Virginia Coastal Plain Groundwater Issues David K. Paylor March 27, 2015

Geology 101

Virginia Physiographic Provinces COASTAL PLAIN PIEDMONT BLUE RIDGE VALLEY AND RIDGE APP. PLATEAU

CONFINING UNITS CONFINED AQUIFERS UNCONFINED AQUIFER IMPACT CRATER BEDROCK Coastal Plain Aquifer System WEST EAST

AQUIFERS YORKTOWN-EASTOVER PINEY POINT AQUIA BASEMENT BEDROCK FLUVIAL SEDIMENTS MARINE SEDIMENTS POTOMAC AQUIFER

VA Coastal Plain Aquifer Cross-Section McFarland & Bruce, 2006

Groundwater Terms and Concepts

Well Water Levels Indicate Direction of Flow AQUIFER HIGH WATER LEVEL LOW WATER LEVEL FLOW

Well Water Levels Indicate Direction of Flow AQUIFER LOW HIGH FLOW AQUIFER FLOW

CONFINING UNIT Well Water Levels Indicate Direction of Flow AQUIFER LOW HIGH AQUIFER HIGH LOW LEAKAGEDOWN LEAKAGEUP

Cone of Depression Confined Aquifer Not a bathtub drain–actually a drop in pressure The pressure in the aquifer changes with distance from the well.

Potentiometric Surface

Groundwater Management in Virginia

Long-term Scientific Study

Scientific Milestones Regional studies (late 1970s –early 1980s) Hydrologic Framework I (1988) Coastal Plain Groundwater Flow Model I (1990) Coastal Plain Groundwater Flow Model II (1998) Chesapeake Bay Impact Crater (1999) Land Subsidence Study (2002) Hydrologic Framework II (2006) Coastal Plain Groundwater Flow Model III (2009) Eastern Shore Model I (2009) Groundwater Quality Trend Study (2010) Program Peer Review (2011) Potomac Aquifer Study (2013, pending publication)

Virginia Groundwater Withdrawals by Aquifer

Legislative History of GW Management Virginia Well Capping Law (1956) Groundwater Management Act of Amendments to Act of 1973 Ground Water Management Act of 1992 Private Wells ( , VDH-1986)

GW Management Areas Management Area 6/17/13 Management Area

Management Issues Reversal of the hydraulic gradient (groundwater flow) leads to salt water intrusion Declining water levels Subsidence and loss of storage

Reversal of Hydraulic Gradient and Saltwater Intrusion

Groundwater Pumping and Reversal of Hydraulic Gradient

Salt Water Intrusion - Upconing Pumping draws the salt water upwards into the well.

Salinity Within the Aquifer System Heywood and Pope, 2009

Groundwater Level Declines

Artesian Characteristics Lost Over Time

Long Term Water Level Decline LONG-TERM DECLINE

Decline from Pre-Pumping Levels % 77% POTOMAC AQUIFER WEST EAST PRE-PUMPING LEVEL PRESENT-DAY LEVEL +30 FRANKLIN 80% LAND SURFACE FLOW

Simulated Change in Storage of Water in the Potomac Aquifer from Pre-development to 2008 Values >1 indicate head is below the 80% criterion

Land Subsidence and Loss of Storage

Land Subsidence 025 Miles West Point Franklin Suffolk Chesapeake Bay Franklin Extensometer Oct – Dec Depth = 255 m Suffolk Extensometer June 1982 – Dec Depth = 484 m Rates of Elevation Change ( ) mm/year Holdahl and Morrison, 1974 Measurement of Compaction and Subsidence Major Pumping Centers

SUFFOLK 3.7 mm/yr FRANKLIN 1.6 mm/yr Subsidence Record MONITORING DISCONTINUED

Conclusions Water levels continue to decline in the primary aquifers. Land is subsiding. Salt water intrusion is occurring. Primary aquifers are not being pumped sustainably for the long-term.

Other States’ Responses Maryland – No irrigation withdrawals from the Potomac Aquifer. No new permits in areas where water levels have reached 80% of pre- development head. North Carolina – Reduce all existing withdrawals from the Potomac Aquifer by 30-75% over 15 years. Began State provided funds to convert to other sources. No new withdrawals from Potomac Aquifer. Georgia–South Carolina – Designated areas where no additional withdrawals are allowed and other areas where only incremental withdrawals are allowed. Mandatory conservation to reduce existing max withdrawals and GW monitoring. Savannah-Hilton Head Regional Management Area – Pumping limited based on areas reaching 500 mg/l Chloride in less than 113 years. Florida – Regional pumping caps on all withdrawals. All withdrawals including agr. are metered and conservation/efficiency mandated.

Options Resulting From Peer Review Regulatory options include: – Reduce pumping – Spread out pumping – Modify management goals – Issue permits in regional or aquifer groupings – Implementation of greater water conservation Program recommendations include: – More data collection: water levels water quality land subsidence – Implement new generation modeling tool – Increase program resources

Short-term Actions Amend GWMA regulations to: – Expand the management area – Determine regulatory compliance using full area of impact – Use land surface instead of pre-pumping head – Add greater clarity on expectations for use of alternative sources and water conservation Implement use of new (2009) model Collaborate with other agencies: – Specific data on well location and construction – Un-captured withdrawals Reinstate GW quality sampling within chloride network starting with samples/year Allow for drought contingencies in permits

Short-term Actions Under Review Begin moving existing pumps above the top of the Potomac Aquifer Improvements to groundwater withdrawal reporting Continue to increase GW quality samples to 50 per year Work with VEDP and local governments regarding availability of GW in recruitment locations Review program and funding resources

Other Longer-term Policy Options Optimize the new model to spread out withdrawals and evaluate impact Add subsidence package to the model Evaluate drawdown criteria for subsidence/salt water intrusion Continue to increase annual GW quality samples

Other Longer-term Policy Options (cont.) Facilitate greater use of alternatives such as wastewater reuse, surface water conjunctive use, and water recycling Consider additional regulatory changes Evaluate need for an across the board reduction target and implementation schedule

Questions?