WSP06933

• File Number: 8272.500
• Description: Colorado River Basin Salinity Control - Colo Dept of Public Health - WQCC and WQCD
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 11/1/1989
• Author: WQCD
• Title: Colorado Nonpoint Assessment Report - November 1989
• Water Supply Pro - Doc Type: Report/Study

..

tN
Q
o
'I

y
,.

Boulder Creek joins St. Vrain Creek downstream of Longmont.

From Hygiene

Road, just west of Longmont, to the South Platte, St. Vrain Creek carries

\s-

significant levels of sediment and salinity. High levels of nutrients are

also present on this reach. The Longmont Soil Conservation district has

.,

identified streambank erosion along St. Vrain Creek and Lefthand Creek which

.~.
,

may be sources of these problems. The Platte Valley Soil Conservation

'::.~
~;'.;
A ;:0;\

district has also identified lower St. Vrain Creek for these problems as well

as urban runoff. North, South, and Middle St. Vrain Creek also have been

~;':"
;~~.:

noted for streambank erosion.

iH
v.
~

Downstream of the Metropolitan region, the South Platte River basin is an, area

of extensive agricultural production. Irrigated, non-irrigated agriculture,

,.'~';
',~',(;
....,
~~,,:!

and cattle production are dominant agricultural land uses in this region.

:?~
:)~9

Shallow groundwater aquifiersalong the South Platte River exhibit high

nitrate levels from Brighton downstream to Ft. Morgan. In many places the

,,~
}~~iJ
'~1:

water supply standard of lO mg/l of nitrate is exceeded in this reach. It is

~j
I"~

assumed that use of fertilizers in agricultural production is at least

partially responsible for this problem. An indepth study is needed to

l:'
'h~
'(;.1
.....IT

determine the source of these nitrates.

J1-j
~~
,.,

,,~~
~:;:,
"':}
[{:1

-69-

'-";~
>,
'..;!;

\'";..":

b