8222

• UCREFRP Catalog Number: 8222
• Author: U.S. Geological Survey.
• Title: Nitrogen and Phosphorus Data for Surface Water in the Upper Colorado River Basin, Colorado, 1980-94.
• USFW Year: 1997.
• USFW - Doc Type: 97-233,
• Copyright Material: NO

Nitrogen and Phosphorus Data for Surface Water in
the Upper Colorado River Basin, Colorado, 1980-94

By Kirby H. Wynn and Norman E. Spahr

Abstract

This report documents, summarizes, and
provides on 3.5-in. diskette the surface-water
data collected from January 1980 through
August 1994 for nitrogen and phosphorus in the
Upper Colorado River Basin from the Colorado-
Utah State line to the Continental Divide.
Ancillary data for parameters, such as water
temperature, streamflow, specific conductance,
dissolved oxygen, pH, and alkalinity, also are
compiled, if available. Data were retrieved from
the U.S. Geological Survey National Water
Information System and the U.S. Environmental
Protection Agency STORET (STOrage and
RETrieval) system. The water-quality data are
presented for sites having five or more nutrient
analyses that reflect ambient stream conditions.
The compiled data base contains 4,927 samples
from 123 sites. The median sample period of
record for individual sites is 2.5 years, and the
seventy-fifth percentile is about 12 years. Sixteen
sites have only five samples each. The median
number of samples per site is 14 samples, whereas
the seventy-fifth percentile is 65 samples. The
compiled data set was used in the design of a
basinwide sampling network that incorporates
sites that lack historic surface-water-quality data.

INTRODUCTION

The Upper Colorado River Basin (UCOL) is
1 of 59 U.s. Geological Survey (USGS) National
Water-Quality Assessment (NA WQA) study units.
The UCOL study began in October 1993 (Driver,

1994). A major part of each NAWQA study is
retrospective analysis of existing water-quality data.
The four goals of the retrospective analysis are:

1. Develop an improved conceptual model of spatial
and temporal patterns of concentrations and loads
within the study unit;

2. Guide additional data collection;

3. Contribute data to the National Synthesis Program
ofNA WQA; and

4. Document findings for future NA WQA work.

The UCOL study-unit team has done a
retrospective analysis of available surface-water
data for nitrogen and phosphorus, which are essential
nutrients for plant and animal growth. Results of
nutrient retrospective analysis have guided the design
of the UCOL surface-water-quality sampling network.
Many of the selected sampling sites lack historic
water-quality data (Spahr and others, 1996), and
one of the priorities of network design was to select
some sites without current or historic water-quality
monitoring to expand the. spatial extent of available
data.

Purpose and Scope

This report documents, summarizes, and
provides on J..5-in. diskette the surface-water nutrient
data that were collected from January 1980 through
August l~. Interpretive analyses of the data are in
Spahr and Wynn (T997). Ancillary data for parame-
ters, such as water1emperature, streamftow, specific
conductance, dissolved oxygen, pH, and alkalinity,
alsoareincluded on the data diskette, if available, but
are not summarized in this report. The compiled data
base contains 4,92Tsamples from 123 sites.

Abstract 1