8250

• UCREFRP Catalog Number: 8250
• Author: Lamarra, V. A.
• Title: Longitudinal Variation in the Trophic Structure of the Upper Colorado River.
• USFW Year: 1999.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

There was a continual reduction in ortho-phosphate concentrations over the four time periods
with the highest concentration occurring in spring 1994 and the lowest in fall 1995. The
spring 1994 concentration was significantly higher than all three subsequent dates (Figure
10).
COLORADO RIVER COLORADO RIVER
Total Phosphorus Orthophosphorus
1 0.025
0.9 ................ ___ ';. ____ .__._ __

a0.8 0.02
...... ,. -

w0.7
c
...
_ p
.015
a0.8
d0.3 .._........_ _........ ............ _... 0 0.01 ...............
°.4
0
C
O

........ ........
..... 0.005
0.2 0
spring94 fall94 spring95 fall95 spring94 fall94 spring95 fall95
PERIOD PERIOD
COLORADO RIVER COLORADO RIVER
Turbidity Total Inorganic Nitrogen
100 0
4
.
so _.......... . 0.3

P 80 EO 2 ......... ._
e 2
f'
H
40 ___.. ... __...
0.1

___ ..... ....

_. _._ ?......._ __._ ......

20

spring94
WIN sfn 95 fall95 m 9 0
spring94
lell94 spring95 lall95
PERIOD PERIOD
Figure 10. The river-wide mean concentrations of nitrogen, phosphorus and total suspended solids for four time periods
in the Colorado River.
Turbidity, expressed as NTUs, had lower levels in spring 1994 and fall 1995 and highest
values in spring 1995. The fall of 1994 had intermediate levels of turbidity. The fall of 1994
and spring of 1995 turbidity values were significantly higher than the spring 1994 and fall
1994 levels.
COLORADO RIVER AT STATE LINE
Data obtained through the USGS WATER QUALITY
WATSTORE system for the Colorado 600 '°
........
River at the Colorado-Utah state line x500 25 (j
(USGS Station No. 09163500) for the ? °°° 20
r
entire study period can be seen in 0 300 " 10
Figure 11. These data show good 200 '° a
5
agreement with the grab samples ~'°° f . / ^-
o ° 0
collected during this study. 27- '-Kw 2-- '-
DATE
Furthermore, the data indicate
p TURBIDITY
TaNCEMTUaE /uaw) ? ITHni STUD
substantial sediment concentrations .rys¢sl _o-
(expressed as NTUs) of 450 occurring Figure 11. Water temperatures and turbidity values in the Colorado
River for 1994 and 1995 at the Colorado-Utah stateline (station
#09163500).
14