Pechanga Indian Reservation

Client: Pechanga Tribe
Project: Pechanga Indian Reservation

Water Rights Negotiation and Water Resources Evaluation

NRCE was retained as an engineering consultant to provide technical evaluation of water rights issues in the Santa Margarita River Basin as part of the Civil Court case in Arizona, 1247-SD-T, United States v. Fallbrook Public Utility District, et al., and to provide engineering services to assist the Tribe in developing, managing, and protecting their water resources. A comprehensive Water Development Plan for the Pechanga Reservation was prepared to serve as a basis for establishing the Tribe’s federally-reserved water rights. NRCE worked with the Pechanga Tribal Council and the Tribe’s water rights attorneys to develop strategies for settling their federally-reserved water rights and to ensure that there was a long-term, reliable, and safe water supply for the Reservation.

The water development plan established an agricultural water claim under Practicably Irrigable Acreage standards for determining Indian reserved water rights and a non-agricultural water claim for the Pechanga Reservation. The water development plan included an evaluation of the historic and current water use; analysis of surface water and groundwater resources; projection of future agricultural and non-agricultural water demands; preparation of a conceptual engineering design for an irrigation project; and economic analysis. Hydrologic and land-use base maps were prepared showing the existing conditions on the Reservation and projected future development.

NRCE attended quarterly meetings of the Santa Margarita River Steering Committee, reviewed the Annual Watermaster Reports for the Santa Margarita River, and advised the Tribe on issues discussed at the meetings, reports that are of special concern to them, and regional water developments that may impact the Tribe.

NRCE provided engineering services for an Exploratory Drilling and Aquifer Testing Program as part of the water supply evaluation for the Reservation. The objective of the program was to evaluate the groundwater resource areas on the Reservation as potential water supply sources. The construction of test wells was the main component of the program. Aerial photographs, satellite imagery, geologic maps, field investigations, and well logs were used to select six sites on the Reservation for construction of test boreholes. One of the boreholes was completed as a production well and the other five were completed as test wells. NRCE prepared contract documents and assisted the Tribe in selecting a well drilling contractor. NRCE provided field management, oversight, and analysis for well site selection; test drilling; geologic sampling and logging; well design; and well construction and development. NRCE performed aquifer tests to determine potential yield and well characteristics, and also installed water-level monitoring instrumentation, telemetry units, and monitoring software for five wells on the Reservation Tract earmarked for development.

NRCE developed a MODFLOW numerical groundwater model of the Reservation’s Pechanga Creek Basin using Groundwater Vistas software. The model was configured and calibrated to simulate transient conditions for a 38-year period of time. A statistical program was designed by NRCE to facilitate model calibration. Transient-state model runs were used to simulate the effects of recharge and pumping on the unconfined and confined aquifers of the Basin. The model was also used to evaluate the potential for land subsidence in the depositional valley that makes up the main underground reservoir for the Tribe and the area water district. Documented land subsidence in the form of ground cracks due to historical water district pumping compelled adapting the model to simulating potential aquifer compaction and subsidence scenarios from increased Tribal and water district groundwater development. In concert with subsidence modeling, NRCE recommended the installation of several extensometers near selected Reservation production wells and the establishment of approximately ten high-accuracy survey benchmarks to proactively monitor subsidence and for the collection of additional data for model data input and simulations.

Border XXI Program

NRCE was retained by the Pechanga Tribe to provide engineering services under the U.S. Environmental Protection Agency (EPA) Border XXI Program. The Tribe received a grant from the EPA through the Border XXI Program to evaluate the water and wastewater infrastructure on the Reservation. This program had three principal elements: an assessment of existing public water supply wells; a feasibility study of the existing Spring Line water system; and a feasibility study of centralized wastewater treatment and collection facilities.

NRCE provided engineering oversight and analysis of the well assessment program. The purpose of the program was to assess the four water supply wells serving the Pechanga Water System to determine their condition and suitability for long-term, safe, and reliable service. The evaluation included video logging of the well casings and screens, sonic logging of the well seals, and well pump tests to determine the well characteristics and reliable water production capacity for each well. Recommendations were made regarding the suitability of the wells for long-term service.

NRCE prepared a Spring Line System feasibility study to evaluate alternatives for the existing Spring Line water system on the Reservation. The Spring Line system was one of the original components of the Reservation water system and still provided primary service to three residences. The purpose of the study was to develop and evaluate alternative improvement measures for the system. The study assessed the condition of the spring line system, the reliability of the service it provides, and the need for improvements. Three alternative improvement measures were developed for providing continued service to the residences served by the Spring Line system. NRCE performed an alternatives analysis and recommended a preferred alternative for implementation to the Tribe. The preferred alternative was to abandon the Spring Line system and connect the remaining users to the Pechanga Water System. A preliminary design was prepared for the preferred alternative to further define facility requirements and to refine the project cost estimates.

NRCE prepared a wastewater system feasibility study to address the current and future wastewater facility needs on the Reservation. At the time of the study, all homes were served by on-site septic systems. The purpose of the study was to develop and define a preferred wastewater management approach for the Reservation. Wastewater collection and treatment alternatives were developed to provide adequate wastewater services to current and future residences over the twenty-year study period. The primary wastewater management issues that were addressed in developing the alternatives were collection system options, wastewater treatment requirements, and effluent disposal. Three wastewater management alternatives were compared: continued on-site treatment; connecting a centralized collection system to the local municipal system; and locating a centralized treatment facility on the Reservation. NRCE performed an alternative analysis and recommended a preferred option for implementation. A preliminary design was prepared for the preferred alternative to further define facility requirements and to refine the project cost estimates.

EPA 106 Program

NRCE was retained by the Pechanga Tribe to provide services under the U.S. EPA 106 Program. The Tribe receives grants from the EPA through this program to comply with National Clean Water Act programs. NRCE has prepared a Wellhead Protection Plan, a Unified Watershed Assessment, a Non-Point Source Management Plan, and a Well Inventory and Schedule for the Pechanga Tribe. NRCE is currently developing a Quality Assurance Project Plan (QAPP) and Draft Water Quality Standards.

Pechanga Creek 100-year Floodplain Analysis

The Pechanga Tribe was interested in establishing a 100-year floodplain for the purposes of planning and disaster preparedness. NRCE conducted a 100-year floodplain analysis on the entire reach of Pechanga Creek lying within the Reservation Boundaries. A hydraulic model was created (utilizing HEC-RAS software) for the reach using 2-foot topography. GIS software was used to create the channel cross sections for input to HEC-RAS. Flows were calculated using USGS gage information and a Log Pearson III analysis. The 100-year floodplain was then delineated using model water surface elevation output. NRCE produced a GIS based map of the 100-year floodplain, and in addition to a professional memo and 24”x 36” floodplain map, also provided both the model output and GIS layers to the Tribe.

Water Resources Database

NRCE also developed a hydrogeological geographic information system (GIS) database containing information on the Tribal and sub-regional surface water and groundwater resources and facilities. The hydrogeological data included groundwater levels, well production, water quality, aquifer test data, borehole locations, site descriptions, lithologic and geophysical logs, and well construction details, surface geology, stream gaging site information and flow records, climate data and other information. The database offered the ability for groundwater data manipulation and visualization, streamlined the analytical process, and provided a powerful tool and interface for hydrogeological studies such as groundwater modeling. This database currently exists in proprietary software – HydroGeo Analyst™.

Drought Contingency Plan and Water Conservation Plan

A Drought Contingency Plan was written for use by the Pechanga Tribe to take measures appropriate for the mitigation of drought impacts to the people and natural resources of the Pechanga Indian Reservation. Experience with past droughts has shown that the most effective approach to accomplish this goal is to coordinate mitigative response actions between state, federal, local, and Tribal governments, and citizen groups, in a timely manner. The Plan was intended for use by Tribal members and departments in assessing current conditions, making short- and long-term preparations for drought, and addressing the effects of drought. The purpose of the plan was to establish a policy and system for the Tribe to monitor, assess, and mitigate drought and its effects. Areas at risk on the Reservation include domestic and municipal, commercial, agricultural, livestock, wildlife, fire suppression, and recreational and ceremonial water uses. Drought indicators were defined and presented in the plan as well as the response actions for the following drought levels: near normal to wet, drought advisory, drought warning, and drought emergency. Drought mitigation measures were also presented to reduce the impact of drought when extended periods of below-average precipitation occur.

In addition, NRCE created a water conservation plan for the Pechanga Tribe that primarily addressed the proposed golf course. The water conservation plan for the golf course depended on several factors: soils, terrain, course layout, grass selection and acreage, irrigation system design, installation, control, and maintenance, irrigation scheduling, and available water sources. By implementing the plan during construction and when irrigating the golf course, the Tribe can maximize water use efficiency and use alternative water sources such as recycled water.

Wastewater Reuse

A preliminary assessment of the feasibility of creating an on-site wastewater treatment facility was conducted for recycling water (also known as water reuse) on the Pechanga Reservation. Information regarding history, laws, and regulations of water reuse were gathered, as well as historic wastewater flow data from the Pechanga Resort and Casino. The assumed intended use of recycled water was for restricted urban reuse on the Reservation, which included areas in which public access can be controlled, such as golf courses, and highway medians.

A range of secondary treatment options were evaluated, each with their own advantages and disadvantages, depending on inflow characteristics, available space, and outflow requirements. A sequencing batch reactor (SBR) was recommended since it has several advantages which make it particularly advantageous to the Pechanga Tribe, including a small footprint, high effluent quality, and relatively low costs for construction, and operations and maintenance (O&M). The costs and benefits of the SBR were presented in the final assessment report.

Golf Course Turf-Grass Water Quality Evaluation

Several sources of irrigation water were available for the proposed golf course on the Pechanga Indian Reservation. These sources ranged from groundwater from the Pechanga wells currently used for water supply to a variety of water delivered from surrounding water districts including reclaimed water, well water, and Colorado River Aqueduct Water. The quality of each of these was evaluated as potential irrigation water sources for the planned golf course. A memorandum was prepared that presented a review of water quality standards for golf course irrigation, water quality concerns for turfgrass irrigation, and a brief evaluation of the effects of irrigation applications with each type of water upon groundwater quality. The evaluation indicated that the soils should be examined closely prior to the selection of an irrigation water source due to the necessity of managing salt buildup by allowing leaching applications of water. Similar studies of groundwater below and downgradient of secondarily treated recycled water applications on golf courses show changes in pH and increasing salt concentrations, particularly chloride. Recycled water sources contain higher concentrations of nitrogen, phosphorus, and potassium, and can provide nutrients to turfgrass, therefore it was recommended that nutrient concentrations should be monitored to prevent excessive fertilizer applications.

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