GROUNDWATER
MONITORING ADVISORY
WORKGROUP
Overview for CV SALTS
24 April 2012
1
PURPOSE
To advise and provide comments to
Central Valley Water Board staff on
technical issues related to how
groundwater monitoring studies are
conducted and evaluation of
monitoring data.
2
Organizations Represented
 State
Water Board
 United States Geologic Survey
 UC Davis Cooperative Extension
 Sacramento State
 Hydrogeologic and Engineering Consulting
Firms
 US Environmental Protection Agency
3
OPERATING PROCEDURES
 Meetings
are open to the public.
 Group has a wide range of expertise. New
members can be added if additional areas
of expertise are needed.
 No compensation for participation or travel
expenses.
 Water Board staff prepare agendas and
minutes of meetings.
 Meeting announcements and agendas are
posted on website.
4
WHITE PAPERS
 Establishing
and applying site-specific
background concentrations
 Site characterization and conceptual
model approach
 Groundwater monitoring techniques,
methods, and tools
5
BACKGROUND ISSUES
Examples of the type of questions we are asking
related to an issue.

What is background?
 How and where should background be determined?
 How and where should compliance be determined?
 Should the monitoring approach vary by the type of site?
 Should the monitoring approach vary by the COCs?
 What type of data need to be collected?
 Are there more effective/efficient methods to collect
groundwater data than monitoring wells?
 Do we have to have groundwater samples?
6
IRRIGATED LANDS
REGULATORY PROGRAM
 The
GMAW reviewed ILRP groundwater
issues
 Developed a series of questions to identify
what type of monitoring is needed.
 Held 2 public meetings to discuss.
 This work was considered in formulating
monitoring requirements for draft orders.
7
QUESTION 1
What are ag’s impacts to beneficial uses of
groundwater and where has groundwater been
affected by ag?
Monitor
COCs of nitrate and salinity, lesser
frequency for general minerals and others.
Use existing data where available although
additional data probably needed.
8
QUESTION 2
Which ag management practices are protective
of groundwater quality and to what extent is the
determination affected by site conditions?
Utilize
academic and commodity research groups to
ID existing practices.
Need to collect shallow groundwater data and may
be able to utilize vadose zone monitoring.
Need to consider site conditions (i.e., determination
of whether practice is protective is dependent on site
conditions.
9
QUESTION 3
To what extent can Ag’s impact on
groundwater quality be differentiated from
other sources (natural or anthropogenic)?
Samples
from wells with known recharge
area.
Critical in areas where other sources exist.
Collect additional data where needed (i.e.,
co-contaminants, tracers, isotopes, etc.).
10
QUESTION 4
What are groundwater quality trends beneath
ag lands and how can you differentiate from
residual impact or legacy problems?
Need
long-term monitoring for trends accounting for
seasonal variation.
Monitor areas where this complexity is minimal.
Monitor for legacy compounds where needed.
11
QUESTION 5
What properties (site conditions) are most
critical in causing groundwater degradation
from ag?
Soil
type and depth to groundwater
Groundwater pumping causes mixing
Redox and cation exchange are important.
12
QUESTION 6
What are the transport mechanisms to affect deeper
groundwater, what rate is this occurring, and are
there interim measures to prevent further degradation
while identifying protective practices?
Lost
wells and poor construction of wells.
Need backflow prevention.
Insufficient information on rate of degradation and
the need for long term monitoring.
Did not address interim measures as dealing with
monitoring questions.
13
QUESTION 7
How can we confirm that implemented
management practices are working?
Properly
designed and constructed
groundwater monitoring network.
Numeric modeling with some groundwater
monitoring to confirm assumptions and
conclusions.
14
ILRP GROUNDWATER
MONITORING
Two types of monitoring recommended
Trend
monitoring
Representative
monitoring
15
TREND MONITORING
 Use
existing wells to monitor trends
 Wells should be shallow (domestic
preferred).
 Need well information (i.e., construction
data).
 In high and low vulnerability areas.
 Program proposed in work plan.
16
REPRESENTATIVE
MONITORING






In high vulnerability areas.
Monitor first encountered groundwater.
Account for range of management practices and
site conditions.
Program proposed in work plan.
Recommend one program region wide (i.e., not
coalition by coalition).
Needed to document improvements in water
quality from improved practices.
17
Questions ?
18