FINAL Retrospective Analysis Of Water Temperature Data And .

FINALRetrospective analysis of water temperature data and larval andyoung of year fish collections in the San Juan River downstreamfrom Navajo Dam to Lake Powell UtahPrepared for:Ecosystems Research InstituteLogan, UtahAndU.S. Bureau of ReclamationSalt Lake City, UtahPrepared by:William J. MillerAndKristin M. SwaimMiller Ecological Consultants, IncPO Box 1383Bozeman, Montana 59771February 14, 2017

rtFebruary14,2017ExecutiveSummaryMiller Ecological Consultants conducted a retrospective analysis of existing San Juan Riverwater temperature datasets and larval fish data. Water temperature data for all years availablewere evaluated in conjunction with the timing and number of larvae captured in the annual larvalfish monitoring surveys that are required by the San Juan River Basin Recovery ImplementationProgram (SJRBRIP) Long Range Plan. Under the guidance of the SJRBRIP, Navajo Damexperimental releases were conducted and evaluated from 1992-1998. After this research period,the SJRBRIP completed the flow recommendations. The SJRBRIP established flowrecommendations for the San Juan River designed to maintain or improve habitat for endangeredColorado Pikeminnow Ptychocheilus lucius and Razorback Sucker Xyrauchen texanus bymodifying reservoir release patterns from Navajo Dam (Holden 1999). The flowrecommendations were designed to mimic the natural hydrograph or flow regime in terms ofmagnitude, duration and frequency of flows. Water is released from the deep hypolimnetic zoneof the reservoir, which results in water temperatures that are cooler than natural, pre-damconditions.Water temperatures in the San Juan River have been monitored and recorded at several locationsas part of the SJRBRIP since 1992. The Navajo Dam release has a clear temperature depressioneffect on temperatures in the San Juan River as far downstream as Mexican Hat, a distance of173 river miles (Miller and Swaim 2013). While the impacts of the temperature depression areunknown, there was concern that the sudden change in temperature could disrupt RazorbackSucker and Colorado Pikeminnow spawning or reduce hatching success and larval survival dueto slower growth rates at lower water temperatures.The objective of this retrospective analysis was to determine if there are any linkages betweenthe water temperature regime of the San Juan River below Navajo Dam and the timing andnumber of fish larvae that could be determined from the monitoring data.We used existing data for the synthesis of water temperature and larval fish collections. Watertemperature data were obtained from the San Juan River Water Temperature Database andUSGS records. We used the USGS gage at Bluff (also known as Mexican Hat) as the point ofcomparison for water temperature since it has the longest and most complete water temperaturedata set. It also has the only pre-dam data for water temperature. Larval fish data were obtainedfrom the San Juan River monitoring database or individual San Juan River monitoring projectreports. Data for both water temperature and larval fish collections were analyzed using standardexploratory statistics and more advanced statistical analysis using R statistical software (RDevelopment Core Team 2013).Mean pre-dam flows peaked at approximately 7500 cfs in early June. Maximum pre-dam flowspeaked at approximately 25,000 cfs and were frequently above 15,000 cfs. In contrast, for thepost-dam period, mean flows peaked at less than 5000 cfs and maximum flows were almostnever above 15,000 cfs. The pre-dam comparison shows numerous days with discharge greaterthan 5,000 cfs and water temperature equal to or greater than 20 C. There are also numerousdays with greater than 10,000 cfs discharge. Post-dam without a specified peak release, there areMillerEcologicalConsultants,IncPagei

rtFebruary14,2017still numerous days with flows greater than 5,000 cfs and water temperatures equal to or greaterthan 20 C. Maximum discharge post-dam is limited to approximately 12,500 cfs. For the postdam period with spring releases there are very few days when water temperature exceeds 20 Cand discharge is greater than 5,000 cfs. For most of the days when flow is greater than 5,000 cfsthe water temperature is less than 20 C.Water temperature depression in the San Juan River varies by year and the proportion of flowattributed to the San Juan River and Animas River. In years where the release from Navajo Damis larger than the flow from the Animas River, the water temperature shows a distinct depression.When the Animas River provides the majority of the flow, the water temperature does not showa distinct water temperature depression. Water temperature can be reduced by as much as 8 C atMexican Hat when a large proportion of the discharge comes from Navajo Dam. This amount ofwater temperature depression could be an impact to the endangered species.Larval density for Razorback Sucker varied by year but was not correlated with watertemperature depressions. The timing of larval collections did not coincide with depressions inwater temperature in the San Juan River in most years. Larval seining in the 2000s wasconducted on a weekly basis and usually occurred both before and after runoff. The larvalcollections did detect reproduction by both Colorado Pikeminnow and Razorback Sucker,however, no correlation between water temperature and larval density of either species could bedetected. Previous research on both species suggests that altered water temperature regimes dueto dam releases could be detrimental to both species. It is unknown if there the watertemperature depression caused by releases from Navajo Reservoir impact growth or survival ofeither species.In summary, analysis of temperature data showed that, for the San Juan River at Mexican Hat,post-dam temperatures were warmer than pre-dam temperatures throughout early spring and latesummer and were the result of reduced flows. Water temperatures at Mexican Hat were coolerwith releases than without releases between May 15 and June 20. Since the mid-May to midJune period coincides with the typical release period, we conclude that the experimental releasesdo have a temperature depression effect that can be detected as far downstream as Mexican Hat.Flows from the Animas River can moderate the effect of coldwater releases from Navajo Dam.MillerEcologicalConsultants,IncPageii

rtFebruary14,2017Table of ESULTS.3TEMPERATUREREGIMESUMMARY.3Pre- ‐Damvs.Post- ‐DamComparisons.3Post- s.7ComparisonofPredam,post–damandpost- etSurveys–1991- ‐2001.20LarvalSeining–2003- st of INSTANTANEOUSWATERTEMPERATURESBETWEENPRE- ‐DAMANDPOST- ICANHAT.17TABLE4.TOTALCOUNTSOFAGE- URINGLARVALFISHSURVEYS.21List of ,1945- ‐1962(PRE- AT,1963- ‐1976(POST- ‐DAM).5FIGURE3.PRE- ‐DAMANDPOST- RATMEXICANHAT.6FIGURE4.PRE- ‐DAMANDPOST- RATMEXICANHAT.6FIGURE5.PRE- ‐DAMANDPOST- GEDAILYFLOWSFORTHESANJUANRIVERATMEXICANHAT,1945- ‐1962(PRE- YFLOWSFORTHESANJUANRIVERATMEXICANHAT,1963- ‐1976(POST- ‐DAM).9FIGURE8.PRE- ‐DAMANDPOST- AT.9FIGURE9.PRE- ‐DAMANDPOST- ANHAT.10FIGURE10.PRE- ‐DAMANDPOST- ANHAT.10MillerEcologicalConsultants,IncPageiii

NOFSANJUANRIVERWATERTEMPERATUREANDDISCHARGEPRE- JUANRIVERWATERTEMPERATUREANDDISCHARGEPOST- JUANRIVERWATERTEMPERATUREANDDISCHARGEPOST- RS.29MillerEcologicalConsultants,IncPageiv

rtFebruary14,2017INTRODUCTIONMiller Ecological Consultants conducted a retrospective analysis of existing San Juan Riverwater temperature datasets and larval fish data. Water temperature data for all years availablewere evaluated in conjunction with the timing and number of larvae captured in the annual larvalfish monitoring surveys that are required by the San Juan River Basin Recovery ImplementationProgram (SJRBRIP) Long Range Plan.The SJRBRIP established flow recommendations for the San Juan River designed to maintain orimprove habitat for endangered Colorado Pikeminnow Ptychocheilus lucius and RazorbackSucker Xyrauchen texanus by modifying reservoir release patterns from Navajo Dam (Holden1999). The flow recommendations were designed to mimic the natural hydrograph or flowregime in terms of magnitude, duration and frequency of flows. A natural flow regime (one thatexisted before human intervention) has a large amount of variability in flow and is dominated byspring snowmelt runoff with low late summer and fall base flows (Holden 1999).Under the guidance of the SJRBRIP, Navajo Dam experimental releases were conducted andevaluated from 1992-1998. After this research period, the SJRBRIP completed the flowrecommendations. Modifications to reservoir operations that mimic the natural hydrographwould assist in conserving endangered fish in the San Juan River downstream from Farmington,New Mexico, while still allowing water development to proceed in the San Juan River Basin.The Bureau of Reclamation (BOR) (2006) evaluated the potential impacts of implementing therecommendations and agreed to change Navajo Dam and Reservoir operations, which wereprimarily focused on meeting irrigation needs and providing flood control. Water is releasedfrom the deep hypolimnetic zone of the reservoir, which results in water temperatures that arecooler than natural, pre-dam conditions.Colorado Pikeminnow adults were documented in the San Juan River at the approximate locationof Navajo Dam prior to construction of the dam (Koster 1960). The San Juan River was treatedwith rotenone from the reservoir pool downstream to approximately Farmington, New Mexicoprior to closure of the dam (Olson 1962). The purpose was to remove the existing fish speciesand restock with game species. Colorado Pikeminnow were reported by Olson as one speciesobserved in the dead fish after the treatment. Colorado Pikeminnow and Razorback Sucker werepresent in low numbers in the San Juan River and the San Juan arm of Lake Powell afterconstruction of Navajo Dam (Meyer and Moretti 1988, Platania 1990, Platania et al. 1991,Roberts and Moretti 1989). Colorado Pikeminnow young of the year were captured post-dam andprior to the specified peak flow releases.MillerEcologicalConsultants,IncPage1

rtFebruary14,2017Water temperatures in the San Juan River have been monitored and recorded at several locationsas part of the SJRBRIP since 1992. Miller Ecological Consultants took over monitoring duties infall 2011. During this first year of data collection (October 2011 to October 2012), we observedthat the Navajo Dam release depressed water temperatures in the San Juan River as fardownstream as Mexican Hat, a distance of 173 river miles (Miller and Swaim 2013). While theimpacts of the temperature depression are unknown, there was concern that the sudden change intemperature could disrupt Razorback Sucker spawning or reduce hatching success and larvalsurvival due to slower growth rates at lower water temperatures. This concern has also beenexpressed in the Upper Colorado and Green Rivers (Kaeding et al. 1986, Kaeding andOsmundson 1988, Muth and Nesler 1993, Muth et al. 2000). Bestgen et al. (2011) synthesized18 years of data regarding Razorback Sucker spawning in the Green River and found thatspawning occurs earlier when the Green River warms earlier and later when the river warmslater. They suggested that rising water temperatures may be a more important environmental cuefor spawning than increasing flow levels. Furthermore, they stated that “given the importance ofwater temperature on initiating reproduction in razorback sucker, it is reasonable to considerwhether reservoir releases play a role in delaying sp

Water temperature data were obtained from the San Juan River Water Temperature Database and USGS records. We used the USGS gage at Bluff (also known as Mexican Hat) as the point of comparison for water temperature since it has the longest and most complete water temperature data set. It also has the only pre-dam data for water temperature.