WSP04654

• File Number: 8200.750
• Description: San Juan River General
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 9/1/1976
• Author: Jack G Troyer
• Title: Water Quality of Williams Creek Reservoir and Williams Creek - San Juan National Forest - September 1976
• Water Supply Pro - Doc Type: Report/Study

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IV. ANALYSIS AND DISCUSSION OF DATA

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This chapter analyzes the data and discusses the significance of each
parameter. The actual data is presented in Chapter V.

A. Nitrogen and Phosphorus

The primary objective of this study is to determine if a eutro-
phication problem exists at Williams Creek Reservoir. The key
parameters in such an analysis are the various compounds pf
nitrogen and phosphorus, and thus will be discussed first.

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Eutrophication is the process that enriches lakes with nutrients
resulting in water quality characteristics that can be undesir-
able for man's use. Plant growth such as algae and aquatic weeds
is generally limited in nature by a lack of nutrients of which
nitrogen and phosphorus. are usually the .limiting factors.. Any
number of other elements can also be limiting but the trace quanti-
ties needed are usually present. Man's activities can speed up the
natural eu~rophication process by the addition of nutrients. Ex-
cessive algae growth can impart taste and odor to the water, result
in the accumulation of dead organic matter on the bottom and be
aesthetically unpleasing. Metabolism of organic matter by bacteria
depletes. the oxygen supply near the bottpmand.can eventually result
in loss of fish. During the summer of 1976 Williams Creek Reservoir
began to exhibit some of these characteristics.

The important forms of nitrogen and phosphorus were measured in this
study. The nitrogen and phosphorus data included total nitrogen
organic nitrogen, nitrates, ammonia, total phosphorus, and or the
phosphate. A brief discussion of each follows:

All nitrogen in organic compounds is considered organic
nitrogen. Most of it that occurs in domestic wastes is in
the form of protein or its degradation products. Much of
the nitrogen in freshly polluted water is in this form.
These compounds are then converted to ammonia which exists
as the ammonium ion NH4+ or in the equilibrium NH4+ NH3 + H+.
Thus high ammonia concentrations may also indicate relatively
recent pollution.

.This ammonia (that exists. in excess of plant requirements) is
then converted to nitrite (N02)by the nitrosomonas group of
bacteria which is then oxidized to nitrate (N03) by the nitro-
bacter group. Total kjeldahl nitrogen refers to a measurement
technique that determines organically.bound nitrogen in the
tri-negative state plus a'llllJonia. Nitrate or nitrite is not
included in total kjeldahl nitrogen. Of the phosphorus data,
orthophosphorus refers to the most soluble and available form
(for plant uptake) of phosphates. Total ~hosphorus includes
all forms of phosphorus, both organic and inorganic.

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