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2.7 Management of Catchment Areas 45
populated river valleys. The less developed they are, the better, relatively, they lend them-
selves to exploitation for steady yields and the production of water of high quality.

2.7.1 Upland Areas

Occasionally, a water utility can, with economic justification, acquire the entire watershed
of its source and manage solely for water supply purposes, excluding habitations and fac-
tories to keep the water safe and attractive; letting arable lands lie fallow to prevent wasteful
runoff and high turbidities; draining swamps to reduce evaporation and eliminate odors,
tastes, and color; and cultivating woodlots to hold back winter snows and storm runoff and
help to preserve the even tenor of stream flow. As competition for water and land increases,
land holdings of water utilities are understandably confined to the marginal lands of water
courses, especially those closest to water intakes themselves. Yet water quality management
need not be neglected. Scattered habitations can be equipped with acceptable sanitary facili-
ties; wastewaters can be adequately treated or, possibly, diverted into neighboring drainage
areas not used for water supply; swamps can be drained; and soil erosion can be controlled.
Intelligent land management of this kind can normally be exercised most economically when
water is drawn from upland sources where small streams traverse land of little value and
small area. However, some upland watersheds are big enough to satisfy the demands of great
cities. The water supplies of Boston, New York, and San Francisco are examples.

2.7.2 Lowland Areas
When water is drawn from large lakes and wide rivers that, without additional storage,
yield an abundance of water, management of their catchments ordinarily becomes the con-
cern of more than one community (examples are the Ohio and Mississippi rivers) and
sometimes of more than a single state (the Delaware River is a notable example) and even
of a single country (for example, the Great Lakes are shared with Canada and the Colorado
River is shared with Mexico). Regional, interstate, and international authorities must be set
up to manage and protect land and water resources of this kind.

2.7.3 Quality Control

To safeguard their sources, water utilities can fence and post their lands, patrol watersheds,
and obtain legislative authority for enforcing reasonable rules and regulations for the envi-
ronmental management of the catchment area. When the cost of policing the area outweighs
the cost of purifying its waters in suitable treatment works, purification is often preferred. It
is likewise preferred when lakes, reservoirs, and streams become important recreational a-
ssets and their enjoyment can be encouraged without endangering their quality. It goes with-
out saying that recreation must be properly supervised and recreational areas suitably
located and adequately equipped with sanitary facilities.

2.7.4 Swamp Drainage

Three types of swamps may occur on catchment areas:
1. Rainwater swamps where precipitation accumulates on flat lands or where rivers
overflow their banks in times of flood
2. Backwater swamps or reaches of shallow flowage in sluggish, often meandering
streams where bends or other obstructions can hamper flow
3. Seepage-outcrop swamps where hillside meets the plain or where sand and gravel
overlie clay or other impervious formations