Difference between revisions of "Low Summer Flow Experiment"
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==LTEMP Experimental Action: Aquatic Resource-Related Experimental Treatments (BA, pages 30-41) [https://www.fws.gov/southwest/es/arizona/Documents/Biol_Opin/120059_LTEMP%20BiOp_11-25-16.pdf] == | ==LTEMP Experimental Action: Aquatic Resource-Related Experimental Treatments (BA, pages 30-41) [https://www.fws.gov/southwest/es/arizona/Documents/Biol_Opin/120059_LTEMP%20BiOp_11-25-16.pdf] == | ||
'''Low summer flows''' may be tested in the second 10 years of the LTEMP period, | '''Low summer flows''' may be tested in the second 10 years of the LTEMP period, | ||
| − | for the purpose of achieving warmer river temperatures ( | + | for the purpose of achieving warmer river temperatures (≥14°C) to benefit |
humpback chub and other native species. Under low summer flows, daily | humpback chub and other native species. Under low summer flows, daily | ||
fluctuations would be less than under base operations (e.g., approximately 2,000 | fluctuations would be less than under base operations (e.g., approximately 2,000 | ||
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|style="color:#000;"| | |style="color:#000;"| | ||
| + | Low summer flows | ||
| + | (minimum daily mean | ||
| + | 5,000 to 8,000 cfs) for three months | ||
| + | (Jul.–Sep.) to | ||
| + | target ≥ 14°C at Little | ||
| + | Colorado River | ||
| + | confluence | ||
|- | |- | ||
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|style="color:#000;"| | |style="color:#000;"| | ||
| − | + | Increase humpback chub growth | |
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|style="color:#000;"| | |style="color:#000;"| | ||
| + | '''Initial experiment:''' in the second 10 years of the LTEMP period (2026-2036) when target temperature of ≥14°C can be achieved only with low summer flow | ||
| + | |||
| + | '''Subsequent experimental use if:''' | ||
| + | # initial test was successful, | ||
| + | # humpback chub population concerns warrant their use, | ||
| + | # water temperature appears to be limiting recruitment, and | ||
| + | # target temperature of ≥14°C could be achieved only with low summer flow. | ||
|- | |- | ||
| − | ! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3bfb1; text-align:left; color:#000; padding:0.2em 0.4em;"> | + | ! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3bfb1; text-align:left; color:#000; padding:0.2em 0.4em;">Offramps</h2> |
|- | |- | ||
|style="color:#000;"| | |style="color:#000;"| | ||
| + | *Low summer flows do not increase growth and recruitment of humpback chub | ||
| + | *Increase in warmwater nonnative species or trout at the Little Colorado River | ||
| + | *Longterm unacceptable adverse impacts on the resources listed in Section 1.3 are observed | ||
| + | *Or sufficient warming does not occur as predicted | ||
|- | |- | ||
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|- | |- | ||
|style="color:#000;"| | |style="color:#000;"| | ||
| + | |||
| + | *Reduce food availability to humpback chub by | ||
| + | # desiccating the nearshore environment with the reduction in flow between June and July, and | ||
| + | # reducing drift with the reduction in daily fluctuation. | ||
| + | *Increasing bioenergetic demands of humpback chub via warmer water while decreasing food supply and availability. | ||
| + | *Increasing sediment transport during the high releases in the months prior to the LFS test in order to get the annual volume commitment to the Lower Basin. | ||
| + | *Increasing the potential for nonnative fish and parasites to proliferate throughout the Grand Canyon. | ||
| + | |||
| + | |- | ||
| + | ! <h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3bfb1; text-align:left; color:#000; padding:0.2em 0.4em;">Implementation Issues</h2> | ||
| + | |- | ||
| + | |style="color:#000;"| | ||
| + | |||
| + | *Scheduling monthly releases | ||
| + | *Science planning to monitor affects | ||
|} | |} | ||
Revision as of 15:33, 2 May 2017
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LTEMP Experimental Action: Aquatic Resource-Related Experimental Treatments (BA, pages 30-41) [1]Low summer flows may be tested in the second 10 years of the LTEMP period, for the purpose of achieving warmer river temperatures (≥14°C) to benefit humpback chub and other native species. Under low summer flows, daily fluctuations would be less than under base operations (e.g., approximately 2,000 cfs). Investigating the anticipated effects of and options for providing warmer water temperatures in the mainstem Colorado River through Grand Canyon is an identified management action in the Humpback Chub Recovery Goals (USFWS 2002a). |
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