WARD H. FISCHER*
Weather Modification and
the Right of Capturet
The life of the law has not been logic:
It has been experience.1
This most famous of the remarks of Mr. Justice Holmes may allow us to
maintain some balance as we plunge into a legal analysis of that most logi-
cal of the sciences: mathematics. Statistical and simulation techniques en-
able the hydrologist to predict the amount of water which may be made
available through weather modification programs. The validity of these pre-
dictions may be technically recognized; but the important and practice!
question is whether or not they will be recognized by a select group of
non-technicians, the courts. Existing cases and statutes do not give the
answers; and, therefore, a lawyer too may engage in the business of pre-
dicting. The lawyer's tools are not those of mathematical precision; and,
logic, while helpful, and even essential, will not invariably lead to a correct
Scope and Limitations of the Predictions
Weather modification attempts have already created controversies; and,
like most controversies, these have generally been resolved by the courts.
The reported cases2 in this field give a broad general description of the
Fischer, Brown, Huddleson and Gunn, Fort Collins, Colorado; J.D., U. of
t This study was financed by the Office of Water Resources Research of the
United States Department of the Interior under Pub. L. 88-379, contract no. 14-
31-0001-9020, awarded to M. W. Bittinger and Associates, Inc., Fort Collins, Col-
1 0. W. HOLMES, THE COMMON LAW 5, (Harvard University Press ed. 1963).
2What purports to be a complete compilation of cases of substance in the field
of weather modification is contained in 4 WATERS AND WATER RIGHTS, at 527-28
(Allen Smith Company), a publication composed of the works of various authors.
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640 NATURAL RESOURCES LAWYER VOL. VIII, NO. 4
areas with which this article is not concerned. These problems with which
| we will not deal include such diverse ones as: who is liable for floods
caused by the modification? What are the relative rights between persons
who want it to rain and those who want the sun to shine? Are we stealing
water from the appropriators in another water basin? Does induced pre-
cipitation in one area wrongfully deprive residents in another area of their
Our present inquiry is much more limited. It is:
1) May the one who develops water through weather modification tech-
niques lay claim to those waters, as a matter of legal theory, as against
'-her owners of water rights in the basin into which the developed waters
; ( precipitated? and,
SC. 2) If the capture is permissible as a matter of legal theory, what can we
S predict as to the type and quality of evidence to be required to be pro-
S duced to allow the application of the rule? and,
3) Does the present state of the art in regard to weather modification
provide the quality and type of evidence required?
We will also necessarily touch upon some of the social-political ques-
tions of public vs. private programs-certainly not to give the answers but
to remind us that the complexities of our Union of sovereign states requires
their consideration. This will also lead us to reflect upon the advantages,
and even the necessity, of interstate cooperation with respect to such pro-
grams in certain river basins.
The reported cases decide matters other than those with which this paper
is concerned. It follows that to predict the-results of our study by analogy
from those cases would be a mistake, although a tempting one; because
lawyers particularly like to base their legal conclusions upon the pro-
( ouncements of the courts. Thus, most authors who have examined our
S' :neral subject matter have analyzed these reported cases at some length
"ven though they ultimately and perceptively conclude, after exhaustive
examination and discussion, that they are inapplicable. To omit them will
WEATHER: THE RIGHT OF CAPTURE 641
Some of the cases are decisions of inferior courts, not published, and therefore not
readily available. The published cases listed are:
Summerville v. North Platte Weather Control District, 170 Neb. 46, 101 N.W.2d
748 (1960): A constitutional law case dealing with the validity of special districts.
Slutsky v. City of New York, 197 Misc. 730, 97 N.Y.S.2d 238 (S. Ct. 1950):
Dispute between resort owners and the City of New York concerning the effect of
weather modification experiments by the City on the business of the resorts.
S.W. Weather Research. Inc. v. Rounsaville, and S.W. Weather Research, Inc. v.
Duncan, 319 S.W.2d 940; 320 S.W.2d 211; 327 S.W.2d 417 (Tex. 1958-59): A case
in which hail suppression efforts were temporarily enjoined on a finding that such
efforts resulted in less precipitation for the lands of local ranchers.
Pa. Natural Weather Association v. Blue Ridge Weather Modification Associa-
tion, 44 Pa. D & C 1 49 (1968): This case is published in reports not readily
-- --- ________ (
save the reader's time and detract not. at all from the validity of any con-
clusions which we reach. One example will perhaps suffice. In one oft-cited
case,3 the Supreme Court of New York said certain complaining property
owners "clearly have no vested property rights in the clouds or the moisture
therein." From this statement one could logically conclude:
1) That no one can engage in cloud seeding, or
2) That anyone can engage in cloud seeding.
But it stands for neither proposition. The questions with which we are con-
cerned are not discussed.
THE EXISTING "LAW OF WATER"
The history of what the law has been is
necessary to the knowledge of what the law ist
While the few existing weather modification cases do not answer our ques-
tions for us, an understanding of the present law of water in the western
states will lead us a long way in. our search for a valid prediction of what
the law is or will be in this newly prominent field,
The expected benefit of increased precipitation is particularly important
to the arid states of the American West. Here waters are so limited, and
futures otherwise so bright, as to make any incremental increase in the
total quantity of available water extremely desirable, and, accordingly, to
justify the expense of the programs, and to make acceptable the uncer-
tainties and delays in the obtaining of recognition of the capture of the
waters thus produced. Hence, we will assume that the applicable water law
with which we must be concerned is that expressed generally as the "doc-
trine of appropriation," it being the basic principal or standard adhered to
by the arid mountain states.
This doctrine was first announced by the courts of Colorado," and subse-
quently adopted, in more or less pure form, by the courts of Nevada,6
Arizona,7 Idaho,8 Utah,9 New Mexico,10 Wyoming," and Montana." The
remaining western states adopted a modified form of the doctrine,1s which
s Slutsky v. City of New York, supra, note 2.
4 Holmes, supra, at 33.
5 Coffin v. Left Hand Ditch Co., 6 Colo. 443 (1882).
eJones v. Adams, 19 Nev. 78, 6 P. 442 (1885).
7 Clough v. Wing, 2 Ariz. 371, 17 P. 453 (1888).
8 Drake v. Earhart, 2 Idaho 750, 23 P. 541 (1890).
9Stowell v. Johnson, 7 Utah 215, 26 P. 290 (1891).
1tTrambley v. Luterman, 6 N.M. 15, 27 P. 312(1891).
11 Moyer v. Preston, 6 Wyo. 308, 44 P. 845 (1896).
Is Mettler v. Ames Realty Co., 61 Mont. 152, 201 P. 702 (1921).
IThe modified doctrine is often referred to as the "Californmjcoctriv be-
.se first announced in that state.
O ~ ~ ~ ~~ L I., oiiddcriei fe eerd oP h "~~c
1~~~-- -~ ~- I-I-- ~~ --~-~--~--`~-~-~'~` ~- -------------- -- -- -------- --------
642 NATURAL RESOURCES LAWYER VOL. VIII, NO. 4
attempted to meld the concept of appropriation with the common law con-
cepts of riparian rights.14 The latter states are continually re-examining
the effects of this unhappy marriage and are tending to more and more reject
the riparian in favor of the appropriative aspects of their doctrine.15 For
our purposes in this Paper, in any event, any remaining riparian modifica-
tions are not applicable; and we can include all of the western states within
those which are governed by the main concepts of appropriative -water
The appropriative doctrine embraces two concepts: the appropriation or
use of water itself, and the protection of that use as against subsequent
The appropriation of water consists in the taking or diversion of it
from some natural stream or other source of water supply, in accordance
( with law, with the intent to apply it to some beneficial use or purpose, and
consummated, within a reasonable time, by the actual application of all of
the water to the use designed, or to some other useful purpose"
The concept of priority can be summarized as follows: he who first ap-
propriates a certain amount of water from a natural stream has the right
to the use of the water to the full amount of his appropriation, so long as
S it is applied, without waste; to some beneficial use or purpose, and to the
exclusion of all others where they interfere with his right.
The two concepts taken together form the "water right" which, in all
As appropriation states, is given the dignity of a property right, unlawful inter-
ference with which is prohibited by the due process clauses of the federal
and state constitutions." In addition, the combined principles of right of
use and priority are specifically protected by constitutional provisions in
some western states.'8
4 The riparian doctrine, from the common law of England announced that the
r of land adjoining a water course had a usufructuary right to enjoy the waters
slieir natural channel undiminished in quantity and unimpaired in quality. See
generally I KINNEY, IRRIGATION AND WATER RIGHTS (2nd ed), Ch. 21, at 759.
15 KINNEY, supra; see also 5 WATERS AND WATER RIGHTS, supra, 401.2(B)
Legislative Trends in the California Doctrine States, and I WATERS AND WATER
RIGHTS, supra, 28.4(A) "Restrictions on Riparianism."
16 2 KINNEY, supra, at 1216.
1 See cases cited in 2 KINNEY, supra, 768. He refers to a water right as
"property of the highest order."
18 As an example, Colorado has two constitutional provisions, both in Article
Section 5. The water of every natural stream, not heretofore appropriated, within
the stale of Colorado, is hereby declared to be the property of the public, and
the same is dedicated to the use of the people of the state, subject to appropria-
tion as hereinafter provided.
Section 6. The c t to divert the unappropriated waters of any natural stream
to beneficial u. t all never be denied. Priority of appropriation shall give the
better right as between those using the water f6o the same purpose; but when the
M-I MI __ ^
Weather modification techniques to augment natural precipitation are
useful only in those basins where there is much demand for water, and
where the dependable flows of the natural streams have been appropriated
by others. If sufficient dependable flow remains after all prior appropriators
have been satisfied in their water requirements, then there is still water
available for the taking, and it is unnecessary and economically foolish to
go to the expense of augmenting the natural supply. The converse, of course,
is true when there is no unappropriated water available, or when an addi-
tional firm supply would make feasible an otherwise marginal project. But
when weather modification techniques cause additional rain or snow to fall,
does not the induced precipitation ultimately become a part of the natural
stream, and subject to being taken by the existing appropriators, in ac-
cordance with the statutes, constitutions, and cases? The answer is: not
necessarily. Just as all concepts of propriety and equity have protected the
senior appropriator in regard to the natural flow of the streams, so have
the same considerations of fairness and equity developed, within the appro-
priation doctrine, the precedent that he, who by his efforts has increased
the flow in the natural stream, has the right to the benefit of such increase
as against all others, including prior appropriators from that stream.
The waters which constitute this increased flow have been variously
termed "salvaged", "artificial" and "developed" waters; and the terms are
often erroneously intermixed, especially in the older cases and texts. For
example, Kinney's classic treatise considers the terms "developed" and
"artificial" as synonomous; and he defines those waters as: "such subter-
ranean or underground water as is discovered and brought to the surface
by the exploitations of man, and which would otherwise run to waste."19
At the time of his writing the interrelationship of ground water and surface
flows was not understood to the same extent as today. We know now that
most of the waters under the surface are, in fact, ultimately tributary to the
natural streams. But, even so, there are some underground waters which
would be lost to beneficial use but for the efforts of man. Thus, in Colorado,
one who drained a mine whose waters theretofore formed no part of the
stream's natural flow is granted a decree affirming his right to the exclusive
use of the waters so developed.20 Similarly treated are waters historically
trapped in an independent formation of impervious shale.21 This rule ap-
waters of any natural stream are not sufficient for the service of all those
desiring the use of the same, those using the water for domestic purposes shall
have the preference over those claiming for any other purpose, and those using
the water for agricultural purposes shall have preference over those using the
same for manufacturing purposes."
9 2 KINNEY, supra, 1205.
20 Ripley v. Park Creek Central Land and Water Company, 40 Colo. 129, 90 P.
21 Pikes Peak v. Kuiper, 169 Colo. 309, 455 P.2d 882 (1969).
WEATHER: THE RIGHT OF CAPl`UR 643
WEATHER: THE RIGHT OF CAPTURE 645
644 NATURAL RESOURCES LAWYER VOL VIII, NO. 4
pears to have full acceptance in all of the western states. But where the
Colorado courts, and the courts of Utah,2 Montana," California,24 and
Oregon" were careful to limit the rule to a truly independent source of
supply (based upon the technology then available), other courts tended to
confuse waters which were truly new waters with those which were, in fact,
the waters of the natural stream but which were salvaged from loss by
evaporation, seepage, and non-beneficial plant growth. Thus in Idaho, the
water saved from such losses by the straightening of the river channel and
the removal of obstructions was decreed to the one who did that work."
In New Mexico, water in a ditch constructed to drain seepy lands was held
to belong to the ditch constructor.2 In both of these examples it is clear
I the waters were not really independent of the natural river flows; and
oe suspects that the courts became confused because of the tendency to
consider the terms "salvaged" and "developed" as interchangeable. Our
Discussion will be clarified if we define our terms. "Artificial" waters is a
S- misnomer and the use of the term should be discontinued. "Developed"
i waters are "new waters not previously part of the water system.""2 "Sal-
Svaged" waters are waters which form 4 supply of a river system, which
Ordinarily would go to waste, but somehow are made available for bene-
ficial use.29 The former are free from river calls, and not junior to prior
Decrees; while the latter are (or should be) subject to call by prior appro-
t If water induced from the clouds is in fact "new water not previously
_ part of the river system" it is clearly developed water." As such it is avail-
22 Mountain Lake Mining Co. v. Midway Irrigation Co., 47 Utah 346, 149 P.
( 23 State v. District Court, 56 Mont. 578, 185 P. 1112 (1919).
C 24 Vernon Irrigation Co. v. Los Angeles, 106 Cal. 237, 39 P. 762 (1895).
5s Jones v. Warm Springs Irrigation Dist., 162 Ore. 186, 91 P.2d 452 (1939).
26 Reno v. Richard, 32 Idaho 11, 78 P. 81 (1918).
27 Hagerman Irrigation Co. v. East Grand Plains Irrigation Dist., 75 N.M. 649,
187 P. 555 (1920).
28 Southeastern Colorado Water Conservancy District v. Shelton Farms, and
Southeastern Colorado Water Conservancy District v. Colorado-New Mexico Land
Co., Colorado Supreme Court #26420 and 26432 (1974) reported at 416, "The Colo-
rado Lawyer" (Colo. S. Ct. Advance Sheets).
2 Id. Foreign Water in Colorado, 42 DENVER L.J. 116-20.
so Southeastern Colorado Water Conservancy District v. Shelton Farms, and
Southeastern Colorado Water Conservancy District v. Colorado-New Mexico Land
Co., siipra: also see discussion in Colorado Water Law, 47 DENVER L.J. 356-57, and
2 WATERS AND WATER RIGHTS, supra, I 52.3(D).
n1 One type of developed water is so-called "foreign" water which is "new" or
developedd" water because it is imported from one watershed into another. Induced
precipitation certainly bears a resemblance to this type of developed water, but it is
not necessary to sep rely define it because the rules concerning "foreign developed
water" are- samf(l for "developed" water in general, whatever its source. See
note 32, inj1 *'
able to the developer without regard to the rights of other appropriators on
the stream. He may use it directly or he may store it for later use; and he
may use it for beneficial uses within or outside of the basin of capture."3
That the induced moisture should fall to the earth with other rain or snow,
or should become co-mingled with other droplets on the ground or under
it, or flow with other waters in the streams, is of no consequence. We are
concerned with volume and time, and not with particular particles of
THE QUESTIONS OF PROOF
Hath the rain a father, or who hath
begotten the drops of dew?3'
The burden of proof is on the developer to clearly show that the water he
is claiming is, in fact, developed water which would not naturally be other-
wise available.35 It is a heavy burden and a proper one. Decades of effort
and much treasure have been-expended by present appropriators to create
farms, ranches, factories, businesses, and cities which are absolutely de-
pendent upon a recognition of their appropriative water rights. The Courts
will be vigilant in protecting them against unfounded and avaricious claims.
Thus, when the developer seeks judicial blessings of his efforts he must
expect to answer questions such as these:
1) How do we know that the increased snowfall which you claim would
not have occurred naturally, and absent your efforts?
2) Even assuming that increased snowfall did occur, how can you
demonstrate that the induced snowfall was as great as you claim?
3) Assuming the snowfall depths are as you claim, how do we know
how much water from the increased snowfall will flow into the streams and
be available for diversion, as opposed to being evaporated, or lost by tran-
spiration, or become part of the groundwater which may not surface for
months or even years?
`12 For general discussions and cases see: WATERS AND WATER RIGHTS. supra.
52.3(C); 2 KINNEY, supra, 866; Hickey. Foreign Water In Colorado, 42 DENVER
LJ. 116 (1965); Trelease, Reclamation Water Rights, 32 RocKY MT. L. REV. 464
.3 This is the universal rule in regard to developed waters, even though-there is
no case directly dealing with development through weather modification. As examples
of the general rule. see 2 KINNEY, supra 798 and 866; United States v. Haga, 276
Fed 41 (S.D. Idaho 1921). Miller v. Wheeler. 54 Wash 429, 109 P. 641; City of Los
Angeles v. City of Glendale. 23 Cal. 2d 68, 142 P.2d 289 (1943); and as an example
not only of the use, but the re-use of such waters, see Denver v. Fulton Irrigation
Ditch Co., 179 Colo 47, 506 P.2d 144 (1972).
34 Job 38:28.
s3 2 KINNEY, supra 658.
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646 NATURAL RESOURCES LAWYER VOL. VIII, NO. 4'
4) How do we know that the water which does ultimately reach the
stream is available in time and amount for the proposed diversion or im-
At least tentative answers to these questions can be offered through
statistical analysis and experimentation, but a pre-requisite to understand-
ing of either the statistics or the experiments is a general understanding of
the weather modification techniques which are likely to form the basis of a
claim to water.
Research has shown considerable promise in the seeding of cumulus and
orographic clouds. The first experiments concentrated on cumulus clouds,
as they are the most common, the most widely distributed, and are the
( st important source of the world's rainfall. While there seems to be
I doubt but that precipitation from such clouds can be induced, the
clouds themselves are so unstable, and subject to such rapid internal,.physi-
cal changes that considerable difficulty has been found in seeding under
optimum conditions. These difficulties have raised serious questions about
Sthe acceptability of statistical results concerning them.36 The least that can
, be said is that from the standpoint of proof of measurable increased pre-
cipitation, they are hard clouds to work with. Since the results of orographic
Cloud seeding are apparently more easily defendable, we will concentrate
Sour inquiry on those clouds, not intending to imply other than that as the
state of the art improves the results we discuss might be equally applicable
Sto cumulus clouds.
S Orographic clouds are clouds which are formed when the wind drives
Smoist air against rising terrain, as in the mountains of the West. As the
Smoist air rises, it cools, forming clouds. The cloud layer consists of small,
Ssupercooled droplets, which remain in the form of water even though they
--e below the freezing point. At temperatures colder than 40F., (-20C.)
( upercooled droplets will begin to form ice crystals around small parti-
such as dust. The more such particles, or nuclei, the more ice crystals
will form. Once the crystals begin to form around their nuclei, they attract
nearby water vapors and droplets, and the ice particles become larger and
larger until they fall as show. Silver iodide particles are introduced into the
cloud, by ground based generators, or by airplanes. They constitute
"nuclei," just as the small particles of dust do;. and in addition, it has been
found that silver iodide particles result in the formation of ice crystals at
temperatures considerably warmer than -4.
While orographic clouds can produce either rain or snow, the critical
temperatures needed for the silver iodide to work its magic are such that
snow is the most likely result. For the remainder of this discussion we will,
i sSee, eg., "Weatl .and Climate Modification." the report of the Committee
on Atmospheric ScientM National Research Council, published by the National
Academy of nces (r ). at 72.
therefore, assume that the precipitation occurs in the form of snow. Seed-
ing experiments with orographic clouds indicate that:
1. The increase in precipitation results from having the clouds snow
longer, rather than harder.
2. Snowfall is significantly increased at least at elevations above 9,000
3. The increased precipitation from seeding is generally in the neighbor-
hood of 10-30% and this increase, by percentage, does not vary between
wet or dry years.37 (This was the indication in experiments conducted in
Colorado, but whether or not similar results would be found in other areas
has not been fully investigated.)
But while it is conceded that there is an increase in snowfall, we still
have not resolved the problems or more exact proof of the amount; nor
does it follow that the waters contained in the increased snowfall are later
available in the stream at the time that the developer wants to divert them.
Statistical analysis and simulation techniques can aid in providing the
answers to these questions. The two approaches are interrelated, but we
will consider them separately for purposes of clarity of technique.
Statistics is a mathematical tool which, by analysis of random events,
leads to conclusion as to what will probably occur in the future. These
areas, carefully selected, are seeded at random and the results of seeding
compared with natural events. Formulas are constructed based upon the
gathered information, or statistics, which enable predictions as to the re-
sults of future seeding efforts.
The difficulty with the conclusions, from a legal point of view, is 1) at
best the results show the incidence of probability of the result, rather than
the fact of the result, and 2) the validity of the probability of result is de-
pendent entirely upon the validity of the assumed hypotheses.
Thus, we probably cannot "prove," from a statistical analysis, the ex-
tent of the increased precipitation. All we can do is to predict it within
certain degrees of error. Even increasing our margin of error may not be
satisfactory, for our result, though more and more likely, is never proved.
It remains a probability, but not a fact.
A simulation or model approach to evaluation of weather modification
is, like the statistical approach, mathematical in form. But where statistics
is a universal science based upon the logic of probability, the model at-
tempts to imitate nature. Many models are physical. Most are aware that
many studies have been made of major river systems by constructing
laboratory models to scale. These have been extremely helpful in determin-
ing the effect of various flows on, say, the Missouri or the Mississippi
Rivers. Models of airplanes have been subjected to study in wind tunnels
3 WEISBECKER SNOWPACK, CLOUD-SEEDING, AND THE COLORADO R 17,
(U. Oklahoma Press, 1974); Weather and Climate Modification, supra,
-1 K -
WEATHER: THE RIGHTOF CAPTRE 647
648 NATURAL RESOURCES LAWYER VOL. VIII, NO. 4
to accurately predict the behavior of the real airplane in flight. Models of
buildings can allow the study of stresses.
Models may be abstract, as well as physical; they may represent the
physical by symbols. 'The symbols selected are generally mathematic in
form, and a mathematical model is simply a description of 'the physical
system which it represents.
The purpose to be served by any model, whether physical or abstract, is
to understand the phenomenon or system under study without actually ob-
serving the system itself. It is a method by which the effect of many things
can be understood, without the necessity of physically observing all of
Them. The popularity of abstract models substantially increased with the
availability of high speed digital computers, which removed the labor of
:~ V station and allowed efforts to be concentrated into making the model
as.,ifect as possible.
Knowing the physical processes in weather modification, from the point
of the seeding of the clouds to the diversion or impoundment of the run-
off, a mathematical model of the process can be constructed to simulate
the process. The construction of any model presupposes a considerable
ability, for invalid premises assure invalidity of result-"garbage in, garbage
out," as they say. But here the simulation technique has the advantage of
Sallowing the interjection of experience. That is to say, a properly con-
structed model should not be taken, in the first instance, to show a neces-
sarily accurate result. It will show a result with precision, as opposed to
accuracy. When a result is compared, however, with the known and ob-
servable physical facts, and is found to disagree with them, the hypothesis
can be adjusted, tested again, and readjusted until the final result corre-
lates accurately, as well as with precision, with the true facts. While the
model never reaches the point where subjective opinions are replaced en-
Sirely by objective facts, the objective control, when coupled with highly
p i'sional subjective input, results in a conclusion which demonstrates
an n curacy far beyond that of the "probabilities" realized from a purely
SThe model which we seek would encompass all factors influencing the
Precipitation from its discharge from the clouds through its diversion by the
Sclaimant. There is no such present model. There are, however, sub-models
which divide the problem into logical components; and there is no reason
why our master model cannot be composed of parts. In fact, the smaller
the model, at least in the development stages, the easier to understand it,
and to modify it as experience and observation dictate.
Since the-first step in augmenting the water supply is to increase the pre-
Scipitation, it is nc(iexpected that models of this phenomenon were
among the first to be extensively tested. The Colorado State University
model is considered to be the best available, having been tested rather
severely in experiments in Colorado's Rocky Mountains and elsewhere.38
This empirical model, based in large part upon a discovered correlation
between cloud top temperatures and seeding results, was designated to pre-
dict the amount of additional precipitation which seeding would produce.
The experimenters recognize that since nature is uncertain, it is to that
extent unpredictable, even under the best analysis. This is recognized by
statisticians in their concepts of standard deviations; and it is recognized
in regard to the model. Thus, if the user of the model is called to testify in
regard to a claim for the developed water, he may say:
I believe that the precipitation induced by the claimant in this case is
equal to 15%- of the total snowfall; but I acknowledge that my belief may
not be entirely accurate for the winter of 1975. However, I am confident,
to 99% accuracy, that the induced snowfall was at least 5% of the total.
This testimony, if adequately supported, should be sufficient to allow a
judicial determination that 5% of the snow was induced by the applicant,
constitutes.developed water, and is available for appropriation by the appli-
cant if he can trace it.
Having determined that a certain percentage of the snowfall in a particular
basin, for a particular winter, is induced precipitation, we face next the
problem of tracing that snowfall. Watershed or run-off models have been
conceived and can serve as an example of the type of data which must be
considered in constructing a model for the particular watershed. Consider-
ations, based upon the best available engineering knowledge, will have to
be given to such diversefactors as evaporation, transpiration, soil condi-
tions, including perosity of the soil, impervious areas, infiltration, existing
ground waters, soil moisture, the characteristics of flows, and the like.
These in turn will be based upon considerations of foliage, terrain, climate,
etc. Without even exhausting the list of considerations, we can readily
conclude that any model which realistically imitates nature will be a com-
plicated one, with many interrelated concepts requiring attention, and, no
doubt, with variations from year to year.
Run-off models have had a relatively long history of development and
their concepts are probably generally accepted within the field of practice.
But both the Colorado State University model and run-off models would
probably have to be adapted to a given area, and verified and modified,
8s National Academy of Sciences, Weather and Climate Modification. lems
' and Progress, (1973); WEISBECKER, SNOWPACK, CLOUD-SEEDING, AND THE RADIO
C IVE (U. of Okla. Pres=, 1974).
WEATHER: THE RIGHT OF CAPTURE 649
650 NATURAL RESOURCES LAWYER VOL. VIII, NO. 4
before an expert witness could confidently assert the extent and timing of
the waters from induced and melted snow within that area.
On the one hand, as we have seen, courts have generally adopted the
realistic view that if water development is to be encouraged, those who are
engaged in such development must be given some assurance that they will
profit from their endeavors. Further, the courts are realistic, and will ap-
preciate that we are dealing with some concepts which are difficult to
measure. On the other hand, the courts will not enthusiastically issue de-
crees which are based upon probabilities, or averages, but will place the
burden on the developed to prove that he did increase the water in the
basin, and that he can take it out without injury to vested rights.
_he proof must necessarily be in the nature of expert opinion, buttressed
Siodels and statistics. If we can avoid saying that the facts themselves
are nebulous, we are still left with the feeling that they are uncertain. We
search for escape from the rule that:
The facts on which an expert opinion is based must permit of reasonably
certain deductions, as distinguished from mere conjectures."9
S Also to be avoided, taking the long view, is any temptation to assert as
absolute that which is tentative, or as fact that which is unverified opinion.
No rule of law prohibits an expert from making foolish or unwarranted
statements, and it is even conceivable that a decree based on them may
be obtained. But if experience shows the facts to be otherwise than as
asserted, not only will the witness be embarrassed, but indeed, the whole
science will be discredited. It will then be at least a difficult task, if not an
t., impossible one, to gain the courts' recognition of these scientific methods
even after they have proved to be extremely accurate, and otherwise uni-
,With these general considerations in mind, perhaps we can suggest some
4/ers to the questions we are probing, and, to the extent that a definitive
answer remains hidden, some initiatives that might sufficiently reveal them.
First, it can be said that the state of the art in regard to precipitation
predictions is such that the meteorologist can prove to an extremely high
degree of accuracy some minimum development of water.
Second, it appears that a competent hydrologist-meteorologist-statistician
could equally conclusively predict the resulting run-off. That is, there ap-
pears to be a high correlation between predicted and actual run-offs in
S certain months of each year; but it is doubtful that these tentative conclu-
sions would be generally accepted as final, or as other than an encouraging
step in the development of the truth, and the proof of it. To avoid pre-
mature and, ultimately, self-defeating assertions, it would be extremely
wise th-t the technique be first demonstrably perfected.
3* 9 31 A 'JR. 2d "Expert and Opinion Evidence" 20, at 515.
Third, in regard to both models, there is an additional advantage that
might be expected to result from further experimentation and model modi-
fication. Present margins of possible error must be recognized, and the
present result may be that, all error removed, the amount of water that may
be confidently claimed is so small as to make its development uneconom-
ical, or at least substantially less economical.
The conclusion to which this study is forced, therefore, is that precipita-
tion and run-off models should be constructed for the particular basin in
which developed waters is to be sought; that the models should be care-
fully and extensively tested against actual experience, and modified to con-
form with it; that a description of the improved models and the results of
the experiments be widely circulated within the scientific community; and
that this be repeated until there is general recognition within that com-
munity of the validity of their predictions (as seems to be the result of the
Colorado State University "Climax" experiments),40 and that thereafter,
but not before, a claim be made for the developed water. The result should
be sound, scientific opinions, fully demonstrable, and fully supported.
Upon such evidence the courts can base their decrees with assurance that
prior appropriators are not harmed.
If we have-not quite reached this point, there is every indication that we
are about to do so; and perhaps science, like the law, "never is, but is al-
ways about to be."1
COMPLICATIONS, LIMITATIONS AND OPPORTUNITIES
Not the origin but the goal is the main things'
Those who wish to develop water must take note not only of applicable
state law, but must also consider the effect of interstate compacts, treaties
with foreign nations, and decisions of the United States Supreme Court
allocating available water between states upon an equitable basis. As il-
lustrative of the potential effect of these documents or decisions, the state
of Colorado may be examined. Colorado encompasses the headwaters of
some of the great rivers of the West: the Colorado, the Platte (North and
South), the Arkansas, the Rio Grande. Because of this, no state is more
enmeshed in restrictions inherent in compacts, treaties and judicial decrees.
Their effect on the water rights of Coloradoans, including their rights under
weather modification programs, will be typical of the effect upon the resi-
dents of other states; although, of course, each treaty, compact or court
40 Weather and Climate Modification, Problems and Progress, supra.
41 B. CARDOZO, THE NATURE OF THE JUDICIAL PROCESS 126.
4 Id., at 102.
--------------~"-----"II~---`~~`~~~~~-- X~"I~.~~~-~~~lll-~`~I~--~I~-^~ ~111~~I
WEATHER: THE RIGHT OF CAPTURE 651
652 NATURAL RESOURCES LAWYER VOL. VIII, NO. 4
decision must be carefully examined as to rights or obligations of each
Interstate Compact aid Treaties
Compacts between states are authorized by the United States Constitu-
A compact, while having the attributes of a contract, arises to a dignity
greater than that of a mere agreement. It operates "with the same effect as
a treaty between sovereign powers;"" A valid compact effectively super-
sedes state constitutional provisions allowing uninhibited appropriation of
S Colorado is a party to the following river compacts: Colorado River
Cr-.act,"' LaPlata River Compact," South Platte River Compact," Rio
A~l de River Compact,49 Republican River Compact,50 Costilla Creek
Compact,5' Upper Colorado River Compact,52 Arkansas River Compact,"
S Animas-LaPlata Project Compact." In addition to the interstate compacts,
Colorado is also effected by the terms of the treaty between the United
States and Mexico."
A. The Colorado River Compact and the Mexican Treaty, and their
related compacts, deal with the waters of the Colorado River. The Compact
requires that the upper basin states, including Colorado, will "not cause
the flow of the river at Lee Ferry to be depleated below an aggregate of
75,000,000 acre feet for any period of 10 consecutive years."'8 The divi-
Ssion of the retained water by the upper basin states is governed by the
Upper Colorado River Compact, by the terms of which Colorado is en-
titled to a percentage of the total flow."
S 3a US. Const. art. I, 10;
44 Rhode Island v. Massachusetts, 37 U.S. (12 Pet.) 88.
r", State v. Simms, 341 U.S. 22 (1951), Teddy v. Tennessee-Missouri Bridge
Cl.i., 359 U.S. 275 (1959); Hinderlider v. LaPlata River and Cherry Creek Ditch
Co., 304 U.S. 92 (1938); see also discussion in Fischer, Management of Interstate
Groundwater, 7 NATURAL RESOURCES LAW., 534-37 (1974).
.4C.RS. 37-61-101 (1973).
47 Id., 37-63-101.
4 Id., 37-65-101.
49 Id., 37-66-101.
51 Id., 37-68-107.
2 Id., 37-62-101.
35 Id., 37-69-107.
54 Id., 37-64-101.
5s Mexican Treaty on Rio Grande, Tijuana and Colorado Rivers, Treaty series
6 Art. llI(d), note 44, supra.
".The flow to wbhch Colorado is entitled is computed after the delivery of
50,000 acre feet of wal .. Arizona, which is the joint obligation of all of the upper
"-basin states. Art. IIl, I '-note 42, supra.
The Animas-LaPlata Project Compact, the Upper Colorado River Com-
pact, and the LaPlata River Compact concern themselves with tributaries
of the Colorado, and the water to which Coloradoans are entitled by their
terms is considered a part of Colorado's share of the Colorado River.
But the Republic of Mexico must also be satisfied from the Colorado
River, and the Mexican Treaty requires that 1,500,000 acre feet of water
be delivered each year to Mexico from the Colorado River.58 Further, the
Colorado River Basin Project Act of 1968 declared that the Mexican Treaty
obligations were national obligations."
Between the Compacts and the Treaty, it is apparent that there is no
guarantee that any additionally induced precipitation will not flow to the
benefit of the lower basin states, or to Mexico. Whether or not there is
sufficient water in the Colorado River under existing conditions to supply
all Compact and Treaty obligations has been bitterly debated, and it is not
appropriate that we now enter into this controversy. It is sufficient to say
that any weather modification program which proceeded on the assumption
of uncontested use of the produced water would be foolhardy. Further-
more, if weather modification would indeed produce surplus water, the
upper basin compact would appear to require that only 51.75% of the
water be retained in Colorado, the remaining being allocated to the other
upper basin states."
B. The Rio Grande River Compact requires Colorado, with certain ex-
ceptions, to deliver 10,000 acre feet of water to the New Mexico state
line.61 Colorado did not fully comply with the compact, causing Texas and
New Mexico to bring suit in 1966 to enforce the compact. Litigation has
been stayed while Colorado delivers water to reduce its deficit, which has
been accomplished by the curtailment of diversions in Colorado, the im-
provement of drainage systems, and the controlling of the extraction of
ground water in Colorado."6
For the short term at least it would appear that any increase in runoff
within the Rio Grande basin in Colorado, will not accrue to the benefit of
the developer, but will rather assist Colorado in reducing its accrued deficit.
Once this has been accomplished, perhaps newly induced precipitation will
be subject to capture by Coloradoans.
C. The Costilla Creek Compact deals with a tributary of the Rio Grande,
arising in Colorado, and crossing the Colorado-New Mexico boundary
three times before its confluence with the Rio Grande in New Mexico."
8s Mexican Treaty, supra.
43 U.S.C.A. 1 1512.
so Art. III note 50, supra.
e1 Arts. III and IV, note 47, supra.
62 Munz, Water Deliveries Under the Rio Grande Compact, 13 NA u.L RI-
soURCES Law. 201-5.
*3 Art. II, note 49, supra.
- 1~. i n.
WEATHER: THE RIGHT OF CAPTURE 653
654 NATURAL RESOURCES LAWYER VOL. VIII, NO. 4
WEATHER: THE RIGHT OF CAPTURE 655
The division of water between the two states is complicated, but the im-
portant provision for our purposes is that, to the extent there is surplus
water, one-half is to go to New Mexico and one-half to Colorado."
D. The Republican River Compact, divides among the states of Col-
orado, Kansas and Nebraska, the "virgin water supply" of the Republican
River basin. The "virgin water supply" is defined as "the water supply
within the basin undepleted by the activities of man."e" While, as we have
seen, the water produced from weather modification techniques would not
ordinarily be thought to be part of the virgin water supply, yet this defini-
tion does not include it. If the definition is literally construed, additional
waters would be allocated among the participating states."
S The Arkansas River Compact, between Kansas and Colorado, is
.:r complex and unusual. John Martin Reservoir, located on the Arkan-
sas in Colorado, is utilized to store and release water; and Colorado appro-
priators may or may not divert under their decreed priorities depending
upon a variety of circumstances. At tiles, therefore, excess waters would
be useful to Colorado water users; and at other times they would accrue to
the benefit of water users in Kansas. The waters which are divided between
the two states include "waters originating'in the natural drainage basin of
the Arkansas River, including its tributaries," but excludes "waters brought
into the Arkansas River basin from other river basins."'7 As in certain
other compacts, there remains a question of whether water produced from
weather modification projects would or would not be such "waters of the
F. The South Platte River Compact requires Colorado, with certain
exceptions, to deliver 120 cubic feet of water per second of time to Ne-
braska, between the Ist day of April and the 15th day of October of each
year."8 With the exception of this summer irrigation season, Colorado has
. full and uninterrupted use of the waters flowing within its boundaries.
hOrado has complied with the Compact, hence any additional water
created in the Platte River basin would inure to the benefit of the water
users of Colorado.
In addition to interstate compacts and treaties, a Colorado developer must
consider the effect of decisions of the United States Supreme Court, exer-
cising its original jurisdiction"" in interstate disputes.
64 Id., Art. IV.
Art. IL. note 48, supra.
i d.. Art. III.
e; Art. Ill (B), noe 51, supra.
S Art. IV, note pra.
U .S. st. arf 2.
Equitable apportionment is a doctrine of federal common law which
found its first full expression in Kansas v. Colorado.'o It established firmly
the principal that, in the exercise of the supreme judicial power of the
United States, the Supreme Court should and could resolve conflicts be-
tween sovereign states as to the use of water of interstate rivers. As it said:
Surely here is a dispute of justiciable nature which ought to be tried and
determined. If the two states were absolutely independent nations it would
be settled by treaty or by force. Neither of these ways being practical, it
must be settled by decision of this court.71
Although the dispute between Kansas and Colorado in regard to the flow
of the Arkansas River was ultimately resolved by Compact, rather than
judicial decree, the firm precedent established in that case was utilized by
the Court to equitably apportion two interstate streams as between Colo-
rado and downstream states.
A. The Laramie River, a tributary of the North Platte, arises in Colo-
rado and flows north into Wyoming.
The Supreme Court was called upon to resolve the controversy between
Wyoming and Colorado irrigators.72 The main portion of the case was
concerned with Colorado's request to be allowed to transport waters out
of the Laramie River Basin by means of a transmountain diversion system
known as the Laramie-Poudre Tunnel. The decree allows the continued
use of the tunnel but limits diversions through it to 15,500 acre feet per
year. It would appear that the development of additional water by means
of weather modification techniques, and the use of that water under Col-
orado law by the developer thereof, would not be in conflict with any pro-
vision of the decree in Wyoming v. Colorado, provided that the tunnel was
B. The North Platte River arises in North Park, Colorado, runs north
into Wyoming and thence east into Nebraska. Litigation was originally
commenced by the state of Nebraska against the state of Wyoming, seek-
ing an equitable apportionment of the waters of the North Platte as be-
To 206 US. 46, 27 S. Ct. 655 (1907).
71 Id., 27 S. Ct., at 668.
It is interesting to note that while the court's opinion in this case furnished a
firm precedent for later equitable apportionment cases, Kansas was singularly
unsuccessful in obtaining judicial relief. In the original case the suit of Kansas
was dismissed "without prejudice to the right of the plaintiff to institute new
proceedings whenever it shall appear that, through a material increase in the
depletion of the waters of the Arkansas River by Colorado, its corporations or
citizens, the substantial interest of Kansas are being injured to the extent of
destroying the equitable apportionment of benefits between the two states re-
sulting from the flow of the river." Kansas accepted the invitation, but even in
a later case could not show circumstances required to justify to suitable
apportionment. 320 US. 383 (1943).
72 Wyoming v. Colorado, 259 US. 419, 42 S. Ct. 522 (1922
656 NATURAL RESOURCES LAWYER VOL. VIII, NO. 4
tween those two states. Wyoming joined Colorado as a party in order to
obtain an adjudication that affected the whole, rather than a part of the
river. The decree apportioned the water between the three states."' In re-
gard to Colorado, its rights were given and limited by its being enjoined (1)
from irrigating by diversions more than 145,000 acres in North Park, (2)
from storing more than 17,000 acre feet of water each year, and (3) from
allowing the exportation out of the basin of more than 60,000 acre feet of
water in any period of ten consecutive years.
An increased supply of water could be utilized within Colorado so long
as the limitations of this decree were not exceeded.74
C judicial decrees do not necessarily pose problems for the developer;
the compacts and treaties do. Many of the compacts contain language
attempting to limit their applicability to the natural, undeveloped waters
of the basin. But weather modification was not envisioned, and it is not at
all clear that the waters thereby developed are not fully subject to compact
S divisions. Further, in some instances,' it is quite clear that increases in the
water supply will clearly benefit residents of other states. Thus, with the
exception of the Platte River Compact, where an increase in water supply
F would clearly accrue to the Colorado water users, it is apparent that the
S many benefits to be derived from weather modification projects on the
other major streams originating in the Colorado mountains could be prac-.
tically.accomplished only by a joint effort of the affected states, or by the
United" States with the consent and cooperation of the affected states. Any
other course is too risky, entailing a maximum of economic risk with a
minimum guarantee of return, and a strong likelihood of expensive and
--olonged litigation for the establishment of relative rights. While this
Snplicates matters, it would be unfortunate if it prohibited continued in-
.,igation and development of this water source; for the potential ad-
vantages which could accrue through a cooperative effort between the
states and the United States are enormous. Let us take the Colorado River
"7 Opinion reported at 325 U.S. 49, 65 S. Ct. 28 (1945); the decree at 325 U.S.
665, 66 S. Ct. (1945); modified decree (by stipulation) 345 U.S. 981, 73 S. Ct. 1041
74 The limitations have not been exceeded. An examination by the writer of the
records of the State Engineer's Office discloses that for the period October 1, 1970,
to September 30, 1971, 120,015 acred of land were irrigated in North Park; 11,774
acre feet of water were stored; and no water was that year exported from Jackson
County. There are, however, two diversion structures capable of diverting water from
Jackson County into the Cache La Poudre Basin, both of which had previously and
have subsequently been used. In the past, diversions from Jackson County have varied
between no acre feet per/ |r to over 7,000 acre feet per year.
C ^ ^ _
as an example. It has been estimated that the increased water supply
which could reasonably be expected to be developed in the Colorado River
basin through weather modification programs would equal the United
States' commitments to Mexico under the treaty.1" The natural flow waters
of equal amount are then useable within the Union, not to the benefit of a
single developer, but certainly to the advantage of the citizens of all of the
affected states. Further, by this joint effort we circumvent some serious
problems. We have said that even though there is wide scientific accept-
ance of the fact that weather modification programs do increase precipita-
tion and run-off, it will be difficult to present satisfactory proof of the
exact amount and timing of the resulting run-off so as to allow recapture.
But if the increased water supply is of general use to all of the states within
the basin, and for this reason useful even though the time and amount is
not precisely known, then these questions are largely avoided. Whatever it
is, and whenever it comes, it is of benefit to somebody (assuming sufficient
Finally, let us note that the concepts of general benefits can be applicable
in some instances to a single state, or, more precisely, to a portion of a
single state. We have observed, for example, that an increase in the flow
of the South Platte River would be to the direct and sole advantage of
Colorado water users. There are certainly many streams in the western
states where the increased precipitation and run-off would be of similar
direct help to the residents of that state, or a portion of them. The legisla-
ture of the state of Utah was sufficiently convinced of this fact that it has
prohibited anyone other than thp state's own division of water resources
from engaging in "cloud seeding" research or implementation,76 and con-
siders all water derived to be a part of Utah's basic water supply."
While it can certainly be agreed that the waters so produced should be
considered public waters, subject to appropriation and use in the same
manner as the naturally flowing streams, yet there remains some prob-
lems, and the most predominant one is that of cost. Will the residents of
the state who live in an unaffected river basin willingly permit their tax
dollars to be used to directly aid others? Will the most senior and always
fully satisfied appropriators of even the affected basin enthusiastically pay
to improve the junior water rights?
Oregon may have suggested the solution. Its statutes allow the creation
of "Weather Modification Districts" in counties bordering the Columbia
River.'7 It is a fine concept, but its effectiveness is curtailed by its limita-
75 WEISBECKER, supra, note 36, at 54.
7e U.C.A. 73-15-3.
77 Supra, 73-15-4.
78 ORE. REV. STAT. 558,200 el seq.
_ I_ IC__II __ I__ I_ __11 -_ _1
WEATHER: THE RIGHT OF CAPTURE 657
658 NATURAL RESOURCES LAWYER VOL.VIII, NO.4
.. tions: 1) a district may be formed only within two counties,79 and 2) it is
financially supported only by a general ad valorem tax.80
To be most useful and practical, and politically acceptable, such a dis-
trict should encompass the entire affected area (which would seldom, if
ever, be represented by the artificial boundary of a county line), and it
should be supported by a tax or charge based primarily upon anticipated
benefits, and not uniform except among those of the same class. Such dis-
tricts could be expected to be well received. There are many examples of
inter-county districts with costs so imposed. Conservancy districts are per-
haps the most common; but the same principle'is found in almost all im-
provement districts, of which area sewer development and flood control
districts are examples.
It may be more difficult, and require greater expertise to properly allo-
Scate the benefits to be received by various classes of water users within a
i weather modification district than is usually the case with some of the more
common districts, but it is surely not impractical. In fact, the models which
we have discussed can be used for precisely this purpose; and it is probably
;: a reasonable prediction to suppose that their main function may well be
directed to this end.
Thus, within our range of opportiflities, we can foresee federal-state,
inter-state and intra-state cooperation. Such cooperation is not developed
without effort, and there will be-much political inertia to overcome. But
the goals are sufficiently worthy, and the end sufficiently clear as to make
the effort worthwhile.
T Supra, 558.210.
so Supra 558.340.
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