BP BHEAD INT H

AN ACT Relating to the hydraulic continuity of ground and surface waters; and adding new sections to chapter 90.44 RCW.

BE IT ENACTED BY THE LEGISLATURE OF THE STATE OF WASHINGTON:

NEW SECTION. Sec. 1. A new section is added to chapter 90.44 RCW to read as follows:

(1) Section 2 of this act establishes criteria to guide the department in making determinations whether the water in wells is in hydraulic continuity with surface water.

(2) For the purposes of this section and section 2 of this act:

(a) "Confined aquifer" means an aquifer in which ground water is under sufficient hydrostatic head to rise above the bottom of the overlying confining bed.

(b) "Confining bed" means a layer of low permeability material immediately overlying a confined aquifer.

(d) "Director" means the director of ecology.

(e) "Hydraulic continuity" means a connection between the water in a body of water located on the surface of land and water located in a subsurface aquifer as determined under section 2 of this act.

(f) "Unconfined aquifer" means an aquifer in which the hydrostatic head at the upper surface of the ground water is atmospheric.

NEW SECTION. Sec. 2. A new section is added to chapter 90.44 RCW to read as follows:

For the purposes of permitting and distributing ground water, the hydraulic continuity of ground water with surface water 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 subsection (2) of this section, the department shall further determine whether the aquifer is hydraulically continuous to the surface water source. Where the aquifer is a confined aquifer, the burden of proof of the determination of whether the aquifer is hydraulically continuous to the surface water source is on the department. The determination of whether the aquifer is hydraulically continuous shall be based on a finding that there exists a clear and direct relationship between a surface water body and the ground water source from which water would be withdrawn. The relationship must be demonstrable through a reasonable and repeatable test, or tests, that can be applied in the field, and that apply generally accepted methods of hydrogeologic science. The information from the field tests shall be provided in the well water 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 continuous 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 by field evidence to be hydraulically continuous 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;

(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;

(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 eighty percent of the 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 thirty days, would result in stream depletion greater than twenty-five 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:

(i) 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");

(ii) A computer program or ground water model that is based on such or similar equations or techniques.

(5) Any wells, other than those covered in subsection (4) of this section, that produce water from an aquifer that is determined to be hydraulically continuous to the surface water source may be determined by the department to cause substantial interference with the surface water source. In making this determination, the department shall consider at least the following factors:

(a) A reduction in streamflow or surface water supply;

(b) An impairment or detrimental effect on a surface water appropriation, minimum perennial streamflow, or instream water right with a senior priority date;

(d) There is interference and such interference would be immediate or delayed; and

(e) Demonstrable cumulative adverse impacts on streamflow or surface water supply.

(6) All wells that produce water from an aquifer that is not hydraulically continuous to a surface water source shall be assumed not to interfere with the surface water source.