7103

• UCREFRP Catalog Number: 7103
• Author: Grabowski, S. J. and S. D. Hiebert.
• Title: Green River Trophic Dynamics Study 1987
• USFW Year: 1988.
• USFW - Doc Type: Draft.
• Copyright Material: NO

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study period. Seasonal water temperature fluctuations were greater

at Ouray than at upstream sites. Main river water temperatures will

likely decrease through the winter.

Dissolved oxygen. - Dissolved oxygen levels at three main river sites
generally exhibited the opposite pattern seen for water temperature
(fig. 4). Dissolved oxygen decreased to a low in early August, then
increased steadily to mid-November. Dissolved oxygen levels at down-
stream sites were usually lower than at upstream sites. The minimum
level of dissolved oxygen was 6.5 mg/L, at Ouray. The lower solubility
of oxygen in warmer water is apparent at the main river sites. There
appears to be a greater seasonal change for both temperature and dissolved
oxygen downstream at Ouray compared to upstream at Island Park.

pH. - pH was usually higher at Island Park than at Jensen or Ouray.
From June to early August pH at Ouray exceeded that at Jensen, but
by mid-August, pH at Jensen was greater than at Ouray, but less than
at Island Park (fig. 5). pH appeared to increase throughout the sampling
period, but decreased in mid-August. This may be in response to increased
flows.

Specific conductance. - Specific conductance at three main river sites
was initially low in June, and increased steadily to late September,
then decreased slightly (fig. 6). Except for late September, specific
conductance increased from Island Park downstream to Ouray, reflecting

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