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August 19, 2015  |  Written by Aaron A. Ferguson

Draft Basin Boundary Regulations Released by Department of Water Resources

The Sustainable Groundwater Management Act (SGMA) established a process for local agencies to request that the Department of Water Resources (DWR) revise the boundaries of a groundwater basin.  The SGMA required DWR to develop regulations that set forth the process for local agencies to request a boundary revision, and include the methodology and criteria that DWR will use to evaluate basin boundary revision requests.  On July 17, 2015, DWR issued draft basin boundary revision regulations.  Local agencies are encouraged to review and comment on the draft regulations as appropriate because the basin delineations could directly impact the ability of local agencies to achieve sustainable groundwater management, as required by the SGMA to avoid state intervention.

Under the draft regulations, a request for a modification may only be made by a local agency whose jurisdiction lies within or borders the basin or subbasin.  The draft regulations would require agencies to coordinate modification requests where multiple requests affect the same basin or subbasin.  The draft regulations propose that DWR use 60-day review periods to evaluate boundary revision requests on their merits and to accept protests.  Importantly, protests would be held to the same scientific and technical standards as a boundary revision request, and DWR will evaluate protests according to the same criteria as the proposed basin modification.

The draft regulations apply to the basins in DWR’s Bulletin 118, which contains the operative basin and subbasin boundary descriptions for the basins subject to the SGMA.  According to the draft regulations, DWR will consider two types of boundary modifications:  (1) scientific modifications based on geologic or hydrologic criteria, and (2) jurisdictional modifications designed to promote adoption and implementation of sustainable management plans and enhance local management of groundwater.

The draft regulations set forth various substantive requirements for scientific modifications, which are defined as a modification that “involves the addition, deletion, or relocation of a boundary based on the geologic or hydrologic conditions” including an external boundary modification or a hydrogelogic barrier modification.  An agency requesting a scientific modification must provide a map and subsurface data describing the geology and hydrogeology of the aquifer.  A scientific request must also include information demonstrating consultation with interested parties.

The draft regulations also contain requirements for jurisdictional modification requests – i.e., an internal boundary modification, a basin consolidation, or a basin subdivision.  Essentially, this type of request involves an adjustment in a boundary shared by two or more basins or subbasins, but that does not propose an adjustment to the external boundary of the basin or subbasins involved.  Proponents of a jurisdictional modification would have to provide an applicable water management plan, and supporting documentation on groundwater levels and quality, land subsidence and groundwater-surface water interactions, recharge areas, and existing and planned coordination efforts.  Agencies proposing jurisdictional modifications must not only provide evidence of notice and consultation with the interested parties, but must also provide evidence of local support from affected agencies.

The SGMA requires DWR to review requests to determine whether the proposed basin can be sustainably managed, whether the proposed basin would limit sustainable groundwater management in adjacent basins, and whether there is a history of sustainable management of groundwater levels in the proposed basin.  Under the draft regulations, for scientific modifications, DWR would consider the technical adequacy of hydrogeologic models, qualified maps and potentiometric surface maps against known geologic and hydrogeologic conditions, and the presence or absence of a groundwater flow boundary.  For jurisdictional modifications, DWR would consider evidence in existing water management plans of the effect of management practices and the response of the aquifer to these practices.  For jurisdictional modifications that involve the addition or deletion of shared boundaries, the regulations call for submittal of technical information.

The draft regulations specify that DWR may deny a request if there are significant unresolvable concerns, including, but not limited to: that the proposed modification would limit sustainable groundwater management in the proposed or adjacent basins, storage, or coordination and use of consistent data by local agencies.  DWR may also deny a request where the local agency is unable to demonstrate a history of sustainable management in the existing or proposed basin, or the boundary modification could result in isolation of areas with known problems, or in the creation of unmanaged areas.

DWR is currently accepting comments on the draft regulations and will hold a series of meetings in late August and September in Sacramento, Bakersfield and Santa Ana to discuss the draft regulations.  The comment deadline is September 4, 2015.  Comments may be submitted by e-mail to DWR at  DWR is proposing to complete formal adoption procedures this fall and have the regulations in place by January 1, 2016.  To view a copy of the draft regulations, visit this site.

For further information, please contact Aaron A. Ferguson at

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