Mitigation must be provided within the zone of impact (location) specified by the Department. In general, WRD identifies a single zone of impact for each groundwater permit application. The Mitigation Program divides the required location of mitigation into two areas – (1) in a general zone of impact and (2) in a local zone of impact. Mitigation under the Mitigation Program is a quantity of water that may be legally protected instream, as a result of completion of a mitigation project, which benefits the zone of impact in which a groundwater permit applicant is required to provide mitigation.
General Zone of Impact
For mitigation in the General Zone of Impact, the concept is that proposed wells with impacts in the general zone are developing water from the “regional aquifer” and their potential groundwater pumping impacts would be on the regional confluence areas of the Deschutes, Crooked and Metolius Rivers. Within this confluence area, groundwater discharges to surface water through a large spring system.
Groundwater applicants identified by WRD as needing to provide mitigation in the General Zone are required to provide mitigation that benefits streamflows in the confluence area of the Deschutes, Metolius, and Crooked Rivers. Instream flows for mitigation must originate upstream from the Madras Gage, located approximately at River Mile 100.1 on the mainstem Deschutes River. By providing mitigation upstream from this point, mitigation is targeted upstream from and into this spring area.
Local Zones of Impact
For proposed wells determined by WRD to have a localized impact on surface water, mitigation must be provided in a local zone of impact. The goal for providing mitigation in local zones of impact is to target mitigation in and above (upstream of) stream reaches, on a sub-basin level, where impacts on streamflows by groundwater pumping occur and where instream flows (instream water rights and scenic waterway flows) were not being met.
The local zones of impact at this time include:
Groundwater permit applications found to have an impact on surface water flows in this zone must provide mitigation that benefits instream flows in Whychus Creek beginning upstream from River Mile 16.
Groundwater permit applicants found to have an impact on surface water flows in the Crooked River must provide mitigation that benefits instream flows in the Crooked River with instream reaches beginning upstream of River Mile 13.8.
Groundwater permit applicants needing to provide mitigation within this zone are required to provide mitigation that originates upstream from River Mile 28 to target mitigation into the reach of the Metolius River that is affected by groundwater use.
Groundwater permit applicants found to impact surface water flows in this zone, must provide mitigation that benefits instream flows in the Little Deschutes River beginning upstream from the mouth of the river.
Groundwater permit applications found to have an impact on surface water flows in this zone must provide mitigation that benefits instream flows within the Deschutes River upstream (above) of River Mile 125.
Groundwater permit applicants found to impact surface water flows in this section of the Deschutes River, must provide mitigation that benefits flows with instream reaches beginning upstream from River Mile 185.
Please note that the zone of impact, as identified by the Department, within which mitigation must be provided may not be the same basin area in which the proposed well(s) is located. Location of the well(s) is only one factor in determination of the zone of impact.