Stakeholder Input

RWMP Feedback

Water quality is one of four main elements in the Department of Water Resources (DWR) specification for an Integrated Regional Water Management Plan. MWA has regional management authority for the rapidly growing and strategically located Mojave and Morongo basins and has developed its Regional Water Management Plan (RWMP) to guide water resource management through year 2020. MWA’s responsibility, and the overall objective of the RWMP, is to develop strategies to balance future demands and to maximize overall beneficial use of water. Water quality is one of six key water management issues identified in the RWMP.

Development of the RWMP involved extensive outreach to the public, cooperating agencies, and other stakeholders. Concern over water quality was a consistent theme in the responses

to these outreach efforts. The following points summarize outreach responses specifically relating to water quality issues:

MWA needs to mitigate significant long term increased salt levels due to import of SWP water and effectively manage recharge of imported water.

The Lahontan RWQCB sees the need for a water quality model to evaluate proposed projects especially those involving recycled water.

The wastewater infrastructure within the MWA area should be effectively monitored and managed.

Water quality planning efforts must consider the interaction between subareas or other management zone delineations.

Important natural recharge sites should be identified and such knowledge incorporated into decisions pertaining to land-use planning and recharge facility siting.

MWA should take steps necessary to limit migration of water of poor quality.

Water quality monitoring should be an important objective of the MWA monitoring network programs.

As a result of extensive investigations into the environmental, cultural, technical, and economic aspects, and incorporating the responses to outreach programs, the RWMP contains a menu of proposed projects and management actions to be initiated in the next three to five years. These actions are grouped as follows:

Monitoring

Improved characterization of the basin

Continued long-term planning

Groundwater protection

Construction and implementation

Financing

Groundwater Quality Analysis Technical Memorandum – Task 2 Page 2-7 A total of 60 specific actions were recommended. Approximately 20 of these actions will require or will indirectly but materially benefit from a comprehensive regional water quality planning model. The water quality planning model will complement other management, engineering, and technical tools to be employed in support of these actions.

Water Quality Workgroup Input

On February 15, 2005 a meeting of the Water Quality Workgroup was held at MWA headquarters in Apple Valley, California. The Water Quality Workgroup is composed of staff from MWA, the Lahontan RWQCB, SWS, and TAC. In attendance were:

MWA representatives Kirby Brill, Norm Caouette, Lance Eckhart, Curt James, and Anna Garcia

Lahontan RWQCB representative Hisam Baqai

Schlumberger representatives Mark Williamson, Bob Will, and Alge Merry

Technical Advisory Committee member Scott Weldy

The meeting was led by Bob Will, who made a presentation covering the following topics:

Overall water quality project tasks and objectives

Task 1 findings

Hydrodynamic and transport modeling fundamentals

Modeling techniques under consideration

Suggested roles of the water quality planning model

This presentation stimulated much discussion concerning the data and calibration requirements for the different modeling options, and the suitability of each option with respect to the water quality study. SWS suggestions regarding the role of the water quality planning model were formulated from the vantage of extensive involvement with MWA during preparation of the 2004 Regional Water Management Plan and earlier phases of the

water quality project. These suggestions, outlined in the introduction to this section, were well received by the Water Quality Work group.

Discussions during the Water Quality Workgroup meeting yielded several important points for consideration in determining the role of the water quality planning model and selecting the appropriate modeling platform.

Model Simplicity – It was agreed that the complexity of the water quality planning model will be constrained by limitations in both the current water quality dataset and the regional scale conceptual hydrogeological model for the area.

Use of a Proxy Hydrodynamic Model – The technical review included the hydrodynamic proxy model using the Stella model platform used in the 2004 RWMP using proxy head-flow relationships derived from the 2001 USGS ModFlow model. The method of developing the proxy relationships was discussed by the Workgroup. It was agreed that this procedure would be acceptable for the water quality planning model.

Proxy Transport Model – The technical review included a discussion of the distinct data requirements for hydrodynamic and transport process modeling. The need for a transport proxy model was acknowledged and discussed by the Workgroup. The different options for using the 2001 USGS MODFLOW model for this purpose were discussed.

Transient vs. Steady State Model – The technical review included a brief discussion of methods available for modeling steady state and transient systems. The method used for “pseudo-transient” modeling for the 2004 RWMP was discussed. The Workgroup agreed that this method would be deemed adequate for use in the water quality planning model.

Model Calibration – It was understood and agreed by the Water Quality Workgroup that transport processes of the water quality planning model could not be rigorously calibrated against historical data. The initial conditions for constituent distributions in

Groundwater Quality Analysis Technical Memorandum – Task 2 Page 2-9 the model will be based upon available data. Once water quality sample data has been interpolated into the discretized water quality planning model framework, the interpolated data will be checked against raw input data for spatial consistency.

Decision Support – Strong emphasis was placed on decision support aspects of the water quality planning model. Alternative evaluation and operational scenario modeling were highlighted as important capabilities. The ramifications of these activities with respect to model input data requirements, flexibility, and usability were discussed. The ability to easily define and model the performance of multiple operational scenarios will be a key requirement in the water quality planning model.