Table 6

AREA AND POPULATION SERVED BY PUBLIC SANITARY SEWERS IN THE REGION BY COUNTY: 1970 AND 1990
Area Served by Public Sanitary Sewers                Population Served by Public Sanitary Sewers
1970                        1990                        1970                        1990
Square        Percent       Square        Percent                     Percent                     Percent
County               Miles        of Area        Miles        of Area      Persons     of Population   Persons     of Population
Kenosha ...............        23.8          8.6           40.6         14.6          94,000        79.7         111,900        87.3
Milwaukee .............       179.0         73.9          190.7         78.6        1,034,700       98.2         954,600        99.5
Ozaukee .............. ...     17.3          7.4           22.3          9.5          36,300        66.7          54,900        75.4
Racine ..................      29.5          8.7           52.3         15.4         135,900        79.6         154,900        88.5
Walworth ................      11.9          2.1           20.5          3.6          35,500        56.0          45,200        60.2
Washington ...........          9.4          2.2           18.0          4.1          30,200        47.3          53,300        55.9
Waukesha ............ ...      38.5          6.6           88.5         15.2         122,100        52.8         219,500        72.0
Region                   309.4          11.5          432.9         16.1       1,488,700       84.8        1,594,300        88.1

Source: SEWRPC.

of the Region in which concentrations of the best
remaining elements of the natural resource base occur. It
was recognized that preservation of such areas is essen-
tial to both the maintenance of the overall environmental
quality of the Region and to the continued provision of
amenities required to maintain a high quality of life for
the resident population, especially where these elements
are concentrated in identifiable geographic areas.
Under the regional planning program, seven elements of
the natural resource base have been considered essential
to the maintenance of the ecological balance, natural
beauty, and overall quality of life in Southeastern Wis-
consin: 1) lakes, rivers, and streams, and their associated
shorelands and floodlands; 2) wetlands; 3) woodlands;
4) prairies; 5) wildlife habitat areas; 6) wet, poorly drained,
and organic soils; and 7) rugged terrain and high-relief
topography. In addition, there are certain other features
which, although not part of the natural resource base
per se, are closely related to, or centered upon, that base
and are a determining factor in identifying and delineating
areas with recreational, aesthetic, ecological, and cultural
value. These five additional elements are: 1) existing park
and open space sites; 2) potential park and open space
sites; 3) historic sites; 4) scenic areas and vistas; and
5) natural areas and critical species habitat sites.
The delineation of these 12 natural resource and natural-
resource-related elements on maps results, in most areas
of the Region, in an essentially linear pattern of relatively
narrow, elongated areas which have been termed "environ-

mental corridors" by the Regional Planning Commission.2
Primary environmental corridors include a wide variety
of the aforementioned important natural resource and
resource-related elements and are at least 400 acres in size,
two miles in length, and 200 feet in width. Secondary envi-
ronmental corridors generally connect with the primary
environmental corridors and are at least 100 acres in size
and one mile in length. In addition, smaller concentrations
of natural resource base elements that are separated
physically from the environmental corridors by intensive
urban or agricultural land uses have also been identified.
These areas, which are at least five acres in size, are
referred to as isolated natural resource areas.
In any consideration of environmental corridors and
important natural features, it is important to note that
the preservation of such features can assist in flood-
flow attenuation, water pollution abatement, noise pollu-
tion abatement, glare reduction, and favorable climate
modification. In addition, because of the many interacting
relationships existing between living organisms and their
environment, the destruction or deterioration of one impor-
tant element of the total environment may lead to a chain
reaction of deterioration and destruction of other elements.
The drainage of wetlands, for example, may destroy fish
2A detailed description qf the process of refining the
delineation of environmental corridors in Southeastern
Wisconsin is presented in the March 1981 issue (Vol. 4,
No. 2) of the SEWRPC Technical Record, pp. 1-21.

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