A-Z Index | Contact Us | Search

Ecology home > Environmental Assessment > Groundwater Assessment in Washington State > Status of Active GW Monitoring Programs in Washington State - 2002

Status of Active Groundwater Monitoring Programs in Washington State - 2002

Contents

• Introduction
• Background - Hydrogeology of Washington
• How did we conduct our survey?
• Survey Results
• What does this mean for the status of ambient groundwater monitoring in the state?
• Future Efforts – Where do we go from here?

Introduction

Although unseen, groundwater is a vital resource to the citizens, economy and environment of Washington state.  Groundwater supplies more than a quarter of the total state water demand, and is estimated to provide at least 65 percent of the drinking water for the state’s residents.  As a fundamental component of the hydrologic cycle, groundwater also plays a critical role in sustaining stream and river baseflow and maintaining the quality of riparian and wetland ecosystems.  Because surface water is already extensively allocated in many areas, groundwater will undoubtedly supply an increasing percentage of our water need as our population grows.  The availability of a clean, plentiful supply of groundwater is an essential element of Washington state’s future.

Accurate information about the ambient quality and quantity of groundwater is critical to the wise management of the resource (the term “ambient” refers to broader-scale or area-wide conditions; conditions not associated with a specific point source, facility, or property).  However, in part due to the large extent and complex nature of the groundwater resources of Washington, there is currently no long-term, systematic state program to monitor and report ambient groundwater quality or water level conditions.

In response to increasing interest in assessing groundwater in a more strategic manner, Ecology’s Environmental Assessment (EA) Program recently conducted a survey of the status of active ambient groundwater monitoring programs for water quality or water levels across the state. The results of this evaluation, described below, will guide the development of future strategies for the Environmental Assessment Program groundwater team to more effectively help monitor groundwater conditions across the state.  For more information about that effort see Strategic Planning for Groundwater Monitoring.

Back to top

Background - Hydrogeology of Washington State

Figure 1 shows a map of the principal surficial aquifers of Washington.  The three major aquifer systems in the state include the basalts and overlying unconsolidated deposits of the Central Columbia Plateau in southeastern Washington, the unconsolidated glacial deposits of the Puget Sound Lowland, and the glacial outwash deposits of the Spokane-Rathdrum Prairie Aquifer in northeast Washington.  The larger state aquifer systems are typically composed of multiple water-bearing units that underlie the surface, often extending many hundreds of feet below ground.  A number of smaller, surficial aquifer systems also exist throughout our state, commonly located within river valleys.  In contrast to the state’s stream and river network, the large extent and three-dimensional character of the groundwater resource greatly complicate the ability to cost-effectively monitor state-wide conditions.

Figure 1 — Principal Surficial Aquifers of Washington (after Miller, 1998)

Back to top

What Were we Trying to Determine?

The key questions we were trying to evaluate during our survey include:

• What is the current state of affairs for long-term ambient groundwater quality and water-level monitoring in the state?
• Where is groundwater systematically monitored over time in the state?
• Who’s doing the work?
• What’s being measured?
• How frequently are the measurements made?
• What is the quality of the data collected?
• Why is the groundwater data collected, and how is it used?
• Could the local monitoring programs collectively comprise a statewide groundwater monitoring system?
• Are there clear gaps in the current monitoring that the Environmental Assessment Program groundwater group could fill?

Back to top

How did we Conduct our Survey?

To help find the answers to these questions, local, state, and federal agencies involved in groundwater characterization or management were contacted for information about their groundwater monitoring activities.  The survey focused on identifying active, on-going groundwater monitoring programs that repetitively measure ambient groundwater quality or water-level conditions over time.

The survey did not attempt to summarize groundwater monitoring efforts that focus on point source conditions (such as landfills and hazardous waste sites), or to describe the many one-time groundwater characterization efforts that have been conducted by local, state, federal, academic or private organizations.  As the federal agency responsible for study and monitoring of water conditions across the nation, the U.S. Geological Survey (USGS) in particular conducts a number of characterization studies across the state that generate baseline data for ambient groundwater quality or water-level conditions.  To learn more about those efforts go to:  USGS Washington District Office - Projects and Studies.

Back to top

Survey Results

The figures below show the location of the active groundwater monitoring programs identified during our survey.  Figure 2 shows the areas where groundwater quality is routinely monitored; Figure 3 shows the areas where groundwater water levels (or elevations) are regularly measured.  Comparing the monitoring program maps in Figures 2 and 3 to the map showing the extent of the principal surficial aquifers of the state (Figure 1) it is clear that large portions of the state’s groundwater resource are not routinely monitored over time.

Figure 2 - Local Groundwater Water Quality	Figure 3 - Local Groundwater Water Level

Table 1 below summarizes the results of our survey.  The monitoring of ambient groundwater quality and water-levels, where it is occurring, is primarily being conducted at the local level.  Local monitoring programs are often designed in response to specific groundwater issues such as known degradation of groundwater quality due to non-point pollution sources or declining water table elevations due to heavy groundwater withdrawals.  Because these programs are largely run by an array of local government departments, the reasons for monitoring, the parameters measured, the frequency of measurement and the quality of the data vary widely.  To learn more about the individual groundwater monitoring programs identified during our survey, follow this link: Groundwater Monitoring Program Descriptions.

Table 1. Groundwater Monitoring Programs Active in Washington state - 2002

Groundwater Quality

In addition to the programs listed in Table 1, the Washington state Department of Health (WDOH) is responsible for overseeing water quality monitoring of public drinking water supply wells.  WDOH requires monitoring of about 5,000 Group A and 12,000 Group B groundwater-derived public water supplies across the state.

Group A systems are required to monitor annually for nitrate, and periodically for bacteria, organic and inorganic chemicals, and other select parameters.  Certain parameter groups (pesticides, synthetic organic compounds) may be waived depending on past monitoring results and the likelihood of contamination.

Group B wells are required to monitor once for inorganics, and every three years for nitrate.  While the WDOH data have not often been evaluated on an area-wide scale, an increasing number of county governments are assembling and analyzing the data for their areas of concern.  To learn more about the state Department of Health’s Drinking Water Program go to: Washington State Department of Health Drinking Water Program.

While the WDOH drinking water monitoring program is an extensive and valuable source of information, the data from this program is of limited use for characterizing ambient state groundwater quality conditions (groundwater water levels are not routinely reported under the WDOH program).   Some of the reasons for this include:

• Public water supply wells tend to be installed in deeper, less contaminated portions of aquifer systems (wells found to be above drinking water standards are often deepened or abandoned), biasing the sampling results away from the most vulnerable portions of aquifers.
• The long screen length and high-volume pumping rates of public supply wells don’t provide representative samples of aquifer water quality conditions.
• The requirements for monitoring certain parameter groups such as pesticides are waived for many systems due to the assumption that there is a low risk of contamination.  Nitrate is the only parameter that is consistently monitored on a state-wide basis.
• The frequency of sampling is often too low and is not designed to evaluate trends or changes over time.  There is little or no quality assurance sampling conducted through this program, further limiting the usefulness of the data.
• The test parameters required are focused on a specific list of drinking water contaminants that don’t necessarily provide a complete picture of aquifer water quality conditions.
• The WDOH program does not provide data for the more than 800,000 private domestic wells currently present in the state.  Domestic groundwater wells tend to be constructed in the shallower, more vulnerable portions of aquifer systems, where early recognition of changes in water quality is most likely and most needed.

One-time sampling of water quality in newly constructed private wells falls under county supervision.  The parameters sampled and the quality of the data varies between counties and limits it usefulness.  Nitrate and bacteria are the parameters most frequently monitored.  Typically, data are stored in paper files.  However, some counties are entering results into databases with other key information such as well location, well log, and water level at time of construction.  The primary reason for collecting these data is to check for compliance with drinking water standards.  Some counties, however, intend to use the data to monitor trends in aquifer water quality over-time.

Groundwater Water Levels

Water level data is collected at both the local and state level.  In most areas, water levels are measured in conjunction with water quality sampling.  Counties that are experiencing rapid growth tend to have more extensive water-level networks.  Ecology’s Water Resource Program operates groundwater water level networks from its four regional offices.  The number and distribution of wells varies by region, with the majority of wells located in the two regions east of the Cascades.  Water level data collected by Ecology provides information on long-term water level changes for use in the analysis of water availability, irrigation impacts and drought effects.  Data from each region are either stored as paper files or electronically and are not easily accessible to other users. 

Back to top

What Does This Mean for the Status of Ambient Groundwater Monitoring in the State?

Here’s a summary of some of the key findings of our survey:

Groundwater Quality

• Local groundwater monitoring efforts cover only a small portion of the primary aquifers of the state and vary in parameters measured, methods of measurement, data quality, and degree of long-term commitment.
• While a valuable resource, the WDOH data from public supply wells has limited usefulness for characterizing ambient aquifer water quality conditions, particularly for tracking changes over time.
• County-supervised, one-time sampling of new private wells provides information on the quality of shallow aquifer systems in developing areas.  In some cases land use in these areas is changing quite rapidly.  However, this monitoring data is of limited use, because there is no follow-up sampling and only a few drinking water parameters are typically sampled.
• While a number of groundwater investigations and sampling studies have been and are being conducted across the state, most of these studies are short-term.   Very few programs are actively collecting and evaluating changes in water quality over time.
• The existing groundwater quality data would be difficult to synthesize on a larger scale.  The spatial coverage is incomplete across the state, parameters tested vary from location to location, data quality and methods are often inconsistent or undocumented, and the data are not always accessible electronically.
• Assembling data for one parameter, nitrate, from various sources around the state could be useful for discerning yet undiscovered problems.  Nitrate is one parameter for which data have been widely collected across the state, there is a relatively long period of record, and the data quality is reasonably reliable.  Nitrate is a common indicator of a variety of contaminant sources, and nitrate concentrations in groundwater are often considered a conservative (early) measure of aquifer vulnerability to surface contamination.

Groundwater Water Levels

• Local groundwater level monitoring efforts usually occur in conjunction with water quality monitoring and therefore cover only a small portion of the primary aquifers of the state.
• Counties that are experiencing rapid growth and/or have a high groundwater use tend to have more extensive water level networks.
• Ecology conducts the most water level monitoring in the state.  The number and distribution of wells varies by region.  Water level networks exist in areas of high groundwater use or where problems have been identified.
• As with groundwater quality data, water level data is limited in its spatial coverage, quality of the data is mixed and data is usually not easily accessible electronically.

Our survey revealed that the extent and quality of monitoring for groundwater conditions falls well short of the value of the resource to the state. This is true particularly in light of our state's increasing reliance on groundwater, and the vulnerability of the resource to contamination or overuse.  One of the most significant gaps in our knowledge about state groundwater conditions is the lack of information about the quality of water in shallow aquifers tapped by private domestic wells or smaller water system wells.  In particular, limited data are collected to track changes in groundwater quality beneath areas undergoing rapid development.  Reductions in recharge, changes in climatic patterns, and increasing pumpage in actively developing areas also highlight a critical need for more data on trends in groundwater levels over time.

Back to top

Future Efforts – Where do we go From Here?

The survey of current monitoring efforts is an early step in the development of strategic recommendations to the Environmental Assessment Program management team outlining priorities for future groundwater monitoring efforts for the program’s groundwater team.  To learn more about this strategic planning project, which is scheduled to be completed by December 2002, go to Strategic Planning for Groundwater Monitoring.

Back to top

For more information, please contact Pam Marti at pmar461@ecy.wa.gov or Barb Carey at bcar461@ecy.wa.gov.

Copyright © Washington State Department of Ecology. See http://www.ecy.wa.gov/copyright.html.

Copyright © Washington State Department of Ecology Contact Us | Privacy Notice | Site Info | Accessibility