Resources
Groundwater Models
for South Deschutes County
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Data and Information Available: (PDF):
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Project Links .. Groundwater Protection Project Home .. Background .. Project News
Financial Assistance .. Financial Assistance for Groundwater Protection .. Pollution Reduction Credit Program .. Transferable Development Credit (TDC)
Wastewater Treatment Alternatives .. New or Expanded Sewer Systems
Technical Information .. How Well do Onsite Systems Work? .. USGS Reports .. Nitrates and Drinking Water .. Pharmaceuticals and Personal Care Products
Historical Information .. Public Record for the Local Rule |
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Model results if no action taken |
Model results if 20 mg/L systems required |
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Summary:
Deschutes County, Oregon Department of Environmental Quality (ODEQ) and the US Geological Survey (USGS) began a partnership in 1999 that resulted in comprehensive groundwater evaluations of south Deschutes County and detailed modeling of the groundwater and nutrient fate and transport in the region. The detailed three-dimensional (3-D model) modeling produced a deep understanding of the vulnerability and capacity of the region's aquifer to accept or be degraded by human sources of pollution. The 3-D model graphically illustrated the potential consequences if no actions are taken to protect groundwater from nitrate pollution.
The model also illustrated how groundwater can be protected using new types of onsite wastwater treatment systems that reduce nitrates in their discharges. (Maps provided are examples of the model scenarios.)
In 2005, the USGS completed additional work that transformed the 3-D model into a more powerful management tool. This new tool, called the Nitrate Loading Management Model, produces performance standards for development in the region given specific conditions that need to be met. Once the desired conditions for the region are entered, the model produces the performance standards that need to be met by onsite wastewater treatment systems in order to protect drinking water quality. Required model conditions can include requiring that the groundwater continues to meet safe drinking water standards and/or the wastewater treatment capabilities of systems currently available in the market.
The map entitled "Loading Reduction: Existing Homes" provides an example of the kind of results the Nitrate Loading Management Model can produce. The numbered and colored areas are called "management areas." This example shows that the existing wastewater treatment systems in the region can be upgraded with nitrogen reducing systems to meet water quality goals. An important fact to note is that the nitrogen reduction standard that needs to be met changes according to the property's location within the region. The difference in standards by management area is caused by differences in development patterns and densities, groundwater vulnerability, and impacts from pollution sources in neighboring management areas.
Bend Bulletin article, December 20, 2006 - PDF of an article describing how the groundwater system works in south Deschutes County.
Bend Bulletin article, December 21, 2006 - PDF of an article about the Groundwater Science Open House.