical base flow required during dry weather periods of 683
t
the year. Lowering of the water table is not always 684
detrimental for all purposes as this technique has been used 686
to control ghreatophyles Jthose plants whose roots extend 688
into the saturated zone) by drawing the water table below 689
the root zone. This technique has reduced transpiration 690
losses from these plants providing more irrigation water 691
flow existing projects, wildlife habitat near these stream 692
beds has suffered however. 693
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Methods of Pollutant Transport 697
The methods of pollutant transport in channelized 700
stream basins are essentially the same as in the unaltered 701
stream basin. certain transport mechanisms are either 703
increased or decreased by the effects of the alteration. 704
BEDLOAD 706
As indicated previously, bedload is the amount of 708
sediment characteristically carried by a particular water 709
course. it is related to several factors but principally 710
the hydraulic characteristics of the stream and the soil and 711
geologic characteristics of the stream channel and drainage 712
basin.
The effects on bedload of a channelization project is 714
generally to cause an increased amount. .Improved hydraulic 716
conveyance produces increased water velocities and enhanced 717
sediment transnort capability. If the streambed is 718
improperly stabilized following construction, this increase 719
can be dramatic. Even though proper stabilization 720
techniques are used, concentration of sediment generally 721
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increase except in the special case of complete channel 722
lining with concrete or other paving materials. Downstream 723
, from the channelization section, these materials can settle 724
, and fill the channel with excess materials destroying
hydraulic efficiency and biological life. 725
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Indirect effects of channelization are to enhance land 727
for higher economic uses such as increased agricultural 728
production or urban and commercial development of some type. 729
Many of the pollutants generated by these increased uses 730
become adsorbed with soil grains. Such organics as 732
herbicides and pesticides are particularly susceptible to 733
such adsorption. When these soil particles are flushed into 73U
the stream, the adsorbed materials are likewise carried 735
along for later deposition downstream. Following such 736
deposition, these materials can enter the life cycle of the 737
stream and through biological concentration mechanisms cause 738
significant ecological desturbances.
Increased bedload can be visible as increased turbidity 740
or opaqueness of the stream water. Such turbidity can be 7U2
dangerous by obstructing swimmers view of hazardous 743
' obstructions. The principal effect is to decrease the 7UU
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aesthetic value of a stream. On larger streams used for 745
water supply purposes, increased turbidity causes increased 746
treatment costs for potable or industrial water users. 747
Bedload increased can therefore cause problems with 749
excess channel scour and downstream deposition; adsorbed 751
pollutant transport; and direct detrimental effects to water 752
suppliers and stream aesthetic values.
DIRECT DRAINAGE 755
The increased uses of land adjacent to streams 757
following the provision of flood protection and drained 759
arable land provide sources of pollution which directly
drain into the water course. Many of the pollutants arise 762
as the normal product of urbanization or farming practices. 763
Others arise because of the removal of natural mechanisms 764
which trap contaminants directly or provide detention time 765
for the adverse effects to decay to acceptable levels. 766
The effects of urbanization include many direct 768
discharges to the surface waters and to ground waters which 769
discharges contain pollutants that upset stream ecology. 770
-------
33
Urbanized areas contain extensive paved areas which are 771
serviced by storm sewers which discharge pollutant laden 772
run-off directly into near-by water courses. Pollutants 77U
„ including inorganic fertilizer nutrients, petroleum
products, rubber, animal feces and sediment are discharged 776
' without treatment. J.f the area is serviced by sanitary 777
sewers, this effluent is discahrged with substantial 778
pollutants even though treatment is provided. If not 780
sewered, septic tanks are used which can pollute ground
waters with pollutants including nitrates and sulfates in 781
properly operating systems; organics, and unoxidized 782
nitrogen and sulfur compounds in improperly operating 783
systems; and synthetic organics such as pesticides in either 784
system. These comoounds pollute the ground water and if not 785
intercepted by a well or diverted to a deeper aquifer may 786
infiltrate along with the ground water into surface waters. 788
Since dry weather stream flows essentially reflect the 789
guality of infiltrating ground waters, the stream water 790
quality may be substantially impaired. 791
With time, many pollutants are degraded into innocuous 793
substances. Nature provides detention time in natural 795
* blackwaters and in ^sluggish meandering streams. Pollutants 797
DRAFT
-------
3U
in solid form or which naturally flocculate and settle are 798
assimilated and destroyed in bottom sediments by biological 799
life forms. Nutrients are chemically removed either as 800
insoluble salts or by conversion to qaseous forms which 801
evolve to the atmosphere. Following channelization and 802
drainage projects these natural places of detention are by- 803
passed or removed which has the effect of increasing 804
pollutant concentrations in the flowing waters. The effects 806
of these pollutants are then transferred downstream
decreasing water quality while in passage. 807
SOLAR INSOLATION 810
The light provided by the sun provides the energy for 812
the biology of natural waters. The so called "food web" 814
begins with primary production by algae which are capable of 816
photosynthetic production, up through the consumer species 817
including aquatic insects and fish. Too little solar 819
insolation produces too few algae, little primary
groduction, and a sparse fishery. Too much sunlight heats 820
the water, jgrovides a competitive advantage for undesirable 821
biological species and an unsatifactory fishery. The 823
DRAFT
-------
35
effects of solar insolation are both on water quality and on 823
the biological response and effects on that water quality. 824
In many streams light penetration extends essentially 826
to the stream bottom and is necessary for the maintenance of 827
a healthy biological condition. The existence of such light 828
provides for attached algae which provide both food and 829
oxygen for animal life. In streams characterized by pools 830
and riffle areas, these productive areas are interspersed 831
along the stream. in deeper streams productive areas are 832
near the edge of the stream extending outward until the 833
incident light is extinguished to less than usable levels. 834
Following channelization, the stream channels are frequently 835
deeper reducing light penetration from former levels and 837
higher velocities occur which scour attached algae or
inundate such areas with sediment. Thus the former habitat 839
is altered and a different biological assemblage develops. 840
Frequently, the new assemblage is composed of less desirable 842
species than previously.
Thermal effects become evident because shading trees
and brush are removed allowing both more time of exposure 846
and increased surface area of exposure to sunlight.
DRAFT
-------
36
Coldwater species of fish can not tolerate the elevated 8U7
water temperatures and are replaced by warm water species. 848
Thus, the direct effect of increased solar radiation 849
indirectly changes the stream fishery. 850
Magnitude and Variation 854
Available statistics for defining the national 857
magnitude and variation of channelization projects indicates 858
that perhaps 200,000 miles of waterways have been altered in 860
the last 150 years in the United States. Since the 862
initiation of Federal projects in the early 1910 «s planning
f^or and development of about 34,240 miles of waterways in 863
1,630 projects have been initiated under the federally- 864
assisted local protection and small project programs of the 865
U.S. Army Corps of Engineers and watershed programs of the 866
soil Conservation service. Additional projects have been 868
initiated by the Bureau of Reclamation, the Tennessee Valley 869
Authority and other Federal, State and local Agencies, 870
The Corps of Engineers have assisted in 889 projects of 872
which 47 percent involve channelization and 53 percent 873
involve levees. Of these projects 6,180 miles (56%) are 874
DRAFT
-------
37
*
completed, 3,896 miles (35%) are under construction and 875
1,001 miles (9%) are planned. The median size for these 876
projects is about U miles with two thirds under 5 miles and 877
80 percent less than 10 miles.
879
"Report on Channel Modifications'* by A.D. Little, Inc. 882
submitted to the council on Environmental Quality, U.S. 884
Gov. Printing Office, Washington, D. C. (March, 1973)
DRAFT
-------
38
The Soil Conservation Service assisted in 558 projects 887
of which virtually all involved channelization. Of these 889
projects 4,209 miles (25%) were completed by 1971 and ^2,426 890
miles (75%) still remaining to be completed. The median 892
size of the projects is about 18 miles with 38.7 percent
JLess than 10 miles and 24 percent less than 5 miles. 893
PROJECT DESCRIPTIONS IN COUNCIL ON ENVIRONMENTAL QUALITY 896
REPORT
The Council on Environmental Quality's sponsored report 898
previously referenced discusses 42 different projects of 4 899
different Federal Agencies. To quote that reports' 902
description of the environmental settings of the projects, 903
range was from virtually untouched, natural 905
conditions to totally altered surroundings. The 42 907
projects encompassed dense swamp forests and mixed hill 908
country and flood plains of the Southeast, intensively
used citrus, sugarcane and cattle-raising leands of the 909
flat Florida interior, the totally urbanized bedrock 910
slopes of the Northeast, the deep-soiled featureless 911
Mississippi details agricultural empire, the rolling 912
-------
39
prairie farm and woodlot country of the Midwest, 913
totally industrialized Detroit, the semi-arid and 91U
treeless northern Great Plains, and an arid Valley in
the southwest. 915
The soils ranged from liqht organic mucklands to heavy 917
clay ^spung", with pure sand, gravel, boulders and 918
clayes-silt in other places. The vegetation was 920
luxuriant to poor grass. Precipitation was a well- 921
distributed 70 inches annually to an intermittent 16 922
inches annually. The stream flow was swift and 923
sluggish, pure and unbelievably contaminated. 924
Streambeds and channels were bankfull with flood flows 926
and bone dry with blowing sand. Fish and wildlife 927
resources were plentiful, diverse and non-existent.
Adjacent lands were canopied forest, high-valued 928
specialty truck gardens, grain farms, fish farms, 929
vineyards, fruit and nut groves, pasture, idle 930
brushland, marshes, factories, shopping centers and
railroads. There were surrounding areas of arresting 932
scenic beauty and depressing ugliness." 933
DRAFT
-------
40
Each project was analyzed amonq othej: things for the
""" I
!
basis of project formulation, physical effects of the
\
completed project and the bioloqical effects on the aquatic
\ ;
and terrestrial systems. The report presets an excellent
format for those evaluatinq additional projects.
ENVIRONMENTAL ASSESSMENT REPORTS
Since the enactment of the National Env conmental
Policy Act of 1969 (P.L. 91-190) each Federa
participatinq in a proposed channelization pi
siqnificantly affects the quality of the hume
must prepart an environmental imoact statemen
Aqency
ject that
environment
These
statements must assess for the project: jTitli 42 U.S.C.,
Sec. 4332)
936
937
938
939
940
943
945
947
949
951
952
11 (i) the environmental impact of the propped action 955
\
)
_Cii) any adverse environmental effects whi<\ cannot be 958
\
avoided should the proposal be
(iii) alternatives to the proposed action
960
-------
U1
_[iv) the relationship between local short-term uses of 962
man's environment and the maintenance and 963
enhancement of long term productivity, and 964
Jv) any irreversible and irretrievable commitments of 966
resources which would be involved in the proposed 967
action should it be implemented.11 968
In accordance with NEPA all Proposed Projects 970
significantly affecting the environment have such reports 971
prepared which initially are made available for review and 972
comment. Final reports incorporating comments of reviewers 973
are submitted to CEQ and are available upon request from the 97U
preparing Federal Agency. 975
The environmental effects of a project are 977
comprehensively covered in these reports. Whether or not 979
the Agency is able to mitigate the adverse effects 980
identified in the environmental assessment, discussion of 981
these effects is included. For most projects these 982
assessments are invaluable in evaluating a project. 983
-------
42
It should also be pointed out that several states have 986
also enacted statutes patterned after NEPA which require an 987
environmental impact statement before the expenditure of 988
state funds or in some cases before permits are issued to 989
private interests for project construction.
-------
" .'-'BV
43
Methods 994
Methods to predict the effects of channelzation 997
projects will not be directly presented in this report as a 999
tremendous volume of literature exists discussing such 1001
« effects, several sources of information will be mentioned 1002
•
as convenient and comprehensive starting places for project 1003
evaluation including the mitigation as much as possible of 1005
the inevitable adverse effects.
•
The previously mentioned CEQ Report on channel 1007
Modifications presents the results of extensive biological 1008
investigations conducted by the Philadelphia Academy of 1009
Natural scieces. Chapter 5 of Volume I of this report 1010
entitled, ^Effects of Channel Modifications on Fish and 1011
* Wildlife Resources, Habitat, Species Diversity, and 1012
Productivity" directly addresses the biological effects 1013
observed in 21 channelization projects analyzed. The same 10 1U
• or similar effects therefore are to be anticipated in other 1015
projects under comparable conditions. Discussion includes 1017
the effects of channelization projects which cause erosion, 1018
ft consequent sediment accumulations and unstable stream beds, 1019
- remove solid substrates, or decrease light penetration which 1021
-------
44
may affect the biological population by disturbing the
number of species, the populations of each, or the
productivity of the stream.
1022
1023
Methods to predict the effects of channelization 1025
projects are in included in a volume produced by the Soil 1026
Conservation Service entitled, ^Planning and Design of Open 1028
Channels." *This document comprehensively presents available 1029
information on channel design including anticipated flows; 1030
location, alignment and hydraulic design; and stability 1031
design. A recently added chapter 7(1971) includes 1033
environmental considerations. The technical methodology 1034
presented in this document is sufficient to predict the 1035
effects of the hydraulic changes caused by a channelization 1036
project including any increases in sediment transport. * 1038
U.S. Dept. of Agriculture, Soil conservation Service,
^Planning and Design of Open Channels", Technical Release 1040
No. 25. December 15, 1964 (Rev. March, 1973) .
increases in the Stream temperature and the diel 1042
variation are not so readily predicted. The calculations 1044
can only be made by estimating the amount of protective 1045
shade removed, changes in depth and changes in channel
K AH .
'•*'? '4 *.,
-------
jLength in conjunction with tables of solar insolation 1046
values. Such calculations will probably only yield 1047
approximate semi-quantitutive amounts of change. 1048
The best technique is the field survey of a nearby 1050
stream which has undergone the changes projected for the 1052
stream of interest. Comparisons of this type of information 1053
establish a more rational basis for predicting the various 1054
physical, chemical and biological changes to be anticipated. 1055
In the absence of such a situation, predictive techniques 1056
from the sources suggested above and in the compenion report 1058
on Methods, Processes and Procedures to Control pollution 1059
resulting from channelization projects must be utlized.
-------
Bibliography 3
!_. A.D.Little, Inc., "Report on Channel Modifications," 7
submitted to the Council on Environmental Quality, U.S. 9
Government Printing Office, Washington, D.C. (March", ]0
1973).
£. Anon., "Planning and Design of Open Channels," ]2
Technical Release No.25, U.S. Department of ]3
Agriculture, Soil Conservation Service (December, 1964, ]4
Revised March, 1973).
3_. Anon., National Engineering Handbook, Section 16, ]6
Drainage, Chapter 6. Open Ditches for Agricultural ]7
Drainage, U.S. Department of Agriculture, Soil ]8
Conservation Service (February, 1959). ]9
£. Todd, O.K., Ground Water Hydrology, John Wiley £ Sons, 22
Inc., New York (1959~n
5_. Anon., Water Quality Criteria, Report of the National 25
Technical Advisory Committee to the Secretary of the 26
Interior, Section 1, Recreation and Aesthetics, Federal 27
Water Pollution Control Administration (April, l9"68).
6_. Dewiest, R.J.M., "Replenishment of Aquifers Intersected 30
by Streams, Jour, of the Hydraulics DivisionT A.S.C.E,, 3]
No. HY6, (November, 1963).
T_* Anon., "Sedimentation Transportation Mechanics: G. 33
Fundamentals of Sediment Transportation," A.S.C.E. 34
Task Committee on Preparation of Sedimentation Manual, 35
Committee on Sedimentation, Journal of the Hydraulics 36
Division, A.S.C.E., No. HY12 (December, 1971). 37
£. Mackenthun, K.M., The Practice of Water Pollution 39
Biology, U.S. Department of the~Tnterior, Federal Water 4]
Pollution Control Administration (1969). "~
-------
U6
Methods, Processes and Procedures to Control Pollution 1066
Resulting from Channel Modification Projects 1067
Discussion under channelization will be limited to 1070
thosp cl^siqn changes in the actual channel modification 1071
project that can be incorporated to enhance and mitigate 1072
undesirable by-products. Additionally, attention will be 107S
directed to consideration of alternatives to channel 1076
modification such as flood plain zoning regulations. 1077
Discussion of other structural alternatives including 1078
upstream storage reservoirs are covered under separate 1079
headings. 1080
Design^Modifications to Minimize Adverse channelization 1083
Impacts 1084
CHANNEL ALIGNMENT 1086
Channel improvement projects generally are designed to 1088
follow existing stream alignment with the exception of 1090
situations where stability or cost factors force an 1092
alternative course. In stream sections passing through 1093
highly erodable soils for example, an alternative course may 1094
-------
be desirable if an alignment through more stable soils 1095
exists. Relocation also may be desirable to avoid passage 1096
through valuable Rowland areas which serve as fish and 1097
r
wildlife habitats.
In constructed channels the alignment generally should 1100
follow a natural pattern which should consider the type of 1101
existing stream, the required hydraulic capacity and
comparison with up-and downstream sections of the particular 1102
water course or nearby water courses. Use of such design 110U
technigues avoids the unnatural appearance of a modified 1105
channel thus improving aesthethic appeal and in many cases
may aid stability by not changing the channel gradient 1106
excessively. 1107
Special features along the stream should be protected 1109
to enhance aesthetic appeal. By proper design of channel 1111
alignment the existence of particularly striking features 1112
can be preserved and perhaps enhanced which adds to the 1113
public appreciation of the projects. Design should 111U
incorporate provisions to protect these features including
special stream and streambank stabilizing measures, land 1115
*"""
treatment methods and grade adjustments. 1116
-------
48
CHANNEL CAPACITY 1119
Channelized streams should convey water discharges 1121
ranging from base flow to the design flood flow without 1122
damage to either the channel itself or the associated fish 112U
and wildlife resources. The low flow channel cross section 1125
should approach the natural stream condition. The bottom 1127
width and side slopes can be designed to simulate the
natural channel so that it will blend with up and downstream 1128
sections of the natural channel and avoid a monotonous 1129
appearance. At bends, the channel side slope can be 1130
steepened on the outside of the channel bend and flattened 1131
on the inside of the bend to simulate natural water ways. 1132
~ *
Use of naturally occurring rocks and boulders can be placed 1133
at selected goints for aesthatic appeal, energy dissipation 113U
and fish habitat development. The bottom width of the 1136
channel can be varied in conjunction with the channel slope 1137
to develop pool and riffle areas to aid fish and wildlife 1138
yet maintain hydraulic capacity, inclusion of these devices 1139
however reguires carefull attention of the designer, on site 1110
inspection personnel and especially the contractor.
-------
49
CHANNEL GRADE 1143
Within the topographic constraints of a given project, 1145
i
the channel gradient can be varied between stream reaches to 1146
achieve naturally appearing pool and riffle areas, cascades 1148
or other such features. To accomodate the existence of 1150
highly erosive soils in certain reaches, gradients can be 1151
flattened and conversely, in erosion resistant soils
gradients can be steepened, all within the natural 1152
topographic constraints of channel elevations at the 1153
beginning and end of channel sections. Use of such grade 1154
variations not only enhances aesthetic appeal but increases
protection against meander development, increases channel 1155
stability and thereby minimizes sediment from channel and 1156
bank erosion.
Adjustment of the channel gradient to develop pool and 1158
riffle areas can also provide increased atmospheric 1159
recreation capacity in the stream. Reaeration increases 1160
with increased velocity and decreasing stream depth. Riffle 1162
'areas additionally provide increased turbulence which also
tends to increase reaeration. The increased dissolved 1164
oxygen supplied by the increased reaeration improves the 1165
-------
50
habitat for fish and aquatic life. £t also provides 1166
additional capacity to satisfy the demands exerted for the 1167
oxidation of naturally occurring or man-contributed organic 1168
material before damage to aquatic life occurs. 1169
SPOIL PLACEMENT 1172
The on-site placement of excavated spoil material 1171
should be accomplished so as to minimize the amount of 1175
clearing required or other land disturbing activities. 1176
Spoil should be nlaced in such a fashion so as to minimize 1178
the potential for the erosion of the material back into the 1179
stream. Placement of spoil should also be made so as to 1180
minimize the adverse effects on wildlife habitats and may be 1181
concentrated at selected locations along the stream section 1182
to accomplish this goal. Through proper re-vegetation and 1183
planning the spoil amy be used to create scenic overlooks 1184
and other contrasting features which may enhance the 1185
aesthetic appeal of a project and avoid the monotony of 1186
continuous spoil banks beside the stream. 1187
The amount of spoil can also be minimized by the use of 1190
one-sided or single stream bank construction where
'\ -•• r
-------
51
appropriate. Other spoil reducing measures can be included 1192
by the use of non-structural alternatives totally or 1193
partically in lieu of actual channel modification.
«
STRUCTURAL MEASURES 1196
Structural measures can be included in a channel 1198
modification groject to alleviate problems of excessive 1199
grade to maintain stability. Structural measures can also 1202
be applied to side stream entry points to control the 1203
introduction of sediment, debris or other pollutants or 120U
effects.
For channels with excessive slopes which would 1207
otherwise erode producing sediment, typical structures
include drop structures, chutes, steepened rock armored 1208
sections and cascade structures. Each of these structural 1209
modifications provides resistance to high velocity flows and 1210
allows the use of stable, moderate gradients upstream and 1211
downstream.
For channels with sufficiently flat gradients so that 1213
*
channel and bank stability are not problems, designs can be 1214
-------
52
incorporated usinq the pond, riffle and pool sequence. The 1216
inclusion of ponding provides sufficient excess elevation
that succeeding oool and riffles can be maintained. Besides 1218
protecting fish habitat, aesthetic appeal is increased.
Side channel structures include pipe drops, iined 1221
chutes and drop spillways. These structures can be used in 1222
conjunction with sediment basins and debris traps to retard 1223
the input of these materials into the main channel. The 1224
principal purpose of these structures is to prevent the loss
of vegetation from stream banks at the point of entry, 1225
slumping of the main channel bank or the cutting of a deeper 1226
tributary channel all of which produce sediment into the 1227
main channel and reduce channel stability. •
-------
53
VEGETATION 1230
The early re-establishment of vegetative covers 1232
following in-channel modifications is most important to 1233
prevent extensive erosion and damage to the hydraulically 1234
improved channel. The selection of the plantings should 1235
incorporate both an initially quick growth to stabilize the 1236
bank and the subsequent development of a cover which will 1237
blend or simulate the natural cover.
Use of proper erosion resistant cover will keep 1239
sediment concentrations and adverse water quality impacts to 1240
a minimum. Proper trees and bushes will enhance biological 1241
productivity within the stream itself and the associated 12U2
wildlife. Shade provides against excessive solar insolation 1213
which helps maintain maximum temperatures within allowable 1244
tolerances and insulate against excessive diel thermal 1245
variations.
Use of aguired right of way for parks, hiking paths or 1248
the provision of access for fishing is also enhanced
aethetically for public use by the use of suitable 1249
revegetation practices.
-------
514
EFFECTS ON GROUND WATER
1252
Any channel modification will tend to alter the natural 1255
circulation of the ground water. Natural recharge to the 1256
ground water may be increased or decreased depending upon 1258
location, depth, and other characteristics of the new
channel. Thorough investigation of possible effects upon 1259
both quantity and quality of ground water should be made 1260
before undertaking a channelization project.
An important distinction in terms of their effect on 1262
ground water Duality is whether channels are lined or 1263
unlined. A lined channel, constructed of an impermeable 1264
material such as concrete, grevents in many reaches the 1265
natural recharge of streamflow to ground water. The water 1266
table may be lowered, and ground water circulation and
dilution reduced, so that quality is impared. 1267
To control this situation water needs to be
artificially recharged to the ground water. This can be
done by installation of ditches or basins for artificial
1269
1270
1271
recharge in the vicinity of the lined channel. High-quality
water diverted from the stream or derived from some other 1272
-------
55
source and released into these structures would infiltrate 1273
to the qroundwater and thus compensate for the loss of 1274
natural streambed recharge. This is extensively practiced 1275
in California.
In unlined channels, a primary effect is that produced 1277
by changing the water table elevation. If a channel is 1278
dredged in an area where the water table is close to the 1279
ground surface, the new channel acts as a drain and lowers 1280
the water table. If the groundwater body is underlain by
saline water, the reduction in freshwater head would cause 1281
the saline water to rise and pollute the fresh groundwater. 1282
Methods to control this effect include: 1285
^Install pumping wells in the underlying saline 1287
water. Removal of a portion of the saline water by 1288
pumping will counteract its upward movement and protect 1290
the overlying freshwater. Means for the disposal of 1291
the saline water must be provided, as by evaporation
from lined basins, disposal to the ocean, or desalting 1292
and use.
. r i
-------
56
Line the channel with an impermeable material. 1294
This will p_revent dewatering of the upper portion 1295
of the aquifer and hence maintain the original 1296
natural conditions of groundwater quality. some 1297
drainage to prevent uplift of the channel lining
would be necessary. 1298
There may be some loss in streambed recharge even with 1300
unlined channels of the hydraulic characteristics are 1301
improved and the gradient steepened, resulting in higher 1302
velocities. The effects on groundwater quality are the same 1303
as for lined channels. Artificial recharge can be used to
compensate for the loss. 130U
Unlined channels may allow polluted water to enter the 1306
groundwater if the groundwater is below the bottom of the 1307
channel and if there is no impermeable layer above the 1308
groundwater body.
Jn some coastal areas (e.g., Florida and California) 1310
natural channels have been deepened or new channels 1311
excavated. These have sometimes cut deeply into or through 1312
the underlying clay formation which originally acted as a 1313
-------
natural barrier and prevented the downward movement of 1314
saline water into the underlying freshwater aquifers.
Serious groundwater pollution has resulted, as from the Los 1315
Gerritos Creek Flood channel near Seal Beach, California. 1316
Such channels should be located, designed, and constructed 1317
with care so that the natural barriers to saline water 1318
intrusion will not be impaired. If this is not possible, 1319
the channels should be lined withal. In some flood control 1320
channels it may be possible to install inflatable rubber 1321
dams to prevent the movement of saline water from the sea or
bay into the channel. 1322
Structural Alternatives to In-Channel Modifications 1327
In many cases in-channel modifications can be reduced 1330
substantially or avoided altogether by the use of various 1331
alternative schemes involving construction of off-stream 1333
facilities. Such facilities as levees, floodways, retarding 1334
basins and land treatment can be incorporated into projects 1335
"to avoid actual channel modification. The construction of 1336
these alternatives themselves potentially contribute to 1337
water quality degradation.
-^ <*, r- r
•; ' \ »-"' P
:••/!' , h
-------
58
Levges 1340
Levees are generally low structures located along the 1342
edges of surface water bodies such as rivers, reservoirs, 1343
lakes, and the sea to prevent inundation of land behind the 1345
levees during periods of high water levels resulting from 1346
floods, storms, or tides. Levees may be constructed to form 1347
a controlled channel. A floodwall ^erves the same purpose 1348
as a levee but is constructed of concrete or masonry to save 1349
on right-of-way acguisition. Only in rare instances do 1350
levees or floodwalls have a subsurface vertical extent
sufficient to form a barrier to groundwater flow. 1351
In coastal areas levees prevent the flooding of land by 1353
seawater. As a result, the quality of groundwater in the 1354
aguifers behind these levees is protected. The principal 1355
harmful effect of levees on groundwater quality occurs in 1356
floodplains of rivers. The mineral quality of most 1357
floodwaters, neglecting their susgended sediment, is higher 1358
than that of groundwater. During periodic inundations of 1359
floodplains, some of the water infiltrates to the 1360
groundwater and acts to improve its quality by dilution.
Where levees prevent this action and thus reduce the natural 1361
-------
59
recharge, the mineral quality of the qroundwater will tend 1362
to deteriorate with time. 1363
To counteract this effect which tends to degrade ground 1365
water, two possibilities deserve consideration. One would 1366
be to pump groundwater from the aguifer behind the levee so 1367
as to increase the circulation of groundwater and to remove 1368
accumulations of salinity. The other approach would be to 1369
divert fresh water to the land behind the levee. By 1370
overirrigation or other means of artificial recharge with 1371
water of a quality equal to or better than that of the
existing recharge, a dilution of the groundwater similar to 1372
that produced by natural floodwaters could be maintained. 1373
The effect on surface water quality of levees located 1375
along a channel is principally the encouragement of erosion 1376
and channel scour during high water periods which contribute 1377
sediment and increase water turbidity. Since the stream is 1378
confined by the levee to a smaller than natural flood 1379
channel, water velocities are increased above natural 1380
conditions causing channel scour to occur. The increased 1381
scour can subject underlying less resistant geological
formation to attack and perhaps even breech aquitards 1382
-------
& FT
t.
-------
61
flowing in a bypass channel and infiltrating into the ground
would tend to improve the local groundwater quality. 1405
Because of the negligible effect in degrading 1(407
groundwater quality, no specific control measures are sugged 1408
to prevent pollution of this resource. 1409
The effect on surface water quality depends on channel 1411
stability measures incorporated into the design of the 1412
floodway and the maintenance provided. Incorporation of 1413
proper replanting, rip-rapping of channel bends prevent the 1414
scour of sediment during high flow periods. Insufficient 1415
maintenace can lead to substantial quantities of sediment 1416
and debris which decreases water guality downstream. 1417
Retarding Basins
1420
These basins ar«? constructed on tributary streams and 1422
in the main stream. By regulating the hydrograph 1423
downstream, flood stages are reduced and damages due to 1425
flooding consequently reduced.
-------
62
Water quality is generally unaffected by these basins 1427
during low flow conditions as the water passes through 1428
essentially unaffected. During the high runoff periods, the 1429
basins help reduce sediment concentrations and trap debris. 1430
If accumulated sediment and debris are not removed during 1431
maintenance operations subsequently, sediment storage will 1432
be filled and any additional quantities will be transported 1433
downstream.
Proper stabilization and planting programs will avoid 1436
erosion and subsequent input of sediment directly into the
basin and prevent caving and slumping of the inundated areas 1437
during high water. 1438
frand Treatment Measures 1441
Land treatment measures include proper farm cultivation 1443
techniques and use of vegetation in the drainage basin. 1444
These measures are effective in reducing sediment bearing 1446
runoff and extending the time for runoff itself during light 1447
and moderate rainfall p.eri°ds but are not particularly 1448
effective during heavy rains that lead to flooding. 1449
-------
63
Basically these measures are beneficial and do not require 1450
abatement measures.
Non-Structural Alternatiyes^to Channglization 1455
The principal purpose of channelization projects is to 1458
reduce the damage caused by periodic flooding. Thus far in 1459
this report, the physical methods to mitigate the water 1461
quality degradation that occurs because of such channel 1462
modification have been discussed. One alternative to a 1463
physical solution to prevent damage from flooding is to 1464
delineate areas subject to flooding and prohibit uses of 1465
these areas that are damaged by floods. Such non-structural 1466
alternatives can eliminate the jaollution effects directly 1467
attributable to channel modification and if properly planned 1468
and enforced can eliminate pollution effects that would 1469
otherwise occur when the project design flood is exceeded 1470
and flooding occurs.
The CEQ Report previously referenced summarizes these 1472
approaches as follows: 1473
-------
64
-structural adjustments take many forms. The three 1175
major measures are regulatory, 1476
technical/administrative/policy, and economic/financial 1477
measures. Powers, programs and incentives are available for 1478
each. Regulatory measures combine State encroachment
statutes, local rural and urban zoning ordinances, 1479
subdivision regulations, building and housing codes, and 1480
open space regulations. Technical/administrative/policy 1481
measures combine flood proofing, temporary (preplanned) and 1482
permanent evacuation, flood forecasting and warning systems, 1483
alternative uses of protective works, lending policies, 1484
local facilities development jjolicies, urban renewal, and 1485
relief and rehabilitation policies and programs. 1486
Economic/financial measures combine flood-risk insurance, 1487
tax adjustments, rights, easements, dedications, 1488
reservations and public or private acquisitions."
In practice, a combination of structural and non- 1490
structural approach is taken to flood damage reduction. For 1491
any given situation, the effects of the 1492
alternatives on water quality ^hould be calculated and 1493
considered in the overall project evaluation. 1494
-------
Bibliography •••-^J -c.^ L 3
]L. A.D. Little, Inc., "Report on Channel Modifications," 7
submitted to the Council on Environmental Quality, U.S. 9
Government Printing Office, Washington, D.C. (March,
1973).
2_. Anon., "Planning and Design of Open Channels," ]]
Technical Release No. 25, Chapter 7, Environmental ]2
Considerations :Ln Channel Design, Installation and ] 3
Maintenance, U.S*. Department of Agriculture, Soil ]4
Conservation Service (October, 1971).
3_. Anon., Water Quality Criteria, Report of the National ]6
Technical Advisory Committee to the Secretary of the ]7
Interior, Federal Water Pollution Control ]8
Administration (April, 1968). ]9
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66
Guidance for the Identification and 1502
Evaluation of Reservoirs 1503
Introduction 1506
This discussion of reservoirs will describe the effects 1510
on water Duality of both storage reservoirs and run-of-the- 1511
river or main stream impoundments. In addition to 1513
distinguishing between these two classes of reservoirs, the 1514
principal differences between lakes and reservoirs should 1515
also be mentioned.
Essentially a reservoir may be considered as the 1517
upstream half of a natural lake with the dam providing the 1518
artificial separation. Since both lakes and reservoirs are 1519
physically similar many of the characteristics of lakes are 1520
reproduced in reservoirs. There are two significant 1521
differences however which produce differences in water 1522
quality in downstream discharges.
-------
67
The first difference involves facilities for 1524
controlling the rate of discharge. Downstream flows may be 1525
reduced to less than natural and in fact, in certain type 1526
operations may be reduced to zero for significant periods 1527
during the daily operating cycle. 1528
The second difference is the depth from which reservoir 1530
discharges are withdrawn when compared with the surface 1531
discharges from lakes. Natural lake discharges are 1532
generally surface waters which are aerobic and therefore 1533
have been subjected to the normal aerobic processes of 1534
natural purification. Reservoir discharges are frequently 1535
withdrawn from deep within the reservoir. If the reservoir 1536
is stratified, this water may be anaerobic and contain 1537
undesirable minerals resulting in decreased water quality. 1538
Run-of-the-river impoundments are located on main 1540
stream rivers and are characterized by relatively low head 1541
dams with impounded waters not extending far from the 1542
natural channel and water detention times of a few days. 1543
water velocities are appreciable and in a positive 1544
downstream direction. Passage of water through the 1545
reservoir is by displacement without significant vertical
-------
68
stratification other than that caused by daily surface 1546
warming by the sun. These impoundments are constructed 1547
principally to deepen rivers for navigation in canalization 1548
projects or to provide re-regulation downstream from peaking 1549
power operated storage reservoirs.
Storage reservoirs are generally located on tributary 1551
streams and are characterized as being relatively deep with 1552
the water surface extending far beyond the natural river 1553
channel. These reservoirs have large storage capacity in 1554
relation to the drainage area and generally have several 1555
months detention time. Because of the operation of these 1556
reservoirs passage of water through the reservoir may be 1557
discontinuous and subject the reservoir to large differences 1558
in water level on a seasonal basis. Because of the large 1559
lake level fluctuation, past designs have placed outlets
deep in the reservoir. These reservoirs are characterized 1560
by stratification aenerally of the classic three layer 1561
system. Primary uses of storage reservoirs include flood 1562
storage, hydro power production and water supply storage. 1563
Recreational use is an important secondary use on many 1564
storage reservoirs.
-------
69
Current Governmental Involvement 1569
Several Federal Agencies are involved in the 1572
construction of storage and main stream impoundments. As 1573
the Agency responsible for navigation on the nation's inland 1575
waters, the Corps of Engineers is responsible for 1576
constructing both types of reservoirs. The Tennessee Valley 1577
Authority which was initially authorized to construct
storage reservoirs to control flooding, has additionally 1578
constructed low head impoundments to facilitate navigation. 1579
The Bureau of Reclamation has constructed storage 1580
impoundments to provide water for the irrigation projects in 1581
the western States. The Federal Power Commission is 1582
responsible for approving private development of hydropower
and is involved in the approval of reservoir construction 1583
for this nurpose. information on reservoir projects for 1584
hydropower production of a regional nature is also available 1585
from other U. S. Department of Interior Agencies including 1586
the Bonneville Power Administration, Alaska Power Admini-
stration, Southeastern Power Administration and the 1587
Southwestern Power Administration. The Department of 1588
Housing and Urban Development has information on reservoirs 1589
constructed in housing projects in which they have an 1590
-------
70
interest. State and local governmental agencies are also 1590
involved in reservoir construction. Such developments may 1591
include recreation reservoirs and public water supply 1592
reservoirs. The name of the appropriate State and local 1593
agency varies from State to State and therefore must be 1594
determined for each particular situation.
Private development of small impoundments has become 1596
commonplace. Private developers construct suburban housing 1597
developments and recreational weekend communities 1598
surrounding man-constructed impoundments. Private
development of small lakes has also occurred in conjunction 1599
with campgrounds, recreational parks and even pay fishing 1600
lakes. A survey of the governmental sources will delineate 1601
the large projects and most of the significant smaller 1602
projects. Other projects may require an examination of 1603
local construction permit files or consultation with local
planning commissions. 160U
-------
71
Pr act i ces 1609
Current planning and justification for large reservoirs 1612
involving the Federal Government are generally based on 1613
multipurpose use. The principal multipurpose uses included 1615
are flood control, nydropower production, navigation, 1616'
recreation, irrigation water supply, public water supply, 1617
low flow augmentation for water quality or other special 1618
purposes, and fish and wildlife propagation. State and
local projects are generally multipurpose also with the 1619
exception that some water supply imnoundments are reserved 1620
solely for that purpose.
FLOOD CONTROL 1623
Extensive use of reservoirs whose initial justification 1625
was for flood control have been constructed by the Corps of 1626
Engineers and the Tennessee Valley Authority. The basic 1629
theory of operation is to reduce storage quantities to a 1630
minimum level prior to the normally wet seasons of the year. 1631
During the wet season, outlet flows are kept to a minimum
while excess tributary drainage is stored. Following the 1632
wet periods the reservoirs are filled to near maximum 1633
-------
72
storage levels. The available storage is then used to 1634
maintain normal or increased stream flows, produce 1635
hydropower when passing through the dam, and provide re-
creational opportunities on the reservoir itself. During 1636
the drier periods of the year the level is gradually lowered 1637
to reach the minimum as the next wet period arrives. 1638
POWER PRODUCTION 1641
Water storage for hydropower production is cne of the 1643
oldest uses of reservoirs. Many small reservoirs have been 1644
constructed to furnish energy to individual mills or small 1646
communities. Current developments are rarely designed for 1647
singe purpose hydroelectric power production but. <-he feature 1648
is primary at many reservoir sites.
Hydroelectric power production is generally used to 1650
meet peak daily loads in conjunction with a steam-electric 1651
facility supolying the base electric nower reguirements. 1652
The steam-electric facilities operate continuously while the 1653
hydroelectric power is produced for 4-8 hours to meet peak 1654
demands for air conditioning, home and industrial electric 1655
consumption demands. Such neaking power operations are the 1656
-------
73
standard operating scheme for many areas including the
Tennessee Valley Authority.
1657
Some storage reservoirs were constructed sufficiently 1659
large in comparison with power demands to allow continuous 1660
power production operations by adjusting water turbine 1661
operations to conform to the applied load. This type 1662
operations is generally inefficient with greater economies 1663
achieved by using steam generated power for the base load 1664
and meeting peaks by hydroelectric power.
Many of the main stream run-of-the-river impoundments 1666
also have gower generating facilities. Since the operation 1667
of these reservoirs is freguently for maintenance of a 1668
specific pool elevation, peaking power with its inherent 1669
rapid pool stage fluctuations is not possible. Power 1670
production is therefore limited by the incoming river flow 1671
and must be marketed on that basis.
-------
NAVIGATION 167U
t
Development of navigation on the nation's inland 1676
. waterways is a major use of run-of-the-river impoundments. 1677
Such dams are serially located alonq a stream with the pool 1679
of the downstream reservoir terminating at the toe of the 1680
next uostream dam. Navigation locks are provided at each 1681
dam to raise and lower river traffic. The use of such 1682
canalization techniques have been applied on the Ohio River 1683
and the Upper Mississippi River to name two examples. 168U
The dams are operated to maintain controlled pool 1686
elevations for the convenience of commercial barge traffic. 1687
Flow at each dam is adjusted by use of weirs, by flow 1688
through electric generating turbines, and by the number of 1689
lockages to maintain the specified pool elevation. 1690
WATER SUPPLY STORAGE 1693
Water supply storage includes small reservoirs for 1695
. public water supply arid industrial water supply and large 1696
reservoirs for irrigation water. Domestic and industrial 1698
water supply reservoirs are frequently small when compared 1699
-------
75
with other types of storaqe reservoirs. These impoundments 1700
are constructed to provide sufficient Quantities of water to 1701
augment the incoming stream flows during low flow periods. 1702
Sufficient detention time is generally provided to allow 1703
natural purification processes such as biochemical oxidation
of organics and sedimentation of particulate matters to 170U
enhance the water quality and reduce water treatment costs. 1705
Storage of water for irrigation use is responsible for 1707
most of the agriculture in the western States. Large 1708
impoundments, exemplified by the reservoirs on the Colorado 1709
River, store water from snow melt and winter rains and 1710
provide irrigation water during the growing season. Huge 1711
complexes of irrigated farms have developed to make use of 1712
the water which is diverted from these reservoirs.
MULTI-PUPPCSE RESERVCIPS
1715
Only infrequently are truly single purpose reservoirs 1717
constructed under conditions presently existina. Most 1718
reservoirs include many uses although one use may 1720
predominate.
-------
76
Flood control reservoirs can combine power production, 1722
water supply storage and recreational benefits although the 1723
operating rules would be mandated by the flood control 172U
purpose. The Tennessee Valley Authority storage reservoirs 1725
generally operate on this scheme. Reservoirs designed with 1726
peaking power as a principal output may be hazardous for 1727
recreational use because of rapidly fluctuating water 1728
levels. However, these reservoirs may provide flood
protection and water supply benefits in addition to hydro- 1729
power generation.
Other combinations of multi-purpose uses are 1731
discernable. Modern planning incorporates all such multiple 1732
uses to calculate the benefits accruing from a proposed 1733
project. Costs are likewise allocated to various projected 1734
uses. The final benefit-cost ratio reflects to total value 1735
of the project as against the cost of construction. 1736
-------
77
Sources of Pollution
1741
The construction of reservoirs of all types produces 1744
direct and indirect changes on water quality of the 1745
inflowing water. Direct changes include the physical, 1747
biological and chemical changes that occur during storage 1748
and because of the changed environment from a moving stream 1749
to a quiescent lake. indirect effects include waterhsed 1750
development which contribute pollutants and nutrients which
ultimately degrade water quality in the impoundment. Many 1751
of the direct changes that occur are also either magnified 1752
or mitigated by the changed encironment from straam to 1753
reservoirs.
BASIC RESERVOIR MECHANICS
1756
The deleterious effects on water quality caused by the 1758
construction of a reservoir or by a series of reservoirs in 1760
a canalization project can best be understood after an 1761
elementary understanding is acquired of basic reservoir 1762
hydraulics.
-------
78
Storage reservoirs in temperate climates frequently 1764
become stratified during the summer and winter with periods 1765
of non-stratification during the spring and fall. The 1766
formation of stable stratification depends on the density of 1767
water. The density of water changes with varied 1768
temperatures reaching a maximum of 4 degrees Celsius and
decreasing with either an increase or decrease in 1769
temperature from that point.
The classic stratification pattern for summer has a 1771
surface layer, the epilimnion, which is well mixed by wind 1772
and wave action. Beneath the epilimnion is a narrow zone of 1773
rapid temperature decline called the thermocline or 1774
mesolimnion, which is characterized by a temperature change 1775
of more than 1 degree Celsius ger meter. The lowest zone, 1776
the hypolimnion, is effectively shut-off from atmospheric 1777
reaeration, has only a small temperature gradient and is 1778
generally stable.
The winter stratification of storage reservoirs is 1780
" characterized by either ice or water of temperature less 1781
than 4 degrees Celsius floating on water of 4 degrees 1782
Celsius which then extends to the bottom of the reservoir.
-------
79
The hypolimnion is again stabile and is effectively removed 1783
from atmospheric reaeration. Because of low temperatures 178U
however biological activity is low and water quality may not 1785
be substantially impaired during the winter stratification. 1786
The point of discharge in most storage reservoirs is 1788
near the bottom so that releases can continue to occur when 1789
the water level is low in the reservoir. Thus, hypolimnetic 1790
water is generally released. If anaerobic, this water may 1791
be initially of poor quality because of no dissolved oxygen, 1792
concentrations of odorous sulfur compounds and 1793
concentrations of soluble metals. The quality of the 1794
discharged water is therefore greatly affected by the
dissolved oxygen concentration in the hypolimnion if 1795
withdrawal is effected from this water mass. 1796
If the dam is constructed so -that water can be 1798
withdrawn from the different depths, stratification allows 1799
the selective withdrawal of water of better quality. This 1800
is accomplished through the phenomena of stratified flow to 1801
accomplish selective withdrawal.
-------
WATER SURFACE.
Figure 1 — Representative profile shoxing lummer (notification in a typical storage reser-
voir (Ref. 3)
DAM
WATER SURFACE
INFLOW TEMPERATURE NORMAL
fig0fe 2 Summer strotifk'jtion in man stream reservoirs (Re<. 3).
-------
Inflow
i . I
Length
0 10 20 30
Temperature, °C
Figure 7 — Storoge retervoir — winter stratification.
rfe
-------
The thermal stratification of storage reservoirs is 1809
governed by a heat balance taking into account solar 1810
radiation, surface losses by evaooration and conduction, and 1911
• the input and outputs of heat by inflows and outflows. The 1812
thermal stratification effects discussed has a dominant 1813
influence on internal flow patterns in the reservoir and 1814
greatly affects outflow water quality.
Main stream reservoirs may exhibit a gradual 1816
temoerature gradient with temperatures decreasing from top 1817
to bottom. This gradient is caused by the absorption of the 1818
sun's energy in the uoper water layers and the existence of 1819
insufficient downstream velocity or wind induced mixina to 1820
insure complete vertical uniformity. If the stratification 1821
is stable enough to continue overnight or exist for several 1822
consecutive days, water guality in the lower layers may be 1823
adversely affected by declining dissolved oxygen levels. 182U
Downstream quality may be affected depending on method and 1825
location of outlet works.
. To summarize, thermal stratification of reservoirs 1827
occurs in both those designed for long term storage or in 1828
main stream reservoirs. The effect is to reduce vertical 1829
-------
82
circulation and the transport of dissolved oxygen to lower 1830
layers in the impoundment. Without some means to discharge 1831
waters from other than the hypolimnion, downstream water 1832
quality may be impaired.
WATER QUALITY CHANGES WITHIN RESERVOIRS 1835
CHEMICAL - PHYSICAL 1837
The annual cycle of storage impoundments in temperate 1839
climates consists of the winter and summer periods of 1840
stratification which are separated by periods of essentially 1842
uniform temperature distributions from top to bottom of the 1843
reservoir during which the waters freely mix. The periods 1844
of mixing are called the spring and fall turnovers. During 1845
the turnover periods soluble material entrapped in the hy-
jDolimnion which was derived from material either settled 1846
from the epilimnion or was leached from the bottom muds is 1847
returned to the biologically active near surface region. 1848
Such materials consist of the inorganic nutrients nitrogen 1849
and phosphorus, reduced heavy metals such as iron and 1850
manganese, and unoxidized organic material. The nutrients 1851
become available to support renewed primary production. 1852
-------
83
This period frequently coincides with the typical fall and 1853
spring plankton blooms observed in many reservoirs.
Durina the turnover periods dissolved oxygen 1855
concentrations are uniform throughout the depth of the 1856
reservoir. As the reservoir warms following the spring 1857
overturn and stratification is created, the supply of oxygen 1858
to the hypolimnion from atmospheric reaeration is
terminated. As the summer progresses dissolved organic 1859
material in the hypolimnion including that present initially 1860
and which is supplemented by material settling from the 1861
epilimnion, exert oxygen demands as bacteria oxidize these 1862
materials. If the organic content is insufficient to
exhaust available dissolved oxygen concentrations then 1863
waters withdrawn from the hypolimnion have improved quality 1864
based on organic concentration. However, if the organic 1865
content is sufficient to exhaust dissolved oxygen 1866
concentrations then anaerobic conditions become established 1867
and water quality is seriously degraded.
Compounds which are chemically stable and insoluble 1869
under aerobic conditions become soluble and enter solution 1870
under anaerobic conditions. This condition leads to the 1871
-------
leaching of materials from the bottom muds. The bottom muds 1872
have an oxidized surface layer during aerobic conditions 1873
which prevents leaching of underlying anaerobic products. 1874
Under anaerobic conditions this oxidized zone is eliminated 1875
and compounds are readily leached. Increases in ferrous,
ammonious, manganeous, silica, phosphate and sulfide ions 1876
have been observed in oxygen depleted waters in contact with 1877
bottom muds. .Increases in soluble organic compounds have 1878
also been reported.
Since many storage reservoirs withdraw water for 1880
release from near the reservoir bottom, the quality of this 1881
water may be much poorer than occurred in the preimpoundment 1882
stream. Low dissolved oxygen concentrations, the presence 1883
of reduced metallic compounds and the presence of odorous 188U
organic compounds are evidence of such deterioration. 1885
Main stream reservoirs as a general rule dc not become 1887
stratified for extended periods of time. Depending on the 1888
dissolved oxygen concentration gradient (if one exists) 1889
however similar leaching from the bottom muds may occur as 1890
that in storage reservoirs. Without stratification and 1891
assuming mixing from top to bottom, the water discharged 1892
-------
85
does not represent a particular zone and thus the depth of 1893
withdrawal is not critical to wat^r quality.
BIOLOGICAL 1896
In addition to various other classification schemes 1898
used for aquatic biological systems are the differentiation 1899
between lentic and lotic communities. Those biological 1901
communities adapted to the moving water stream system are 1902
termed lotic; those adapted to still water or lake 1903
environments are termed lentic.
In the process of converting a stream into a reservoir 1905
the biological community must adapt from lotic to lentic. 1906
The entire system may change significantly in storage 1907
reservoirs whereas only minor changes may occur in main 1908
stream reservoirs depending on prior conditions. 1909
Anticipated changes include plankton, rooted aquatic plants, 1910
aquatic invertebrates, and fishery speciation.
-------
86
SITE PREPARATION
1914
A critical process to the future water quality of an 1916
impoundment is the preparation of the area to be flooded. 1917
Older impoundments for power production frequently performed 1919
little if any site preparation but simply flooded an area. 1920
Such reservoirs are typified by highly colored waters and 1921
low dissolved oxygen concentrations. Current practice 1922
usually provides clearing at least from the minimum pool 1923
elevation to several feet above the maximum flood gool 192U
elevation. Organic deposits such as peat boggs are
generally either removed or covered with sufficient material 1925
to effect a seal. The remaining brush and shrubbery below 1926
the minimum pool level if left to decay will produce 1927
undesirable color, provide organic material which 1928
subsequently depletes dissolved oxygen, and provides
nutrient and growth factors which supports plankton growth. 1929
-------
87
RELEASED WATER 1933
The water quality downstream from a reservoir is 1935
obviously affected by the design and operations of that 1936
reservoir. If lower guality water is discharged than 1938
previously existed before the reservoir then the effect is 1939
the same as caused by a pollution source.
Additionally, the discharge may be of a temperature 1941
unnatural for natural biological systems. This occurs 1942
frequently during the summer because the hypolimnetic water 1943
released reflects the cooler water stored during the high 1944
flow winter-early spring seasons. Such low temperature 1945
discharges interfere with natural fish spawning cycles as 1946
well as the existence and reproduction of invertebrates and 1947
other low life forms.
The effects on downstream water users from the effects 1949
of impoundments include increased treatment costs at points 1950
of withdrawal for water supply use. Taste and odor, color, 1951
iron and managanese concentrations all may be increased 1952
above previous stream concentrations and require treatment 1953
for removal. Increased nutrients, principally phosphorus
-------
88
and ammonia-nitroqen may be present In increased amounts if 1954
the reservoir hypolimnion was anaerobic. These nutrients 1955
can stimulate rooted aquatic plant qrowth as well as 1956
plankton in downstream reaches. Plankton in nuisance 1957
amounts can produce water treatment problems by contributinq 1958
taste and odor to water and by interferinq with filtration 1959
processes. Both plankton and rooted aquatics reduce the
aesthetic quality of water, reduce recreational aopeal and 1960
pose subsequent oxygen demands on the stream^ dissolved 1961
oxyqen resources.
EFFECTS ON GROUND WATER
The most important effect of a dam on qroundwater 1966
quality occurs where the foundation of the structure 1967
provides a substantial or complete cutoff of qroundwater 1969
flow in an aquifer. For example, Prado Dam on the Santa Ana 1970
River in southern California, is located at the uoper end of 1972
a narrow, V-shaped canyon which forms the natural outlet for 1973
both surface and aroundwaters from the Upper Santa Ana
Valley, an extensively developed reqion. The cutoff wall 1974
extends to bedrock and blocks subsurface flow out of the 1975
upstream qroundwater basins. Such a stoppaqe reduces the 1976
-------
89
hydraulic gradient of the groundwater upstream of the dam. 1977
This causes an increased accumulation of 2°Hutants i-n fc^e 1978
groundwater, because of slower movement or complete
stoppage; the natural disposal of salinity from the basin or 1979
aquifer is reduced or eliminated. Under these circumstances 1980
the resulting accumulation of salts from natural or man-made 1981
sources, such as irrigation return flows, could markedly 1982
increase the groundwater salinity. 1983
A second and related effect is due to the higher water 1985
table created back of a dam. This brings the groundwater 1986
closer to the ground surface where the opportunity for 1987
pollution from agricultural and septic system sources, for 1988
example, may be increased. Marshy areas, swamps, and pools 1989
may be created; evapotranspiration losses then concentrate 1990
salinity in the groundwater. There may also be adverse 1991
effects on surface-water quality.
Even in situations where the dam and its foundations do 1993
not substantially alter the total groundwater flow through 1994
the underlying aquifers, the localized effects on 1995
groundwater levels and on the original pattern of 1996
-------
90
qroundwater flow may have significant adverse impacts on 1997
groundwater quality.
™he reservoir created by the dam may have somewhat 1999
similar effects on the groundwater of the area. If water is 2000
stored in the reservoir for significant periods of time, the 2001
effects may be more pronounced than those resulting from the 2002
dam itself. Seepage losses from the reservoir also 2003
contribute to the groundwater. .If the quality of the water 2004
in the reservoir is better than that of the groundwater, 2005
improvement in groundwater quality results. Conversely, 2006
seepage losses from a reservoir storing poorer quality water 2007
(e.g., reclaimed water) degrade the groundwater.
WATERSHED DEVELOPMENT 2010
In certain areas development of land areas tributary to 2012
reservoirs may constitute major sources of pollution and 2013
nutrient fertilization. On small reservoirs constructed in 2015
conjunction with suburban housing developments direct 2016
drainage from streets and lawns constitutes the primary 2017
cause of water quality degradation. On large reservoirs 2018
increases in upstream tributary population and development 2019
-------
91
on the periphery of the lake shore must be considered in 2020
projecting water quality although these sources may not be
of immediate concern. 2021
Suburban development surrounding a small reservoir can 2023
deteriorate water quality by direct wastes disposal through 2024
the use of package sewage treatment plants not providing 2025
nutrient removal, discharges from watercraft, run-off from 2026
yards and streets and by polluted groundwater where septic 2027
tanks are used. Contamination in the feeding stream 2028
upstream from the reservoir intensifies the pollution 2029
problem.
Larger reservoirs are also adversely affected by the 2031
direct sources described above but because of the volume of 2032
dilution available, these effects may not be noticeable. 2033
Large direct discharges from industries or municipalities 203<4
however can seriously degrade water quality unless adequate 2035
treatment is provided these sources. Nutrient 2036
concentrations from upstream point and non-point sources may 2037
accelerate eutrophication processes causing algal blooms and 2038
subsequent dissolved oxygen problems.
-------
92
In order to estimate future water quality rationally, 2040
mass balances of waste and nutrient sources are required to 2041
determine accumulations and future increased constituent 2042
concentrations and the corresponding development of water 2043
quality deteriorating conditions. 2044
CHANNEL MAINTENANCE 2047
Frequently, since one of the principal reasons for the 2049
main stream reservoir is to maintain minimum depths for 2050
navigational use, channel maintenance is a key feature to 2052
maintaining the system. Such maintenance qenerally consists 2053
of some method of dredging but may include channel bank 2054
maintenance where affected by wave action or propeller wash. 2055
Water quality is affected by the dredging operation itself, 2056
the total extent is determined by the spoil disposal method 2057
employed.
The dredging itself resusoends silt and other fine 2059
grained material which increases- turbidity. These materials 2060
later settle blanketing downstream sections of the 2061
impoundment. Adsorbed materials, such as organic coumpounds 2062
and nutrients, which travel with these siltaceous materials, 2063
-------
93
may be released to the aquatic phase either stimulatinq or 2064
inhibiting bioloqical life.
NAVIGATION RELATED SPILLS 2067
Any stream which is maintained for navigation is 2069
subject to accidental spills of carqo and fuel while in 2070
transit plus the possibility of catastrophic accidental 2072
spills from shore facilities. These potential pollution 2073
sources are unpredictable as to time of occurence but can be 2074
expected from time to time. The effects of these spills can 2075
be disruptive to other water uses and disastrous to aquatic 2076
life.
REDUCTION IN WASTE ASSIMILATIVE CAPACITY 2079
Waste assimilative capacity has traditionally been 2081
based on the dissolved oxygen requirements necessary to 2082
maintain fish and aquatic life. The calculation of the 208U
dissolved oxygen concentration profile downstream from a 2085
waste source essentially is a balance between the amount of 2086
oxygen required to oxidize organic material and the amount 2087
of oxygen supplied by atmospheric reaeration. Reaeration is 2088
-------
increased by an increase in water velocity and decreased by 2089
an increase in water depth. A reservoir both decreases
velocity and increases depth and therefore reduces 2090
reaeration by both factors. 2091
The decreased water velocity also provides for 2093
sedimentation of particulate material in waste discharges 209U
usually near the outfall. This material intensifies oxygen 2095
demands near the outfall and reduces oxygen levels even more 2096
rapidly.
The biochemical oxidation of organic material is 2098
generally assumed as a function of time. By reducing the 2099
water velocity the distance over which this demand is 2100
exerted is reduced.
The net effect of the reservoir is to reduce the 2102
distance over which dissolved oxygen concentrations are 2103
reduced below acceptable levels but to greatly intensify 2104
the amount of depletion that occurs with that reach. For 2105
dischargers, this means increased waste treatment. 2106
-------
95
For main stream reservoirs the effects on dissolved 2108
oxyqen resources are readily calculable using standard 2109
techniques; for storage reservoirs the hydraulics are 2110
complicated and variable and such changes are predicted with 2111
great difficulty and little precision. 2112
Types of Pollutants 2116
Water quality changes which are related to reservoirs 2119
are of concern within the reservoir itself and in the 2120
downstream reaches receiving discharges from the reservoir. 2121
The water quality at the surface is of importance for 2123
recreational, biological and aesthetic purposes; that in the 2124
hypolimnion affects water quality of released water for 2125
downstream uses. At times of non-stratification the 2126
existing quality affects all uses and establishes the mixing
of materials which will determine water quality in both 2127
zones following re-establishment of stratification. 2128
Reference is here made to a report entitled "Measures 2131
For the Restoration and Enhancement of Quality of Freshwater 2132
Lakes" which was prepared to comely with section 301 (i) of 2133
P.L.92-500. The Appendix to this report covers the source 213U
-------
96
of pollutants more thoroughly than here. For more detail 2135
the report should be obtained.
BIOLOGICAL FACTORS 2138
The biological life in the epilimnion indicates many 2140
water Duality changes in both this zone and in the 2141
hypolimnion. Bacteria, plankton, rooted aquatic plants, 2143
invertebrates and fish all contribute and react to these 2144
water quality changes.
The plankton as primary producers in the system use 2146
available inorganic nutrients in developing and sustaining 2147
their populations. increases in nutrients provide material 2148
for increased plankton numbers. The major nutrients 2149
required include inorganic nitrogen, carbon and phosphorus. 2150
So-called minor nutrients and growth factors may also be 2151
reguired. Plankton populations generally are related to 2152
nutrient concentrations assuming adequate light and the 2153
absence of toxic materials.
The population of plankton in relation to other factors 2155
is used as indicators in the estimation of the eutrophic 2156
condition of a body of water. Dense populations are 2157
-------
97
indicative of eutrophic waters while sparse populations are 2158
indicative of oligotrophic waters. The concept of eutrophy 2159
however is not strictly applicable to reservoirs as to age 2160
but is more indicative of aesthetics and water quality as 2161
affected by plankton populations.
Dense plankton populations directly effect the chemical 2163
guality of water. During daylight hours these algae remove 2164
carbon dioxide from solution which causes increases in pH; 2165
and by photosynthetically producing dissolved oxygen in 2166
quantities that frequently exceed the water solubility of 2167
this element. At night carbon dioxide is released by 2168
respiration which reduces pH and depletes dissolved oxygen 2169
concentrations below values that would otherwise occur. 2170
These diel fluctuations in pH and dissolved oxygen can have 2171
detrimental effects on other biological life. For example, 2172
in extreme situations dissolved oxygen levels may approach 2173
zero at night because of plankton respiration.
Upon the death of these algae so-called "algae rains" 2175
occur as the remains settle into the hypolimnion. Bacterial 2176
decay exerts a demand on the hypolymnion oxygen resources 2177
which may ultimately cause total dissolves oxygen depletion. 2178
-------
98
Rooted aquatic plants along the shoreline of the 2180
impoundment detract from aesthetic qualities, reduce 2181
recreational opportunity for swimming or other water contact 2182
sports, provide protection for insect development which may 2183
pose a health hazard, and become a liability on the 218U
reservoirs oxygen resources when death occurs. These plants 2185
require stable water levels and clear water allowing light 2186
penetration in order to become established.
The higher organisms in the biological chain feed 2188
directly on plankton, their detrital remains in the bottom 2189
muds, or on those organisms that do. The population of 2190
these higher organisms depends on the productivity of the 2191
plankton. Detrimental effects on these organisms, which 2192
include fish, are caused by dissolved oxygen depletion, pH 2193
changes, or olankton-produced toxins. These effects occur 2194
through the plankton activity.
Microbiological factors must also be considered. 2196
Tributary drainage, waste treatment plant discharges and 2197
direct water craft discharges potentially contribute disease 2198
causing oraanisms. For recreational use bacteriological 2199
guality must be maintained so that disease transmission from 2200
-------
99
fecal discharges is minimized. Monitoring by using the 2201
fecal coliform test is the standard technique for 2202
determining the sanitary microbiological guality of 2203
reservoir waters.
AESTHETIC FACTORS 2206
Aesthetic appeal of an area can be enhanced or degraded 2208
by reservoir design and operation. Ignoring shoreline 2209
development and concentrating on water quality aspects the 2211
most important factors are the control of aquatic plants; 2212
maintenance of dissolved oxygen, color, turbidity and other 2213
chemical constituent concentrations in the range conducive 221U
to desirable fish and aquatic life development and 2215
maintenance; and maintaining lake levels sufficiently high 2216
during the recreation season to safely allow reservoir 2217
recreational use. A balance of these factors aid in the 2218
enjoyment of the water resource.
CHEMICAL FACTORS 2221
Maintenance of the water quality in a reservoir for 2223
multiple uses requires control of the water chemistry, 222U
inputs of point and non-ooint waste materials and any toxic 2225
materials. Common measures of chemical water quality 2227
-------
100
include dissolved oxyqen, color, pH, various inorganic 2228
salts, metals, nutrients and organic compounds including 2229
pesticides and herbicides. Specific levels for these 2230
materials are contained in the various State Water Quality
Standards. Discussion of these materials with recommended 2231
levels are also available in a book entitled "Water Quality 2232
Criteria" published by the Environmental Protection Agency. 2233
Chemical factors are important for maintaining the
usefulness of the reservoir for recreational use, water
suoply use, maintenance of fish and aquatic life and for
preserving downstream water uses.
2235
2236
2237
PHYSICAL FACTORS 2240
The physical factors of water quality include 2242
determinations such as temperature and turbidity which 2243
affect the usefulness of v>ater and mediate other chemical 2245
and biological reactions.
Temperature affects the rate of physical, chemical and 2247
biological reactions. In terms of reservoir hydraulics, 2248
temperature related density changes in water causes the 2249
development of the stable summer stratification with its 2250
-------
101
pronounced affect on water Quality. Chemically, th^ 2251
solubility of gases with dissolved oxygen principally being 2252
of interest; the solubility of chemical compounds is 2253
affected; and the reactiveness of certain constituents all
are affected by water temperature. Biologically, reaction 225U
rates roughly double for every 10 degree Celsius increase in 2255
temperature as well as regulating reproductive mechanisms 2256
and life itself. Temperature is obviously most important 2257
consideration in reservoir water quality evaluations. 2253
Turbidity is a measure of the reduction in incident 2260
light penetration caused by suspended particulate matter. 2261
As a aeneric term i.t includes measurements such as suspended 2262
solids and secchi disc in addition to a turbidimetric 2263
measurement. The suspended matter in epilemnetic waters may 2264
be plankton while in hypolimnectic waters it may be sediment
clays or silts. In surface waters turbidity is used as a 2265
factor in determining the depth of light penetration in 2266
determining the so-called euphotic zone or zone of 2267
photosynthetic activity. In water supply uses of various 2268
types it is a factor in treatment costs. In reservoir
hydraulics a turbid inflow may be more dense than certain 2269
existing layers and produce a phenomenon known as an inter 2270
-------
102
flow which would insert a layer between existing water 2271
layers and subsequently affect discharged water quality. 2272
Turbidity is both an economic and quality parameter to be 2273
excluded in Reservoir water quality.
of_ Pollutant Transport 2277
The basic hydraulics of both storage reservoirs and 2280
main stream reservoirs has been previously discussed. The 2281
movement of soluble p_ollutants through a reservoir simulates 2283
the hydraulic movement. Particulate pollutants, if organic, 2284
may be biologically solublized; inorganic materials may be 2285
indefinitely held up by being incorporated into the 2286
reservoir sediments. other factors such as solar insolation 2287
and the reservoir operating schedule influence water quality
in the reservoir itself and the stream downstream from the 2288
reservoir.
Pollutant transport in a stream is generally quite 2290
simple as the pollutant travels at the same rate as the 2291
water itself. This generalization has exceptions as for 2292
example sediment bed load which varies with respect to the 2293
water velocity and temperature. This same essential
-------
103
transport process occurs in main stream impoundments where 229U
velocities are typically discernable and sufficient to 2295
maintain particulate matter in suspension. Stratified 2296
storage reservoirs in contrast have extemely ecomplex 2297
hydraualics. Density effects, surface mixing caused by 2298
winds and the level of water release all bear on pollutant
residence time. 2299
TRANSPORT INTO THE STORAGE RESERVOIR 2302
Discharges directly into reservoirs which includes 2304
direct runoff, tributary streams or waste streams are 2305
segregated in the reservoir by their density. Beginning in 2306
the spring as discharges typically become progressively 2308
warmer and less dense, the flows form layers above the
existing cooler waters. Toward fall when inputs become 2309
cooler and therefore more dense than stored water the inputs 2310
may form interflows between existing layers. Waste 2311
discharges would also tend to be density segregated which in 2312
that case may include ionic density effects in addition to
thermally caused density effects. Thus the location of an 2313
incoming pollutant depends on the existing density regime in 2314
* the reservoir and the density of the water tranporting the 2315
pollutant.
-------
10U
TRANSPORT WITHIN THE STORAGE RESERVOIR 2318
The princiapl controlling factor on water release is 2320
the location of the outlet. Normally, the water discharged 2321
is the densest existing layer above the outlet structure. 2323
In storage reservoirs with fixed deep outlets progressively 2324
less dense water is released during the summer stratified 2325
period which approximates the time of entry into the
reservoir. This progressive release may be interrupted by 2326
the occasional passage into and through of more dense 2327
sediment-laden storm water or some other density anomaly. 2328
As the fall season approaches, but before the fall overturn, 2329
cooler tributary inflows may also flow beneath existing
storage and pass through the reservoir ahead of existing 2330
storage. Soluble pollutants which are stable (eg salts) 2331
would be transported in a similar fashion. 2332
Particulate pollutants if off sufficient size, tend to 233t
settle toward the reservoir bottom. These materials settle 2335
at different rates depending on a myriad of factors but may 2336
finally reach the bottom or be retained by buoyant forces 2337
occurring in more dense water layers. Thus a density
segregation of particulate matter also occurs. Particulate 2338
pollutants that reach the bottom may be essentially 2339
-------
105
permanently removed while those trapped in lower lying 2340
denser flows may pass through the reservoir more rapidly 2341
than the initial transporting water.
Many organic pollutants are biologically degradable and 2343
during the storage provided in the reservoir are destroyed. 2344
These may be either soluble or particulate in form but are 2345
amenable to biological attack. These materials are 2346
therefore not transported out of the reservoir but are 2347
decayed.
TRANSPORT OUT OF THE STORAGE RESERVOIR 2350
Older dams frequently were designed and constructed 2352
with low level outlets only. Newer designs incorporate 2353
multiple outlets so that water from various levels within 2355
the reservoir can be released. Because of density effects, 2356
the water withdrawn will principally be from the densest 2357
layer above the outlet level. With a^multiple outlet 2358
system, water of the best available quality can be withdrawn
to protect downstream uses. This is especially important 2359
during the late summer period when normal hypolinion 2360
releases contain the worst water quality of the year in 2361
terms of dissolved oxygen, nutrients, metals and odorous 2362
-------
106
compounds. Release of aerated epilimnion waters avoids this 2363
problem to the maximum available extent.
hypolimnetic releases during late summer may release 2365
materials that settled to the bottom and became biologically 2366
solubilized or those chemically precipitated with subsequent 2367
settling to the bottom which become resolubilized under the 2368
low oxygen conditions near the reservoir bottom. Examples 2369
include detritus of plaaktonic origin which decay and 2370
metallic phosphates which become soluble under anaerobic 2371
conditions. Thus hypolimnetic releases contain the non-re-
active dissolved materials contained when the water entered 2372
the reservoir plus those products initially removed but 2373
resolubilized.
Epilimnetic releases contain the active biological life 2375
in this zone plus the existing surface water quality as 2376
affected by those biological processes and other physical 2377
processes. These waters are generally characterized by high 2378
quality water including substantial concentrations of 2379
dissolved oxygen.
-------
107
§ and Variation of Pollutant Effects 2384
Water quality transformation for reservoirs as compared 2387
with the preimpoundment streams have been prepared on 2388
several basins under the auspices of the constructing 2390
•
agency. For main stream reservoirs one series is available 2391
for the Ohio River which includes changes observed following 2392
the initial installation of low head impoundments.
subsequently many of the low head impoundments have been 2393
replaced by higher head impoundments for which pre-and post- 2394
water quality investigations have been conducted. (See 2395
bibliography for references)
Similar studies are available from the Tennessee Valley 2397
* Authority for both main stream and storage impoundments. 2398
Monitoring information for each operating year for various 2399
water quality parameters are also available in addition to 2400
• special studies performed during the year.
The Bureau of Reclamation Reservoirs also have water 2402
ft quality studies available for their reservoirs. Such 2403
studies are required for determining the quality of 2404
-------
108
irrigation water in addition to monitoring ^for recreational 2405
and other uses.
State and local controlled reservoirs whether for
recreation or water supply purposes, monitor the water
quality to meet public health requirements. These
2407
2408
2409
measurements are available in annual State monitoring system 2410
reports or local water supply annual reports.
In addition to these governmental sources of guality 2412
information, engineering and biological literature is 2413
replete with special water quality studies of reservoirs. 2414
Examples are included in the bibliography to this section. 2415
Methods
2420
The prediction of water quality in reservoirs has been 2423
performed by several methods. Included among the various 2424
techniques are empirical techniques, hydraulic model 2426
studies, and mathematical model studies. All of these . 2427
techniques require field data for verification QT 2428
calibration. Such surveys include chemical, biological and
-------
109
physical studies to ascertain existing water quality and 2429
establish baseline conditions. 2430
EMPIRICAL TECHNIQUES 2433
Empirical methods are generally developed specifically 2435
for one reservoir and include analyses of data recorded for 2436
a number of seasons or years. Although simpler analyses are 2438
used, statistical correlations are developed between input 2439
water quality variables, reservoir water quality and output 2440
water quality. Operating rules for the reservoir can be 244]
modified based on such analyses to maximize one set of 2442
parameters as opposed to another.
Simpler techniques than statistical methods would be 2444
simple graphs with trend line development. Obvious problems 2445
with such methods includes: the applicability to only one 2447
site, predictive ability only in range used for development, 2448
no mechanism to correct for changes in physical conditions, 2449
lack of fundamental understanding in reservoir mechanics,
and extended record required for development. 2450
The principle advantages are the relatively inexpensive 2452
development cost and simplicity in use. Depending on 2453
-------
110
precision required such techniques may be adequate for many 2452
purposes.
HYDRAULIC MODELS 2455
Hydraulic models range in scope from simple laboratory 2457
scale aquariums to multidam basin models coverinq several 2458
acres. These models are used to verify dam desiqns for 2460
hydraulic properties, effects on reservoir stratification of 2461
these desiqns, or entire river conditions for various flow 2462
reqimes.
Data from the models are collected by usinq various 2464
tracer and staqe-velocity measurement techniques. The data 2465
is then fitted to a mathematical formulation for 2466
incorporation into a particular desiqn. These data are also 2467
valuable for evaluatinq mathematical models as some water 2468
quality parameters can be empirically or theoretically 2469
scaled from model to prototype.
MATHEMATICAL MODELS 2472
Mathematical models are used for many purposes in 2474
reservoir desiqn and operation. The hydroloqy of an entire 2476
basin may be modeled to aid in sizinq and locatinq the 2477
-------
111
optimum number of reservoirs or the amount of water storage 2478
required to meet certain objectives. Internal reservoir 2479
hydraulics and mixing have also been simulated by
mathematical models frequently as a first step in predicting 2480
the distribution of pollutants in the reservoir or to 2481
(r
predict the discharge sequence of stored water with a given 2482
water quality for each stratified layer. Recent attempts 2483
have been made at ecological modeling. These models begin 2484
with material inputs from which plankton and fish
populations are ultimately predicted. Hydraulic 2485
simulations, water guality constituent distributions, 2486
phytoplankton production, zooplankton controls on 2487
phytoplankton populations, and fish populations are all 2488
incorporated in such models.
The basis for the water quality and ecological models 2490
is a basic understanding and prediction of the thermal 2491
stratification process in reservoirs. Recent research 2492
efforts have extended knowledge of the stratification 2493
process to the extent that reasonable predictions of the 2494
internal temperature distributions can be made. Using the
system hydraulics as the basic transport process, the 2495
chemical, physical and biological reactions are imposed 2496
-------
112
using the laws of conservation of mass and from general 2497
kinetic principles. Equations are constructed for each 2498
constituent with the entire set of equations subsequently 2499
being solved using numerical techniques with the aid of the 2500
digital computer. The model outputs include the important
water quality characteristics for water quality models and 2501
additionally populations cf principal biotic species in 2502
ecologic models.
The predicted concentrations and biological populations 2504
from the models generally follow the observed trends of the 2505
data used fpr verification with numerical values being 2506
representative of actual. For most management decisions 2507
concerning reservoirs the results offer adequate accuracy 2508
and a valuable tool for evaluating alternative waste 2509
treatment schemes including input locations, operating rules
jjor the reservoir to maximize water quality, and the 2510
projected water quality for various uses. 2511
WATER QUALITY SURVEYS 2514
The use of any statistical or modeling technique 2516
requires adequate information for verification and 2517
development. The usefulness of the various models depends 2519
-------
113
on the accuracy of the predictions made which can only be 2520
verified by field observations. The basis for the validity 2521
of predictive techniques requires the performance of 2522
intensive water quality surveys auqmented by routine
monitoring. Key parameters of water quality require 2523
delineation both temporally and spatially within a reservoir 252U
as well as in the inflows and the outflow. These data 2525
provide information for compliance with water quality 2526
standards in addition ro providing data for future 2527
improvements in analytical and modeling technology.
\ rV
\ r
-------
Bibliography
1. Water Resources Engineers, Inc., "Mathematical Models
for the Prediction of Thermal Energy Changes in
Impoundments," Water Poll. Contr. Res. Series 16130EXT
12/69 Environmental Protection Agency (December, 1969).
2. Markofsky, M. and D.R.F. Harleman, "A Predictive Model
for Thermal Stratification and Water Quality in
Reservoirs," Water Poll.Contr.Res. Series, 1630DSH
01/71 Environmental Protection Agency (January, 1971).
3. Markofsky, M. and D.R.F. Harleman, "Prediction of Water
Quality in Stratified Reservoirs," Jour, of the
Hydr.Division, A.S.C.E., Vol. 99, No. HY5, pp 729-745
(May, 1973).
4. Anon., Hydraulic Models, Manual of Engineering Practice
No. 25, American Society of Civil Engineers.
5. Imberger, J. and H.B. Fischer, "Selective Withdrawal
from a Stratified Reservoir" Water Poll.Contr.Res.
Series, 1540EJZ 12/70, Environmental Protection Agency
(December, 1970).
6. Chen, C.W. and G.T. Orlob, "Ecologic Simulation for
Aquatic Environments," Office of Water Resources
Research, U.S. Department of the Interior (December,
1972).
7. Di Toro, D.M., D.J. O'Connor and R.V. Thomann, "A
Dynamic Model of Phytoplankton Populations in Natural
Waters," presented at a course, Advanced Topics iri
Mathematical Modeling of Natural Systems, Manhattan
College, Bronx, New York" (1971) .
8. Guarraia, L.J. and R.K. Ballentine, "Influences of
Microbial Populations on Aquatic Nutrient Cycles and
Some Engineering Aspects, "Technical Studies Report TS-
00-72-06, Environmental Protection Agency, Washington,
D.C. (May, 1972).
9. McCaw, W.J., III, "Water Quality of Montgomery County
Streams and Sewage Treatment Plant Effluents; December,
1969-January, 1973," Montgomery County, Maryland, Dept.
of Environmental Protection, Division of Resource
Protection (June, 1973).
-------
/'=»
10. Anon., "TVA Activities Related to Study and Control of
Eutrophication in the Tennessee Valley," Papers
Discussed at Meeting of the Joint Industry/Government
) Task Force on Eutrophication, National Fertilizer
Development Center, Muscle Shoals, Ala. (April 29-30,
1970).
11. Brooks, N.H. and R.C.Y. Koh, "Selective Withdrawal from
Density-Stratified Reservoirs," Jour, of the Hydraulics
§ Division, A.S.C.E., No. HY4(July, 1969).
12. Mackenthun, K.M., The Practice of Water Pollution
Biology, United States Department of the Interior,
Federal Water Pollution Control Administration,
Washington, D.C. (1969).
13. Vanderhood, R.A., "Changes in Waste Assimilation
Capacity Resulting from Streamflow Regulation" in
Symposium on Streamflow Regulation for Quality Control,
999-WP-30, DHEW, Public Health Service (June, 1965).
^ 14. Churchill, M.A. and W.R. Nicholas, "Effects of
Impoundments on Water Quality," Journal of the Sanitary
Engineering Division, A.S.C.E., No.SAG (December,
1967).
15. Kittrell, R.W., "Thermal Stratification in Reservoirs"
ill Symposium on Streamflow Regulation for Quality
Control, 999-WP"-30, DHEW, Public Healtn""Service (June,
1965) .
16. Anon., Water Quality Criteria, Report of the National
Technical Advisory Committee to the Secretary of the
interior, Federal Water Pollution Control
• Administration (April, 1968).
17. Anon., "A Study of the Pollution and Natural
Purification of the Ohio River" Public Health Bulletin
No. 143, U.S. Public Health Service (July, 1924).
^ 18. Anon., "Ohio River: Markland Pool, "Investigation by
the Federal Water Pollution Control Administration
During 1957, 1960 and 1963 (Pre and Post Impoundment,
Compiled and Presented by Ohio River Division, U.S.
Army Corps of Engineers (June, 1968).
-------
Methods, Processes and Procedures to Control Pollution
Resulting From the Impoundment of Water
The principal water quality changes that occur by
transforming a flowing stream into a reservoir are the
obvious ones related to the reduced water velocity and
extended detention time and those changes affected by
thermal stratification of the stored waters.
Reduced water velocity enhances sedimentation of
inorganic suspended material and tends to increase water
clarity. Such quiescent conditions in conjunction with
increased light penetration and sufficient nutrient
materials are ideal for the production of aquatic plants.
Under certain conditions this may lead to phytoplankton
production while in others rooted aquatic or floating
aquatic plants may develop. Such production ultimately may
produce organic materials for decomposition in the
-------
117
hypolimnetic waters or bottom muds followinq the death of 2569
such organisms.
Thermal stratification, especially the classical three 2571
layer system typical of summer conditions, creates an 2572
effective trap in the hypolimnion (lower layer) for material 2573
initially there at the time of stratification or accumulated 2574
there by sedimentation or other processes. If sufficient 2575
organic material accumulates in the hypolimnion, dissolved 2576
oxygen may be totally depleted creating anaerobic 2577
conditions. Such conditions eliminate desirable biological 2578
life, produce reduced compounds which contribute taste and 2579
odor to water and presents conditions conducive to re-
solubilization of many chemical compounds. These effects 2580
decrease the quality of water released downstream which may 2581
violate water quality standards. 2582
This brief discussion of changes in water guality 2584
caused by water impoundments demonstrates the typical 2585
problems faced. Available methods, processes and procedures 2586
to ameliorate or mitigate these problems will be presented 2587
and discussed. A bibliography will be presented to enable a 2588
-------
118
more detailed presentation of a particular subject for those 2589
contemplating use of a particular method.
Reference is here made to a report prepared in 2591
compliance with Section 30U(i) of P.L.92-500 entitled, 2592
"Measures for the Restoration and Enhancement of Quality of 2593
Freshwater Lakes." That report covers in more detail many 2594
of the same techniques which are applicable to both lakes 2595
and reservoirs.
SITE PREPARATION 2597
Water quality may be affected by many characteristics 2599
of the location site. Factors which affect future water 2600
quality include maximum and operating depth range, 2601
configuration, relation of principal axis to prevailing wind 2602
direction, geology of area, characteristics of the 2603
underlying soil, and the type of native vegetation.
The characteristics of the underlying soil and the 2605
vegetation that remains before inundation are important to 2606
future reservoir water guality. Both the soils and 2607
vegetation require investigation to determine the amount of 2608
organics present in the soil and its state of decay so that 2609
-------
119
the amount of leachable color, nutrient release, organic and 2610
production and decrease in pH can be predicted. Additional 2611
soil analysis can determine the amount of leachable
inorganic salts present which tend to increase the total 2612
dissolved solids in the overlying water. Based on such 2613
determinations, decisions regarding the necessity of 2614
removing organic soils prior to inundation or using a 2615
mineral soil covering of the organic soils to prevent their
undesirable effects. 2616
The chemical, physical and biological reactions that 2618
occur at the soil-water interface are complex and not 2619
particularly well understood. It has been shown however 2620
that these reactions are more of a biochemical nature than 2621
purely chemical or physical. The organic content of the 2622
soil and pre-inundation vegetative cover are responsible
more than other characteristics for the undesirable effects 2623
on overlying water. The adverse effects caused originally 2624
by freshly inundated soils are reduced with time. This 2625
aging process is a combination of leaching, or organic 2626
destruction and of being covered by sediment transported 2627
into the reservoir. Estimates of the time required for 2628
reservoir bottoms to stabilize so that tastes, odors and 2629
-------
120
color are not imparted to the water indicate that 10-15 2629
years may elapse. The equilibrium condition is defined as 2630
the point where reservoir water quality is determined by the 2631
quality of the inflowing water. The effects on dissolved 2632
oxyqen concentrations usually are significant for only the 2633
1-2 years with normal reservoir site preparation although 2634
minor effects may occur for substantially longer geriods. 2635
It is generally agreed in the literature that to 2637
minimize changes in water quality caused by natural 2638
materials it is necessary to remove all standing timber, 2639
brush, stumps, logs, structures and man-made debris. Grass 2640
and other forms of herbage should be mowed with trimmings
removed just prior to inundation. Additionally organic 2641
mucks from swamps should be substantially removed with the 2642
residual covered with 2 or more inches of clean sand. It is 2643
also desirable to cut channels to pockets within the 2644
reservoir bottom to provide drainage when water levels are
lowered. To protect the sanitary quality of the reservoir 2645
cleaning of barnyards, privies and cesspools should be 2646
performed.
-------
k Ar
121
Occasionally, soil stripping is employed -to remove 26U8
soils with heavy organic content (IX to 2%). This operation 2649
is expensive and of only temporary benefit when compared 2650
with non-stripped reservoir bottoms. Without the effects of 2651
significant sediment inflows, the effects on overlying water 2652
quality are equivalent in 10-15 years as between stripped 2653
and non-stripped reservoir sites. Sediment in reservoir 2654
inflows may reduce this time for equilibrium to occur.
MULTILEVEL OUTLETS 2656
Multilevel outlets are increasingly incorporated in 2658
storage reservoirs to provide flexibility in the withdrawal 2659
level for released water. Two principal water quality 2660
criteria are used to gage the need for such variable 2661
releases: temperature and dissolved oxygen. 2662
Multilevel outlets provide the ability to withdraw 2664
aerated epilimnetic (near surface) water during periods when 2665
hypolimnetic _£near bottom) water may be low or devoid of 2666
dissolved oxygen. This release procedure provides water of 2667
suitable quality to support fish and aquatic life 2668
downstream.
-------
122
When dissolved oxygen levels are sufficient throughout 2670
the reservoir, the temperature of the released water may be 2671
critical to support anadromous fish runs, induce spawning or 2672
to maintain cold water species of fish. Multi-level outlets 2673
provide the opportunity to furnish water of the desired 2674
quality if available at any level in the reservoir. 2675
The hydraulics of selective withdrawal have been 2677
extensively researched in recent years. It is on the basis 2678
of this theory that multi-level outlets can be rationally 2679
designed. Several reports listed in the bibliography 2680
discuss the prediction of thermal stratification and others 2681
discuss the hydraulics of selective withdrawal. 2682
DESTRATIFICATION AND HYPOLIMNETIC AERATION 2684
In reservoirs with deep withdrawal points that do not 2686
contain multilevel outlets or any method to release aerated 2687
epilimnetic waters, methods to provide aerated water at the 2688
withdrawal point provide alternatives to construction of 2689
such facilities. Two principal methods have been developed, 2690
reservoir destratification and hypolimnetic aeration without 2691
destratification.
-------
123
Destratification is most commonly accomplished by 2693
compressed air diffuser aerators or mechanical pumping. By 2694
either method mixing of the hypolimnion and epilimnion is 2695
accomplished to destroy the thermally-induced density 2696
stratification. The induced mixing provides aerated water 2697
at all reservoir depths which prevents water guality 2698
deterioration within the reservoir caused by anaerobic
processes and thereby maintains the quality of water 2699
released downstream. Aerobic conditions inhibit leaching of 2700
color, solubilization of metals and nutrients from the 2701
bottom sediments, and provide for biological distribution 2702
throughout the affected area.
Compressed air aeration has an advantage in that oxygen 2701
is absorbed directly from the rising bubbles in addition to 2705
the aeration of the surface that occurs because of the 2706
mixing. However, in deep reservoirs operating costs may be 2707
greater than pumping because of the necessity to increase 2708
air pressure above the static level of the depth of water 2709
above the diffusers. Pumping conversely only requires 2710
sufficient lift to move the water from the water surface up
to the £ump (plus minor intake pipe friction losses) which 2711
may be only a few feet. 2712
-------
124
Both relatively large and small reservoirs can be . 2714
destratified. Under given morphologic conditions a long 2715
reservoir has been mixed for a substantial distance upstream 2716
from the dam by providing mixing from a single location. 2717
Smaller reservoirs can be entirely mixed. It is not 2718
necessary to destratify an entire lake to achieve outflows
of good quality water. Only the area near the outlet's 2719
structure may require aeration. 2720
Hypolimnetic aeration is a procedure to provide 2722
aeration of the hypolimnion without destroying the existing 2723
thermal stratification. The purpose of avoiding the 2724
disturbance of the thermal stratification is to protect 2725
existing cold water in the hypolimnion. This water may be 2726
required for releases to support anadromous fish runs and
fish spawning. By restricting aeration to the hypolimnion 2727
the temperature change inherent in mixing is prevented but 2728
the water quality is protected or enhanced. 2729
Several techniques for accomplishing hypolimnetic 2731
aeration have been developed. U-tube designs, that is where 2732
water is withdrawn f_rom the hypolimnion, pumped to the 2733
surface and returned to the hypolimnion are a common method. 2734
-------
F •?.'„; ***». A
125
Compressed air may be injected into the water at the intake 2735
of the U-tube, which provides contact time while traveling 2736
to the surface, and be subsequently vented at the surface;
or low pressure air or pure oxygen may be injected at the 2737
surface of the TJ-tube before returning to the hypolimnion 2738
utilizing the increased pressure during the descent to 2739
effect oxygen absorption. Care must be exercised in 2740
operation to avoid creating sufficient turbulence to destroy 27m
the thermal stratification.
DERATION OF RESERVOIR RELEASES 2743
In order to discharge water with sufficient dissolved 2745
oxygen concentrations to meet water quality standards and 2746
thereby meet downstream water use requirements, it may be 2747
necessary to provide aeration of the discharge. Proper 2748
design of multilevel outlets and other procedures may be 2749
insufficient to meet downstream needs. Several methods of 2750
discharge aeration are available including turbine aeration 2751
by venting, Venturi tubes and Howell-Bungen valves.
The Venturi tube aeration device has not been tested on 2753
full scale reservoir releases and therefore must be 2754
considered experimental. In the device, air was injected 2755
-------
126
into the throat of a Venturi section. The air was admitted 2756
used the inherent vacuum created by these devices. The 2757
maximum efficiency of such a device occurs with only 0.5 2758
mq/1 increases; higher oxygen transfers required increased 2759
water velocity and subsequent friction losses. The device
may only be efficient on small flows and not full size 2760
reservoir discharges. 2761
Turbine aeration uses the water flowing through the 2763
power turbines which are vented with air to produce 2764
increased dissolved oxygen levels. In the older horizontal 2765
type turbines existing draft tube vents have been used which 2766
are frequently available to control cavitation. Oxygen 2767
transfer efficiencies of 37* have been reported with turbine
power losses of about 5X. Modern turbine units may have the 2768
turbine water wheel at elevations less than tail water 2769
elevation which produces only small negative pressures and 2770
is not conducive to efficient aeration. One solution to 2771
this constraint has been the installation of wedge shaped 2772
deflector plates in the draft tubes slightly below the 2773
turbine wheel. The negative pressure created in the wake of 2774
the turbulent flow past, the deflectors is used to induce
aeration flow. Aeration efficiency for water initially 80S 2775
-------
127
saturated with oxygen varied from 25% - 50*. Turbine 2776
efficiency was decreased by 0.83X. 2777
The Howell-Bunger valve is a fixed dispersion cone 2779
valve which can be used for reservoir releases to provide 2780
aeration. The Tennesse Valley Authority has performed 2781
extensive evaluation of this device for aeration purposes. 2782
The valve produces a spray discharge which is similar to the 2783
common garden hose spray nozzle except that the cone is
fixed rather than adjustable. Aeration efficiencies were 2784
determined during the TVA testing program and were defined 2785
as the ratio of final dissolved oxygen deficit to the 2786
initial dissolved oxygen deficit. Efficiencies of 80% were
achieved when exit velocities exceeded 6 meters per second 2787
for a free discharge. Initial dissolved oxygen 2788
concentrations for these tests were less than 1 mg/1.
In addition to the possibilities for aeration while 2790
passing water through the dam, the aeration may be applied 2791
in the tailrace or immediately downstream. Methods 2792
previously discussed such as U-tube aerators and diffused 2793
air aerators can be used as well as mechanical surface 2794
-------
128
aerators which are frequently used in waste treatment 2794
processes. 2795
Factors to be considered before installing aeration 2797
include feasibility and costs. Many methods are 2798
theoretically available but selection requires evaluation of 2799
local factors in addition to theoretical considerations. 2800
CONTROL OF BIOLOGICAL NUISANCE ORGANISMS 2802
Nuisance organisms in reservoirs related to water 2804
quality include excessive numbers of algae and rooted 2805
aquatic plants. The 2°Pulations of these plants depend on a 2806
myriad of factors including nutrient concentrations and 2807
sufficient light. The most satisfactory and only long term 2808
control of these plants requires the institution of measures 2809
to reduce the causative factors. Nutrient reduction in
inflows, shoreline alteration to reduce existence shallow 2810
areas, and the implementation of reservoir operation 2811
schedules are factors in controlling aquatic plant 2812
populations.
Temporary control measures are principally mechanical 2814
or chemical. Operational techniques of fluctuating 2815
-------
129
reservoir water levels can also be practiced. In addition 2816
to reservoir destratification previously discussed, 2817
mechanical techniques include algae harvesting by
centrifuqation, coagulation and filtration, microstraining, 2818
and flotation; and the use of special cutting machines for 2819
harvesting rooted aquatics. 2820
Harvesting algae from natural water bodies by any of 2822
the above methods has not received extensive investigation. 2823
The efficiency of such harvest is inversely proportional to 2824
the population density because of the volumes of fluids to 2825
be processed to recover a given amount of algae. Without a 2826
market for the removed alqae to recover substantially the 2827
cost of removal, in-situ chemical treatment methods for
alqal control are less costly to apply. There appears to be 2828
little hope of developing an economically feasible 2829
harvesting technique for the naturally occurring relatively 2830
dilute algal population densities.
The development of efficient, specialized cutting and 2832
harvesting machines allows the direct removal of rooted 2833
aquatic plants. In addition to the expense of operating the 2834
machines, disposal of the voluminous plant residue also must 2835
-------
130
be taken into account. Various methods have been employed 2836
to reduce the volume of the plant material before final 2837
disposal.
Mechanical removal in natural waters is also a nutrient 2839
removal process. The typical standing crop of algae of 2 2841
tons per acre (wet weight) would contain about 15 pounds of 2842
nitrogen and 1 1/2 pounds of phosphorus. Typical yields for 2843
submerged aquatic plants are 7 tons per acre Jwet weight) 2844
which contain 32 pounds of nitrogen and 3.2 pounds of
phosphorus. Under nuisance conditions yields may be 2845
substantially higher. Comparison of mechanical removal 2846
costs of nutrients with other control techniques generally 2847
are unfavorable at least where controllable point discharges 2848
are the principal nutrient source.
The usual application of mechanical methods is for 2850
control where chemical methods would possibly cause a severe 2851
oxygen demand because of the dead plant residues and 2852
subsequent development of anaerobic conditions. The odorous 2853
conditions and fish kills caused may be more aesthetically 2854
undesirable than the nuisance organisms in the water.
-------
131
Chemical control methods use alqicides on herbicides to 2856
control giant populations. Attributes of a satisfactory 2857
alqicide or herbicide include: reasonably safe to handle 2858
and apply; kill specific nuisance plants; be relatively non- 2859
toxic to fish, other aquatic animals and terrestrial animals 2860
at plant-killing concentrations; be safe for water contact 2861
by humans or animals or for withdrawn water uses; and be of
reasonable cost. Table 1 presents those herbicides 2862
presently registered in accordance with the Federal 2863
Insecticide, Fungicide, and Podenticide Act for use in or on 2864
water. Table 2 lists those registered for use at or above 2865
the water line. These tables indicate dosages and typical
application locations and limitations. 2866
The suppression of rooted aquatics by water-level 2868
management has been utilized because of its practical 2869
advantages in economy and simplicity. Various kinds of 2870
plants can be controlled by drowning if depth and duration 2871
of submersion are sufficient. Use of lowered water levels 2872
is also efficient to control some plants although care must 2873
be exercised because other varieties of plants than the
target species may become established while water levels are 287U
down. Flooding following mechanical cutting or herbicide 2875
-------
132
application may assist in eliminating the return of nuisance 2876
species.
-------
f* F''-;"A'"
/ -, '- fj
'33
HERBICIDES
REGISTERED FOR USE
IN OR ON HATER
Chemical
Summary Page
Acrolein
I-A-1
Amitrole
Amitrole - T
Copper sulfate
5!120
I-C-14
Dosage
As Active Ingredient
1.2 - 7.2 ppm
1.2 - 46.0 ppm
8 - 20 Ibs./A.
10 Ibs./A.
8-20 Ibs/A.
1.5 Ibs./A.
0.05 - 2.3xppm
Sites, Types of
__Weeds ,„ Li mi tati ons
(psntahydra'te) (exeunt) reservoirs ; algae
Lakes, ponds; algae, submersed
weeds.
Do not apply to water used for
domestic purposes.
May use for irrigation and farm
uses 3 days after application.
Irrigation canals and drainage
ditches.
Do not use treated water for
irrigation until concentration
falls to 13.8 ppm.
Site unspecified - cattails.
nn nnt rnntaminflte water used
for domestic or irrigation
purposes.
Drainage ditches, marshes; cattails
Do not apply where water may be
used for domestic or irrigation
purposes.
Drainage ditches, marshes;
phragmites.
Do not apply where water may be
used for domestic or irrigation
purposes.
Drainage ditches, marshes; water
hyacinth.
Do not apply where v/oter may be
used for dories tic or irrigation
purposes.
Lakes, ponds, potable water
-------
/JV
- 2 -
Chemical
J>tpmary_ Page,
Dosage
Copper sulfate
chelated
I-C-14
Dalapon
Dehydroabietyl-
amine acetate
Dichlobenil
I-B-4.3
Dichlone
I-D-5
Diquat
I-D-25.2
1.0 - 4.0 ppm
(pentahydrate)(exempt)
1.6 - 12.0 ppm
(pentahydrate) (exempt)
11 - 22 Ibs acid/A
(10 - 15 Ibs)
( 100 gal. H20)
0.4 - 0.68 ppm
1.0 - 12 ppm
10 - 15 Ibs/A
0.025 -.Q;055
2 - 4 Ibs cation/A
Sites, Types of
Jjee ds,.Limitations.
Lakes, ponds, potable water
reservoirs; algae.
Industrial ponds.
Drainage ditches, spot treatment;
cattails.
Do not contaminate water used for
irrigation or domestic purposes.
Lakes and ponds; algae. Do not
appTy to water used for domestic
purposes.
Irncation canals, ditches; algae.
Do not use treated water on crops^
Lakes, ponds; submersed weeds.
Apply to water surface.
Do jiot use treated water for
irrigation or for human or
livestock consumption.
Do not use fish for food or feed
within 90 days after treatment.
Lakes, ponds, canals:, certain
blcom producing blue green algao..
Do not use in potable water.
Lakes , ponds , di tc'nes , 1 aterals:
submersed weeds. Do not use
treated water for animal con-
SL'roticn, swimming, spraying, or
irrigation until 10 days after
tric'trc'ivt. Do not use treoteci *
water for drinking purposes until
14 days after treatment.
-------
- 3 -
Chemical
Sugary Page
Diquat (continued)
I-D-25.2
Endothall
(dimethyl
alkylamine)
I-E-1.2
Endothal1
(dipotassium)
(disodium)
Dosage
As Active Ingredient,
1-1.5 Ibs cation/A
2 Ibs cation/A
0.5 - 1.5 ppm cation
0.05 - 0.83 ppm
0.5 - 2.5 ppm
1 - 5 ppm
0.36 - 3.5 ppm
Sites, Types of
Heeds, Limitations
Lakes, ponds, ditches, laterals;
floating weeds. Do not use
treated water for animal con-
sumption, swimming, spraying, or
.irrigation until 10 days after
treatment. ' Do not use treated
water for drinking purposes until
14 days after treatment.
Lakes, ponds, ditches, laterals;
emersed marginal. Do not use
treated water for animal con-
sumption, swimming, spraying, or
irrigation until 10 days after-
treatment, uo nou use uredLeu
water for drinking purposes until
14 days after treatment.
Lakes, ponds, ditches, laterals;
algae. Do not use treated water
for animal consumption, swimming,
spraying, or irrigation until 10
days after treatment. Do not use
treated water
until 14 days
for drinking purposes
after treatment.
Lakes and ponds; algae. Do not
use treated water within 7 days
at 0.3 ppm, 14 days at 3.0 ppm.
Lakes and ponds; submersed weeds.
Do not. use treated water within
7 days at 0.3 ppm, 14 days at
3.0 ppm.
Irrigation canals, drainage ditches
weeds. Do not use treated water
within 7 days at 0.3 ppm, 14 days
at 3.0 ppm, and 25 days at 5.0 ppm.
Lakes and ponds: weeds. Do not
use treated water for irrigation
or domestic purposes within 7 days.
-------
13 (•
- 4 -
Chemical
^Summary _Page
Petroleum Solvents
I-P-3.5
Si 1 vex
I-S-1.2
Simazine
Sodium penta-
chlorophenate
2,4-D
I-D-7.7
Xylsnc
I-X-1
Dosage
As Active Ingredient
Sites, Types of
Weeds, Limitations
1000 ppm
8 Ibs/A Liquid
40 Ibs/A Granular
9 9 nnm I i m 11 H
40 Ibs/A Granular
0.78 ppm
4.5 - 18 ppm
2.4 Ibs acid/A
43.5 Ibs acid/A
6.0 Ibs ac-k!/A
740 ppm (exemnt)
Irrigation and drainage ditches,
inject into water.
Do not contaminate water used
for domestic purposes.
Do not use treated water for
irrigation until emulsion breaks
or waste treated water.
Lakes, ponds; emerged floating
weeds.
Do not contaminate water intended
for domestic, irrigation, or crop
spraying purposes.
I at/oc nnnrlc • c i ihmo vcorj i'
Do not contaminate water intended
for domestic, irrigation, or crop
spraying purposes.
Ornamental ponds.
Do not use in water intended for
domestic or irrigation purposes.
Paper mill supply impoundments,
algae.
Lakes, ponds; floating weeds.
Do not use treated water for
domestic or irrigation purposes.
Lakes, ponds: submersed weeds
(granular).
Do not use treated water for
domestic or irrigation purposes.
Lakes, ponds; emerged marginal
weeds .
Do not use treated water for
do:rc-stic or irrigation purposes.
Irrigation ditches, inject into
water. Treated v:ater may be used
for furrow or flood irrigation.
-------
137
HERBICIDES
REGISTERED FOR USE
AT OR ABOVE WATER LINE
Chemical
Summary Page
Dosage
As Active Ingredient
Sites, Types of Weeds,
Limitations
Amitrole
Amitrole-T
Ammonium Sulfamate
I-A-7
Bromaci 1
Dimethyl
arsinic acid
Diuron
DSMA
Erbon
Fenuron
4 - 10 Ibs/A
2 - 4 Ibs/A
57 - 171 Ibs/A
(57 lbs/100 gals.)
95 - 190 Ibs/A
(95 lbs/100 gals.)
1.8 - 4.8 grams/plant
3.0 - 24.0
(2.6 - 5.2 Ibs.)
(100 gals. H20 )
16 - 48 Ibs/A
2.3 - 4.5 Ibs/A
5.33 Ibs )
100 gals H20 )
120 - 174 Ibs/A
10 - 30 Ibs/A
Drainage ditchbanks. Do not
contaminate edible crops.
Ditchbanks. Keep livestock
off treated areas.
Around lakes, ponds, potable
water reservoirs and their
supply streams; brush.
Do not contaminate water.
Around lakes, ponds, potable
water reservoirs and their
supply stream; weeds.
Do not contaminate water.
Drainr.ge ditchbonks - spot
treatment; brush control.
Do not contaminate water or
use in irrigation ditches.
Ditchbanks; weeds. Do not
contaminate domestic water.
Drainage ditches; weeds.
Do not contaminate water used
for domestic or irrigation
purposes.
Drainage ditchbanks.
Ditchbanks, spot treatment.
Do not contaminate water used
for domestic or irrigation
purposes.
Drainage ditchbanks. Do not
contaminate domestic or
irrigation water.
Drainage ditchbanks; brush
control.
-------
Chemical
Sun>n_ary Page
Dosage
As Active Ingredient
Sites, Types of Weeds,
Limitations
Fenac
Hexachloro-
acetone
MCPA
MSMA
Petroleum
solvents
I-P-3.5
Picloram
Sodium TCA
TBA
2,4-D
I-D-7.7
4.5 - 18 Ibs/A
(4.5 - 36 Ibs)
(TOO gal. H20)
2.6 - 5.3 gals/A
3/4 - 3.0 Ibs/A
2 - 4.5 Ibs/A
(4 - 8 lbs/100 gals.)
100 gals/A
2-3 Ibs/A
33 - 166 Ibs/A
20 - 40 Ibs/A
6.0 Ibs/A
Ditchbanks. Do not contaminate
water used for irrigation or
domestic purposes.
Drainage ditchbanks; weeds.
Apply in oil.
Ditchbanks; weeds.
Drainage ditchbanks, spot
treatment. Do not contaminate
water used for domestic or
irrigation purposes.
Ditchbanks, irrigation and
drainage. Do not contaminate
irrigation water.
Non-crop area - outer slope of
ditches only, spot treatment.
Do not contaminate water used
for irrigation or domestic
purposes.
Drainage ditchbanks. Do not
contaminate water used for
domestic or irrigation purposes.
Ditchbanks.
Margins of lakes, ponds; emerged
weeds. Do not use treated water
for domestic or irrigation
purposes.
-------
131
HERBICIDES
REGISTERED FOR USE
ON MUD BOTTOMS AFTER DRAWDOWN
Chemical
Summary Page
Dosage
As Active Ingredient
Sites, Types of Weeds,
Limitations
Dichlobenil
I-D-4.3
Diuron
I-D-27.8
Fenac
Monuron
I-M-10.2
Xylene
7-10 Ibs/A
16 - 48 Ibs/A
15 - 20 Ibs/A
32 - 80 Ibs/A
100 gals/A
Lakes, ponds; submersed weeds.
Apply to exposed shore and
bottom.
Drainage and irrigation ditches.
Drain off water, spray moist soil
in ditch. Fill ditch and let
stand 72 hours, then waste contained
water before use of ditch. Do not
contaminate domestic water,
Lakes, drainage ditches; submersed
weeds. Drain area and apply to
exposed bottom. Do not use treated
water for domestic purposes.
Irrigation and drainage ditches;
drain water off area, spray bottom,
fill ditch and hold 72 hours, then
waste contained water before use
of ditch.
Ponds, canals; drain off water and
spray vegetation. Do not refill.
for 5 days.
w f\
-------
1UO
gONTROL OF ADVERSE EFFECTS ON GROUNDWATER 2919
Methods to control groundwater pollution by dams could 2921
include use of one or several of the alternatives. The dam 2922
and its foundation could be designed so that there is a 2923
minimum restriction to the down-valley flow of groundwater. 2924
The feasibility of this approach will depend, of course, on 2925
the size and type of dam as well as the geologic conditions 2926
of the dam-site. The design could make provision for
controlled releases of groundwater past the dam. 2927
The water table upstream from the dam could be lowered 2929
by appropriately placed pumping wells. This would reduce 2930
the opportunity for pollution from ground surface sources 2931
and would reduce the residence time of stored groundwater. 2932
In general, water pumped from the wells would be of 2933
satisfactory quality for any available local beneficial
uses; if none existed, the water could simply be released 2934
downstream from the dam. This procedure would increase the 2935
outflow of salts from the basin, minimizing accumulation. 2936
A more drastic measure would be to minimize potential 2938
sources of pollution in the area upstream of the dam. This 2939
could involve changes in land use, reduction in application 2940
-------
of agricultural fertilizers, or removal of cattle from the 2941
area. Justification for such a measure would require the 2942
absolute necessity for good quality water down gradient.
If the reservoir is to store poor-quality water, a site 2944
should be selected where seepage losses will be minimal. If 2945
such a site does not exist, it may be necessary to wholly or 2946
partially line the reservoir bottom using, for example, 2947
compacted clay.
-------
142
Bibliography
2950
1. Fair, G.M. and J.C. Geyer, Water Suggly and Waste-Water 2952
Disposal. John Wiley 6 Sons, Inc., New York~(195U), pp 232-239. 2953
2. Anon., "Measxires For The Restoration and Enhancement of Quality
of Freshwater Lakes," a. S. Environmental Protection Agency, 2956
Washington, D.C. (1973). 2957
2955
3. Toetz, D., J.William, and R. Summerfelt, "Biological Effects 2959
of Artificial Destratif ication and Aeration in Lakes and 2960
Reservoirs - Analysis and Bibliography,1* Bureau of Reclamation 2961
Report REC-ERC-72-33, O.S. Department of the Interior, Denver, 2962
Colorado (1972). 2963
-------
143
10. Mackenthun, K.M. , Thg Practice of Water Pollution 2996
Biology» U.S. Department of the Interior, Federal Water 2998
Pollution Control Administration (1969).
jll. Martin, A. C., R.C. Erickson, and J.H. Steenis, 3000
^Improving Duck Marshes by Weed Control," Circular 19- 3002
Revised, 1-60, U.S. Department of the Interior, Fish
and Wildlife Service (1957). 3003
-------
12. Elder, R.A., M.N. Smith, and W.O. Wunderlich, "Aeration
Efficiency of Howell-Bunger Valves," Jour. Water Poll.
Control Federaiton, 41, 4, 629 (April, 1969).
13. Sylvester, R.O. and R. W. Seabloom, "Influence of Site
Characteristics on Quality of Impounded Water",
Jour.Amer.Water Works Assoc., 57, 1528 (December,
1965).
14. Deutsch, M., "Hydrologic Aspects of Ground Water
Pollution, "Water Well Journal, 15, 9, pp 10-39 (1961).
-------
Guidance for the Identification and Evaluation 3
of the Effects of Urbanization 4
INTRODUCTION 7
Urbanization is the concentration of people and of 9
domestic, commercial, and industrial structures in a given 10
geographic area. Urban areas commonly include both suburban 11
and central city complexes. The rapid trend toward 13
urbanization is indicated by the fact that more than two 14
thirds of the nation's population now reside in urban 15
centers that occupy about 7 percent of the land area of the 16
United states. By the year 2000 the urban population may 17
include as much as three-fourths of the population. 18
This concentration of people and their activities 20
results in a concentration both of water resources and of 21
the wastes produced. Water may be diverted and conveyed to 23
an urban area from sources hundreds of miles away. An 25
example is the Los Angeles-San Diego metropolitan complex
which receives water from the Colorado River and from 26
Northern California. Runoff and infiltration in urban areas 28
are markedly different than in the original undeveloped 29
area. Thus, urban areas produce hydrologic and hydraulic 30
problems connected with development of water supplies; 31
increases in peak streamflows; and increased mineralization 32
-------
of water resources due to changes in land-use patterns. 33
These urban-area problems are discussed briefly in the 34
material that follows. 35
Extensive research has been directed toward the effects 37
of urbanization especially directed toward surface water 39
quality and surface water hydrology. This discussion will 40
concentrate on the degradation of ground water resource, 41
which has not been as extensively recognized. Bibliographic 43
material for both surface and subsurface material are 44
included.
SOURCES OF POLLUTION 46
§eawater intrusion in coastal aguifers is often 48
associated with urban areas due to overpumping, reduction in 50
natural recharge, and sometimes loss of recharge from septic 51
systems that have been replaced by public sewers. Runoff 53
from urban areas is heavily polluted, especially the initial 54
flows. Urban leachate, the source of ground water 55
pollution, owes its composition to dissolved organic and 56
inorganic chemical constituents derived from a multiplicity 57
of sources such as dirty air and precipitation, leaching of 58
asphalt streets, inefficient methods of waste disposal, and 59
poor housekeeping techniques at innumerable domestic and 60
industrial locations. Urban leachate can be a direct 61
-------
contributor to stream pollution because many urban centers 62
are located in lowlands adjacent to large streams. In 6U
reverse, ground water withdrawals may permit flow of
polluted water from streams to hydraulically interconnected 65
aquifers. The expansion of densely populated urban and 66
suburban developments into former rural or heavily 67
fertilized agricultural areas has compounded the problem of 68
ground water pollution by causing a mingling of the effluent 69
from cesspools and septic tands with fertilizer contaminated 70
ground water. Moreover, in many urban and suburban areas, 71
wastes that are accidentilly or intentionally discharged on 72
the land surface often reach shallow aquifers. 73
The pollutional effects of urbanization change as 75
development proceeds. Initially, large amounts of erosional 77
debris are produced as the original land surface is 78
disturbed by construction. Jn the mature stage, domestic 79
and industrial sewage, street runoff, garbage and refuse are 80
the principal sources of pollution, which intensify with 81
time.
Pollution from urban areas is not confined to the areas 83
themselves or to the immediately adjacent areas. The 85
effects often extend for considerable distances in ground 86
waters as well as in surface waters. A relatively recent 87
-------
and unique problem that has attracted Considerable attention 88
is the pollution of ground water resulting from application 89
of deicing salts to streets and highways in winter. The 91
region affected is largely the Northeast and the North-
Central states. The salt appears to reach the ground water 93
both from storage stockpiles (Figure ) and from solution 94
of salt that has been gpread on roadways. 95
Long-term degradation of ground water guality has been 100
the experience of the New Hampshire Highway Department with 101
highway deicing salts. Year after year, chloride contents 103
of water in certain shallow wells rose, to concentrations of 104
3800 mg/liter. Not only was the ground water guality 105
degraded, but also the casings and screens of the wells were 106
badly corroded, so that 37 wells had to be replaced. A 108
similar situation has been reported in Michigan where water
-------
,
/LAND SURFACE / '
V
\
'/y////'////////////////////////
' '/;?//'///7rrfi.'r//> //////"'/..
LT STOCK PILE////// /
/
'/
' / / ' PUMPED WELL// '/
'"'"/'//I
J_ / _/__/ ' ' /
/I ? /
FRESh WA1LI!
WATER TABLE.
I I
Figure 5-2. Flow pattern showing downward leaching of
contaminants from a salt stockpile and
movement toward a pumped well (Dcutsch,
1963).
5-6
-------
from wells was found to contain as much as 4400 mg/liter of 109
chloride due to infiltration of highway salts. 110
An analysis of the steady-state concentration of road 112
salt added to ground water has been made for east-central 113
Massachusetts. Assuming an application rate of 20 metric 114
tons of salt per lane mile per year, and taking into account 115
local rainfall and infiltration values, a chloride 116
concentration of 100 mg/liter was obtained for the gross
area. Ijocal deviations from this regional average could 118
easily be from two to four times this figure, especially 119
near major highways, wells in at least 15 communities in 120
eastern Massachusetts produce water containing more than 100 121
mg/liter of cloride per leter.
The problem is widespread, litigation on the matter is 123
not uncommon, and research on alternative non-polluting 124
substances is underway.
Ground water iff an urban environment^ may contain 126
almost every conceivable inorganic and organic pollutant. A 128
brief summary by source of the principal potential urban
pollutants is given in Table . 129
-------
Table
Summary of urban ground water pollutants
133
Source
Atmosphere
Precipitation
Seawater encroachment
Industrial lagoons
Cesspool, septic tank, and
sewage lagoon effluents
Leaky pipelines and
storage tanks
Spills of liguid chemicals
Urban runoff
Landfills
Leaky sewers
Stockpiles of solid raw
materials
Surface storage of solid
wastes
134
Principal Potential Pollutants 136
137
Particulate matter, heavy metals, 139
salts. 140
Particulate matter, salts, dissolved 142
gases 143
High dissolved solids, particularly 145
sodium and chloride 146
Heavy metals, acids, solvents, other 148
inorganic and organic substances 149
Sewage contaminants including high 151
dissolved solids, chloride, sulfate, 152
nitrogen, phosphate, detergents, 153
bacteria 154
Gasoline, fuel oil, solvents, and other 155
chemicals 156
Heavy metals, salt, other inorganic 158
and organic chemicals. 159
Salt, fertilizer chemicals, nitrogen, 161
and petroleum products 162
Soluble organics, iron, manganese, 164
methane, carbon dioxide, exotic 165
industrial wastes, nitrogen, other 166
dissolved constituents, bacteria 167
Sewage contaminants, industrial 169
chemicals, and miscellaneous highway
pollutants 171
170
Heavy metals, salt, other inorganic and
Organic chemicals 174
173
Heavy metals, salt, other inorganic and 176
organic chemicals 177
Deicing salts for roads
Salts
179
-------
TYPES OF POLLUTANTS 18U
Degradation of water quality may occur in both shallow and 186
deep aquifers. Increased mineralization, including 188
increases in the content of nitrogen, chloride, sulfate, and 189
hardness of the water, has resulted in limitations on 190
pumping from some shallow aquifers in California and Long 191
Island.
In scattered places illnesses have resulted from 193
contamination of water by sewage and industrial wastes. The 195
occurrence of nitrate, MBAS (detergent), and phosphate in
ground water in Nassau County, Long Island, New York, has 196
been investigated in detail. Figure shows the location 197
and subsurface extent of MBAS contamination in shallow 198
ground water beneath an unsewered suburban residential area 199
in southeastern Nassau county. Long Island, New York. The 201
Nassau-Suffolk Research Task Group (1969) has made detailed
studies of pollution near individual septic systems in Long 202
Island.
Gaining streams in Long Island also show significant 204
contents of nitrate and MBAS from inflow of contaminated 205
ground water. High nitrogen content of ground water in 206
Kings County, Long Island, New York, is attributed largely 207
to long-term leakage of public sewers. Contamination of 208
-------
EXPLANATION
_____^ ,
.. aw*mo ******
1 ""
-fe
! ^'
f'lf.-Vl
-,;,--:;•-; " _.~[~ .1
_---!-- -
. ,d i^ ^j"" ' ;' ._r;o'
term tfpostt*
-\
=-1
1
Figxire 5-1. Hydr o^eochemicr ] t,*.--. ,ius obLnvi^ to tlxe clifcction of
grouiif'v-:ater flow, f-i.i\^mg b:u:^ o' ^qual concentration
of NiJjAo in Nabrtu-.i 'Z-- .iiy, I^i-:.'.1; i.uand, New York.
Contaminated water i-, :iado«..; l.-v«-i liira: shown at
about 0. 1 mg/lif-r >"i iniuttu:-, ..'. 'd, 1°>VS).
i-4
-------
shallow public-supply wells by detergents from cesspoll 208
effluent in Suffolk County, Long Island, New York, has 209
resulted in shutdowns of wells except during periods of peak 210
demand. Similar problems occur in California. The contents 212
and trends in salinity and nitrate in the Fresno-Clovis area 213
have been analyzed to confirm this trend.
METHODS OF POLLUTANT TRANSPORT 215
Urbanization grossly alters the hydrology of an area. In 218
general, this results in a decrease in the natural recharge
to underlying ground water unless compensated by artificial 220
recharge. This, in turn, has an adverse effect on ground 221
water guality if the guality of the natural recharge was 223
high. The decrease is due to the impervious surfaces of an 224
urban area—houses, streets, sidewalks, and commercial, 225
industrial, and parking areas, which reduce direct 226
infiltration and deep percolation of precipitation. Peak 227
storm runoff and total runoff is increased but over shorter 228
time periods, resulting in decreased streambed percolation.
Natural streambed recharge is further decreased by concrete 229
storm drains and the lining of natural channels for flood 230
control purposes.
1 'I
-------
In the Santa Ana River Basin in Southern California, 239
pollution of ground water has resulted from the importation 240
by municipalities of Colorado River water, which is high in 241
salinity (750-850 ing/liter total dissolved solids) . 242
pollution has resulted from artificial recharge and also 243
from percolation of water used for irrigation of lawns and 244
- parks,
High local ground water temperatures attributed to 246
recharge of warm water used for air conditioning have been 247
investigated in Manhattan, the Bronx, and in Brooklyn, New 248
York. A 5-to80-degree Celsius rise in the summer 249
temperature of water in gaining streams on Long Island has 250
been attributed to a variety of urban factors such as pond 251
and lake development, cutting of vegetation, increased
stormwater runoff into streams, and decreased ground water 252
inflow.
Several pollution incidents related to urbanization in 254
Minnesota have been reported. These included drainage of 256
surface water through wells in sumps which produced
discolored and turbid water as well as positive coliform 257
determinations, pollution from leachate in poorly designed 258
•landfills, and pollution from solvents disposed of in pits 259
and basins. Poor housekeeping practices at an 80-acre 260
-------
industrial site resulted in the saturation of the area with 261
creosote and other petroleum products over a lonq period of 262
time. The severity of the cresosote leaching problem was 263
recoqnized when the water from a nearby municipal well 26U
developed an unpleasant taste.
The principal mechanism of ground water pollution in 266
urban areas are infiltration of fluids placed at or near the 267
land surface and leaching of soluble materials on the 268
surface. The sources of fluids include deliberate disposal 269
through wells, pits, and basins, and seepage from hundreds 270
or thousands of miles of leaky storm water and sanitary 271
sewers, water mains, gas mains, steam pipes, industrial 272
pipelines, cesspools, septic tanks, and other subsurface
facilities. some natural treatment of the fluid occurs as 273
it seeps downward through the soil zone; however, large 274
quantities of pollutants, particularly the mineral 275
constituents, may reach the water table in the uppermost 276
aquifer. From there, the polluted water may move laterally 277
toward natural discharge areas or toward pumping wells. 278
MAGNITUDE AND VARIATION 281
Major surface water sources have quality information 283
available for urbanized areas. Smaller streams draininq 285
localized watersheds frequently do not have such 287
-------
DRAFT
information. Frequently the local drainage streams, do not 288
have flow other than during the annual wet season or 289
following rainstorms. The effects of urbanization or these 290
waters is most noticeable when street, drainage and storm 291
water from sewers constitutes the flow.
Ground water quality information in general is not 293
nearly as available as surface water quality information. 294
wells are frequently sampled upon completion for chemical 295
and becteriological analyses, in urban areas where few 297
wells exist and these principally for lawn sprinkling, 298
quality analyses are relatively rare.
Information in areas with particularly severe ground 300
water problems associated with urbanization is available. 301
For example, extensive efforts have been made to determine 302
the ground water quality on Long Island, New York. Much of 304
this information is available in a professional paper series 305
(No. 627) of the U.S. Geological Survey. Additional 306
information is available from state geological surveys.
Surface water quality is available for some local 308
streams from counties and cities in addition to the state 309
water guality monitoring agency. Many of these agencies 310
DRAFT
-------
DRAFT
produce annual monitoring reports describing water guality 311
in local streams.
Where urban areas use ground water from local wells, 313
the wells should be monitored for pollutants that are 314
associated with urban activities but may not be included in 315
standard water analyses; for example, heavy metals. When 317
specific threats to ground water guality from past or
present practices of waste disposal (accidental or 318
deliberate) can be identified, special monitor wells may be 319
warranted to provide advance warning of pollutants 320
approaching water-supply wells.
Even though local ground water may not be a presently 322
important source of supply in many communities, monitoring 324
of its ambient guality is highly desirable in order to
detect degradation and take action to reduce or prevent 325
further pollution. 326
:AFT
-------
DRAFT
PREDICTION METHODS 329
Prediction methods for the effect of urbanization .for 332
surface waters traditionally utilize basic hydroloqical
methods to predict the quantity of run-off produced for 333
various intensity storms coupled with field surveys of the 334
pollution sources tributary to the stream. The most common 336
hydrological model is the so called "rational method" which 337
takes into acount the imperviousness of the area and the
time of concentration for rainfall to runoff to the 338
collection point. Experience factors for determining 339
pollutional loads from storm sewers and direct run-off can 340
be applied to determine resulting water guality 3U1
More sophisticated techniques have been devised using 343
the concepts of synthetic hydrology and stochestic processes 344
to develop expected runoff and resulting water quality from 345
various intensity storms, such models are useful for 346
planning channel capacity requirements as well as justifying 347
treatment of incoming wastes. By projecting changes in 348
runoff characteristics, the projection of future conditions 349
is also possible.
Ground water prediction methods are generally much more 351
crudely designed than surface water models. Highly 353
sophisticated mathematical hydraulic models are available
-------
but these lack the ability to predict mass transport of 354
adsorbed or 2arti.ally soluble compounds because of the 355
difficult chemistry involved. Additionally, surveys of 356
ground water conditions are expensive because of the great 357
number of observation wells required to establish flow 358
directions and existing water quality. Jhus models must use 359
scanty field data for verification or development. As 360
ground water in urbanized areas becomes a more important
source of supply and its quality continues to deteriorate 361
adversely affecting the uses to which that water which is 362
extracted is put, quality prediction techniques will be
improved.
-------
Procedures and Methods to Control Pollution 366
Resulting jfroin Urbanization 367
Control of the effects of urbanization for surface run- 370
off has received extensive research attention, control 372
methods have been identified and in some cases demonstration
projects performed for evaluation. 373
Ground water effects have not received this research 375
effort so that suggested control methods are more intuitive 376
in some cases rather than proven techniques. For this 378
reason, these ideas are presented in a brief form.
The following list suggests procedures that can 380
prevent, reduce, or eliminate pollution in urban and 381
suburban areas. The applicability of any particular method 382
depends, of course, on local circumstances. 383
- Pre-treatment of industrial and sewage wastes 385
before disposal into lagoons and pits. 386
- Lining of disposal basins where the intent is to 388
prevent leaching into ground water. 389
-------
Collection, by means of drains and wells, and 391
treatment of leachate derived from landfills, 392
industrial basins, and sewage lagoons. 393
Proper management of ground water pumping to 395
prevent or retard seawater encroachment in coastal 396
aquifers.
Creation, by means of wells, of injection ridges 398
or pumping troughs to retard seawater 399
encroachment.
Abandonment or prohibition of cesspool and septic 401
tank systems in densely populated areas and 402
replacement by sanitary sewer systems. 403
Proper construction of new wells and plugging of 405
abandoned wells. 406
Implementation of better housekeeping practices 408
for land storage of wastes, and monitoring of 409
potential industrial polluters through permits and 410
on-site inspection.
Reduction in use of road deicing salts. 412
-------
Storage of stockpiles of chemicals under cover and 414
on impermeable platforms to prevent leaching; 415
recovery and treatment of leachate which has 416
occurred.
Publicizing procedures for optimal applications of 418
lawn fertilizers and garden chemicals to minimize 419
potential leaching.
Freguent and adeguate cleaning of streets. 421
Provision for artificial recharge with high 423
guality water to compensate for reduction in 424
natural recharge.
use of high-guality water for municipal and 426
industrial purposes where return flow from those 427
uses will contribute to ground water;
alternatively, desalination of wastewaters before 428
discharge.
Provision for adequate treatment of runoff from 430
urban areas grior to discharge into streams which 431
recharge ground water.
-------
References 434
I, Brashers, M.C. Jr., "Ground water Temperatures on Long 436
Island, New York as Affected by Recharge of Warm 437
Water," Economic Geology^ Vol. 36, pp. 811-828 (1941). 438
2. Cohen, P., Vaupel, D.E., and McClymonds, N.E., 440
"Detergents in the Streamflow of Suffolk County, Long 441
Island, New York," ^.S^Geo!. Survey Prof.Paper 750-C, 442
EP- 210-214 (1971). - - - - ^3
3. Deutsch, M., Ground Water Contamination and Legal 446
Controls in Michigan, U.S. Geological Survey Water 447
Supply Paper 1691, 79 p. (1963). 448
4. Hackett, J.E., "Water Resources and the Urban 450
Environment," Ground Water, Vol. 7, No. 2, pp. 11-14 451
(1969) .
5. Hanes, R. E., Zelazny, L. W., and Blaser, R. E., 453
Effects of Deicing Salts on Water Quality and Biota, 455
Highway Research Board, Report 91, 71 p. (1970)". 456
6. Ruling, E.E., and T. C. Holocher, "Ground Water 458
Contamination by Road Salts: Steady-state 459
Concentrations in East Central Massachusetts," Science, 460
Vol. 176, pp. 288-290, April 21 (1972).
7. IRS Research Company, water Pollution Aspects of Street 463
Surface Contaminants San Mateo, California, 464
Environmental Protection Agency, Office of Research and 465
Monitoring Report R2-72-081, 236 pp. (1972). 466
8. Kimmel, G.E., "Nitrogen Content of Ground Water in 468
Kings county. Long Lsland, New York," U.S. Geol. Survey 470
Prof. Paper 800-D, pp. D199-D0203 (1972).
9. Leopold, L. B., Hydrology for Urban Planning—A 473
Guidebook on Hydrologic Effects of Urban Land Use.U.S. 475
Geol. Survey Cir.~554, 18 pp. (1968).
10. Little, Arthur D. Inc., "Salt, Safety, and Water 477
Supply," Interim Report of the S_ep.cial Commission 013 479
Salt Contamination of Water Supplies and Related 480
Matters, Commonwealth of Massachusetts, Senate No, 481
!18J>/ 97 pp. (1973) .
11. Nassau-Suffolk Research Task Group, The Long Island 484
Gj.o.SSd Wa.£e.r. Pollution Study, New York State Dept. of 485
Health, 395 pp. (1969).
DRAFT
-------
12. Nightingale, H. I., "Statistical Evaluation of Salinity 487
and Nitrate Content and Trends Beneath Urban and 488
Agricultural Areas-- Fresno, California, "Ground Water, 489
Vol. 3, NO. 1, EP- 22-29 (1970). 490
15. Perlmuter, N.M. and Arnow, Ground Water .in the Bronx* 492
New York, and Richmond Counties, with Summary Data on 494
£i.B2§ and Queens Counties, New York, N..Y.., New York 496
Water Resources Comm. Bull. 32, (1953) .
14, Perlmutter, N.M., and Guerrera, A. A., Detergents and 499
Associated Contaminents in Ground Water at Three 500
Public- supply WeJLl Fields in Southwestern Suffolk 501
£2ufitY» L2D3 I^i5DJ» E£.V I2£k» U.S. Geol. Survey Water 502
Supply Paper 2001-B, 22 pp. "(1970).
15. Perlmutter, N.M. and Koch, E. , "Preliminary Findings on 505
the Detergent and Phosphate contents of Water of
southern Nassau County, New York," U-.S.. Geol. Survey 507
Profi £§EeE 750-D. pp. D171-177 (1971) .
16. Perlmutter, N.M. , and Koch, E. , "Preliminary 509
Hydrogelogic Appraisal of Nitrate in Ground Water and 510
Streams, Souther Nassau County, Long island, New York," 511
U.S.. Geol.. Survey. Prof... Paper 800-g, pp. B225-B235 512
Il972) .
_17. Permutter, N.M. , Lieber, M. and Frauenthal, H. L. , 514
^Contamination of Grcund Water by Detergents in a 515
Suburban Environment — south Farmingdale Area, Long 516
Island, New York, "U..S.. GepJ.. Survey Prof,. Paper 501-C, 517
EP. 170-175 (1964). ~ 518
J.8. Pluhowski, E.J., Urbanization and its Effects on the 520
Temperature of_ Streams on Long Island, New York U.S. 522
Geol. Survey~Prof. Paper 6^7-D, 108 pp. (1970).
19. Rantz, s. E. , Urban Scrawl and Flooding in southern 524
California, U.S. Geological Survey Circular 601-B. 11 525
pp. (1970).
JO. Schneider, W. J. and Spieker, A.M., Water for the 528
Cities — the Outlook, U.S. Geol. Survey Circ. 60l-A, 6 529
pp. (1969).
21. Seaburn, G.E. , Effects on Urban Development on Direct 532
Bu.22.ff to East Meadow Brook, Nassau County, Long 533
!§!aQcJ» New York, U.S. Geol. Survey Prof. Paper 627-B,
14 p. (1969). 534
-------
22. Santa Ana watershed Planning Agency, California, Finai 537
to the Environmental Protection Agency (1973) .
23. Sartor, J. D. , and Boyd, G.B. , Water Pollution Aspects 539
2t Strget Surface contaminants. EPA-R2-72- 081, "office 541
of Research and Monitoring, EPA, 236 pp. (1972).
24. Soren, J. , Ground Water and Geohydrolggic in O.ueens 5U4
County, Long Island, JN.Y_. U.S. Geol. Survey Water- 545
Supply Paper 2001-A (1970) .
25. Thomas, H. E. , and Schneider, W.J. , Water as an Urban 548
Resource and Nuisance, U.S. Geological Survey Circ. 549
601-D, 9 pp. (1970) 7"
26. Varrin, R.D. and Tourbier, J.J., "Water Resources as a 551
Basis for Comprehensive Planning and Development in 553
Urban Growth Areas," international S^ossosiunj on Water 554
Resources Planning, Mexico City, Vol. 2, 33 pp. (1970). 555
21. Wikre, D. , "Ground Water Pollution Problems in 557
Minnesota," Report on Ground Water 2ua^i.ty 558
§ubc_o.mm:i.£t:ee7 Citizens" Advisory Committee, Governor's 559
Environmental Duality Council, Water Resources Center, 560
Univ. of~Minnesota7 pp. 59-78 (1973). 561
28. Butler, s. , Engineering Hydrology, Prentice-Hall, Inc., 564
Englewood Cliffs, N.J. (19577.
29. Todd, O.K., Ground Water Hydrology, John Wiley 6 Sons, 567
Inc., New York, N7 Y. (1959)."
JO. Anon., "Urban Water Resources Research" A study by ASCE 570
sponsored by Office cf Water Resources Research, U.S. 571
Department of the interior (1968) .
-------
O&?Ar 3
\ND
OF DREDGING
Current Involvement
The Corps of Engineers has been concerned with the
development and maintenance of navigable waterways in the
United States ever since congressional Authorization was
received in 1821 to remove sand bars and snags from major
navigable rivers. The Code of Federal Regulations, Title
33, Chapter II, Part 209 assigns tc the Corps of Engineers
responsibility for enforcement of the principal laws for
protection and preservation of navigation and navigable
waters with respect to work or structures in or over such
waters. Not only is the Corps of Engineers responsible for
its own operations in navigable waters, it is also
responsible for issuing permits for such activities by other
Federal agencies, state or municiapl goverments, and private
citizens or corporations, all of which are subject to the
provisions of the laws for protection and preservation of
navigable waters.
The River and Harbor Act of 1970 (Public Law 91-611)
authorizes the secretary of the Army, acting through the
Chief of Engineers, to construct, operate, and maintain
contained disposal facilities to handle polluted dredge
-------
spoil from the Great. Lakes. The National Environmental
Policy Act of 1969 requires a detailed statement of
environmental impact of proposed new navigation projects and
projects requiring maintenance dredging. In a report on
"Ocean Dumping A National Policy" submitted to the President
in 1970 by the Council on Environmental Quality it was
recommended that ocean dumping of polluted dredge spoil be
phased out as soon as aternatives can be employed and that
dumping of unpolluted spoil be regulated to prevent damage
to estuarine and coastal areas. The Federal Water Pollution
Control Act Amendments of 1972 under Section 104 requires
the Administrator of the Environmental Protection Agency to
develop guidelines for selection of spoil disposal sites and
gives the Administrator authority to restrict the use of any
defined area for spoil disposal. These recently enacted
laws indicate the public's increasing awareness and concern
over the adverse environmental effects associated with
dredging and dredge spoil disposal. While most of the
public attention has been directed at the effects on the
aquatic environment (which will be extensively treated under
Section i»01 of the Act) this section will focus mainly on
the pollution of ground water from dredging and dredge spoil
disposal.
-------
Current Practices
Dredging is currently empolyed in channel development
and maintenance, construction of canals, to provide material
for landfill, in lake and pond improvements, and in mining
of minerals including sand and gravel.
Methods available for dridging can be classified as
either mechanical dredging or hydraulic dredging.
Mechanical dredges are analogous in operating principal to
land-based excavation equipment such as the dragline,
shovel, or treching machine, and can be operated from either
dry land or the water surface. Hydraulic dredges employ a
pump to lift the material from the lake bottom and transport
it by boat or pump it through a pipeline to the point of
disposal. Cutter heads of various configurations are
employed depending on the nature of the materials to be
removed. Primary concern in dredging operations is
generally with the volume of material to be removed and the
location of the disposal site. Until recently little
consideration was given to potential dangers to the
environment, and even now little thought is given to the
possible consequences to the ground water region.
-------
Sources of Pollution
The environmental impacts associated with dredging are
those resulting from the removal of bottom material and
those resulting from the redeposition of this material. The
physical alterations resulting from the removal of bottom
material include changes in bottom geometry and the creation
of deep water regions, new open water, changes in bottom
substrates and habitats, alterations in water velocity and
current patterns, changes in future sediment distribution
pattersn, alteration of the sediment water interface with
subsequent release of biostimulatory or toxic chemicals, and
the creation of turbidity clouds. The most common adverse
environmental effects associated with spoil disposal
include: turbidity which is aesthetically displeasing,
reduces light penetration, flocculates planktonic algae, and
decreases the availability of food for aguatic organisms;
sediment build-up which destroys spawning areas, smothers
benthic Organisms, reduces bottom habitat diversity, reduces
food supply and vegetative coverings; and oxygen depletion
which suffocates organisms in the area and releases noxious
materials such as methane, sulfides, and metals.1
-------
Potential sources of ground water pollution associated
with dredging and dredge spoil disposal include: the
breaching of aquicludes and the resultant direct
introduction of contaminated surfaces waters to shallow
ground waters; changes in surface water flow or circulation
patterns with subsequent seepage of contaminated surface
waters to the ground water regime; and infiltration of
seepage and leachate from land deposited spoil.
Types of pollutants
Types of Pollutants Resulting from
Dredging Operations
Sediment
The principal pollutant created by dredging operation
is sediment. Disturbance of the channel, harbor, estuary,
lake or other water body results in the development of
suspended solids in the dredge area. These vary in
physical, chemical and biological character and may result
in both short-term and long-term effect on the quality of
DRAFT
-------
water at the site or even at some distance from the actual
operation.
Direct effects of bottom disturbance is the generation
of suspended solids. If these are composed of a large
amount of very fine clays, silt and organic materials, the
resulting increase in turbidity will effectively reduce
light penetration and subseguently impair primary food
production necessary to the survival of higher organisms.
In relatively deep water, turbidity effects can alter the
rate of temperature change and promote thermal
stratification.
Disturbance and resuspension of sediments following
dredging can blanket an undisturbed bottom, thereby burying
and smothering benthic organisms, destroy fish eggs, and
generally destroy spawning areas and bottom-dwelling animals
and plants.
Direct effects of sediment created during dredging on
fish includes such harmful effects as reduction of gill
function, impairment of swimming ability reduction of rate
of growth and increase in susceptability to disease.
-------
Sediments associated with chemically and
physically sorbed toxic materials and biostimulants such as
heavy metals, pesticides, phosphates, nitrates and organics,
may be reintroduced to further solution, thus degrading
water quality. Exposure of organic materials through
disturbance often reduces the dissolved oxygen content of
the water. Oxygen depletion, in turn, suffocates organisms
whose decay may release methane and other toxic gasses,
further degrading water quality.
Ordinarily, the most adverse effects of sediment on the
aquatic ecology result from maintenance dredging where the
volume of fine silt, clay, mud, organic muck, sewage and
sludge, together with municipal and industrial debris is
high. Maintenance spoil (sediment) may also contain
considerable amounts of heavy metals, sulfides, phenols, and
other toxic elements.
Sediments dredged from previously undisturbed areas are
ordinarly of relatively high chemical and physical quality
inasmuch as their composition is similiar to that of the
geologic strata which they represent. These sediments are
primarly, sand, gravel, rock particulates clay and shale .
DRAFT
-------
7V
• V
Contamination by organic and toxic materials, nutrients,
pesticides and municipal-industrial wastes may be
slight or even absent, in "new" work areas.
Adsorbed Chemicals Attached to Sediment
Among the principal pollutants sorbed on sediments are
plant nutrients and pesticides. The sorption usually takes
place while the sediment is a part of the land surface,
i.e., topsoil, or a compound of an industrial or municipal
procedure, i.e., waste water facility.
Sorbed constrtuants ordinarily give rise to long-term
pollution effects on water. Prior to disturbance, the
sediment with their sorbed chemicals have a minimum exposure
to the water. As a result the release of sorbed material is
very slow inasmuch as detachment normally only occurs at the
sediment water interface. This releace on intercharge is a
function of bottom sediment movement.
Desorption is the release of adsorbed molecules from
the surface of particles including colloidal sizes.
Desorption has been demonstrated for a number of herbicides
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including 2, H-D, amiber, monuron, dalapon, atrazine, and
simazine. These are concentrated in the bodies of aquatic
animals and the stored pesticides passed on the to their
consumers. The estuary is the primary breeding ground and
nursery of many oceanic species. Any accumlation of
pesticide in these species will be carried to the ocean and
then passed on to higher trophic forms of the open ocean and
then to man.
Aquatic vegetation can sorb significant quantities of
pesticides which may be metabillieally degraded or stored.
Those stored may become a part of the flood sequence or ?
retired to the bottom sediment where they become again
subject to resuspension.
Nutrient sorption on sediment is limited almost
entirely to phosphatic compounds. The principal organ of
these constitrent are in the soil system and in sewage,
wasted or discharged into the area of dredging. Disturbance
leading to resuspension and redistribution of the bottom
sediments encourages solution of the slowly-soluble
phosphatic compounds, facilitating excessive algal growth as
a result of phosplorous enrialment.
Corbed secondary and micronutrient such as the compound of copper, nickel
mnranese, iron, etc. released as a result of disturbance nay be a factor in
accelerated water degradation. .1
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T'F:.n;oDP or pomn'ANT TRANSPOPT
Leaching from Freshly Exposed Surface
Nutrients
^suspension of dredged and otherwise excavated materials,
particularly those 3n heavily populated or intensely tilled
areas may contain excessive amounts of relatively insoluble
nutrients associated with the sedlmsnt. These are usually in the
form of phosphate cortpounds originating from Industrial
processes or agricultural pursuits. A signlfleant percentage
of the municinal contribution may stem from small homeowner
fertilization of lawns and gardens, flushed Into the storn
runoff system following heavy precipitation or indiscriminate
irrigation. Limited treatment of municipal sewage effects
little or no reduction in phosphate compounds and these
will subsequently find their way into the water body to
either combine chemically with, or be sorbed by, the sediments.
nitrate compounds are much more soluble than phosphates and tend
to be removed to more remote areas by currents and wave action.
Disturbance of the bottom sediment along with its sorbed
nutrients exooses a surface areas to the surrounding solvent
(water) far greater than existed in the undisturbed
condition which prevailed within the quiescent sediment-
water interface and vastly Increases the amount of nutrient
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entering Into solution—previously held in the nutrient "bank".
This access may cause accelerated eutrophication, particularly if
the dredged body is a pond, lake or reservoir. In other instances
the sudden or catastrophic increase in nutrient concentration
may be toxic to certain aquatic biota.
Metals
Sediments polluted by compounds containing metals are common
in highly industrialized areas where discharges have been
occurrinp- over long periods of time. These metallic
conpounds vary widely in character and in their toxicity to
aquatic biota, particularly animals. The principal metals
are conpounds of iron, cadium, copper, chromium, arsenic
and nickel. Disturbance resulting from resuspension during
dredging displaces, relocates and tends to dissolve these
compounds to the detriment of aquatic animal life within
their environment. Knowledge of the spoil comnosition, with
particular attention Accused on toxic metal content is
necessary in order to evaluate the pollution status of the
sedir.ient.
0?'garde "aterials
Organic conpounds associated with dredge spoil include peat,
sludre, organic muck and municipal-industrial wastes. Host
o*" this material is very fine-pained and the components nay
i**^t
Di
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17?
ranfie down to colloidal size. If disposed of in open water,
orririic material can cause adverse effects such as serious
oxy,<-en (depletion in addition to the release o^ toxic and
noxious "Tser, such as methane, hydroren sulfide, etc. Organic
opo51 conronly contains penticider- oripinatinr from both municipal
anti a;Ticultural sources. Industrial phenols comprise a group
of chemicals toxic to aquatic biota and are highly detrimental
to rrunicipal and domestic vater supplies. Bottom sediments
may also contain undesirable quantities of organic carbon—now
believed to be an irnoortant factor in accelerated eutrophication.
^abitat Destruction in Dredge and Spoil Disposal Areas
Direct effects o^ dredginr on biological communities and/or
vrater quality are the result of the physical disturbance and
chemical pollutional effects on the aquatic biota. The
principal concern is ordinarily with the direct effect on
biological communities but lonf-term effects cannot be
ij-Tiored. Destruction or impaiment of the benthic
environment and its inhabitants conprise a very serious
nroblem associated with dredging. The effects may vary
greatly. The possibility of benthic extermination or, at
a mininum, extensive damage, is greater in those locales where
"new" work has been instituted than in old or maintenance areas.
The reason for this difference is that areas previously disturbed
repeatedly have discouraged extensive benthic development.
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17*
T'he direct effect of dredging activity confined to the project
area, and usually short-tern, are:
Turbidity Effects aesthetically displeasing;
reduction of light penetration;
flocculation of nlanktonic algae;
and reduction of availability of
flood in the initial stage o^ the
food chain.
Sediment Buildun
Oxygen Depletion
Removal of substrate where
Benthic Organisms Grow,
results in:
Resuspension of Solids and
burial or organisms including
direct destruction of fish eggs.
destruction of spawning areas;
smothering of benthic organisms,
reduction of benthic habitat
diversity and reduction of food supplies.
suffocation of organisms; release
of toxic and noxious gases such as
methane, sulfides and metallic
compounds.
destruction of bottom dwellers;
destruction of burrowing forms;
destruction of spawning areas.
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Suburbanization
The development of or the addition to, existing urban areas increases
the likelihood of pollution of sediments by municipal and industrial
wastes. Potential pollutants also stem from domestic usage of fertilizers
and pesticides on lawns and gardens. Spoil is often placed near or
adjacent to urban centers or in congested areas as fill. In the past
many fill areas developed as a result of a secondary or indirect
(by-product) effects of dredging. In more recent years such fill was
intentionally carried out to reclaim or improve land. This practice
is proceeding at an accelerated rate. Under these conditions spill is
confined or contained and tends to limit destruction that ordinarily occurs
in unconfined areas of land disposal. Suburban development Involves land
that is scarce and costly. Foundation conditions are generally competent,
allowing spoil to be placed to considerable heights. There are, however,
coastal community, coastal resort, and other recreational areas where
poor foundation conditions prevail, (i.e., wetlands and marshes) due
to the proximity of the groundwater table. Disposal in these locales is
further aggravated by the fact that drainage is poor. In the initial
stage of a new fill, seepage may be excessive and must be controlled.
Teepagp through and beneath containment dikes should be analyzed to determine
the pollution potential. The extent of possible groundwater contamination
:-,hru!-' be established and reiTedial npasures adooted. Spoil containing
a high percentage of fine-grained organic material yields very compressible
mC. v;e?L (incompetent) foundation. The unstable condition is aggravated
viiori the ^111 is placed on vet, organic and compressible subsurface soils, many
of which are found in reclaimed areas such as marshlands, wetlands and low-lying
coastal areas of the continental margins.
fV> ;"'-. " •>*•
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Increased Commercial and Recreational Use —
Land environments adjaoent to the ocean, estuaries, and major
streams offer valuable sites for oontnercial, industrial and
recreational development. Spoil disposal practices in these
areas can be very useful if properly managed. The construction
of spoil islands to provide additional habitat for fish and
wildlife is a worthwhile method of utilizing spoil. Spoil
islands/ particularly on the Atlantic and Gulf Ooast have
attracted a wide variety of waterfowl and other forms of wildlife,
both migratory and sedentary. In addition to the creation of
artificial habitat, spoil landfill can be directed to the develop-
ment of recreational areas to the benefit of man. The use of
life-supporting "top" material on a spoil fill will encourage
rapid development of terrestrial vegetation.
Fills created specifically for land development including
commercial and industrial purposes need be composed of ccnpetent
material inasmuch as foundation requirements relating to heavy
loads for structures such as industrial plants and multistory
buildings are relatively severe. This places a requirement for
"cleaner" spoil, i.e., sand, gravel and medium grained soils,
and may create a necessity for development of "new" work
areas which, in turn, will create water pollution problems.
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METHODS OF POLLOTANT TRANSPORT
Instream Activities
Pollutants stemming from dredging operations are transported both
in the solid and dissolved phase. This is true whether the
removed and redeposited material is discharged into water or
transferred onto land.
If the discharge is into water, the solids will be carried in
the direction of current movement. In a river, the downstream
effects of the pollutant are a function of the quantity, particle
size, particle density, current velocity and amount and type of
turbulence. Additional factors affecting travel are slope of
channel, irregularity of stream bottom, slope or gradient, depth,
and discharge volume. The rate of change of velocity is an
inportant factor regarding the range of sediment travel. In
streams of low velocity laminar flow predominates and at this
rate sediment, along with other pollutants, may be transported
along the maximum cross-section over considerable distances.
Sorbed pollutants and those in solution follow the same pattern.
Spoil discharged into large water bodies such as estuaries,
harbors and bays form turbidity plumes whose extent and geometry
are a function of the water movements with which they come in
contact. Restoration of lakes, either partial or total, is
accompanied by removal of sediment, nutrients, organic and
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toxic materials. Dredging, then, is a method of in-lake (or
reservoir) treatment and eutrophication control measures. Lake
deposits are largely a product of the adjacent land. Sediments
derived from sheet/ gully and shoreline erosion constitute the
inorganic phase of bottom particles. A lake is also the storage
basin for products or organic composition, soluble and relatively
insoluble nutrients, domestic sewage, sorbed and free pesticides
and entrapped gasses ordinarily the products of decomposition of
the aggregate whole (collectively referred to as "nuck").
Dredging disturbs the bottom material and may release entrapped
gasses along with toxic substances which may be poisonous to
aquatic biota and domestic water supplies. Sediment, along with
sorbed pollutants may be distributed by lake currents and wave
action to fish spawning areas. Aesthetic and recreational
pastimes such as boating, swimming and fishing may be adversely
affected by resuspension of sediments created by dredging operations.
Care must be exercised during the operation in order to avoid
disturbance, rupture or removal of any sediroantery bottom seal
in areas where the lake immediately overlies porous formations
into which the contents could drain by percolation.
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D8°% A ^**w*
RAFT •
Runoff from Disposal Sites IncliyHng leachates
- -
Qn-land dredge spoil disposed sites, unless carefully chosen,
are frequently instrumental in polluting both adjaoant water
bodies and the groundwater environment beneath the landfill.
In addition to objectionable odors, spoil masses, if fine -
grained, may retain their high water content and remain slurry -
like for considerable periods of time. This condition results
in a high degree of instability, particularly in marginal areas
destined for residential, commercial, and industrial sites and
often creates intolerable and ever dangerous foundation problems.
Where disposal takes place in a containment area, consideration
must be given to outlet structures such as outfalls and return
ditches necessary to discharge and convey the fluid fraction
of the spoil. The return flow is comncnly contaminated and may
contain a high percentage of suspended solids, dissolved chemicals
and sorbed pollutants. Removal efficiency of these pollutants
in the fill area is often very low due to limited retention time.
A large percentage of the escaping solids are colloidal and
essestially impossible to remove by relatively inexpensive,
conventional, procedures. Channelization at the outlet works
and further erosion of the land surface by discharged water
may occur. The fill area often becomes a mosquito breeding
ground and haven for undesirable forms of wildlife. High
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fs,"-a Mr F
bacteria counts are frequently encountered in the fill area.
Leaching of Materials into Ground Waters
Damage to the groundwater province beneath, and adjacent to
fill areas through leaching of soluble minerals, chemicals,
nutrients and toxic substances is an ever-present hazard
associated with any landfill operation. Cnce contaminated,
damage to the aquifer may be "permanent" — or at best — long
term and may result in the ultimate abandonment of water wells.
Mater quality effects on the aquifer in a proposed fill area
should be carefully evaluated prior to disposal.
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Magnitude and Variation
To date over 22,000 miles of waterways have been
modified for commercial navigation and over 19,000 miles of
waterways and some 1,000 harbcr projects are currently being
maintained by the Corps of Engineers. Annual quantities of
material being removed are currently averaging about
300,000,000 cubic yards in maintenance dredging and about
80,000,000 cubic yards in new work dredging. Total annual
costs are now exceeding $150,000,000.00.* The volumes of
material removed at a single project may vary from a few
thousand cubic yards in a harbor maintenance project to many
millions of cubic yards in channel development projects.
Variation in the nature of the material removed ranges from
clean sand and gravel to organic muck, sludge and municipal
and industrial wastes or any combinations thereof.
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It?
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Figure 1, illustrates the average annual quantities of
spoil generated by CE district and methods of disposal;
figure 2, illustrates the average annual quantities of spoil
type generated by CE District; and figure 3 illustrates the
amount of polluted spoil generated in maintenance dredging
operations by deposition area and district.
The following criteria for determining the
acceptability of dredged spoil for disposal to the nation's
waters have been developed by the EPA:
Criteria
The decision whether to oppose plans for disposal of
dredged spoil in United States waters must be made on a
case-by-case basis after considering all appropriate
factors; including the following.
(a) Volume of dredge material.
(b) Existing and potential quality and use of the
water in the disposal area.
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(c) Other conditions at. the disposal site such as
depth and currents.
(d) Time of year of disposal (in relation to fish
migration and spaqning, etc.)
(e) Method of disposal and alternatives.
(f) Physical, chemical, and biological characteristics
of the dredged material.
(g) Likely recurrence and total number of disposal
requests in a receiving water area.
(h) Predicted long and short term effects on receiving
water quality. When concentrations, in sediments,
of one or more of the following pollution
parameters exceed the limits expressed below, the
sediment will be considered polluted in all cases
and, therefore, unacceptable for open water
disposal.
Sediments in Fresh and Marine Waters cone % (dry wt basis)
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*Volatile Solids 6.0
Chemical Oxygen Demand (C.O.D) 5.0
Total Kjeldahl Nitrogen 0.10
Oil-Grease 0.15
Mercury 0.001
Lead 0.005
Zinc 0.005
*When analyzing sediments dredged from marine waters,
the following correlation between volatile solids and
C.O.D. should be made:
T.V.S.X (dry) = 1.32 + 0.98 (C.O.D.*)
If the results show a significant deviation from this
equation, additional samples should be analyzed to
insure reliable measurements.
The volatile solids and C.O.D. analyses should be made
first. If the maximum limits are exceeded the sample can be
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V
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characterized as polluted and the additional parameter would
not have to be investigated.
Dredged sediment having concentrations of constituents
less than the limits stated above will not be automatically
considered acceptable for disposal. A judgement must be
made on a case-by-case basis after considering the factors
listed in (a) through (h) above.
In addition to the analyses required to determine
compliance with the stated numterical criteria, the
following additional tests are recommended where appropriate
and pertinent:
Total Phosphorus SuIfides
Total Organic Carbon (T.O.C) Trace Metals (iron,
cadmium, copper,
chromium, arsenic,
and nickel)
Immediate Oxygen Demand (I.O.D) Pesticides
Settleability Bioassay
%
The first four analyses would be considered desirable in almost all
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instances.
They may be added to the mandatory list when sufficient experience with their
interpretation is gained.
+
For example, as experience is gained, the T.O.C. test may prove to be a valid
substitute for the volatile solids and C.O.D. analyses.
Tests for trace metals and pesticides should be made where significant
concentrations of these materials are expected from known waste discharges.
Prediction ^ethods
To predict the potential for water pollution from a dredging program ^
requires the consideration of a number of interacting
factors involving the hydraulics of the altered channel, the adjacent waters
and the spoil pile; and the chemistry of the spoil, •
the water involved and the newly exposed surfaces.
Prediction of the flow patterns and associated bank scouring, silt %
deposition, bottom scouring and flooding is facilitated by mathematical
modeling and, where the data, resources and time available are adequate,
scale modeling is an excellent tool. ^
In those instances that involve the scalping of an aquifer, or the
•
alteration of the flow of groundwater, hydrogeological investigations are
also in order wlftch may involve surface geological mapping, strati graphic dr,i!J
core analyses, pumping tests and mathematical or analog modeling.
U.S. Er.v'.c ' .M Agency *
Regie.! V •' ^>
230 Sc;jt:! i _\
Chicago, !!!,M;,, , • .. .... j. ,fj
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Very little work has been done in the •effects on groundwater1 area.
Groups currently involved in predictive studies include:
United States Geological Survey
Environfmental Protection Agency
United States Army Engineers
North Carolina State University
Skidway Institute of Oceanography
Clemson University
Northwestern University
Oklahoma State University
Texas ASM University
University of Hawaii
University of Rhode Island
University of Southern Mississippi
University of Maryland
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BIBLIOGRAPHY
O'Neal, Gary and Jack Seeva, "The Effects of Dredging on Water
Quality in the Northwest." Region X, Environmental Protection
Agency, Seattle, V/ashington. July 1971.
Boyd, M.B., R.J. Saucier, J.H. Keeley, R.L. Montgomery, R.D. Brown,
D.B. Mathis and C.J. Guice, "Disposal of Dredge Spoil Problem
Identification and Assessment and Research Program Development."
Tech. Report H-72-B. Office, Chief of Engineers, U.S. Army Engineer
Haterways Experiment Station, Vicksburg, Mississippi. November 1972.
Pierce, Hed D., Inland Lake Dredging Evaluation." Tech. Bulletin No. 46,
Department of Natural Resources, Madison, Wisconsin. 1970.
N
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