Effects of Drought on Water Quality of Lake Powell and Glen Canyon ...

<strong>Effects</strong> <strong>of</strong> <strong>Drought</strong> on WaterQuality <strong>of</strong> Lake Powell and GlenCanyon Dam ReleasesWilliam S. VernieuGrand Canyon Monitoring and Research CenterFlagstaff, AZbvernieu@usgs.govColorado River Commission <strong>of</strong> NevadaImplications <strong>of</strong> Lower Lake LevelsApril 21, 2010U.S. Department <strong>of</strong> the InteriorU.S. Geological Survey

Topics• GCMRC Water Quality Monitoring Program• Recent <strong>Drought</strong> Hydrology – Powell & Mead• Lake Powell Limnology• Results <strong>of</strong> Reservoir Drawdown• Temperature• Dissolved Oxygen• Rechannelization

Lake Powell Water QualityMonitoring Locations•Monthly forebay surveys•Quarterly reservoir-wide surveys•25-30 stations•Pr<strong>of</strong>iles•Major Ions - Nutrients•Chlorophyll - Plankton

Parameters <strong>of</strong> Interest• Temperature• Affects density and fate <strong>of</strong> inflow currents• Affects aquatic life in downstream environment• <strong>Effects</strong> for endangered fish• Dissolved oxygen• Supports aquatic life in downstream ecosystem• Affected by organic material and respiration• Affected by primary productivity

Lake Mead History – 1962 to present•Glen CanyonDamcompleted in1963•Lowest level1083.6 ftMar 1956•Current level1099.0 ft•Projected low1082.5Nov 2010Full Pool 1220 ft

Recent Inflows to Lake Powell•2000 – 62% •2005 – 105%•2001 – 59% •2006 – 73%•2002 – 25% •2007 – 68%•2003 – 51% •2008 – 101%•2004 – 49% •2009 – 95%

Lake Powell Inflows and Releases14.012.0100%105%101%95%MAF10.08.06.062%59%51%49%73%68%4.025%2.00.02000 2001 2002 2003 2004 2005 2006 2007 2008 2009InflowRelease

2005 Glen Canyon Dam ReleasesTwo Unusual Events• Highest Release Temperature Since 1971• 16°C (61°F) on October 8, 2005• Lowest Dissolved Oxygen on Record• 3.3 mg/L on October 8, 2005 from draft tubes• (Data since 1990 – no evidence <strong>of</strong> prior hypoxia)

Lake Powell and Glen Canyon Dam•3 Dischargestructures•Reservoirstratified bydensity•Longitudinalzonation

Fate <strong>of</strong> Inflows•Destination depthdetermined by density•Temperaure•Salinity•Sedimnentj•Lake Powell•Seasonal overflow•Lake Mead•Constant underflow

Glen Canyon Dam Release Temperature753750•Temperaturefluctuationsconfined at higherreservoir levels•Warmesttemperature inwinter fromreservoir mixing•Recent releasetemperatureshighest since 1971•Max 2005temperature 61 °FTemperature (°F)706560555045403600 ft37003650360035503500345034003533501964 1967 1971 1975 1979 1983 1987 1991 1995 1999 2003 2007 2011YearElevation (ft)

Lake Powell Water Quality History

Formation <strong>of</strong> Delta Deposits

Dirty Devil R. Colorado R.

Lake Powell03/09/2003

Lake Powell09/18/2003

Lake Powell03/01/2004

Lake Powell12/23/2004

Lake Powell Hydrology - 2005• Pre-Run<strong>of</strong>f Conditions• Surface elevation - 3555 ft on April 8, 2005• Lowest elevation since May 1969• 38 % <strong>of</strong> total capacity• 2005 Run<strong>of</strong>f• Apr-Jul 2005 unreg. inflow - 111% <strong>of</strong> normal• Surface elevation - 3608 ft on July 13, 2005• Run<strong>of</strong>f increased elevation by 53 ft in 2005• 55% total capacity

2005 Inflow to Lake Powell• Above averageinflows caused headcutting <strong>of</strong> deltaicsediments• Resuspension <strong>of</strong>large amount <strong>of</strong>sediment from inflowareas• Resulted in lowdissolved oxygenlevels in inflow plumeas it traveled throughreservoir

<strong>Effects</strong> <strong>of</strong> Sediment ResuspensionLake Powell Dissolved Oxygen – September 2003

Result <strong>of</strong> Hypoxic Inflow 20059/8/05 10/12/05 11/2/05

Glen Canyon Dam Releases 2005Mean daily values•Lowest dissolvedoxygen on record(since 1990)•3.3 mg/L onOctober 8, 2005from draft tubes•Hypoxia dissipatedby reservoir surfacemixing•Data since 1992 –no evidence <strong>of</strong> priorhypoxiaT (deg C) - D.O. (mg/L)1817161514131211109876543201JAN05 01APR05 01JUL05 01OCT05 01JAN06NOTE: Specific Conductance in mS * 10pH16.1°C – 10/14/05TemperatureSpecificConductanceDissolvedOxygen3.3 mg/L – 10/08/0513.012.512.011.511.010.510.09.59.08.58.07.57.06.56.05.55.0S.C. (mS/cm*10) - pH

Reaeration ExperimentLong-termmonitoring atthree locations:•CRDT (red)GCD Draft Tube•CRBD (blue)GCD tailwater•CRLF (green)Lees Ferry3 @ 2670 cfs 5 @ 1600 cfs 3 @ 2670 cfs 2 @ 2800 cfs Day:Day:2 @ 1200 cfs3 @ 3000 cfsNight:2 @ 2600 cfs1 @ 1300 cfs2 @ 3300 cfs2 @ 1200 cfsNight:2 @ 2600 cfs1 @ 1300 cfs

Applicability to Lake Mead• Quality <strong>of</strong> inflows• Determines density and depth <strong>of</strong> inflow• Quantity <strong>of</strong> inflows• Determines amount <strong>of</strong> sediment resuspension• Sediment quality• Basin characteristics• Controls to deltaic erosion• Withdrawal elevation and intended use

William VernieuGrand Canyon Monitoring & Research Center(928) 556-7051 bvernieu@usgs.gov