WSP00036

• File Number: 8200.750
• Description: San Juan River General
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 3/1/1975
• Author: BOR
• Title: San Juan Ecology Project - Interim Progress Report - March 1975
• Water Supply Pro - Doc Type: Report/Study

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

"

001572

1. INTRODUCTION

The San Juan Ecology Project was at the three-quarter
mark of its anticipated four-year life after the 1973
field season. As part of the Bureau of Reclamation's
Upper Colorado River Basin Pilot Project, it is expect-
ed to provide technical information on the likely
ecological consequences of increasing winter snowpack
in the San Juan Mountains of southwestern Colorado.
Its conclusions will hopefully play a part in the
decision making process pertaining to an operational
program of snow augmentation in the Upper Colorado
River Basin.

Tbis report contains the results of the third field
season's research, and is a sequel to three previolls
reports in this series. It presents the conclusions
of a number of cooperative projects which are attemp-
ting to establish valid relationships between snowpack
variation, plant and animal communities, and abiotic
processes or parameters.

Few changes were initiated in the past year. Most
projects have accumulated sufficient data to permit
at least partial modelling of the basic processes
involved, and it is anticipated that several models
will be available by the end of the project. These
include plant distribution relationships with snowpack,
alpine soil movement, tree moisture stress relations
with temperature and soil moisture, and silver distrib-
ution in surface soil. While complete quantification
of matter or energy flows could not be undertaken here,
the development of partial~process models will hope-
fully develop to the stage where they will be applic-
able in other areas.

4.'0,
'.

It should be stressed that no 'control' time or area
could be used in this study, that seeding commenced
concurrently with the ecological investigations and
that only a limited number of organisms were selected
for study. The rationale for these selections has ~.
been discussed in the three previous reports of the
project.

Two studies in the Forest Ecosystems terminate with
this report - the phytosociology and tree biomass
projects. The former is a benchmark study which
largely met its objectives in two field seasons, and
the latter used standard and tested methods which
permitted completion of objectives in three field
season.

Intensive study sites are located in three major
areas in the forest ecosystems network (sites 3,4 and
5, Fig i), and in two alpine basins on the Continental
Divide (sites 1 and 2, Fig i). Several projects,
such as the ecological overview, dendrology and
silver studies, are concerned with larger segments of
the original target area.

,
,

.
,
"
I
,
1
,
.'
.'
,.,
,
,
,
'.
.....~\.Q
0'
\
,,~_ _J
"co';TiH€.HTAL

,,;~.~

~~~
IIi'!1l \
~-,..

.,
Mil..

40

o

ALPINE SITES
1- Eloorado Lake
2 - William. Lake
FOREST SITES
3 - Missionary Ridge
4 - Wolf Creek
5 - Rico

~""
"-
"

Figure i. San Juan cloud seeding target area, intensive study area.

4

J. ~-:;;.