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Groundwater Trends in Utah. Patrick M. Lambert, U.S. Geological Survey, Utah Water Science Center 2011 Utah Water Users Workshop March 14-16, 2011 St. George Utah. The groundwater resource in Utah. - PowerPoint PPT Presentation
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Groundwater Trends in Utah
Patrick M. Lambert, U.S. Geological Survey, Utah Water Science Center2011 Utah Water Users Workshop
March 14-16, 2011St. George Utah
The groundwater resource in Utah
An aquifer can be compared to a bank account and groundwater occurring in the aquifer as money in the account
Recharge/Deposits
Storage/Savings
Discharge/Withdrawals Infiltration of
precipitation
Seepage from surface water
Percolation of irrigation water
Subsurface inflow
Discharge to streams and springs
Transpired by plants
Subsurface outflow
Artificial recharge – Injection, infiltration ponds
Withdrawal from wells
Just as a bank account must be balanced, withdrawals from an aquifer must be balanced by some combination of increased recharge, decreased discharge, or removal from storage.
Predevelopment conditions
Natural and Induced recharge
4,500 cfs
Natural and Induced recharge
13,400 cfs
Discharge to surface-water bodies, springs, ET4,500 cfs
Development conditions
Pumpage13,500 cfs
Discharge to surface-water bodies, springs, ET1,600 cfs
Rate of decrease in storage: 1,700 cfs
… withdrawals from an aquifer must be balanced
Hypothetical groundwater system
Why do we care what the balances of Utah groundwater accounts are and which way we are trending?
Development conditions
Pumpage13,500 cfs
Discharge to surface-water bodies and ET1,600 cfs
Rate of decrease in storage: 1,700 cfs
Increased pumping costs
Changes in water quality
Reduced flows to streams, lakes, springs, flowing wells
Land Subsidence
Potential negative effects of groundwater depletion
Such effects, while variable , happen to some degree with any groundwater withdrawal.
Why do we care what the balances of Utah groundwater accounts are and which way they are trending?
As with other resources, society must weigh the benefits against the consequences of groundwater use.
In order to preserve and optimize the use of critical groundwater resources, we observe and assess to provide the information necessary to make informed choices in issues that have long-term effects.
Utah Groundwater Resources
Withdrawal from the 16 areas shaded in the figure made up 87% of total withdrawal for the state in 2009 (2009 statewide withdrawals = 969,000 acre-ft)
Areas of groundwater development in Utah
From Groundwater Conditions in Utah, Spring of 2010: Utah Division of Water Resources Cooperative Investigations Report no. 51 - http://ut.water.usgs.gov/publications/GW2010.pdf
Utah Groundwater Resources
Most wells in Utah yield water from unconsolidated basin fill deposits.
Smaller percentage of withdrawal occurs from consolidated rock mainly in eastern and southern parts of the state where basin fill aquifers have limited occurrence and capacity.
2009 estimated withdrawals from wells = 969,000 acre-ft
Trends in groundwater use in Utah
(Modified from Gates, 2004, Groundwater Development in Utah and Effects on Groundwater levels and Chemical Quality: in Groundwater in Utah; Resource, Protection, and Remediation, Utah Geological Association Publication 31)
Trends in groundwater use
State wide annual total groundwater withdrawal has increased by about 740,000 acre-ft since 1939 and about 340,000 acre-ft since 1963.
Irrigation withdrawals made up over 57% of total withdrawals in 2009.
Fluctuations in irrigation withdrawals are the main cause of the fluctuations in total withdrawal.
Irrigation, and thus total annual withdrawals, fluctuate mostly in response to changes in precipitation and resulting changes in surface-water flow and its availability for irrigation.
Withdrawals of groundwater from wells in Utah, 2009
2009
From Groundwater Conditions in Utah, Spring of 2010: Utah Division of Water Resources Cooperative Investigations Report no. 51 - http://ut.water.usgs.gov/publications/GW2010.pdf
Utah Groundwater State-Wide Monitoring Network
Program began in 1962 Annual water-level
measurements in about 1,000 wells
Water-quality sampling at about 100 wells
Cooperatively funded by Utah Department of Natural Resources, Divisions of Water Rights and Water Resources and the USGS Cooperative Water Program, more recently by the UDEQ (2005)
Average declines in water levels in major groundwater basins – March 1980 to March 2010
Groundwater Trends
Depicted range of declines represents average of water-level changes at all measured wells within a basin.
Based on data presented in Groundwater Conditions in Utah, Spring of 2010: Utah Division of Water Resources Cooperative Investigations Report no. 51 - http://ut.water.usgs.gov/publications/GW2010.pdf
Curlew and Cache Valleys Groundwater use is
predominantly for irrigation Currently, no significant
trend in annual withdrawals Moderate fluctuations
groundwater levels and storage – Generally declining water levels
Groundwater Trends – Northern Utah
Water-level change from March 1980 to March 2010
1930 2010
Cache ValleyUnless otherwise stated, water-level change maps in this and subsequent slides are from Groundwater Conditions in Utah, Spring of 2010: Utah Division of Water Resources Cooperative Investigations Report no. 51 - http://ut.water.usgs.gov/publications/GW2010.pdf
East Shore, Salt Lake Valley, Tooele Valley, Utah and Goshen Valleys
Groundwater use is predominantly for public supply
Substantial public-supply withdrawals in high-population basins – Salt Lake (137,000 acre-ft in 2009) and Utah valleys (109,000 acre-ft)
Zones of significant water-level declines including flowing well areas
Groundwater Trends – North-Central Utah
Water-level change from March 1980 to March 2010
1930
2010
1930 2010
East Shore Area
Water-level change from Feb 1980 to Feb 2010
Groundwater Trends – North-Central Utah
Salt Lake Valley
201019301930 2010
1930 2010
Northern Utah Valley
Groundwater Trends – North-Central Utah
Water level change in the principal basin-fill aquifer, 1981-2004
1930 2010
Negative values indicate water-level declines From Hydrology of Northern Utah Valley, Utah County, Utah, 1975-2005: U.S. Geological
Survey Scientific Investigations Report 2008-5197 http://pubs.usgs.gov/sir/2008/5049/
Groundwater Trends – Southwestern Utah
Pahvant, Milford, Parawan, Cedar Valley, Beryl-Enterprise, Central Virgin River
Groundwater use predominantly for irrigation
Significant increases in total withdrawals from 1940 through mid 70’s
Largest and most extensive water-level declines observed in groundwater basins with significant groundwater development
Water-level change from March 1980 to March 2010
Groundwater Trends – Southwestern Utah
Pahvant Valley
1930 2010
1930 2010
Water-level change from March 1980 to March 2010
Groundwater Trends – Southwestern Utah
Cedar Valley
1930 2010
Water-level change from March 1980 to March 2010
Groundwater Trends – Southwestern Utah
Beryl-Enterprise area
Water Quality trends are also important!
Withdrawals from aquifer zones containing good-quality water can allow adjacent poorer-quality water to migrate and degrade water quality.
Where groundwater is withdrawn from an aquifer, surface water of differing quality may be drawn into the aquifer.
Curlew Goshen Pahvant Milford Beryl-Enterprise Cedar Valley (Iron County) Salt Lake Valley
Increasing trends in dissolved-solids concentrations indicated in Utah long-term monitoring network
Areas where increases in dissolved-solids concentrations in groundwater are observed
Groundwater quality monitoring network
• Water quality sampling began in 1964.
• Sampling ended after 2001.
• Restarted in 2005, 60 wells.
• Sampled about 104 wells in 2010
• Network of about 300 wells, each sampled every 3 years.
Trends in chemical quality of groundwater
8-27
-80 9
Curlew Valley
Graphs of annual withdrawals and dissolved solids concentrations in this and subsequetn slides are from Groundwater Conditions in Utah, Spring of 2010: Utah Division of Water Resources Cooperative Investigations Report no. 51 - http://ut.water.usgs.gov/publications/GW2010.pdf
Pahvant
Trends in chemical quality of groundwater
Trends in chemical quality of groundwater
Beryl-Enterprise
Groundwater comprises about 30% of water use in the valley (most groundwater withdrawals are for public supply)
Range of water-quality results from different sources of water to the aquifer and water rock interaction
Salt Lake Valley - dissolved-solids concentrations
Distribution of dissolved-solids concentrations in the principal aquifer in Salt Lake Valley, 1998-2002
< 250 mg/l
250-500 mg/l
500-1,000 mg/l
1,000-2,000 mg/l
2,000-5,000 mg/l
> 5,000 mg/l
Decadal-Scale Changes in Dissolved-Solids Concentrations in Groundwater Used in Public Supply, Salt Lake Valley, Utah: U.S. Geological Survey Fact Sheet 2010-3073 - http://pubs.usgs.gov/fs/2010/3073/
Confining layers and upward vertical gradients inhibit vertical flow of poor quality water to confined aquifer however…
Substantial increases in TDS in the principal aquifer are occurring in some areas
Salt Lake Valley groundwater quality trends
Central and Eastern and Salt Lake Valley
• Colored zones indicate distribution of dissolved solids.
• Outlines indicate areas where concentrations of dissolved solids increased by 20% or more from 1988-92 to 1998-2002.
< 250 mg/l
250-500 mg/l
500-1,000 mg/l
Decadal-Scale Changes in Dissolved-Solids Concentrations in Groundwater Used in Public Supply, Salt Lake Valley, Utah: U.S. Geological Survey Fact Sheet 2010-3073 - http://pubs.usgs.gov/fs/2010/3073/
Northern Utah Valley
Utility of basic data and groundwater flow models to understand the effects of water use on groundwater systems – an example
Goal – Information to preserve and optimize the use of critical groundwater resources
• Lower water levels (drawdown) in large areas of the aquifer
• Reduced natural discharge
Application to groundwater resource management From USGS Northern Utah Valley (NUV) Groundwater assessment and flow modeling project - Projected effect of future increased pumping in Northern Utah Valley - Test case of 2x current pumping
30 ft
25 ft
20 ft
Drawdown, comparedto 2004 water levels
(Computed drawdowns from simulated 2x 2004 pumping for 30 years) Utah
Lake
Decision Variables 47 individual wells
Constraints Maximum flow rate of
2,500 gpm per well Drawdown ≤ 20 ft Total of all withdrawal ≥
89,000 acre-ft/year
Objective Maximize Withdrawal
Simulation-Optimization modeling to assess groundwater systems - NUV Optimization Example 1: Problem design
Application of the USGS groundwater flow and optimization (Groundwater Management (GWM) process tool) models for Northern Utah Valley
• > 70 wells pumping 44,500 acre-ft/yr in 2004
• Increase to 89,000 acre-ft/yr over 30 years
Scenario to meet future groundwater demands
Existing wells in 2004 with capacity > 300 gpm
Example 1: results
19 ft
19 ft
17 ft
Example 1 Drawdown,Compared to 2004 water levels.Resulting from optimized pumping from existing wells.
• Only 86,300 acre-ft/yr could be withdrawn and still meet constraints
• Results show which wells must be pumped & how much• 27 wells versus >70 wells• 100 to 2,400 gpm• most average 500 gpm• 4 wells > 1,500 gpm• 11 wells > 1,000 gpm
• Reduced overall drawdown by 5 to 10 ft
• This result was achieved in one run of the model
(Computed drawdowns from simulated 2x 2004 pumping for 30 years)
% change (base case)
Changes in ground-water discharge
-23%-39%-15%
Utah LakeDrains, springs, & flowing wellsEvapotranspiration
30 ft
25 ft
20 ft
Drawdown,
19 ft
19 ft
17 ft
Drawdown,Ex.1
% change (Ex.1) -25%-35%-14%
Example 1: comparison2x 2004pumping
• 97% of the target withdrawal using only 27 wells (versus more than 70 wells)
• Significant improvement in drawdown
(Computed drawdowns from simulated 2x 2004 pumping for 30 years)
Groundwaterwatch.usgs.gov or NWIS Mapper
http://ut.water.usgs.gov/
References
Groundwater Conditions in Utah, Spring of 2010: Utah Division of Water Resources Cooperative Investigations Report no. 51 - http://ut.water.usgs.gov/publications/GW2010.pdf
Groundwater Development in Utah and Effects on Groundwater levels and Chemical Quality: in Groundwater in Utah; Resource, Protection, and Remediation, Utah Geological Association Publication 31
Decadal-Scale Changes in Dissolved-Solids Concentrations in Groundwater Used in Public Supply, Salt Lake Valley, Utah: U.S. Geological Survey Fact Sheet 2010-3073 - http://pubs.usgs.gov/fs/2010/3073/
Groundwater Depletion Across the Nation, U.S. Geological Survey Fact Sheet-103-03 - http://pubs.usgs.gov/fs/fs-103-03/
Hydrology of Northern Utah Valley, Utah County, Utah, 1975-2005: U.S. Geological Survey Scientific Investigations Report 2008-5197 http://pubs.usgs.gov/sir/2008/5049/
Three-Dimensional Numerical Model of Ground-Water Flow in Northern Utah Valley, Utah County, Utah - http://pubs.usgs.gov/sir/2008/5049/
Use of Simulation-Optimization Modeling to Assess Regional Groundwater Systems: U.S. Geological Survey Fact Sheet 2005-3095 - http://pubs.usgs.gov/fs/2005/3095/
O.E. MeinzerUSGS Groundwater Division Chief, 1912-1946
Questions?
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