Event Title

Survival of Woundfin Minnow in the Virgin RIver: Water Temperature and Water Diversion

Location

Eccles Conference Center

Event Website

http://water.usu.edu/

Start Date

3-27-2006 2:15 PM

End Date

3-27-2006 2:30 PM

Description

The woundfin minnow (Plagopterus argentissimus) is a unique spiny-rayed minnow from the Colorado River system that was listed as Endangered in 1970 under the Endangered Species Act of 1973. Prior to listing, the historical range was hundreds of miles of river that included the Gila, Colorado and Virgin Rivers in Arizona, Nevada and Utah. At the time of listing, woundfin were only found in approximately 80 miles of the Virgin River (Utah, Arizona, Nevada). Since listing, the woundfin has declined in the Virgin River due to non-native species (red shiner, Cyprinella lutrensis), extended drought, and water development (Federal Register 2000). Woundfin currently exist primarily in a 17 mile reach of the upper Virgin River between the Quail Creek Diversion/ Pah Tempe Springs and the Washington Fields Diversion near St. George, Utah. Both diversions are large structures that typically divert most of the water from the Virgin River during the summer. At the top of the reach a thermal spring (Pah Tempe Springs) adds approximately 10 cfs of hot water to the reach. Groundwater, two small tributaries, a small hydropower plant discharge and a reservoir release (in the middle of the reach) add additional flow to the river.

Woundfin numbers in the 17 mile reach have been critically low in recent drought years (especially 2001-2003). Woundfin Recovery Team fishes monitoring data since the late 1970’s indicate that woundfin numbers are lowest in the upper portion of this reach (Below the Ash Creek/La Verkin Creek confluence) and woundfin numbers fluctuate due to water year type. Woundfin numbers are low during low flow years and higher during high flow years (UDWR unpublished data). During the extreme drought year of 2002 (lowest water year on record), only 7 woundfin were captured in over 40 seining locations during fall collections. The most recent sampling (fall 2005), which followed an extremely wet year, showed that the number of woundfin captured for the same seining effort increased significantly to 1,384 young-of-year (YOY) fish and 14 adults (UDWR unpublished data).

The exact cause of the decline in the woundfin population during low flow years is still speculative, but some hypotheses suggest that the decline is related to high temperature and low turbidity during the low summer flow period and low dissolved oxygen during Quail Creek Diversion sluicing events (Fridell and Morvilius 2005a).

Here we focus on the effect high temperature--caused by low natural flows, natural hot springs, and water diversions--may be having on the woundfin population.

We present the results of a laboratory growth and critical temperature study and river temperature data that indicate during the low flow years acute thermal tolerance and longer-term chronic temperatures for woundfin are periodically being exceeded.

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Mar 27th, 2:15 PM Mar 27th, 2:30 PM

Survival of Woundfin Minnow in the Virgin RIver: Water Temperature and Water Diversion

Eccles Conference Center

The woundfin minnow (Plagopterus argentissimus) is a unique spiny-rayed minnow from the Colorado River system that was listed as Endangered in 1970 under the Endangered Species Act of 1973. Prior to listing, the historical range was hundreds of miles of river that included the Gila, Colorado and Virgin Rivers in Arizona, Nevada and Utah. At the time of listing, woundfin were only found in approximately 80 miles of the Virgin River (Utah, Arizona, Nevada). Since listing, the woundfin has declined in the Virgin River due to non-native species (red shiner, Cyprinella lutrensis), extended drought, and water development (Federal Register 2000). Woundfin currently exist primarily in a 17 mile reach of the upper Virgin River between the Quail Creek Diversion/ Pah Tempe Springs and the Washington Fields Diversion near St. George, Utah. Both diversions are large structures that typically divert most of the water from the Virgin River during the summer. At the top of the reach a thermal spring (Pah Tempe Springs) adds approximately 10 cfs of hot water to the reach. Groundwater, two small tributaries, a small hydropower plant discharge and a reservoir release (in the middle of the reach) add additional flow to the river.

Woundfin numbers in the 17 mile reach have been critically low in recent drought years (especially 2001-2003). Woundfin Recovery Team fishes monitoring data since the late 1970’s indicate that woundfin numbers are lowest in the upper portion of this reach (Below the Ash Creek/La Verkin Creek confluence) and woundfin numbers fluctuate due to water year type. Woundfin numbers are low during low flow years and higher during high flow years (UDWR unpublished data). During the extreme drought year of 2002 (lowest water year on record), only 7 woundfin were captured in over 40 seining locations during fall collections. The most recent sampling (fall 2005), which followed an extremely wet year, showed that the number of woundfin captured for the same seining effort increased significantly to 1,384 young-of-year (YOY) fish and 14 adults (UDWR unpublished data).

The exact cause of the decline in the woundfin population during low flow years is still speculative, but some hypotheses suggest that the decline is related to high temperature and low turbidity during the low summer flow period and low dissolved oxygen during Quail Creek Diversion sluicing events (Fridell and Morvilius 2005a).

Here we focus on the effect high temperature--caused by low natural flows, natural hot springs, and water diversions--may be having on the woundfin population.

We present the results of a laboratory growth and critical temperature study and river temperature data that indicate during the low flow years acute thermal tolerance and longer-term chronic temperatures for woundfin are periodically being exceeded.

https://digitalcommons.usu.edu/runoff/2006/AllAbstracts/1