Oregon Administrative Rules › Chapter 690 - WATER RESOURCES DEPARTMENT › Division 9 - GROUNDWATER INTERFERENCE WITH SURFACE WATER › Section 690-009-0040 - Determination of Hydraulic Connection and Potential for Substantial Interference

Current through Register Vol. 63, No. 7, July 1, 2024
For the purposes of permitting and distributing ground water,
				the potential for substantial interference with surface water supplies shall be
				determined by the Department.
(1) The
			 Department shall determine whether wells produce water from an unconfined or
			 confined aquifer. Except for wells that satisfy the conditions in section (2)
			 of this rule the Department shall further determine whether the aquifer is
			 hydraulically connected to the surface water source. The basis of the
			 determination shall be information provided on the Water Well Report for any
			 well in question. If there is no Water Well Report available or if the
			 information provided is inadequate, the Department shall make the determination
			 on the basis of the best available information. Such information may include
			 other Water Well Reports, topographic maps, hydrogeologic maps or reports,
			 water level and other pertinent data collected during a field inspection, or
			 any other available data or information that is appropriate, including any that
			 is provided by potentially affected parties.
(2) All wells located a horizontal distance
			 less than one-fourth mile from a surface water source that produce water from
			 an unconfined aquifer shall be assumed to be hydraulically connected to the
			 surface water source, unless the applicant or appropriator provides
			 satisfactory information or demonstration to the contrary. Department staff may
			 provide reasonable assistance to the applicant or appropriator in acquiring the
			 satisfactory information.
(3) The
			 Department shall determine the horizontal distance between any well in question
			 and the nearest surface water source on the basis of the edge of the surface
			 water source as also determined by the Department.
(4) All wells that produce water from an
			 aquifer that is determined to be hydraulically connected to a surface water
			 source shall be assumed to have the potential to cause substantial interference
			 with the surface water source if the existing or proposed ground water
			 appropriation is within one of the following categories:
(a) The point of appropriation is a
			 horizontal distance less than one-fourth mile from the surface water source;
			 or
(b) The rate of appropriation is
			 greater than five cubic feet per second, if the point of appropriation is a
			 horizontal distance less than one mile from the surface water source;
			 or
(c) The rate of appropriation is
			 greater than one percent of the pertinent adopted minimum perennial streamflow
			 or instream water right with a senior priority date, if one is applicable, or
			 of the discharge that is equaled or exceeded 80 percent of time, as determined
			 or estimated by the Department, and if the point of appropriation is a
			 horizontal distance less than one mile from the surface water source;
			 or
(d) The ground water
			 appropriation, if continued for a period of 30 days, would result in stream
			 depletion greater than 25 percent of the rate of appropriation, if the point of
			 appropriation is a horizontal distance less than one mile from the surface
			 water source. Using the best available information, stream depletion shall be
			 determined or estimated by the Department, employing at least one of the
			 following methods:
(A) Suitable equations and
			 graphical techniques that are described in pertinent publications (such as
			 "Computation of Rate and Volume of Stream Depletion by Wells", by C.T. Jenkins,
			 in:
"Techniques of Water-Resources Investigations of the United States
			 Geological Survey: Book 4, Chapter D1")
;
(B) A computer program or ground water model
			 that is based on such or similar equations or techniques.