River and flood plain: friend or foe

(1)

f

/()&i

(

t

i

THE

_ol

:;.

BAL

m

l

a

diacuaaion

AN

of

conservation

ieeuae ....

DEPARTMENT OF THE INTERIOR Bureau of Outdoor Recreation

a

Mid-Continent Region Denver, Colorado 80225 july 16, 7969

RIVER AND FLOOD PLAIN FRIEND OR FOE Preface

This issue of the Balance is on the advantages of reserving the flood plain to provide for open space purposes, such as recreation and agriculture and to reduce flood losses. The historical back-ground of how flood-prone lands have been used and developed; past and current trends in flood con-trol methods; and some of the ways in which flood plains can be managed to benefit outdoor recrea-tion, natural beauty, and open space all are gen-erally discussed.

Introduction

Commercial cities in America grew up along the coast where great rivers flowed into the Atlantic. Rivers became the roads outward for an expanding new nation--highways which didn't have to be hacked out of the wilderness. The story of the westward expansion is replete with the names of the nation's rivers. The Potomac, the Hudson, the Wabash,the Ohio, the Illinois, the "Father of Waters"--the Mississippi, the Missouri, the Platte, the Rio

Grande and the Columbia were in great measure the avenues used to settle the country. Wagon trains following the river courses carried people and goods into new territory, just as barges and ships continue to traffic the Mississippi, Ohio and Ar-kansas today.

It was inevitable then that most of our cities grew up near river banks. And today's population growth and industrial expansion have increased the use of land convenient to the cities' population centers. In many instances, this has meant an in-creased use of land subject to flooding. Had our forefathers the wisdom of Solomon, the land away from the river not subject to frequent flooding would have been developed with homes, factories, and stores. The river bottom would have been re-served for necessary structures such as docks and

warehouses and for open space devoted to farming

and to recreation. But instead, many of our cities are in competition with their river for use of the flood plain.

photo by r.i. blewitt

PaJLt

06 Ve.nvVl.

,i,6

£.oc.at.e.d

-<J1

.t.he. 6£.ood pia,i.n,

and .t.he.

1tv.iu.UJ.,

wVte. fua1.,.t.JtoU6

in 1965.

A flood plain is the nearly level land along either side of a river which is subject to peri-odic flooding. The stream staked out a claim on the plain milleniums ago to take care of floods which have been occurring since the beginning of time and which will continue to occur. A stream will

over-flow,on the average,once every two or three years.

From Sea to Shining Sea, a recent report on our environment prepared by the President's Coun-cil on Natural Beauty, states the problem and

(2)

Encroachments upon flood plains in the aggregate nave a significant adverse ef-fect upon the public interest and destroy

natural beauty opportunities along

hun-dreds of miles of both rural and urban water ways each year. Such opportunities, once lost, are gone forever. The benefits of such waterways to people, coupled with

the major economic loss potential when

flood plains are encroached upon unwisely, are of such great importance to the nation that positive action is needed to preserve them as open space.

Natural waterways that are used by flood waters have, in effect, an easement placed upon them by nature for intermittent use. Man's encroachment into the flood plain violates the natural easement and often

ad-a_ff cts the vested ublic interest. (From Sea to Shining Sea; p. 156; emphasis added.)

Traditional Approaches to Flood Control

-2-After the Mississippi flood losses of 1916, Congress passed the first flood control act of 1917. However, it was not until the Flood Control Act of 1936 that the federal government took on a

general responsibility for flood control. Since

1936, the federal government, mainly through the Army Corps of Engineers, has spent better than $7 billion to protect life and property from flooding. Yet, despite the large investment, damages are in excess of $1 billion each year from floods w:1ich we commonly, but incorrectly, call "natural

catas-trophies." We have spent money to reduce the eco-nomic impact of floods--some of it with success. But what is or will be the complete price for sec-urity? What is the best kind of investment we as taxpayers can make to alleviate flood risk?

photo by r.i. blewitt

Tfu.6 hoMe. loc.ate.d ai..ong .the. Sou.th Pla..t.te.

IUveJt

Wa.6

du:tJr.oye.d

ht

.the.

'65

f/.ood.

Most of the money spent to reduce flood dam-ages has been for dams and other structures such as levees, flood walls, channel improvements, and flood proofing of buildings that must be located in the flood plain. These have been partially suc-cessful, but, to some extent, they are a confession of poor planning. Their purpose is to protect de-velopments in the flood plain that often should not have been built there in the first place.

A dam controls floods by holding excess water in its reservoir during times of flooding. When the flood stage has abated, the water is released from the dam at rates which will not cause flood-ing downstream. Multi-purpose reservoirs have done

much for outdoor recreation. Lands adjacent to

reservoirs have been developed for all kinds of recreation activities--boating,water, skiing, swim-ming: camping, picnicking, hiking and fishing.

national park service photo

Boiling

,u.,

a po pula.Jt ac;t<_v..Lty

a.t

JtV.,

e.Jtvow.

But dams, as well as flood control structural devices of all kinds, will often result in in-creased use o a oo p a1

of security from flooding which they engender.

Thus, when a large flood in excess of the

struc-ture's capacity does occur, the damage may be

greater than it would have been had the structure not been constructed in the first place.

Earthen levees or dikes and concrete flood

walls help to protect land adjacent to the river from flooding by acting as a barrier and confining flood waters to a floodway area where they will cause the least damage.

Channel improvements reduce floods by making a stream flow straighter and faster, thereby increas-ing the water capacity within the channel. This

involves deepening and widening of the stream

channel, clearing it of brush, trees and other ob-structions, and sometimes lining it with concrete.

(3)

Levees, floodwalls and channel improvements which all involve straightening the river and re-moving vegetation often result in aesthetic, rec-reation, and fish and wildlife habitat losses. Straight channels lacking vegetation are not as salubrious or attractive as meandering tree-lined streams.

A New Look

Dams and other works have been an important part of flood control. But there has been a grow-ing awareness that somethgrow-ing is wrong with depend-ing almost entirely on expensive structures. The cycle of flood protection construction, more flood plain developmen~ and then the need for more flood control measures is endless.

One of the most significant recent docume;ts on our water planning policies was sent to Congress in 1966. This report, A Unified National Program for Managing Flood

Losses,

was prepared by a Task Force on Federal Control Policy. The report noted

that:

"To hold the Nation's toll of flood losses in check and to promote wise use of its valley lands, requires new and imaginative action. ·~ature will always extract some price for

use of her flood plains. However, this Nation's annual flood damage bill of more than $1 billion per year is excessive, even in the growing economy. Beyond the dollar loss, the accompanying toll in personal hardship cannot be calculated. In addition, opportunities are being lost to use flood plain lands effectively for recreation and wildlife purposes. 11

Rather than placing buildings in the flood plain and then clamoring for the federal govern-ment to provide flood control projects, the goal

should be to keep most s true tures on higher ground. At times it is necessary to locate structures in the flood plain. Moreover, before building in a flood-prone area, all the costs should be con-sidered and the benefits of someone occupying the flood plain should exceed both the public and pri-vate costs. Flood control devices required to pro-tect the new building and post-flooded disaster relief, clean up,and other rehabilitation measures should all be regarded as part of the cost of locating on fl0od-hazard lands.

It's just possible that the emphasis on non-structural flood control methods makes for good economics, as well as wise use of land. And

keep-ing the land near rivers from bekeep-ing developed,even in rural areas, will surely provide many desirable areas for outdoor recreation, fish and wildlife, and natural beauty. The following examples illus-trate the "traditional" and "new look" approaches and some of their advantages and disadvantages.

A hypothetical housing development is construc-ted in an area subject to flooding. Associated shopping centers, gas stations and light industry are also located in the flood plain. Meanwhile, other developers build and replace trees and other vegetation with houses and paved streets. Water which once seeped gradually into the ground now quickly runs off. The flood threat to people in the low-lying areas is greater not only because of their location, but also due both to the increased volume and destructive force of the water poured down from above. This situation results in pres-sure on the government to construct expensive flood control structures. If they are built, federal taxes are used for the protection of a relative few.. Almost everyone loses, and in the process, land

that would have been useful for outdoor recreation, open space, agriculture, etc., has been usurped.

But there is another way. This same community could have initiated a comprehensive study combin-ing sound ecological and economic principles, such as the one recently completed by the Minneapolis-St. Paul Metropolitan Council. Stream valleys, marshes and other flood plain lands that would be worth far more to man in the long run if left un-disturbed are identified and the hazard of en-croaching on the flood plain pointed out. Through regulatory devices, these lands will be dedicated to appropriate uses, including outdoor recreation, fish and wildlife, and open space. Structures sub-ject to flood damages are encouraged in areas not subject to flooding.

Everyone benefits from ecological studies such as this if the plans are carried out. Needed lands, located near people, are assured for outdoor rec-reation and open space. Expensive flood control structures are not required and the general tax-payer is spared.

Zoning

Regulations, a state and local responsibility, provide a legal means for reducing flood damage. Ordinances and laws which prohibit channel en-croac ment and provide flood plain zoning are ex-amples of regulations which can wisely and reason-ably restrict certain uses to which an owner may put his property. Regulations can be quite effec-tive if people are willing to impose them upon themselves. However, regulations have a built-in weakness, typical of most zoning-type laws,in that they can be changed by continual pressure for ex-ceptions. Some critics have said that zoning works fine until the land is needed for other uses.

Because local zoning has often not been suc-cessful, some states have considered it advisable to become more involved in local zoning practices. In Hawaii, the state has withdrawn from the coun-ties certain rights to zone in order to stop uncon-trolled growth in the islands. Also, Minnesota has recently passed a law establishing a metropolitan park board which will assist local governments in a seven-county area with flood plain zoning.

(4)

-4-I

I

Beyond Maximum Probable Flood Limit Suggested Flood Proofing

I

Floodway

I

Floors Fringe

I

Above

I

Floods Agriculture Open Uses Parking Recreation Storage !Floodway I Fringe I Floors I Above I Floods IFloodRroof

I

Buildings Suggest Flood Proofing jBeyond Maximum

I

Probable Flood Limit

I

Flood.proof Buildings I

I

W-i.l,e. Me.

06

frf-ood-pJWne. .tan~.

Basically, the two important areas to treat in a system of flood plain zoning are the floodway and the floodway fringe. The floodway is the area immediately adjacent to the river through which a rapid flow and a large volume of water passes dur-ing a flood. Structures that could be seriously damaged by inundation should not be permitted in this zone. Rather, a long-range goal should be to remove all existing buildings and leave this area for outdoor recreation uses, parking lots, wildlife and forest preserves, farming or grazing, nurs-eries, parks and roads.

The floodway fringe is immediately adjacent to either side of the floodway. This is an overspill area which is characterized during floods by large volumes of water moving at a much slower rate. Un-fortunately it is the most difficult with which to deal because it frequently contains some of the l rty--in-the c-emmunit::y, ReS-i-den-tial development is definitely not a part of this zone. Only those structures that do not engender life or significantly restrict the carrying capac-ity of the designated floodway fringe should be permitted. A policy of gradual elimination of in-compatible development should be initiated. In summary, an effective regulatory zoning program has the dual advantage of providing flood protection and low cost open space and recreation in areas where maximum benefits can be obtained from both.

The surest way its natural state the river is to lands, especially the most expensive

Acquisition

to maintain the flood plain in and preserve the character of purchase the most flood-prone in cities. Although it may be initially, in the long run it

may well be the most economical. There are no en-forcement costs as would be required in the case of zoning and other regulations which must be mon-itored constantly to spot violations. Also acqui-sition need not always involve outright purchase of land. Conservation easements or development rights may be bought or leased to accomplish the intended purpose, with the land remaining in pri-vate ownership restricted to compatible uses such as grazing or nurseries.

Conservation easements combine private owner-ship with a reservation of certain rights for pub-lic use or development. They have two principle advantages over fullscale acquisition. Such de-vices are often less expensive, and they leave the land in taxpaying private ownership, although the amount of tax assessment is lower. Purchase of restrictive easements is generally confined to ru~ i~uations as their cost in built-up areas is usually t o ~ h .

Double benefit for the tax dollar can be achieved if park and open space acquisition pro-grams are coordinated with flood control needs. Nearly any good-sized American city needs parks, as well as ways to control local floods. Some cities, Milwaukee and San Antonio, have already begun acquiring environmental corridors or "strip parks" along waterways.

Acquisition of this type reflects good multi-purpose planning. Land is purchased to meet com-bined outdoor recreation, flood plain management, and scenic beauty preservation needs. More often

than not at least part of the wandering course of a stream will be within reach of many people in the community.

(5)

Flood Insurance

A flood insurance program is, in effect, a flood plain occupancy charge. Indemnification of flood losses theoretically is an ideal procedure to assure that the wisdom and economics of locat-ing in the flood plain are adequately considered. A flood insurance program, properly applied, would require each new development to pay an annual charge in proportion to its hazard, requiring that the benefits of occupying the flood plain would exceed the costs. In addition, if the occupancy charges were taken into account in the benefit-cost tests of whether flood control structures are worthwhile, the structures' economic benefits could be more accurately determined. But if the cost of the insurance is less than the actual risk, occu-pancy of the flood plain would be promoted. A ~ni-form premium not related to actual costs would both provide a windfall for those who own developments

in the flood-prone areas and result in additional pressures for traditional flood protection.

The National Flood Insurance Act of 1968 (Ti-tle XIII of the Housing and Urban Development Act of 1968, P. L. 90-448) sets up a 15-member Flood Insurance Advisory Committee and authorized the U.S. Department of Housing and Urban Development to develop a national flood insurance program. This program would be operated jointly by the fed-eral government and private insurance companies. By August 1970, the President is required by the Act to submit to Congress a program for flood

in-surance and flood plain management. Other Necessary Steps

Proper watershed management, especially in rural areas, should go hand in hand with all other

soil conservation service photo

Cou.ntouJt

6aJ1Jn<.ng

,i.n

.the. Midwu.t.

flood control measures to reduce the need for expensive dams and channeling projects. Countour farming, strip cropping, crop rotation,proper range management, planting grass waterways and

reforesta-tion are examples of good land management prac. tices. These measures, complemented by the development of small retention dams and terraces, reduce runoff and thus the severity of flooding. Poor land man-agement practices promote increased runoff and pro-duce flooding of greater frequency and intensity.

Before good flood plain management decisions can be made,several questions need to be answered. Should zoning be applied to protect against a 50-or 100-year frequency flood? What uses should be prohibited and promoted in the flood plain? What exceptions will be made for existing developments?

~ To answer these questions we need to know the flooding history of an area--where past floods have occurred, how often, and how much d-ama~e has resulted. If public agencies and private citizens

~ are to make wise decisions regarding the use of flood plains, it is vital that this kind of infor-mation be available.

The Task Force on Federal Flood Control Policy, mentioned earlier, recommended that the U.S. Army Corps of Engineers in cooperation with the Depart-ment of Housing and Urban DevelopDepart-ment develop a

technical information service to provide data on flood plain regulations and other subjects con-cerned with reducing flood losses. The Corps is now doing this through the flood plain information reports it prepares for local agencies at their request. In addition, special flood hazard infor-mation reports are made for federal agencies con-sidering locating any buildings in a flood-prone area.

Rebuilding a City

New communities ought to be planned and old cities ought to be redesigned with flood plain management principles in mind. Rebuilding of ur-ban America, a job necessitated by a variety of social and physical ills,will give ven our oldest cities an opportunity to correct some past mis-takes. Many of which have aggravated the cost of flood damage, economic dislocation and repair, and have resulted in loss of life and physical suffer-ing. Flood control projects in cities should be planned in combination with land use planning to achieve useful, attractive and effective results.

Properly implemented, rehabilitation efforts of these types can replace blighted and ignored areas with scenic riverfront developments. Often in the past, flood control projects have been de-bilitating to the city environment. Yet such pro-jects can provide needed open space; low cost, but high quality recreation areas; as well as better flood control. The San Antonio development and the ambitious plans for the South Platte River Valley in Denver offer just two outstanding examples of what can be done.

(6)

Sununary

Man may provide himself with a degree of protection from floods with his dams, levees and dikes, channel im-provements, flood proofing, and improved building prac-tices. But to a certain ex-tent these methods represent incomplete or inadequate plan-ning. That is, they may be providing protection for de-velopments which should not have been located in the flood plain in the first place.

Non~tructural approacnes

such as the dissemination of information, regulations to control use of the flood plain, acquisition of land or ease-ment in the hazard areas, in-surance programs, and proper watershed management practices lessen damage by discouraging incompatible and hazardous de-velopment and reducing runoff.

-6-Rivers will use their flood plain, and devel-opments that are subject to damage by flooding should not, in most cases, be located there. By

restricting the use of flood-prone land, a

com-UNITED STATES

DEPARTMENT OF THE INTERIOR

BUREAU OF OUTDOOR RECREATION

BLDQ, 41, DENVER FEDERAL CIEN'l'SII

DENVER,COLORADO 80225 OFFICIAL BUSINESS

bureau of outdoor recreation photo

J

munity can work with nature and lessen.the need for costly control structures. At the same time, badly needed beauty and recreation can be