Summary of Streamflow Conditions and USGS Low-Flow Activities

State Drought Task Force MeetingState Drought Task Force MeetingMarch 29, 2012March 29, 2012

St Paul, MN - WebinarSt Paul, MN - Webinar

U.S. Department of the InteriorU.S. Geological Survey

James Fallon, Dave Lorenz, Greg MittonUSGS, Mounds View, MN

jfallon@usgs.gov 763-783-3255

Photo of dry channel at Minnesota River at Montevideo, 1932

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TopicsTopics• Summary of Streamflow ConditionsSummary of Streamflow Conditions• Mississippi Low-Flow Report FindingsMississippi Low-Flow Report Findings• Low-Flow Statistics & Web ResourcesLow-Flow Statistics & Web Resources• Low-Flow Triggered ActivitiesLow-Flow Triggered Activities

– Extra low-flow measurementsExtra low-flow measurements– Mississippi River GW Seepage Study between St Cloud and Elk RiverMississippi River GW Seepage Study between St Cloud and Elk River

Le Sueur River near RapidanSept. 28, 2011 31 cfs

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Summary of Streamflow Summary of Streamflow ConditionsConditions

1.1. Background: snowmelt peaks are often greatest flows of year for northern 2/3’s of MinnesotaBackground: snowmelt peaks are often greatest flows of year for northern 2/3’s of Minnesota

2.2. Most streams have peaked due to snowmeltMost streams have peaked due to snowmelt

3.3. Peaks are about 1-month earlier than usualPeaks are about 1-month earlier than usual

4.4. Most peaks are smaller than normal Most peaks are smaller than normal Typically about 25Typically about 25thth percentile percentile

Some flows extremely low but masked from seasonSome flows extremely low but masked from season

5.5. Spring rains could change all thisSpring rains could change all this

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OverviewOverviewMuch of US experiencing below-normal Much of US experiencing below-normal streamflowstreamflow

Northern US gages not reporting: ice-affected

http://waterwatch.usgs.gov/new/index.php?id=dryw http://waterdata.usgs.gov/usa/nwis/rt

Minnesota Flow Conditions Minnesota Flow Conditions SimilarSimilar

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First glance: flows seem normalwith low flows in south & NE

Look closer at hydrographs with respect to season and timing

http://waterdata.usgs.gov/mn/nwis/current/?type=intro

7Pigeon

Flow-Duration Hydrographs Flow-Duration Hydrographs from Selected Streamgages from Selected Streamgages

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7Buffalo

7DesMoines

5Kawishiwi

7Prairie

Red-Fargo 8

Basswood8

7Miss-B

Crow8 7Miss-AnokaMN-Monte8

7MN-Jordan

71. Snake current

7StraightLeSueur8

WaterWatch Duration Hydrographs http://waterwatch.usgs.gov/new/index.phpCurrent Streamflow Conditions http://waterdata.usgs.gov/mn/nwis/current/?type=flow

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Mississippi River Low Flow Mississippi River Low Flow ReportReport

“Normal” snowmelt runoff peak at Le Sueur River near Rapidan, March 23, 2007. Measured 3,260 cfs after peak (trees on left bank).

So what do these low-flow conditions look like?

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Mississippi River Low Flow Mississippi River Low Flow ReportReport

Same view of channel last fall.September 28, 2011. 33 cfs

Cobble Riffle

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Flow this spring: March 7, 2012. Just past snowmelt runoff peak. Peak was <1,000 cfs (about 1.5 ft higher than shown in picture). View looking upstream of same cobble riffle.

Low-Flow Characteristics Low-Flow Characteristics of the Mississippi Riverof the Mississippi River

Dave Lorenz and Erich KesslerUSGS Minnesota Water Science Center

Research supported by the Met Council (2008)

http://pubs.usgs.gov/sir/2010/5163/

Study Objective and Study Objective and ApproachesApproaches

Characterize the regional low flows in the Mississippi River upstream of Minneapolis.

Part 1. Review low-flow duration statistics for the Miss. R. near Anoka, one upstream site (Grand Rapids), and three tributaries (Crow R., Crow Wing R., and Rum R.) as well as the headwaters reservoirs.

Part 2. Construct a very large sample of potential flows, by superpositioning observed summer flows on observed snowmelt flows.

Implications, Part 1Implications, Part 11. The greatest threat from low flows occurs when the

Mississippi River near Anoka and the upstream basins experience low flows.

2. The assumption that droughts and corresponding low flows are widespread is not necessarily true. There are several instances of low flows in one or two basins and not in the other basins.

3. In general, the headwaters reservoirs are at or below their summer operating range during lowest flows in the Mississippi River.

Approach, Part 2Approach, Part 2

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

5000

10000

15000

20000

25000

30000

Flow.1976Flow.2003Synthetic Flow

Implications, Part 2Implications, Part 2The greatest threat from the lowest flows occurs before the end of June when a dry spring follows a snowmelt peak of less than 11,300 cubic feet per second.

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Low-Flow Triggered Low-Flow Triggered ActivitiesActivities

1.1. Discharge Discharge measurements measurements at low-flow sitesat low-flow sites

2.2. Mississippi River Mississippi River Groundwater Groundwater Seepage Seepage Synoptic Synoptic MeasurementsMeasurements

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Additional Drought Additional Drought ResourcesResources

http://mn.water.usgs.gov/infodata/lowflow/

Low-Flow Statistics Web PageDrought-related Web Page

http://mn.water.usgs.gov/drought/

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Questions?Questions?1.1. Snowmelt peaks are often greatest flows of year for northern 2/3’s of MinnesotaSnowmelt peaks are often greatest flows of year for northern 2/3’s of Minnesota

2.2. Most streams have peaked due to snowmeltMost streams have peaked due to snowmelt

3.3. Peaks are about 1-month earlier than usualPeaks are about 1-month earlier than usual

4.4. Most peaks are smaller than normal Most peaks are smaller than normal Typically about 25Typically about 25thth percentile percentile

Some flows extremely low but masked from seasonSome flows extremely low but masked from season

5.5. Many conditions in Upper Mississippi Basin “right” for severe low flow in MetroMany conditions in Upper Mississippi Basin “right” for severe low flow in Metro

6.6. Spring rains could change all thisSpring rains could change all this