The Deschutes Basin Groundwater Mitigation Program controls how much groundwater can be pumped out of the ground for municipal, agricultural, manufacturing, and other uses.  Written into law in 1995 and first implemented in 2002, the Mitigation Program established a cap of 200 CFS (cubic feet per second) of new groundwater rights and requires that most withdrawals be “mitigated” by new surface flows from another source.  After 20 years, there is still approximately 20 CFS left in the cap.  By statute, every 5 years the Oregon Water Resources Department is required to submit their review of the program, including the consideration of public comments.  That review is currently underway with comments due by August 25, 2021.  Comments can be made to Sarah Henderson, OWRD Flow Restoration Program Coordinator, at sarah.a.henderson@oregon.gov.

This is a hugely complex and contentious issue, but one that has been, and will continue to be, exceptionally impactful on all Central Oregonians.  It will weigh heavily on long term population growth, local agriculture, recreation, and the health of fish and wildlife.  Keep reading for more.

The west side of the Cascade Range in Central Oregon is composed of relatively young volcanic deposits that have not had time to break down and therefore remain extremely porous.  As a result, both rain and melting snow are quickly absorbed into the ground. There is very little surface runoff as commonly found in other parts of the Cascades and other mountain ranges.  This permeability creates a large aquifer that emerges as springs starting high in the Cascades and continues all the way down to Lake Billy Chinook (LBC).  The Deschutes, Metolius, Fall, and Spring Rivers as well as east slope creeks such as Whychus, Tumalo, Bridge, and Jack are the result of spring discharges at their headwaters and are fed by additional springs over their lengths.  It is believed that the entire aquifer is discharged by the time it meets LBC.

In the 1990s the United States Geological Survey conducted a study showing the direct connection between ground and surface water in the Upper Deschutes Basin.  Every gallon of water taken from the aquifer via a well reduces the flow of a spring and hence a river downslope from the well. Under the state Scenic Waterway Act, this meant that the state could no longer issue groundwater permits unless “mitigation” was provided.  The Mitigation Program is quite complex, but the goal is to protect surface flows in rivers and streams by requiring some, but not all, groundwater pumping to mitigate its impact on flows by providing water from another source.  

If someone wants to take a gallon of water out of the ground they must find water to put back in the impacted surface waterway.  (Note that mitigation is not one for one, see below.)  Given that the rights to 88% of the available water in the Upper Deschutes Basin is controlled by irrigators, essentially all the water available for mitigation comes from them.  A cap of 200 CFS of new groundwater pumping was created, of which there is still approximately 20 CFS remaining.

Every 5 years the Oregon Water Resources Department is required by statute to submit their review of the program to the Oregon legislature, including the consideration of public input.  That review is currently underway with comments due by August 25, 2021.  Comments can be made to Sarah Henderson, OWRD Flow Restoration Program Coordinator, at sarah.a.henderson@oregon.gov.  Here is the OWRD website for the mitigation program.

The draft report is 74 pages long, including comments on the prior draft.  If you are not familiar with the program, absorbing the report will be challenging, so here is my executive summary.  The bottom line is that this is a hugely complex and contentious issue, but one that is, and will be, exceptionally impactful on all Central Oregonians. 

The interest groups can be grouped into 4 categories.  OWRD, irrigators, cities, and those concerned with environmental issues such as Oregon Department of Environmental Quality, Oregon Department of Fish & Wildlife, WaterWatch of Oregon, and others. 

OWRD acknowledges some issues but characterizes the Mitigation Program as a success and claims that the goals of the program have been met.  I disagree.  OWRD’s claim of success is based on measuring average flows in various waterways, they do not take into consideration the timing and variability of flows, which can be extreme.  Fish, wildlife, and even recreational users need constant flows at an acceptable minimum to meet the goals of the program.  Measuring flows as averages masks when they are low enough to kill fish and wildlife or make the river unsuitable for recreational use.  Like us, fish and other forms of aquatic life need oxygen to breathe every day, not just most of the time. 

OWRD also does not take into consideration the quality of the water being used for mitigation.  Cold, clean spring water replaced with warm, possibly polluted water stored for irrigation is not an equal replacement.  Protecting water quality is not a specific goal of the program, but I believe it should be.

In their submitted comments, the Oregon Farm Bureau and local County Farm Bureaus dispute the science that is the basis of the Mitigation Program and question the need for the program at all.  They state that water rights owned by irrigators should not be used for mitigation, even if an individual water right owner wishes to do so.  They argue that reduced water consumption by an irrigator lowers the value of other agricultural lands and threatens the local agricultural economy.

The Central Oregon Cities Organization questions some of the rules in the Mitigation Program in their comments.  They want to obtain mitigation credits more easily and increase the 200 CFS cap to meet their water needs in the future.  To that end, they also believe that water quality and stability of flows should not be considered in the program.  It is important to note that local cities are not in danger of running out of water in the near term.  The City of Bend, for example, believes they already have enough to meet their projected needs in 2040. 

ODFW, ODEQ, WaterWatch, and one individual citizen commenter expressed far different perspectives.  There are many details that I am omitting, but the big picture is that even with the Mitigation Program in place, the aquifer is shrinking, discharges from springs appear to be declining, and waterway flows are erratic and sometimes lethally low.  Most of the Deschutes River is covered by the State Scenic Waterway Act which states that the best uses of the river are for recreation, fish, and wildlife.  As Oregon courts have stated, this is not occurring.

I agree with the comments made by ODFW, ODEQ, and WaterWatch but want to highlight a couple of issues.

“Exempt” wells are not covered by the mitigation program.  Frequently, these are wells that are drilled for an individual home but can also be for small scale commercial, industrial, and agricultural uses.  There are over 21,000 exempt wells in the Basin. There are stated limits on how much water is to be extracted from an exempt well, but there is no monitoring or enforcement of the rule.  This is a problem and provides a significant loophole for continued development.  Rather than building multiple homes connected to a shared water system that would need mitigation, individual homes can be built, each with their own, unmonitored well.  Full disclosure: I have an exempt well and support the idea of requiring monitoring and enforcement of water use limits.

Another issue is that the amount of mitigation required is based on the concept of “consumptive use”.  The idea is that if water is taken out of the ground, a portion returns to the aquifer.  For example, some of the water used in irrigation will be consumed by a plant, but some will not.  OWRD has a table in the report that gives their assumptions on how much water is consumptively used by irrigation, municipal use, mining, domestic use, etc.  They provide no supporting evidence for their “consumptive use coefficients” nor do they cite any research supporting these claims.

The concept makes intuitive sense, and probably occurs in places.  Unlined irrigation canals, for example, do leak water and it appears that water makes it back to the aquifer (although far downstream from the point of diversion).  I believe that the volume of water and constant saturation for most of the year that occurs in a canal is an exception.  The very dry soil conditions in the high desert, especially in our frequently occurring drought conditions, leads me to question the amount of aquifer recharge occurring outside of irrigation canals.  Just how much water sprinkled on a lawn really makes its way down to the aquifer? 

In my mind, this is very important.  If a gallon of water is pumped out of the ground but only 40% of that is replaced by mitigation water (the figure for municipal use), and the other 60% does not eventually return to a river, then the program will never meet its goals.