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.
|For detailed descriptions of the individual groundwater monitoring programs identified during our survey, see Groundwater Monitoring Program Descriptions.|
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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.
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The key questions we were trying to evaluate during our survey include:
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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.
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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.
|Area No.||GWMA||No. of Wells||Water Level||Water Quality||Nitrate||Bacteria||General Chemistry||Metals||Organics|
|Water Quality Networks|
|King County - GWMAs||5||·||59||·||·||·||·||·|
|City of Lacey||9||6||·||·||·||·|
|City of Olympia||9||20||·||·||·||·||·||·||·|
|City of Tumwater||9||16||·||·||·||·|
|Water Level Networks|
|King County Vashon/Maury||5||·||21||·|
|Washington Dept. of Ecology|
|Central Regional Office||12A||244||·|
|Eastern Regional Office||12B||70||·|
|Northwest Regional Office||12C||22||·|
|Southwest Regional Office||12D||33||·|
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:
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.
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.
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Here’s a summary of some of the key findings of our survey:
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.
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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.
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For more information, please contact Pam Marti at firstname.lastname@example.org or Barb Carey at email@example.com.
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