Expedited Reconnaissance Study
Section 905(b) (WRDA 1986) Analysis
Newport Bay/San Diego Creek Watershed, California
August 1998

"....for the Corps of Engineers to Undertake a reconnaissance study for management of the Newport Bay/San Diego Creek Watershed in the interest of environmental preservation and restoration, water quality and sediment control, and the avoidance or minimization of undesirable impacts resulting from urbanization and other present and future watershed activities".

2. STUDY PURPOSE: The purpose of the reconnaissance study is to determine if there is a Federal interest in conducting a cost-shared feasibility study that will develop information and analytical tools to define water, and related resource, problems and opportunities within the Newport Bay/San Die-o Creek watershed. The study will also address restoration opportunities, and identify measures that will strike a balance between the need for economic development and the need to preserve valuable watershed (and bay) resources. The reconnaissance phase effort includes the development of a Project Study Plan (PSP) and the execution of a Feasibility Cost Sharing Agreement (FCSA) that is supported by both Federal and non-Federal interests.

3. LOCATION OF PROJECT/CONGRESSIONAL DISTRICT: The Newport Bay/San Diego Creek Watershed is located alone, the southern California coast, approximately 40 miles south of Los Angeles and 75 miles north of San Diego (Figure 1). The major cities that occupy portions of the watershed include Newport Beach, Irvine, Tustin, Orange, Laguna Hills, Lake Forest, Costa Mesa and Santa Ana. The watershed itself encompasses an area of approximately 154 square miles, and is encircled by mountains on three sides. Overland flows drain across the Tustin Plain, toward the Pacific coast, emptying into Newport Bay. The Bay includes the Upper Newport Bay Ecological Reserve, supporting threatened and endangered species and is considered a vital ecological system in Orange County. The principle watercourse is San Diego Creek which drains 122 square miles of the total watershed area. Major tributaries of San Diego Creek include: Peters Canyon Wash, Rattlesnake Canyon, Hicks Canyon, Bee Canyon, Round Canyon, Agua Chinon Canyon, Borrego Canyon, and Serrano Canyon to the north and east; and Bonita Creek and Sand Canyon Wash (includes Bommer Canyon and Shady Canyon) to the south and west. Also to the southeast is Big Canyon Wash which drains to Newport Bay separately. The highly urbanized areas north and west (Santa Ana, Orange, Costa Mesa, and Tustin) are drained to San Diego Creek via a number of urban channels including: El Modena-Irvine channel, the Tustin channel, the Santa Fe channel, the Red Hill channel, the Como channel, and the Barranca channel. The Santa Ana-Delhi channel and its tributary - the Paularino channel - drains portions of Costa Mesa and Santa Ana to Newport Bay separate from San Diego Creek. The study area lies within the 47th Congressional District, currently represented by Congressman C. Cox.

4. PRIOR STUDIES, REPORTS, ANT EXISTING WATER PROJECTS.

A. Prior studies and reports:

There are numerous reports related to Newport Bay and the watershed, documenting harbor development in Lower Newport Bay, environmental preservation and restoration in Upper Newport Bay, sediment control within the watershed and the Bay, watershed flood control studies, surface and ground water quality studies and water storage projects. The following, is a partial list of prior studies and reports:

"Newport Bay Watershed, San Diego Creek Comprehensive Storm Water Sedimentation Control Plan", (Section 208 Study) initiated in the early 1980's. This study included a number of hydrologic, hydraulic, geomorphic and sedimentation reports, prepared by Boyle Engineering Corporation. Elements of the "208 Plan" include in-Bay desilting basins, in-channel sediment basins and foothill basins. There are also numerous site specific reports in connection with design of flood control, sediment control and drainage projects.

"Regional Flood Control Master Plan for San Diego Creek", Volume 1, prepared for the City of Irvine, the City of Tustin, and the Irvine Company by John Tettemer and Associates, April 1989.

"Natural Community Conservation Plan &, Habitat Conservation Plan (NCCP/HCP), joint programmatic EIR/EIS, and implementation agreements, Orange County Environmental Management Agency, 1996.

B. Current Environmental Protection Agency (EPA) funded watershed work efforts:

"San Diego Creek Watershed Enhancement Plan", EPA wetlands grant to the California Coastal Conservancy, estimated 1998-1999. The purpose is to develop a comprehensive watershed enhancement plan, especially for the lower creek, which addresses sedimentation, water quality problems, habitat restoration, and recreation. The focus of the plan will be on developing and recommending specific actions to enhance the creek and its resources.

"Upper Newport Bay - San Diego Creek Water Quality Planning Initiative", EPA/SWRCB 205j Grant, estimated 1998-1999. The purpose is to support watershed enhancement actions by creating and maintaining a central repository of watershed information, conducting watershed studies, implementing an Evaluation Monitoring Program, and establishing a stakeholder group to facilitate watershed enhancement actions. As part of this report, Orange County is close to finishing an annotated bibliography of available information and is creating a central information with over 280 documents at the University of California - Irvine Library. This is a key to resource in determining what data is already available.

"Upper Newport Bay Water Quality Enhancement Project", EPA/SWRCB 319h Grant, 1998 - 2000. The purpose is to reduce or eliminate vegetative and urban trash debris -in the watershed and thereby reduce or eliminate aquatic life toxicity from these sources.

"Total Maximum Daily Loads (TMDLs) for Sediments and Nutrients for the Upper Newport Bay - San Diego Creek Watershed", EPA, 1998. The purpose is to reduce or eliminate water quality problems in the creek and Bay and to protect the beneficial uses of the receiving waters.

C. Corps studies and projects:

The Corps of Engineers (COE) is currently working on an ecosystem restoration feasibility study for Upper Newport Bay. The study sponsor is Orange County Resources Development Management Department (OCPFRD). The feasibility study is scheduled to be completed in the fall of 1999. The COE also maintains the Federal navigation channels in Lower Newport Bay.

The Los Angeles District COE is currently developing a plan of action for preparation of a Special Area Management Plan (SAMP) for aquatic and riparian resources in Orange County. The work will build on the past accomplishments of the NCCP/HCP and previous planning efforts.

D. Existing water projects:

Flood Control efforts by Orange County, local municipalities, and the Irvine Company include channel improvements to San Diego Creek and its tributaries; and the construction of retarding basins at Lower Peters Canyon Wash, Eastfoot, Orchard Estates, Hicks Canyon, East Hicks Canyon, Bee Canyon, Round Canyon and the Mashburn site, to reduce peak discharges and trap coarse sediment.

There are also several water storage reservoirs within the watershed used for agricultural water storage, flood control/reclaimed water storage, and municipal drinking water storage. They include Siphon and Lambert Reservoirs (agricultural water storage), Big Canyon Reservoir (municipal drinking water storage for the City of Newport, San Joaquin reservoir (municipal drinking water storage), and Rattlesnake and Sand Canyon Reservoirs (flood control/reclaimed water storage). Peters Canyon Reservoir is a former agricultural water distribution reservoir that is currently a regional park feature.

The Irvine Ranch Water District's Michelson Road Water Reclamation Plant treats municipal wastewater to reclaimed standards and distributes it within Orange County.

5. PLAN FORMULATION

A). Identified Problems (o) and Opportunities

Urbanization:

Development within the Newport Bay watershed increase significantly following World War II. Today, urbanization has encompassed Newport Bay and the entire western portion of the watershed. Urbanization continues through the eastern and southern portions of the watershed. Most of the remaining open spaces and potentially developable lands are located within the San Diego Creek watershed. This drainage area accounts for about 122 square miles of the 154 square mile Newport Bay watershed. Approximately 27 square miles of the open space area within the Newport Bay watershed will be set aside for 75 years under the Natural Community Conservation Plan & Habitat Conservation Plan, as development continues within the San Diego Creek watershed and other portions of Orange County. Other open spaces, such as agricultural fields and military bases are being, converted to high density residential, commercial and light industrial land uses.

(1) The watershed has experienced a loss in wildlife habitat within stream corridors as channels have been realigned and improved for flood control in connection with urban development.

• Approximately 170 acres of seasonal, perennial, and intermittent warm water aquatic habitat and riparian wetland habitat that exist sporadically within the numerous drainage channels in the watershed may be disturbed or destroyed by channel modification projects.

(2) Continued development could further the loss of wetlands and wildlife corridors and will fragment those that remain.

• Future urbanization will continue throughout the watershed. Both the Tustin Marine Corps Air Station and the El Toro Marine Corps Air Station will be converted from military to local land uses, leading to increased residential and commercial densities on these currently open areas. Agricultural areas will also continue to convert to high density urban areas.

(3) Future urbanization may reduce sediment delivery to Newport Bay, however, there may be an increase in the in-flow of nutrients and toxic substances from non-point source urban runoff.

• The agricultural contribution of sediment and nutrients to Newport Bay is expected to eventually be reduced as the agricultural areas are taken out of practice and replaced by residential and commercial uses.

(4) Upstream urbanization may lead to greater erosion of downstream natural channels.

• Piecemeal development within the watershed has increased runoff to receiving, channels, creating high velocity, short duration peak discharges that erode banks and channel inverts. An example is within four miles of Serrano Creek channel in the City of Lake Forest, where severe erosion problems began in the early 1990's, after upstream urbanization. Recent estimates of channel velocities during peak flow events are about 30 feet/second, much higher than pre-urbanization conditions.

Sedimentation, Flood Control, and Erosion:

The hydrologic, hydraulic and sediment transport regime within the Newport Bay watershed has been drastically altered as a result of urbanization. Channelization has increased the quantity and - efficiency of freshwater and sediment transport to Newport Bay from the San Diego Creek watershed. This clearly became evident during the 1969 storm season, when storms deposited about 400,000 cubic yards of sediment in Upper Newport Bay. Erosion and sedimentation studies in the early 1980's proposed a watershed and bay comprehensive plan known as the "'208 Plan". This plan has resulted in the implementation of best management practices for construction and agricultural sites within the watershed and the construction of foothill basins, in-channel basins and two in-Bay basins to trap sediment. The coarse-grain16 sediment is trapped in the foothill and in-channel basins allowing fine sediments (mostly silts and clays) to settle in the in-Bay basins through flocculation of particles in contact with saline waters. Although the "208 Plan" has greatly reduced the potential for sedimentation within Newport Bay, significant deposition continues to adversely affect estuarine species and habitats and navigation channels south of the Upper Newport Bay Ecological Reserve.

There are still significant erosion problems in many of the main and tributary channels of San Diego Creek. Portions of the watershed are experiencing, high erosion which has threatened homes, transportation facilities, and utilities crossing the stream channels.

Related problems are:

(1) There are no comprehensive, up-to-date hydrologic, hydraulic, and sediment transport studies for the Newport Bay watershed

• The last comprehensive hydrologic, hydraulic and sediment transport studies were based on watershed conditions in the late 1970's and early 1980's. These studies do not include the extensive urban development that has occurred since that time, or the inclusion of the "208 Plan" flood and sediment control facilities.
• More recent analyses were prepared for individual projects in portions of the watershed and do not take into account the cumulative beneficial or detrimental impacts of facilities.
• There is no single hydrologic model that incorporates all of the existing flood control and sediment control facilities and features within the San Diego Creek watershed.
• There is no easy tool for regulatory agencies to determine trade-offs between flood control needs and environmental preservation (or restoration) from a regional, watershed-wide approach.

(2) Bay sedimentation continues to affect sensitive estuarine habitats and navigation channels to the south of the Ecological Reserve:

• Without sediment control in the Bay and the San Diego Creek Watershed, sedimentation within the Bay will continue to accumulate in the future, degrading habitat and filling in navigation channels.
• In Newport Bay, the accumulation of sediment has dramatically altered the bathymetry and the potential for tidal exchange, in turn leading to significant changes in the type and availability of aquatic and wildlife habitat. Sedimentation has been linked to adverse impacts to the bottom-dwelling benthic community, reducing the food supplies available for other organisms.
• Alternative measures for ecosystem restoration and sediment control within Newport Bay are being investigated as part of the ongoing COE Newport Bay feasibility study. The study is limited to restoration measures within the Bay.
• Total Maximum Daily Load (TMDLs) for sediments prepared by the Environmental Protection Agency (EPA) and the Santa Ana Regional Water Quality Control Board (SARWQCB) call for a 50% reduction in the total volume oz sediment delivered to Newport Bay in the next ten years. No plan has been developed to address this TMDL objective.

(3) The Serrano Creek channel within the City of Lake Forest has experienced extensive erosion damage along a four-mile-long stretch upstream of Serrano Creek Community Park.

• It is estimated that about 400,000 cubic yards of channel banks were lost to erosion this past storm season alone.
• A Los Alisos Water District sewer line was damaged as a result of erosion in 1992; on-site protection for a 65-inch water supply line to the south county has been constructed because channel incising has exposed a portion of the line. Southern California Edison has moved a utility pole twice at the cost of about $110,000/move due to bank erosion, and several other poles are threatened.
• A significant amount of riparian habitat has been lost through bank erosion and channel cutting. Loss of riparian cover has also raised water temperatures.
• The local community is interested in restoration opportunities that restore channel stability and the riparian habitats using a natural approach, not a concrete-lined channel. The city of Lake Forest is in the process of completing, a study of the creek. This report includes mapping of channel cross-sections and preparation of a biologic field studies.

(4) Erosion within the watershed has impacted some existing flood control facilities.

• Grade stabilizers located in the vicinity of Lion Country Safari are no longer functional due to erosion damages. This is also true in areas of Serrano Creek, in and above the City of Lake Forest.

Water Quality:

Tailwaters from the irrigation of agricultural crops and from several commercial nurseries in the watershed have been the predominant source of nutrients to Newport Bay. Substantial reductions in nutrient loads have been achieved by the nurseries and agricultural sites through installation of drip irrigation systems and/or recycle systems. These improvements, coupled with the increased tidal flushing caused by the in-bay basins, appears to have resulted in lower nitrate concentrations in the Bay. However, algal blooms still occur. Newport Bay and San Diego Creek are listed as water quality impaired due to nutrients, pursuant to Section 303(d) of the Clean Water Act.

Total Maximum Daily Load (TMDL's) for total nitrogen and total phosphorus (nutrients) have been established for Newport Bay and San Diego Creek. The objective for the nutrient TMDL is a seasonal, annual and daily load reduction within the watershed and the Bay. The quantifiable targets set by EPA and the Santa Ana Regional Water Quality Control Board are a 30% reduction of the annual loading of total nitrogen and phosphorus by 2002, and a 50% reduction by 2007. TMDL's are also being developed for toxics and pathogens. Bacterial contamination affects water-contact recreation and shellfish harvesting and the Upper Newport Bay has been closed to these uses since 1974.

(1) Nutrient loading to Newport Bay, particularly from the Son Diego Creek Watershed contributes to seasonal algal blooms which create a recreational and aesthetic nuisance.

• The Newport Bay feasibility study has water quality modeling included as a component of the current study. The modeling is a cooperative effort between The Regional Water Quality Control Board, the Corps of Engineers, and Orange County. Restoration alternatives will also address potential water quality improvements within the Bay.

(2) Groundwater may supply nutrients to surface waters at several locations within the watershed.

The Orange County Water District has monitored groundwater quality in the Newport Bay watershed for decades. Multiple groundwater monitoring wells and production wells are distributed throughout the watershed. The newly constructed transportation corridor pumps groundwater into San Diego Creek. Some treatment has been required prior to release into the surface waters due to high nutrient levels. Other areas within the watershed may also be contributing nutrients to surface waters. High concentrations of monitoring wells are located around the El Toro Marine Corps Air Station (MCAS) where a trichloroethene (TCE) plume is located. The plume is generally to the west of the MCAS.

(3) Constituents from urban runoff (nutrients, toxics, pathogens) as well as vegetative and urban trash are entering Newport Bay from the Santa Ana-Delhi channel.

• Vegetative and urban trash are being investigated at San Diego Creek- under the "Upper Newport Bay Water Quality Enhancement Project", EPA/SWRCB 319h Grant (Section 4.B.). The Santa Ana-Delhi channel drains 18 square miles of highly urbanized area to Upper Newport Bay and warrants similar study. There is a potential for environmental restoration in the channel and golf course areas just upstream of the Bay.

Water Supply:

(1) Opportunities may exist to increase or improve water storage behind several reservoirs in the Newport Bay watershed for environmental restoration purposes.

• Additional water storage may provide environmental restoration opportunities around the reservoirs, or to feed created wetlands for water quality improvements.
• Local communities and water districts may object to use of reservoir water for environmental restoration purposes if this leads to competing uses for the stored water (i.e. drinking water storage vs. use for wetlands).

Regulatory Issues:

(1) Environmental impacts related to development are currently resolved on a project-by-project basis. Cumulative impacts to the watershed may or may not be adequately addressed tinder these individual actions.

• This watershed, and others in Orange County, may be included in a proposed Special Area Management Plan (SAMP) study. Watershed regulatory issues may also be addressed through a proposed NCCP/HCP amendment process that will address wetlands and riparian areas that may be impacted by future development.

B. General Objectives of the Watershed Study

It is the goal of the watershed study to develop the necessary baseline data and analytical tools, and a realistic set of objectives that will encourage management decisions that help reverse negative trends or enhance positive trends to maintain or improve the health of the watershed and bay. The Corps is currently addressing problems, needs, opportunities, and associated alternative environmental restoration alternatives within Newport Bay as part of the Upper Newport Bay feasibility study. Therefore, this study proposes to address the problems and needs within the watershed, and address the impacts of watershed restoration or other opportunities on the Bay environment. EPA has also funded several efforts addressing water quality issues within portions of the watershed. Agencies are working cooperatively to avoid duplication of work efforts. Toward that end, the watershed feasibility study will include:

A comprehensive update of hydrologic, hydraulic, and sediment (yield and transport) models for a range of flow rates for existing conditions and future conditions within the San Diego Creek watershed.

• Existing conditions will include the recently installed flood control or drainage facilities. For the future condition, the modeling will include proposed land use changes, any additional flood control or sediment control facilities, and the effects on the delivery of sediment to Newport Bay.
• Operations and maintenance (O&M) of sediment control facilities will be investigated through the a use of the models to see if there are opportunities to improve sediment trapping abilities within the watershed through modification of O&M activities (i.e. a non-structural approach).
• Potential environmental restoration sites will be investigated at several sites within the watershed. Multi-use alternatives will be considered to maximize the benefits for the greatest number of stakeholders. For example, in addition to restoration, some of the sites may also provide some additional sediment control benefits. Those potential benefits will also be investigated using the models.
• Any potential modifications of sediment delivery to the Bay and the effects on the Bay will be documented. It is assumed that improved sediment trapping would only result in changes to the frequency of O&M activities within the Bay for the in-Bay basin(s) being investigated as part of the ongoing Newport Bay feasibility study.

Investigation of environmental restoration opportunities within the Newport Bay watershed.

• Investigate the following restoration sites for potential erosion control and water quality improvements of surface waters in the San Diego Creek and Santa Ana-Delhi watersheds. These sites include both in-channel and off-channel alternatives and are being proposed based on land availability, hydrologic concentration points, existing problems, and from local input.

  (1) Lower San Diego Creek and the San Joaquin Marsh
  (2) Lower San Diego Creek at the San Joaquin Golf Course
  (3) San Diego Creek near the "Lion Country Safari" (potential link between coastal and inland NCCP areas)
  (4) San Diego Creek at the Barranca Parkway Extension, including City of Irvine and The Irvine Company's mitigation sites
  (5) Peters Canyon Wash at Tustin Marine Corps Air Station (MCAS)
  (6) Peters Canyon Wash through the Tustin Ranch Golf Course
  (7) Borrego Canyon Wash at the El Toro MCAS Golf Course
  (8) Serrano Creek from Serrano Creek Community Park upstream to Portola Parkway
  (9) Sand Canyon Wash at William Mason Park
  (10) Lower reaches of the Santa Ana Delhi Channel
  (11) Lower Bonita Creek

• Address use of water storage facilities, or water releases, for restoration purposes.
• Examine potential enhancement opportunities through creation of wildlife riparian corridor(s) along existing channel networks, if current or future land uses do not prohibit such an action.
• Investigate eradication programs for exotics, such as Arundo Donax within the watershed.

Evaluation of ground water and surface water interaction and the relationship to environmental conditions in Newport Bay watershed and the Bay.

• Study groundwater and surface water interactions. Investigate influences of this relationship to surface water issues. Determine methods to improve quality of inflow and in-situ water.
• Collect and analyze data regarding temperature, dissolved oxygen, depth, water movement criteria, sediment loading and other components of water quality within the watershed to determine what constituents are constraining to environmental resources and recreational activities.
• Develop cost effective treatment measures for the Newport Bay watershed for controlling excessive transport of sediments, nutrients, pathogens and toxic substances to the Bay.

An update of recreation needs assessment and user opportunities

• Study recreational constraints and opportunities. Identify opportunities for incorporation of recreation features into existing and planned water resource projects.

6. FEDERAL INTEREST: In accordance with current administration policy, there is a federal interest in watershed based studies that provide a holistic approach to evaluating water resource problems and opportunities, leading to the development of a watershed management plan that effectively balances the need for sustainable economic development with the need for protection of watershed natural resources.

7. PRELIMINARY FINANCIAL INTEREST: A local sponsor would be required to cost-share (50/50) the feasibility phase of the watershed planning effort. Half of this local share can be in the form of in-kind services. Knowing this requirement, the County of Orange has indicated their willingness to be the local sponsor. Acting as the lead local agency, the county will enter into a multi-party agreement with other cities that have indicated their willingness to actively participate (and financially contribute) to the cost-shared study.

8. RECOMMENDATION: The recommendation resulting from the reconnaissance level investigations is that the Los Angeles District proceed with a cost-shared, feasibility phase watershed study of the problems and opportunities of the Newport Bay/San Diego Creek Watershed, California. The U.S. Army Corps of Engineers shall finalize negotiations of the Project Study Plan and enter into a Feasibility Cost Sharing Agreement (FCSA) with the County of Orange. The feasibility study is estimated to cost $2.3 million and take 26 months to complete.

9. POTENTIAL ISSUES EFFECTING INITIATION OF FEASIBILITY PHASE: None.

10. PROJECT AREA MAP. This button will open the Project Area Map in a new window.