3 August 1998
SURFACE WATER SUPPLIES
6-1. SURFACE WATER SOURCES. Surface water supply sources include streams, lakes,
and impounding reservoirs. Large supplies of surface water are generally available throughout
much of the eastern half of the United States where rainfall averages about 900 mm (35 in) or
more annually and is reasonably well distributed through the year. On the other hand, good
surface water sources are much more limited in many western regions with the exception of
the Pacific Northwest, where surface water is plentiful.
6-2. WATER LAWS. Any investigation directed toward development of new or additional
sources of supply must include consideration of applicable State water laws. Most of the
States in roughly the eastern half of the United States follow the riparian law of water rights,
and only a few have permit systems. Under this doctrine, the right to use water is associated
with ownership of the land through which the stream flows. The riparian rights doctrine is
essentially a legal principle which may be used, in some form, to settle disputes. It does not
automatically provide for State water management and record keeping. Planning for water
supply systems under the riparian doctrine is not absolutely certain for present and future
water availability and security. In contrast, western law is based largely on the doctrine of
"prior appropriation." In the 17 Western States where this doctrine prevails, sophisticated
legal, administrative and management machinery exists. In these States, water rights and land
ownership are separable and most Western States authorize a water-right owner to sell the
right to another. The new owner is permitted to transfer the water to another point of use or
put it to a different use, provided the transfer conforms to the State's administrative
6-3. QUALITY OF SURFACE WATERS. The quality of stream and lake waters varies
geographically and seasonally. Streams, in particular, often exhibit fairly wide seasonal
fluctuations in mineral quality, principally as a result of variations in stream flow. In general,
streams and lakes east of the 95th meridian, which includes most of Minnesota, Iowa,
Missouri, Arkansas, Louisiana, and states east thereof, exhibit dis- solved mineral solids in the
range of 100 or less to about 700 milligrams per liter (mg/L). The water from these sources,
after conventional treatment in a well-designed filtration plant, will meet standards prescribed
for potable water (see appendix A of TM 5-813-3/AFM 88-10, Vol. 3, for these standards).
Unusual local conditions; e.g., pollution may render some eastern waters unsuitable as a
source of supply; but in general, eastern streams and lakes are a satisfactory raw water
source. Similar comments are applicable to surface waters of the Pacific Northwest area.
Streams in many other areas west of the 95th meridian are much less satisfactory, often
showing dissolved mineral solids in the range of 700 to 1,800 mg/L. High concentrations of
hardness- producing and other minerals such as sulfate and chloride are found in some
western surface waters.
6-4. WATERSHED CONTROL AND SURVEILLANCE. Raw water supplies should be of the
best practicable quality even though extensive treatment, including filtration, is provided. Strict
watershed control is usually impractical in the case of water supplies obtained from streams.
However, some measure of control can be exercised over adverse influences, such as waste