Mapping and GIS Data

• PDF Version 
  
• Excel Version (includes full data set) 
• Notes​

This dataset includes total square miles and total percentage of land use for each generalized land use/ownership category for each surface water source area. Excel table can be sorted by watershed, county, population served, or specific land use. See Notes for data sources, methods, and data limitations.  ​

​Map 1:  Oregon surface water drinking water source areas with land use/ownership

Expanded views 

• Map 1A: Northwest Oregon 
  
• Map 1B: Southwest Oregon  
• Map 1C: Eastern Oregon 

Figure 1: Approximate percentage of land uses with drinking water source areas for surface water ​

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​​Map 2: Surface water drinking water source areas with land use/ownership and soils with high erosion potential​​​​

The high soil erosion potential data is based on Natural Resource Conservation Service and National Forest Service data for slope (>30%) and “Kf” (a “rock-free” soil erodibility factor of 0.25 or greater) which quantifies the susceptibility of soil particles to detachment and movement by water including the effects of rainfall, runoff and infiltration. Soils with "high" soil erosion potential are considered more sensitive to ground disturbance. Other assessment methods (see Maps 6 and 7) ay be more appropriate for flatter terrains, varied slopes, or in areas where Kf  is not available. In the Updated Source Water Assessments, this method is primarily used only for US Forest Service lands where the other assessment methods (Maps 6 and 7) are not available.

Expanded views

• Map 2A: Northwest Oregon  
• Map 2B: Southwest Oregon   
• Map 2C: Eastern Oregon​​

​​​Map 3: Oregon surface water drinking water source areas with DOGAMI landslide inventory

Expanded views

• Map 3A: Northwest Oregon
• Map 3B: Southwest Oregon 

• Map 3C: Eastern Oregon ​
  

​Map 4: Domestic/Private surface water rights

EPA and Oregon regulations that protect public drinking water systems do not apply to private water supplies, however knowing where domestic withdrawals occur is important to identify water users in watersheds and protect public health. This map shows the density of “domestic”(private) points of surface water diversion identified in the Oregon Water Resources Department water rights database.  It is important to note that this is likely a subset of all domestic water users as many domestic water users may not hold water rights. ​

Map 5: Treatment system susceptibility for public water systems using surface water 

This map shows the types of drinking water treatment technologies employed by public water systems in Oregon and their relative susceptibility to particulate matter and turbidity in the water.​​

​Map 6: Surface water drinking water source areas with NRCS Soil Erosion Hazard Ratings - Off-Road/Off-Trail  (for management activities such as silviculture, grazing, mining, urban development, fire, firebreaks, etc with <75% soil surface disturbance)

This dataset provides surface erosion hazard ratings for areas where up to 75% of the soil surface is disturbed by non-road and non-trail uses (such as uncontrolled grazing, forestry, heavy equipment use, fire control, and mining). The erosion hazard ratings are calculated by the Natural Resource Conservation Service using inherent soil properties for whole soil erodibility and slope. This method underestimates erosion hazard for Histosol soils and for gully erosion, plowing or other disturbances that “disturb up to nearly 100 percent of the area and change the character of the soil”. Other assessment methods (see Map 7) may be more appropriate for flatter terrains with 75-100% soil disturbance. In the Updated Source Water Assessments, DEQ mapped only those locations where risk is moderate or higher AND that are within 300 feet of surface water in order to estimate those places where delivery to water is possible. Where NRCS soils data is not available (typically National Forest Lands) Soil Resource Inventory information from the US Forest Service can be used to evaluate erosion potential (see Map 2).

Expanded views

• ​ Map 6A: Northwest Oregon  
• Map 6B: Southwest Oregon   
• Map 6C: Eastern Oregon​

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Map 7: Surface water drinking water source areas with Oregon Department of Agriculture (ODA)
Soil Erosion Vulnerability Index Ratings (for areas with >75% soil disturbance (such as tilled or bare soil with lower slopes (i.e. valleys and agricultural lands)
 
This dataset shows ODA’s Erosion Vulnerability Index that is calculated utilizing USDA Natural Resource Conservation Service Revised Universal Soil Loss Equation-2 (RUSLE2) assuming exposed soil without plant roots and lacking conservation practices to reduce erosion. Therefore, this index reflects erosion risk from severe agricultural disturbance without mitigating measures in place. It does not evaluate delivery to surface waters. In the Updated Source Water Assessments, DEQ maps only those locations where RUSLE2 values are moderate or higher AND slopes are low enough for intensive agriculture (<=30%) AND that are within 300 feet of surface water in order to estimate those places where delivery to water is possible. Where NRCS soils data is not available (typically National Forest Lands) Soil Resource Inventory information from the US Forest Service can be used to evaluate erosion potential (see Map 2).

Expanded views