Revised Draft Big Bear Lake Tmdl Action Plan

REVISED DRAFT BIG BEAR LAKE TMDL ACTION PLAN

Prepared for Big Bear Lake Nutrient TMDL Task Force August 26, 2010

9665 Chesapeake Drive, Suite 201 San Diego, California 92123

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Big Bear Lake TMDL Action Plan

TABLE OF CONTENTS

TABLE OF CONTENTS ...... III LIST OF FIGURES...... V LIST OF TABLES ...... VI LIST OF ABBREVIATIONS ...... VII EXECUTIVE SUMMARY ...... 1 1. INTRODUCTION...... 1-1 1.1 Watershed Setting ...... 1-1 1.2 Big Bear Lake Watershed and Lake Characteristics ...... 1-5 1.3 Big Bear Lake Water Quality ...... 1-7 1.4 Regulatory Context ...... 1-9 1.4.1 TMDL Development ...... 1-9 1.4.2 Big Bear Lake Nutrient TMDL Task Force ...... 1-11 1.5 Other Related Activities ...... 1-11 1.5.1 Nuisance Aquatic Plant Management ...... 1-11 1.5.2 Fisheries Management ...... 1-12 1.5.3 Model Updates ...... 1-12 2. SEDIMENT NUTRIENT REDUCTION PLAN ...... 2-1 2.1 Approach ...... 2-1 2.2 Findings ...... 2-1 2.2.1 Water Level Management ...... 2-2 2.2.2 Dredging ...... 2-3 2.2.3 Lake Treatment ...... 2-9 2.2.4 Aeration and Destratification ...... 2-14 2.2.5 Other Possible Activities ...... 2-24 2.3 Recommendations ...... 2-24 2.3.1 Alternatives Screening ...... 2-25 2.3.2 Sediment Disposal and Beneficial Re-use: Planning for the Future...... 2-26 2.3.3 Updates to Lake Monitoring Plan ...... 2-28 2.3.4 Comprehensive Schedule ...... 2-28 2.3.5 Summary and Perspective ...... 2-29 3. WET WEATHER STRATEGIES FOR CONTROLLING NUTRIENT INPUTS TO BIG BEAR LAKE ...... 3-1 3.1 Introduction ...... 3-1 3.2 Overview of Best Management Practices ...... 3-1 3.2.1 Overview of Nutrient Removal Mechanisms ...... 3-1 3.2.2 BMPs for Nutrient Removal ...... 3-2 3.2.3 Performance Locally ...... 3-4

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3.2.4 Nutrient Removal Efficiencies ...... 3-6 3.2.5 Nonstructural and Operational BMPs ...... 3-7 3.3 Project Approach ...... 3-8 3.3.1 Review of BMP Documents ...... 3-8 3.4 Interview Findings ...... 3-11 3.4.1 City of Big Bear Lake ...... 3-11 3.4.2 San Bernardino County Flood Control District ...... 3-12 3.4.3 San Bernardino County ...... 3-12 3.4.4 US Forest Service ...... 3-12 3.4.5 Big Bear Mountain Resorts ...... 3-13 3.4.6 California Department of Transportation ...... 3-13 3.5 Implementation of BMPs ...... 3-14 3.5.1 Opportunities and Constraints ...... 3-14 3.5.2 Costs ...... 3-14 3.6 Conclusions ...... 3-17 4. NUSIANCE AND NOXIOUS AQUATIC PLANT MANAGEMENT PLAN ...... 4-1 4.1 Introduction ...... 4-1 4.1.1 NAPMP Objectives ...... 4-2 4.1.2 Problem Statement ...... 4-3 4.2 Background ...... 4-3 4.2.1 Aquatic Plant Species in Big Bear Lake ...... 4-4 4.2.2 Historical Aquatic Plant Management Efforts ...... 4-6 4.2.3 Pilot Programs to Eradicate Eurasian Water Milfoil ...... 4-7 4.3 Noxious and Nuisance Aquatic Plant Monitoring Program ...... 4-7 4.3.1 Aquatic Plant Monitoring Approach ...... 4-8 4.3.2 Aquatic Plant Monitoring Schedule ...... 4-8 4.3.3 Aquatic Plant Monitoring Parameters ...... 4-8 4.3.4 Aquatic Plant Biomass Sub-Sampling ...... 4-11 4.3.5 Equipment ...... 4-11 4.3.6 Data Management ...... 4-11 4.4 Aquatic Plant Numerical Index ...... 4-12 4.5 Aquatic Plant Control Strategies ...... 4-14 4.5.1 Eradication Treatment Technologies ...... 4-14 4.5.2 Control Objectives for Non-Native Aquatic Plants...... 4-15 4.6 Adaptive Response on Plant Management Strategies ...... 4-15 5. MODEL UPDATE PLAN ...... 5-1 5.1 Background ...... 5-1 5.2 Regulatory Requirements ...... 5-1 5.3 Objectives and General Approach ...... 5-2 5.4 Planned Updates for the HSPF Model ...... 5-3 5.5 Planned Updates for the WASP Lake Model ...... 5-4

5.6 Tetra-Tech's Recommended Changes to the TMDL Models ...... 5-4 5.7 Schedule for Updating Existing TMDL Models ...... 5-5 6. LIMITATIONS ...... 6-1 Report Limitations ...... 6-1 REFERENCES ...... REF-1

LIST OF FIGURES

Figure 1-1. Locator Map of Big Bear Lake, California ...... 1-2 Figure 1-2. Map of the Big Bear Lake Watershed ...... 1-3 Figure 1-3. Bathymetric Map of Big Bear Lake ...... 1-4 Figure 1-4: Lake Level Recurrence Frequency ...... 1-6 Figure 2-1. Comparison of Lake Drawdown Levels Under Current Operations with the In-Lieu Water Program Hypothetical Conditions in the Absence of the In-Lieu Water Program...... 2-3 Figure 2-2. Comparison of the Lake Area When Full With 2004 Conditions Under Current Operations and Modeled 2004 Conditions Without the Exchange Agreement...... 2-4 Figure 2-3. Dry Land Excavation behind a Coffer Dam During the East End Deepening Project...... 2-7 Figure 2-4. View of the Coffer Dam from the Lake during the East End Deepening Project...... 2-7 Figure 2-5. Application of alum on Big Bear Lake, May through June 2004...... 2-10 Figure 2-6. Soluble Reactive Phosphorus Flux from Sediments in Big Bear Lake, 2002 to 2006...... 2-11 Figure 2-7. Floc Formations Settle to the Bottom of a Jar Test ...... 2-12 Figure 2-8. Example of a Silt Curtain Containing Sediment Impacts from a Lakeside Construction Project in North Carolina...... 2-13 Figure 2-9. Location (Upper) and Close-up View (Lower) of the Aerator on the West End of Big Bear Lake..... 2-15 Figure 2-10. July Dissolved Oxygen Profiles in Big Bear Lake in 2000 and 2009...... 2-16 Figure 2-11. August 2009 Dissolved Oxygen Profiles in Big Bear Lake ...... 2-17 Figure 2-12. Conceptual Diagram of a Speece Cone ...... 2-19 Figure 2-13. Current and Potential Future Operations to Manage Dissolved Oxygen in the Western Portion of Big Bear Lake ...... 2-23

LIST OF TABLES

Table 1-1. Impervious & Pervious Land Use Distributions in the Watershed (a) ...... 1-5 Table 1-2. Big Bear Lake Characteristics (a) ...... 1-6 Table 1-3. Numeric Targets Established by the TMDL ...... 1-10 Table 1-4. TMDL for Phosphorus During Dry Weather Conditions ...... 1-10 Table 2-1. Dredging Projects History at Big Bear Lake, 1983- 2000 ...... 2-5 Table 2-2. 2001 Cost Estimates for the East-End Deepening Project, Escalated to 2010 Dollars ...... 2-8 Table 2-3. Comparison of Hypolimnetic Oxygenation Technologies ...... 2-18 Table 2-4. Summary of Hypolimnetic Oxygenation Projects ...... 2-20 Table 2-5. Screening Matrix for Enhancements to Existing Activities ...... 2-27 Table 2-6. Proposed Comprehensive Schedule for Sediment Nutrient Management Plan Implementation ...... 2-30 Table 3-1 BMPs and Relative Effectiveness1 ...... 3-2 Table 3-2 Description of BMPs (From Sayre et al. 2006)1 ...... 3-3 Table 3-4. Nutrient Removal Efficiencies (%) for Select BMPs1 ...... 3-7 Table 3-5. Summary of Best Management Practices (BMPs) in Place in 2004 ...... 3-9 Table 3-6. BMP Costs Adjusted for Inflation (From Caltrans 2004)1 ...... 3-15 Table 3-7. Source Control Costs Adjusted for Inflation (from APWA 1992) ...... 3-15 Table 3-8. BMPs Costs Adjusted for Inflation (From APWA 1992) ...... 3-16 Table 3-9. Short-Term Strategies to Control Particulate Nutrient Inputs to Big Bear Lake ...... 3-18 Table 3-10. Long-Term Strategies to Control Particulate Nutrient Inputs to Big Bear Lake ...... 3-19 Table 4-1. Big Bear Lake Nutrient TMDL Response Targets for Aquatic Plants ...... 4-2 Table 4-2. 1977-1978 Aquatic Plant Species and Biomass In Big Bear Lake ...... 4-4 Table 4-3. 2006 Aquatic Plant Species and Relative Dispersion In Big Bear Lake ...... 4-5 Table 4-4. Aquatic Plant Index Value Assignments ...... 4-13 Table 4-5. Examples of Aquatic Plant Index Calculation ...... 4-13 Table 4-6. Aquatic Plant Index Number versus Management Actions ...... 4-14 Table 4-7. Schedule Of Deliverables ...... 4-16 Table 5-1. Model Update Tasks for 2010 ...... 5-5

LIST OF ABBREVIATIONS

Acre-ft acre-feet Resorts Big Bear Mountain Resorts AGR Agricultural irrigation supply RWQCB Regional Water Quality Control Board BBMWD Big Bear Municipal Water District SAWPA The Santa Ana Watershed Project Authority BMP Better Management Practice SOD sediment oxygen demand Caltrans California Department of Transportation SRP soluble reactive phosphorus CEQA California Environmental Quality Act STPUD South Tahoe Public Utility District cfs cubic feet per second Task Force Big Bear Lake Task Force City The City of San Bernadino TMDL Total Maximum Daily Load COLD Cold water aquatic life habitat ug-P/L micrograms Total Phosphorus per liter County The County of San Bernadino USACE United States Army Corps of Engineers cy cubic yard WARM Warm water aquatic life habitat Dam Bear Valley Dam WILD Wildlife habitat DO dissolved oxygen yr year EBMUD East Bay Municipal Utility District μg/L micrograms per liter EIR Environmental Impact Report EIS Environmental Impact Statement Flood Control San Bernadino County Flood Control District Forest Service United States Department of Agriculture, Forest Service, San Bernadino National Forest ft foot g AL/m3 gallons of liquid alum per meter cubed HOS Hypolimnetic Oxygenation System ICR Indian Creek Reservoir Lake Big Bear Lake LTMS San Francisco Bay Long Term Management Strategy for Dredged Sediments mg/L milligrams per liter mg/m2/day milligrams per meter squared per day MUN Municipal and domestic water supply NEPA National Environmental Policy Act O&M Operations and Maintenance ºF degrees Fahrenheit Permit National Pollutant Discharge Elimination System permit issued by the Regional Board – NPDES No. CAS 618036, Order NO. R8-2010-0036 Plan Sediment Nutrient Management Plan for Big Bear Lake, California ppd pounds per day PSA pressure swing absorption RARE Protection of rare and endangered species REC1 Water contact recreation REC2 Water non-contact recreation Regional Board Santa Ana Regional Water Quality Control Board

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BIG BEAR LAKE TMDL ACTION PLAN

EXECUTIVE SUMMARY

This report presents a plan and schedule for implementation of actions (Plan) by Big Bear Lake stakeholders that will show meaningful progress towards attainment of goals set forth in the Nutrient Total Maximum Daily Load (TMDL) for Dry Hydrologic Conditions for Big Bear Lake. The goal of the Big Bear Lake TMDL Task Force (Task Force) in preparing the Plan for submittal to the Santa Ana Regional Water Quality Control Board (SARWQCB) is to: . Meet the requirements for a deliverable established by the Nutrient Total Maximum Daily Load (TMDL) for Dry Hydrologic Conditions for Big Bear Lake and section V.D.4 of the National Pollutant Discharge Elimination System (NPDES) Permit for Urban Stormwater issued to San Bernardino County Flood Control District and Copermittees (Order No. R8-2010-0036; CAS618036); . Integrate the findings of previous technical studies on Big Bear Lake (Lake) to document the analysis of alternatives for reducing nutrient releases from sediments in the Lake; and . Define stakeholder expectations for success: • What endpoints are appropriate measures of attaining beneficial uses? That question is to be addressed through periodic review of the TMDL by the Task Force. • What actions would lead to attainment of endpoints? That question is the main focus of this Plan. • What is the engineering and economic feasibility of those actions? This Plan presents some preliminary information on engineering and economic feasibility; early actions in this Plan include developing more detailed engineering and economic feasibility information. This document fulfills Provision V.D.4.e of SARWQCB Order R8-2010-0036, and is consistent with the requirements specified in Task 6 of the TMDL. Section 1 of this Plan provides a brief introduction, including the watershed setting and regulatory context. Section 2 presents the findings and recommendations of the sediment nutrient reduction strategy that addresses the most significant nutrient source to the Lake: release of nutrients from bottom sediments during dry hydrologic conditions. Past and current nutrient management approaches and associated activities are reviewed in this Plan, along with scientific studies conducted over the past decade, as a basis for identifying the measures most likely to lead to success. Section 2 also reviewed certain in-Lake activities that relate to release of nutrients from bottom sediments and blooms of alga and nuisance or noxious aquatic plants: . Water level stabilization; . Dredging; . Lake treatment with alum; . Aeration and destratification; . Nuisance aquatic plant management; and . Carp removal. For each of the above activities, opportunities to enhance the benefit of the activity are briefly explored in this Plan. The two approaches that show the most promise for success are:

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. Enhancement of the aeration technique by evaluating the cost, feasibility, and potential benefit of a hypoliminetic oxygenation system (HOS) as a way to metabolize the existing reservoir of sediment oxygen demand in Lake sediments; and . Enhanced management of watershed sediment inputs to the margins, by improving existing detention basins, deploying silt curtains around tributaries during wet weather, using alum, Phoslock®, or other lake treatment chemicals, and performing strategic dredging to remove nutrients and sediments contained by these measures. An HOS would get directly at the cause of the problem: a large, legacy reservoir of sediment oxygen demand in the Lake sediments. Previous evaluations have looked at dredging as the only way to remove the legacy reservoir of sediment oxygen demand. The capital cost of an HOS is potentially as much as forty-fold lower than a massive dredging project to attain the same ends. Based on experiences in other lakes, there is a reasonably high degree of certainty that the system would show significant improvements over current practices. Although the operating costs are approximately 10-fold higher than the current aeration operating costs, an HOS would likely provide commensurately large benefits. Experience in other lakes indicates that the operational cost may decline over time as the legacy reservoir of sediment oxygen demand is consumed. The rate of recovery of the Lake may depend in part on the rate at which oxygen is introduced using the HOS. Therefore, progress toward water column targets using this approach may depend in part on the available budget for HOS operation. Concurrent with pre-design and analysis of an HOS, techniques for management along the margins would be pilot tested, detention basins would be enhanced, and approaches using silt curtains and/or limited flocculant application and follow-up dredging would be explored. This alternative likely has lower startup costs compared to HOS design and construction costs. Similar to the HOS, the operating costs of sediment management along the margins can be increased or decreased depending on the level of effort and available funding resources. There is not enough information available at present to determine as to which approach (HOS or management on the margins) is the most cost-effective, or whether a combination of the two would be needed to attain all causal and response targets established by the TMDL. Therefore, the schedule of activities includes initial steps of pre-design evaluation of the HOS, as well as pilot testing of management on the margins techniques. A comprehensive, three-staged schedule of activities has been developed for sediment nutrient management actions. Stage 1 activities would take place over the next 18 months and involve the planning and scoping activities necessary to implement proposed actions. Monitoring will continue during Stage 1 to evaluate whether current activities are sufficient to attain response targets, and whether the causal targets established by the TMDL are appropriate to response targets. In Stage 2, CEQA procedures necessary to enable implementation actions would be completed and cost sharing and compliance crediting agreements would be established. Enhanced management activities would commence in Stage 3 if they are deemed necessary and all needed approvals, agreements, and funding arrangements have been completed. Section 3 of this Plan describes wet weather strategies for controlling nutrient inputs to Big Bear Lake. The section begins with general overview of Best Management Practices (BMPs) for nutrient load reduction, followed by a summary of BMPs implemented by local watershed stakeholders. The section concludes with a summary of opportunities and constraints for additional BMP implementation. In addition to carrying out ongoing activities required under Order No. R8-2010-0036, Section 3 recommends stream bank stabilization projects, improvement of curb and gutter storm drain infrastructure within the City of Big Bear Lake, and improvement of roads and erosion control measures on United States National Forest Service lands.

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Section 4 of this Plan describes activities under way and planned for the future for the control of nuisance and noxious aquatic plants. These activities are carried out by Big Bear Municipal Water District (the District) as part of its core mission. It is reasonable to assume that the District would continue to take actions to prevent the spread of nuisance and noxious aquatic plants, including surveillance and eradication of nuisance and noxious aquatic plants. Data provided by District surveillance activities would be available to the SARWQCB to track attainment of TMDL targets. Section 5 of this Plan summarizes effort to date to develop and validate numeric models for watershed nutrient loading and nutrient cycling within the Lake. The HSPF model is used to characterize wet weather sediment and nutrient loads. The WASP model is used to characterize cycling of nutrients within the Lake under dry hydrologic conditions. According to existing models, regulated parties are in attainment of their Wasteload Allocations (WLAs) established by the existing TMDL for dry hydrologic conditions. The WASP model will be updated to account for the decay of soluble reactive phosphorus. This modification is needed to be able to account for how past wet weather nutrient inputs contribute to the present release of nutrients from bottom sediments. The WASP model will also be revised to account for the effects of the activities described in Section 2 that serve to reduce internal nutrient loads. The updated model is expected to provide a basis for establishing the accounting system needed to support a pollutant trading program to address average and wet weather load reductions.

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BIG BEAR LAKE TMDL ACTION PLAN

1. INTRODUCTION

This report presents a Sediment Nutrient Management Plan for Big Bear Lake, California (Plan). The goal of the Big Bear Lake Nutrient TMDL Task Force (Task Force) in preparing the Plan for submittal to the Santa Ana Regional Water Quality Control Board is to: . Meet the requirements for a deliverable established by the Nutrient Total Maximum Daily Load (TMDL) for Dry Hydrologic Conditions for Big Bear Lake and Section V.D.4 of the NPDES Permit for Urban Stormwater issued to San Bernardino County Flood Control District and Copermittees (CAS618036); . Integrate the findings of previous technical studies on Big Bear Lake to document the analysis of alternatives for reducing nutrient releases from sediments in Big Bear Lake; and . Define stakeholder expectations for success: • What endpoints are appropriate measures of attaining beneficial uses? That question is to be addressed through periodic review of the TMDL by the Task Force. • What actions would lead to attainment of endpoints? That question is the main focus of this Plan. • What is the engineering and economic feasibility of those actions? This Plan presents some preliminary information on engineering and economic feasibility; early actions in this Plan include developing more detailed engineering and economic feasibility information. The introductory materials in the sub-sections that follow describe the watershed setting and regulatory context for this plan. The second section describes the approach to analyzing alternatives for managing the Big Bear Lake to attain TMDL targets. The third section summarizes the findings of the alternatives analysis. Finally, the fourth section presents proposed activities, the time frame for action, and a process to move forward with the planning, funding, and implementation of projects to protect and enhance the water quality of Big Bear Lake.

1.1 Watershed Setting Big Bear Lake (Lake) is located in the San Bernardino Mountains, in the southeastern quadrant of San Bernardino County (Figure 1-1). It was created in 1884 by the construction of the Bear Valley Dam, flooding a natural complex of marshes and small eutrophic ponds and lakes on the floor of the Bear Valley (Leidy, 2006). A second, larger dam was constructed in 1912 approximately 300 feet downstream of the original dam. Local stream runoff and precipitation on the Lake are the sole water supply sources to the Lake; the major inflows are Rathbun Creek, Summit Creek and Grout Creek (Figure 1-2). The Lake has a surface area of approximately 3,000 acres, a storage capacity of 75,332 acre-ft and an average depth of 24 feet (Fugro Pelagos, Inc., 2006). Its drainage basin is approximately 23,000 acres. The lake reaches its deepest point of 72 feet at the dam. The western arm of the Lake is generally deeper than 42 feet, whereas the eastern arm is no deeper than 30 feet in most places, with broad shallow expanses along the margins (Figure 1-3).

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Section 1: Introduction Big Bear Lake TMDL Action Plan

Figure 1-1. Locator Map of Big Bear Lake, California

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Figure 1-2. Map of the Big Bear Lake Watershed Red triangles indicate watershed monitoring locations along major tributaries.

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Figure 1-3. Bathymetric Map of Big Bear Lake Blue indicates deeper than 40 feet; yellow to green indicates 10 to 30 feet; orange to red indicates shallow areas along margins. Inset map shows detail western arm; note that old dam contours are clearly visible in bathymetry. Image from Fugro Pelagos Inc. (2006)

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Section 1: Introduction Big Bear Lake TMDL Action Plan

The lake level rises to its maximum during El Niño years of above average rainfall, and gradually falls during periods of drought. Some (approximately 0.7 cfs) water is released from the Lake to provide habitat support for Bear Creek downstream of the existing Dam. The primary water removal mechanism is evaporation, due to the arid climate of Southern California and the Lake’s broad morphology. Evaporative concentration of minerals tends to buffer the Lake around pH 8.5. Storm flow from tributaries brings approximately 10,000 to 20,000 tons of sediment into the Lake each year (Hydmet, 2008). This estimate expresses the long-term average, and explains the approximately 0.2- to 0.8-cm sediment accumulation rate measured in the Lake (Kirby, date unknown). Sediment transport in the Lake is complicated, as most of the load occurs in only a few storm events, and the rate of sedimentation is higher in the deep portion of the Lake compared to the shallows.

1.2 Big Bear Lake Watershed and Lake Characteristics The Big Bear Lake watershed drainage basin encompasses 37 square miles of area and includes Big Bear Lake as well as 10 to 20 ephemeral or perennial streams. Precipitation, in the form of snowfall, rainfall, and surface runoff is the sole source of water supply to the watershed, and therefore, to the lake. Due to a strong rain shadow effect, precipitation varies significantly across the Big Bear Lake watershed with the western end of the watershed receiving an average of 36 inches a year, while the eastern end receives an average of 12 inches a year. The United States Forest Service (USFS) is the largest landowner in the Big Bear Lake watershed. In addition to USFS lands, other dominant land uses identified for the watershed include resort, residential, and high density urban. Table 1-1 provides a detailed distribution of land uses (with pervious and impervious areas) within the watershed.

Table 1-1. Impervious & Pervious Land Use Distributions in the Watershed (a) Land Use Impervious Pervious Total % of Watershed Forest North (b) 38 ac. 7,595 ac. 7,633 ac. 33 Forest South (b) 35 ac. 6,876 ac. 6,911 ac. 30 Resort 35 ac. 669 ac. 704 ac. 3 Residential 580 ac. 3,287 ac. 3,867 ac. 17 HDU (c) 644 ac. 644 ac. 1,288 ac. 6 Watershed contributory area 1,302 ac. 19,071 ac. 20,403 ac. 88 Big Bear Lake - - 2,808 ac. 12 Total Watershed 1,332 ac. 19,071 ac. 23,211 ac. 100 Notes: (a) Re-created from SARWQCB (2005). (b) Forest North refers to forested land facing north, while Forest South refers to forested land facing south. (c) HDU = High Density Urban Big Bear Lake is approximately 7 miles in length (depending on water level) and approximately 0.5 mile in width. The length of the water body is oriented in a west-east direction. During maximum (full) pool, water level of the lake has a surface elevation of 6,743.2 ft, a water surface area of approximately 2,971 acres and maximum lake storage of about 73,320 acre-feet (af). A summary of lake characteristics is given in Table 1-2.

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Table 1-2. Big Bear Lake Characteristics (a) Lake Elevation 6,743.2 feet Lake Length 7 miles Average Lake Width 0.5 miles Shoreline 22 miles Maximum Depth at Dam 72.33 feet Maximum Lake Storage Capacity 73,320 acre-feet Mean Depth at Maximum Pool 24.7 feet Average Lake Storage Capacity 58,500 acre-feet/year Mean Depth at Average Pool 19.7 feet Big Bear Valley Length 12.5 miles Average Inflow 17,300 acre-feet/year Average Outflow at Dam 5,510 acre-feet/year Average Evaporation Rate 11,300 acre-feet/year Hydraulic Retention Time (b) 11 years Notes: (a) Re-created from SARWQCB (2005). (b) HRT = average lake storage capacity/average outflow at dam. Eighty percent of the time, the Big Bear Lake water level is less than five feet down from full pool (Figure 1-4). In average rainfall years, the lake level is maintained so that it fluctuates no more than plus or minus 5 feet. But, during prolonged drought periods, the lake level can drop as much as 17 feet below full pool.

Figure 1-4. Lake Level Recurrence Frequency

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1.3 Big Bear Lake Water Quality The available water quality data for Big Bear Lake are briefly summarized below. Intensive water quality monitoring of Big Bear Lake was initiated in June 2001. At that time, the water level and corresponding water volume of Big Bear Lake were in a state of decline. Due to an extended period of drought in Southern California, lake water levels steadily declined from June 2001 until approximately November 2004. In June of 2001, lake level was about 7.0 ft below full pool (lake surface elevation of 6,743 feet). By the end of August 2002, lake level was almost 13 ft below full pool, and at the end of August of 2003, lake level decreased to 14 ft below full pool. By the end of the summer of 2004, lake levels had decreased to approximately 17 ft below full pool. Decreasing lake levels affected lake water quality measurements as constituents became more concentrated in the available water volume. Then, in the winter of 2004 to 2005, record amounts of rain fell within the Big Bear Lake watershed and an estimated 39,600 acre-ft of water inflow was received by Big Bear Lake. At the end of the summer of 2005, water level was restored to approximately only 3 ft below full pool and a water volume of 64,275 acre-ft, respectively. The immense water volume received by the lake served to dilute water quality constituent concentrations. Concurrent with lake water level fluctuations, the BBMWD was conducting lake management activities that also had an effect on lake water quality. In 2002 and 2003, aquatic herbicide applications were performed that substantially reduced the aquatic plant biomass in Big Bear Lake. Then in 2004, a full-scale alum application was conducted. The full-scale alum application was employed as a direct phosphorus mitigation measure to both bind and precipitate bio-available phosphorus in the water column and to control the release of nutrient phosphorus from the lake sediments. The impact and effectiveness of the full-scale alum treatment on sediment nutrient release rates and water quality concentrations were described in the report entitled, Big Bear Lake 2004 Full-Scale Alum Application (BBMWD, June 2005) and again re-described in the sediment report prepared by Anderson and Wakefield-Schmuck (2006). In Big Bear Lake, water quality monitoring is conducted at established open-water main lake sampling stations. The water quality station identifications and sample types for Big Bear Lake are as follows: . Dam – MWDL1 or TMDL Site No. 1 – Photic Zone Composite . Dam – MWDL1 or TMDL Site No. 1 - Discrete bottom . Gilner Point – MWDL2 or TMDL Site No. 2 – Photic Zone Composite . Gilner Point – MWDL2 or TMDL Site No. 2 - Discrete bottom . Mid Lake Middle – MWDL6 or TMDL Site No. 6 – Photic Zone Composite . Mid Lake Middle – MWDL6 or TMDL Site No. 6 - Discrete bottom . Stanfield Middle – MWDL9 or TMDL Site No. 9 – Photic Zone Composite . Stanfield Middle – MWDL9 or TMDL Site No. 9 - Discrete bottom Water quality data collected during the extended drought which ended in the winter of 2004-5 reflect what is considered to be a critical condition of the lake from a management perspective. Decreasing lake levels affected lake water quality measurements as constituents became more concentrated in the water volume due to the combined influence of evaporation, sediment-water recycling, and decreased flushing rate. Water quality in Big Bear Lake varies spatially and seasonally. Spatially, the highest median levels of total phosphorus, total nitrogen, chlorophyll a, total suspended solids (TSS), volatile suspended solids (VSS), and pH were observed at the shallow, eastern end of the lake. In contrast, the highest median total dissolved nitrogen, ammonia-nitrogen and nitrate-nitrite levels were generally observed in the deeper, western end of the lake. These spatial trends were observed for 2001, 2002, and 2003 water quality data. The observed spatial trends for the water quality constituents appear to generally correspond with prevailing lake conditions. At

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the eastern end of the lake, the higher levels of total phosphorus, total nitrogen, chlorophyll a, TSS, VSS, and pH were likely attributed to the presence of shallower water, a greater degree of vertical mixing resulting in increased entrainment of nutrients and sediment re-suspension, which in turn give rise to more eutrophic conditions. The reverse spatial trend in median ammonia-nitrogen and nitrate-nitrite levels are attributed to the higher sediment release rates for ammonia-nitrogen in the deeper lake waters due to the focusing of degradable material near the dam (Kirby, 2005). Interpretation of lake water quality data for 2004 was affected by conduct of the full-scale alum application on the lake. The 2004 full-scale alum treatment involved the application of liquid aluminum sulfate to over 1,300 acres of lake surface area. Sediment nutrient release rates (sediment flux rates) strongly indicate that the alum treatment was successful in reducing the release of phosphorus from lake sediments. The more recent water quality data (2004 and 2005) demonstrate the influence of water volume on several of the nutrient water quality parameters measured. In photic zone samples, total and dissolved phosphorus as well as total nitrogen and total dissolved nitrogen were almost 50 percent lower in 2005 (lake water volume 60,000+ acre-feet) compared to the levels observed in 2004 (lake water volume ~30,000 acre-feet). To date, the water quality results for Big Bear Lake suggest that water volume has a substantial impact on water quality. Furthermore, the degree of water volume will control whether or not the lake will be well- mixed and polymictic or able to vertically stratify for a period of time. This in turn, will affect both photic zone and bottom discrete concentrations of nutrients. Seasonal peaks in phosphorus species, total nitrogen, and chlorophyll a occur during the late summer and fall. Seasonal peaks for most of the water quality constituents were much more pronounced in 2003 than in either 2001 or 2002. This may have been due to the continued decline in lake water levels and/or due to the consecutive years of aquatic herbicide treatment (2002 and 2003 aquatic herbicide application) resulting in a decrease in the nutrient sink that the plants and periphytic algae would have provided. In 2002, the seasonal peak in nitrate-nitrite levels appeared to coincide with the snow melt season in the watershed and suggest external loading as the primary source of this inorganic nitrogen source to the lake. Although surface runoff to the lake appeared somewhat limited at this time (based on tributary observations), nitrate-nitrite may have been transported to the lake through lateral subsurface flow and leaching from surrounding soils. Seasonal trends in ammonia-nitrogen levels in the lake appeared to increase with increasing water temperatures, and a relatively higher concentration found in bottom discrete samples versus photic zone composite samples suggesting that the organic decomposition in the sediments are the primary source of this nutrient to the lake. Despite the lake’s polymictic nature, weak thermal stratification does occur during the spring and summer months. This weak thermal stratification is significant enough to limit exchange between surface and bottom waters within the lake. This results in the low dissolved oxygen levels in the deeper waters of the lake. Lake conductivity measurements appeared to respond to precipitation inflows. During the snow melt/spring runoff and wet season, lake conductivity measurements tended to decrease. This demonstrates the importance of dilution and flushing rate on the water quality of the lake, especially during low inflow years. The highest water temperatures at all of the main lake monitoring stations were observed in July and August of each year. By the first to middle of September, water temperatures would usually begin to decline for Big Bear Lake, reflecting the impact of the lake’s elevation on the seasonal cycle observed for water temperatures. As expected, the lowest concentrations of dissolved oxygen generally occurred during the summer or early fall. However, there were several occasions when low dissolved oxygen concentrations were observed in May and June. The findings suggest that dissolved oxygen level is a function of both water temperature and the oxygen demand of the hypolimnion and sediments due to organic decomposition.

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1.4 Regulatory Context

1.4.1 TMDL Development Big Bear Lake supports a variety of beneficial uses, including: . Agricultural irrigation supply (AGR); . Municipal and domestic water supply (MUN); . Protection of rare and endangered species (RARE); . Water contact recreation (REC1); . Water non-contact recreation (REC2); . Wildlife habitat (WILD) . Warm freshwater habitat (WARM); and . Cold freshwater habitat (COLD). In 2006, the Santa Ana Regional Water Quality Control Board (Regional Board) adopted a Nutrient Total Maximum Daily Load for Dry Hydrologic Conditions in Big Bear Lake (the TMDL). The TMDL was adopted to establish the appropriate numeric targets that would indicate protection of beneficial uses, along with an implementation plan that specifies activities and a schedule to attain TMDL targets. The basis of the TMDL, as defined in the Problem Statement developed by the Regional Board, is that nuisance aquatic plants and low dissolved oxygen (DO) impair the beneficial uses of COLD< WARM< WILD, REC1, REC2, and RARE. Nuisance aquatic plants, including blue-green algae blooms and dissolved oxygen, are response targets – they describe how the Lake responds to certain stressors. The TMDL establishes causal targets that are thought to relate to the response targets. Nutrients are the primary cause of nuisance plant growth. In Big Bear Lake, the limiting nutrient is usually phosphorus. The primary external source of phosphorus to the Lake is from wet- weather discharges of watershed sediments. The primary source of phosphorus to the Lake during dry hydrologic conditions is internal owing to the release of phosphorus from sediments within the Lake. Biostimulation of algal growth due to excess phosphorus leads to excess organic carbon production; as algae die off and sink to the bottom, the decomposing algae deplete dissolved oxygen, especially in bottom waters. Anoxic conditions worsen during thermal stratification events that keep atmospheric oxygen from mixing into deeper water. Anoxic conditions can lead to unpleasant odors, discolored water, fish kills, and other undesirable effects. Sediments also tend to release phosphorus into the water column under anoxic conditions, which then becomes a positive feedback driver that leads to more nuisance algae and macrophyte growth. To address beneficial uses impaired by phosphorus, the Regional Board established the numeric targets for the TMDL as shown in Table 1-3 below. The causal target, phosphorus, was translated to a total annual load allocation of approximately 26,000 lbs per year using numeric models and simplifying assumptions. Although the total annual load necessary to attain the target and the resulting allocation into source categories is an estimate, the values do provide important information about phosphorus sources to the Lake under dry hydrologic conditions. Internal sediment release and macrophyte decay together represent the dominant phosphorus sources to the lake under dry hydrologic conditions (Table 1-4); therefore, to attain responsible targets, actions to attain the causal target of phosphorus will need to focus on reducing phosphorus releases from sediments. That finding established the regulatory driver for this Plan.

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Table 1-3. Numeric Targets Established by the TMDL Indicator Target Value Annual average no greater than 35 μg/L; Total Phosphorus Concentration to be attained no later than 2015 (dry hydrological (Causal target) conditions), 2020 (all other times) 30 to 40% on a total lake area basis; Macrophyte Coverage to be attained by 2015 (dry hydrological conditions), 2020 (Response target) (all other times) 95% eradication on a total area basis of Eurasian Percentage of Nuisance Aquatic Vascular Plant Species Watermilfoil and any other invasive aquatic plant species; (Response target) to be attained no later than 2015 (dry hydrological conditions), 2020 (all other times) Growing season average no greater than 14 μg/L; Chlorophyll-a Concentration to be attained no later than 2015 (dry hydrological (Response target) conditions), 2020 (all other times)

Table 1-4. TMDL for Phosphorus During Dry Weather Conditions Current Load TMDL Reduction Source Load Type (lbs/yr) (lbs/yr) (lbs/yr) % Change Sediment Internal 21,388 8,555 12,833 -60 Macrophytes Internal 17,943 15,700 2,243 -13 Atmosphere External 1,074 1,074 0 0 Forest External 175 175 0 0 Urban External 475 475 0 0 Resorts External 33 33 0 0 Loads as cited in Big Bear TMDL Task Force (2008). Although the TMDL is for total phosphorus, there are many forms of phosphorus in the environment that impact eutrophication differently. Soluble reactive phosphorus is much more available to algae as a nutrient than more inert, sediment-bound forms. This is important to keep in mind, as many of the scientific studies to assess the effects of remediation activities focus on concentration of soluble reactive phosphorus (SRP) in the water column and the concentration of loosely bound phosphorus in the sediments. In addition to the in-Lake Sediment Nutrient Reduction Plan (a.k.a. the Sediment Nutrient Management Plan in this report) specified in Task 6B of the TMDL, Task 6A required a Watershed Model Update (currently being implemented as a Model Update Plan), and Task 6C required an Aquatic Plan management plan. Those plans are not the subject of this Plan directly, but are referred to because those activities relate to this Sediment Nutrient Management Plan. Task 4 of the TMDL and Section V.D.4.d of the NPDES Permit require watershed-wide nutrient monitoring and in-Lake nutrient monitoring. That information will be used to evaluate target attainment. Potential improvements to existing monitoring approaches are discussed in the recommendations section of this Plan. Task 7 of the TMDL provides for review and potential revision of applicable water quality objectives, development of biocriteria (i.e., criteria developed based on response targets), and development of information on natural background conditions. Those activities will support the review of TMDLs and associated requirements once every three years, as specified in Task 10.

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1.4.2 Big Bear Lake Nutrient TMDL Task Force The Big Bear Watershed stakeholders formed the Big Bear Lake Nutrient TMDL Task Force in 2007 to address water quality in Big Bear Lake and its surrounding watershed. This Task Force was formed specifically to respond to requirements established by the TMDL for Big Bear Lake. The Task Force works together with stakeholders and the Regional Board to implement a number of actions required in the Basin Plan Amendment. Task Force members include: . United States Department Of Agriculture, Forest Service, San Bernardino National Forest (“Forest Service”); . California Department Of Transportation (Caltrans); . San Bernardino County Flood Control District (Flood Control); . County Of San Bernardino (County); . City Of Big Bear Lake (City); . Big Bear Municipal Water District (BBMWD); . Big Bear Mountain Resorts (Resorts); . Santa Ana Regional Water Control Board (SARWQCB); and . Santa Ana Watershed Project Authority (SAWPA) The Task Force developed a draft plan to achieve compliance with the TMDL (Big Bear Lake TMDL Task Force, 2008). The 2008 draft plan addressed sediments as an internal source of nutrients to the lake during dry weather conditions through a combination of actions that will result in overall improvement of the Lake and attainment of biological indicators of beneficial uses. The draft was submitted to the Santa Ana Regional Water Quality Control Board (Regional Board) in December 2008. The Regional Board provided comments on the draft plan in January 2009. The NPDES stormwater permit (Permit) for the County of San Bernardino (NPDES No. CAS 618036, Order No. R8-2010-0036) includes a provision (V.D.4.g) that requires a Plan and Schedule for In-Lake Sediment Nutrient Reduction to be submitted to the Regional Board no later than April 15, 2010. This report is a refinement of the 2008 draft plan that will satisfy the deliverable for a Plan and Schedule for In-Lake Sediment Nutrient Reduction required by the Regional Board.

1.5 Other Related Activities There are several related activities that directly address other specific habitat quality and management needs, but are also related to reducing phosphorus releases from in-Lake sediments during the dry hydrologic condition.

1.5.1 Nuisance Aquatic Plant Management The growth of nuisance aquatic plants, specifically Eurasian Watermilfoil, is a consequence of the Lake’s shallow morphology and excess nutrients. Task 6c of the TMDL requires the development of a Management Plan to Control Noxious and Nuisance Aquatic Plants in Big Bear Lake (the NAPMP). This requirement was also reflected in a provision of the San Bernardino County NPDES Permit for Urban Stormwater (Part V, Effluent Limitations and Discharge Specifications, Section D.4.e). The NAPMP was submitted to the SARWQCB on February 25, 2010. Aquatic plant management is related to in-Lake nutrient processes. Aquatic plants incorporate SRP into biomass. Mechanical harvesting removes biomass phosphorus, whereas herbicide application tends to release SRP back into the Lake as plants decay, as noted in 2003 (See Figure 2-6 on Page 3-10).

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There are two points of overlap between the NAPMP and nutrient management: . Herbicide application can increase SRP in the Lake. The lake may benefit from follow-up actions to sequester SRP, such as Phoslock application. . Nuisance plants such as Eurasian Watermilfoil thrive in shallow water habitats. Dredging projects along the margins can have the dual benefit of removing nutrients associated with sediments and also contouring the Lake to decrease the habitat area that promotes noxious plant growth.

1.5.2 Fisheries Management Carp can exacerbate the release of SRP because they forage in the shallows, stirring up sediments, eating plants, and releasing nutrients in their fecal matter. Carp also can displace other more valued fisheries resources. Large-scale carp removal using electrofishing and seine netting techniques was initiated in 2007 and continues to the present. The Annual Carp Round-up contest promotes public awareness and involves bowfishing enthusiasts in fisheries management activities. The California Department of Fish and Game Lake also stocks the Lake annually with trout to promote recreational fishing.

1.5.3 Model Updates The TMDL relies upon the conclusions of two models. The HSPF model is used to estimate phosphorus and sediment loads from watershed runoff. The WASP model is used to simulate in-lake processes to estimate how elevated phosphorus loads contribute to water quality impairments. Stakeholders have developed a plan to update the modeling approach using more sophisticated computer simulation tools. The Plan and Schedule for Updating the Big Bear Lake Watershed Nutrient Model and the In-Lake Nutrient Model was submitted to the SARWQCB on March 31, 2010. Two significant updates are proposed: . The WASP Lake Model will be updated to include a decay function reflecting the rate at which SRP is rendered inert. That calculation is essential to determining how much of the legacy phosphorus loads from external sources are currently contributing to in-Lake releases from sediments. . The WASP model will be revised to account for the effects of the management activities described above, such as aeration, carp removal, and aquatic weed control.

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BIG BEAR LAKE TMDL ACTION PLAN

2. SEDIMENT NUTRIENT REDUCTION PLAN

2.1 Approach This section presents an alternative analysis that documents the costs, constructability, constraints and opportunities for different strategies to reduce releases of nutrients from Lake sediments under dry hydrologic conditions. The analysis also includes a proposed monitoring approach to quantify reductions of in-Lake sediment nutrient releases. The alternatives analysis approach starts by examining all of the techniques applied to date to control eutrophication and enhance beneficial uses. Those techniques are: . Water management; . Dredging; . Treatment of the Lake with alum to bind soluble reactive phosphorous (SRP) in sediments; . Aeration and destratification; . Aquatic nuisance plant management; and . Carp removal. For each of those techniques, the following questions were investigated: . What has been done to date? . What did it cost? . What benefits were realized? . Are there ways to enhance effectiveness? . What would the benefits be of enhanced effectiveness? . What would the costs be of enhanced effectiveness? . What are the potential environmental consequences? . What are the institutional or regulatory constraints and opportunities? . To what extent is the timing and sequencing of different activities important? The answers to those questions form the basis of the findings in Section 2.2 below. The questions were investigated through review of the reports in the references section of this Plan, as well as discussions with Task Force members. The findings in Section 2.2 are the foundation of the proposed schedule of activities in Section 2.3.

2.2 Findings Task Force members have been working together to improve water quality in the Lake since 2001. By the time the Agreement to form the Big Bear Lake Nutrient TMDL Task Force was signed by all parties in 2008, a total of $12 million had been invested in various remediation projects designed to alleviate Lake impairments due to nutrients. This section summarizes those activities, along with lessons learned, as a basis for supporting the recommended next steps.

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2.2.1 Water Level Management

Current Activities – Lake stabilization was the first adaptive management activity to protect the Lake’s beneficial uses. Bear Valley Dam was originally constructed to provide water for agricultural users. Those users still own the water rights through the Bear Valley Mutual Water Company. In the 1950s and 1960s, California was experiencing a prolonged period of drought and the Lake levels dropped dramatically, as they had in the past due to withdrawals. Recognizing the growing recreational value of the Lake, the community was determined to gain control of Big Bear Lake. The Big Bear Municipal Water District (BBMWD) was formed in 1964 with the specific mission of stabilizing the level of the Lake to protect recreational uses. In 1977, BBMWD acquired the dam, the land underneath the Lake, and the surface recreation rights to the Lake for a purchase price of $4.7 million1. The cost of acquiring the water rights, however, was prohibitive at the time. Instead, after a prolonged sequence of litigation and negotiation, an agreement, known as the “In-Lieu Water Program,” was reached whereby BBMWD agreed to provide up to 65,000 acre-ft of water each year to Bear Valley Mutual Water Company, either from Lake releases or from purchasing water from the State Water Project and other sources.

Benefit to Water Quality – The result, according to hydrologic models, was a significant stabilization in Lake levels (Figure 2-1). Although the Lake still has been as much as 18 feet below full pool elevation during the last two major drought periods, the drawdown has been nowhere near historic levels that preceded the In- Lieu Water Program. Stabilization of Lake levels has maintained a much greater Lake surface area and allowed shoreline access for most users even under the most severe drought conditions observed in 2004 (Figure 2-2).

Cost Information – In addition to the $4.7 million acquisition cost, BBMWD spends approximately a third of its $3.8 million annual operating budget on water purchases for the In-Lieu Program (www.BBMWD.org) to maintain Lake levels.

Opportunities to Enhance Current Activities – Given the scarcity of water resources in California, the inertia of California Water Rights adjudications, and the value of water rights, it is assumed for this Plan that substantial enhancements to water management practices would not be a part of this Sediment Nutrient Management Plan in the foreseeable future. In other words, it is assumed that Lake levels will continue to rise and fall as they have since the implementation of the 1977 In-Lieu Water Program. The benefit of Lake stabilization is an essential starting point to understand the complete history of adaptive management in Big Bear Lake. If opportunities do arise to further stabilize Lake levels, there would likely be significant benefits to water quality, recreation, and habitat for wildlife and aquatic life.

1 The Forest Service retains ownership of some parts of the bottom of the deepest parts of the Lake.

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Figure 2-1. Comparison of Lake Drawdown Levels Under Current Operations with the In-Lieu Water Program Hypothetical Conditions in the Absence of the In-Lieu Water Program. The blue line indicates the actual Lake levels since 1977 when the In-Lieu Water Program went into effect. The red line indicates what hypothetical Lake levels would be without the In-Lieu Water Program. Figure developed by ReMetrix, LLC. 11550 N. Meridian St. Suite 600, Carmel, IN 46032.

2.2.2 Dredging

Current Activities – Dredging is necessary to allow boaters to access the marinas, especially during drought periods. Dredging projects are primarily scoped and contracted by BBMWD. Between 1983 and 2000, more than 415,000 cy of sediment were dredged for navigational enhancement (Table 2-1). The primary intent of all the projects from 1983 to 2000 was navigation, not specifically targeting nutrient removal; however, the projects did provide some benefit to nutrient removal, as sediments containing nutrients were removed from the Lake. In 1999, a more substantial remedial dredging project was scoped out that combined navigational improvement goals with nutrient removal and habitat modification goals (Moffat and Nichol, 2001). The intent of the project, known as the East End Deepening Project, was to provide access to Marinas on the east end, to contour the Lake shoreline in a way that removes shallow water habitat where noxious Eurasian Milfoil thrives, and to investigate remedial dredging as an alternative for reducing eutrophication in the Lake. Because of the nexus to water quality improvements, the project was awarded Proposition 13 funds.

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Section 2: Sediment Nutrient Reduction Plan Big Bear Lake TMDL Action Plan

Figure 2-2. Comparison of the Lake Area When Full With 2004 Conditions Under Current Operations and Modeled 2004 Conditions Without the Exchange Agreement. Figure developed by ReMetrix, LLC. 11550 N. Meridian St. Suite 600, Carmel, IN 46032

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Table 2-1. Dredging Projects History at Big Bear Lake, 1983- 2000

Year Project Name/Location Amt dredged (cy) Berkley 1,254 Rick Thomas 3,934 1983 Big Bear MWD (Mallard Lagoon/Canvasback Cove) 40,000 Boulder Bay 2,000 Ski Beach 35,000 1984 Shelter Landing 500 1985 Bruin Trailer Park 25,000 Jefferson 950 1986 Fisher 1,200 1987 Berkley 750 Metcalf Bay Projects 27,347 Viking Estates 850 Kehle (sand on beach) 20 1988 Nakamura 10 Meadow Park (asphalt removed) 200 Newell 500 Stevens (beach cleanup) 50 Snapper (remove beach mud) 90 North Creek Restoration 500 1990 Lighthouse Marina (harbor improvement) 1,200 Grout Bay/Grout Creek (lake bottom) 1,500 Frontier Lodge (grade/remove silt) 40 Real Williams/Grout Bay 2,400 Ricks (illegal Launch Ramp) 20 Rounds 815 1991 Big Bear Shores (launch ramp/beach) 350 Hamilton Estates 28,000 Marina Riviera 100 Sapper 4,200 1992 BBMWD East Boat Ramp 3,000 Eagle Point Harbor 160,000 1994 BBARWA 75 1996 Salzor 49 Maggi/Thompson/Kelly 8,750 1997 Gilligan 80 Kulby 100 Presbyterian Conference Center 300 1999 Foulkes 39 Eagle Pt. Estates 100 Landsbury 38 2005 East End Dredge 208,136 Rathbun Creek 6,915 2009 Pine Knot Marina 73,849 TOTAL 640,211 Dredging projects, dates, and quantities as reported by Moffat and Nichol (2001)

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The East End Deepening Project was completed in 2005 (URS, 2007b). Several alternatives were evaluated, each with different assumptions about the dredging footprint and disposal options. Approximately 220,000 cy were excavated and transported to the Big Bear Sanitary Landfill for use as a landfill cap, which was one of the least expensive options. The dredging was initially planned using dry land excavation techniques. Winter storms of 2004 to 2005 re-filled the Lake before dredging started; however, a coffer dam was constructed and dredging proceeded as planned using dry land excavators (Figure 2-3, Figure 2-4).

Benefits to Water Quality – The benefits of the East End Dredging project were evaluated by monitoring soluble reactive phosphorus flux rates in sediment core incubation studies, and phosphorus, nitrogen species (ammonia, total nitrogen, organic nitrogen), and chlorophyll-a in water before and after the remedial dredging (Anderson and Wakefield-Schmuck, 2006; Anderson and Paez, 2007). Sequential extractions to measure soluble reactive and refractory forms of phosphorus in sediments provided additional insights (Reddy and Wang, 2008). Other activities took place within that same time frame, including an herbicide addition to kill off Eurasian Milfoil in 2003, and an alum addition project to bind soluble reactive phosphorus in 2004. In addition, winter storms in 2005 and 2006 brought new loads of sediment and nutrients into the reservoir; therefore, the specific benefits attributable to the dredging project may be difficult to separate from the impacts of runoff and phosphorus release from decaying plants, and the benefits that resulted from the alum addition; however, the monitoring studies have shed some light on the benefits of dredging activities. The consensus of researchers is that phosphorus diffusion from bottom sediments into the water column did indeed decrease in the dredging area following dredging (Anderson and Wakefield-Schmuck, 2006). Prior to dredging, the sediments in the dredging area were a net source of soluble phosphorus to the water column. Reddy and Wang (2008) estimated that the phosphorus-supplying capacity of sediments in the area prior to dredging would last from 10 to 100 years, based on their findings on the distribution of phosphorus between soluble reactive and more inert forms. After dredging, sediments in the area became a net sink; therefore, the benefit established by this dredging project was a reduction, at least temporarily, in the inventory of soluble reactive phosphorus releases from sediments in a shallow area of the link. Other demonstrable benefits to water quality include improved navigation and reduced habitat area for Eurasian Milfoil. Two follow-up questions that needs to be addressed through monitoring is how long the benefits would last following dredging, and whether or not sediments left behind at the sediment-water interface would gradually increase the fraction of labile phosphorus available to the water column. Another benefit is maintenance of Lake capacity. The total amount of sediment dredged since 1983 (640,211 cy), is very close to the estimated sediment input of 800,000 cy during that same time frame (Liedy, 2006).

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Figure 2-3. Dry Land Excavation behind a Coffer Dam During the East End Deepening Project.

Figure 2-4. View of the Coffer Dam from the Lake during the East End Deepening Project.

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Cost Information – BBMWD reports that the total cost of the East End Deepening Project was $7.2 million (M. Stephenson, Personal Communication on March 26, 2010). Of this total amount, $1.55 million was paid by the Proposition-13 grant fund (Agreement 04-204-558-0) for the cost of dredging only (H. Boyd, personal Communication on March 29, 2010). This difference between the total cost and the dredging-only cost underscores the fact that in addition to the unit cost of dredging itself, there are substantial costs for equipment mobilization and demobilization, and most importantly, sediment re-use and disposal. The dredging cost alone was $7 per cubic yard (in 2005 dollars), whereas the total project cost, including mobilization, disposal and engineering support, came to approximately $32 per cubic yard (in 2005 dollars). The original 2001 (Moffat and Nichols, 2001) cost estimates for the East End Deepening Project, escalated to 2010 dollars, are shown below in Table 2-2. Although this table is a broad extrapolation from a report now 10 years old, it is still relevant for order-of-magnitude cost estimates to evaluate the potential cost of larger dredging projects. Also, the table shows that sediment disposal or re-use options determine the cost. For a given disposal scenario, the cost increases one-to-one in proportion to volume, but can vary as much as five-fold depending on the disposal option (see shaded cells in Table 2-2). That finding is important when considering how dredging activities could be better planned and enhanced to maximize the cost-benefit ratio of the activity. The limiting factor is more often planning, permitting and implementing the disposal alternative.

Table 2-2. 2001 Cost Estimates for the East-End Deepening Project, Escalated to 2010 Dollars Disposal via East End Fill Disposal via Disposal via Adjusted Project/Big Bear East End Fill East End Fill Disposal via Volume Landfill/Baldwin Project/Big Bear Project/Baldwin East End Fill Dredging Alternative (cy) Lake/Quarries Landfill/Quarries Lake/Quarries Project/Riverside/Quarries Alternative 1 (-15 feet) 190,402 $3,200,000 NA NA NA Alternative 2 (-17 feet) 275,548 $4,400,000 NA $4,400,000 $13,000,000 Alternative 3 (-19 feet) 458,417 $6,900,000 $14,000,000 $18,000,000 $38,000,000 Alternative 4 (hybrid) 288,636 $4,500,000 NA $4,500,000 $15,000,000 Based on Cost Data in Table 9-1 of Moffat and Nichol (2001, Escalated to 2010 costs using standard ENR tables.

Opportunities to Enhance Current Activities – The United States Army Corps of Engineers (USACE) began a feasibility evaluation of restoration measures for Big Bear Lake (URS, 2007b). That draft report evaluated large-scale dredging, as well as capping activities and a more cursory description of Lake treatments. It contains preliminary guidance on scoping the planning design and construction elements of dredging projects. Unit cost factors for dredging were $5 to $35 per cy, comparable to the actual costs for the East Side Deepening Project cited above. Disposal alternatives in the USACE Report were developed through discussion with the USACE and BBMWD. A total of 20 disposal/reuse alternatives that fell into the following general categories were proposed: . New islands for bird sanctuary; . Shoreline restoration and enhancement; . Upland fill projects . Widening of state highways . Restoration of abandoned quarry/mining excavations; and . Use on U.S. Forest Service property.

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The USACE report stated that the initial recommended approach was to dredge as much as five million cy from the bays and another six to eight million cy from central portions of the Lake. This was refined through the feasibility analysis to recommend a more targeted, but unspecified, dredged volume to be determined by collecting sediment cores throughout the lake. Many cores were collected by the USACE as part of the feasibility evaluation (URS, 2007b; URS 2006a; URS 2006b). Most samples were restricted to geotechnical analyses, but a subsample also provided analyses of deionized-water extractable nutrient (nitrogen, phosphorus, organic carbon) concentrations. The results noted that the highest nutrient in sediment concentrations were located in the bays near the mouths of tributaries and in the center of the lake (URS, 2006b). That observation is consistent with the findings of Kirby, who suggested that rising and falling lake levels, combined with wind-wave action along the shoreline, may result in a sediment focusing effect whereby sedimentation rates are higher in the center of the lake. This was presumably the rationale for the recommendation to focus on more strategic areas of elevated nutrient concentration where “newer” sediments tend to accumulate near tributary sources, in quiescent bays, and in the center of the Lake. The cost considerations alone tend to constrain dredging opportunities to the maintenance levels, or a small increment larger than that. Maintenance dredging volumes are typically 10,000 to 20,000 cy per year. The 220,000 cy East End Deepening project cost $7.2 million in total in 2005; opportunities for local disposal available at that time are not available now. The trucking costs for a larger project would not only be cost prohibitive (nearly $40 million for a half a million cubic yards) the air emissions and traffic impacts would likely be profound. Three key concepts introduced in the USACE feasibility evaluation will be carried forward through the recommendations: . Because of cost and disposal/reuse constraints, the amount and timing of dredging is constrained. A 220,000 cy project can be done, but there are significant costs, and visual impacts on the landscape. A million cy project, done all at once within a single construction season, would multiply the visual impacts shown in Figure 2-3 and Figure 2-4 five-fold. . Sediment disposal or re-use, not excavation techniques or even quantities, is the determining factor for the cost and constructability of dredging projects; therefore, it would help to have a long-term plan for sustainable, low-cost re-use of dredged sediments. The cost savings and planning certainty could make dredging above current maintenance levels more affordable and acceptable. . There are certain areas where sediments have higher nutrient concentrations, and they appear to be where “newer” sediments would be found; therefore, it may make sense to trap sediments closer to the tributaries after storms, before they can disperse and settle in deeper parts of the Lake. This is explored further below when discussing opportunities to enhance Lake Treatment.

2.2.3 Lake Treatment

Current Activities – In 2004, an in-Lake alum (aluminum sulfate) addition was conducted by BBMWD, with support in part from a Proposition 13 grant (Agreement No. 03-126-558-0). The Primary goal of the project was to reduce internal loading. A secondary goal was to collect data to evaluate the effectiveness of alum addition, and to provide monitoring data required by the Waste Discharge Requirements issued to BBMWD that covers application of herbicide and alum. Alum was added for 12 hours per day from May 24 though June 19 (with the exception of seven days during mobilization and holidays; Figure 2-5). Approximately 700,000 gallons of liquid alum was applied over about half the lake (about 1330 acres). The average dose was approximately 29 g Al/m3. Operations were carried out by an experienced professional applicator, Sweetwater Technology.

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Figure 2-5. Application of alum on Big Bear Lake, May through June 2004. Photo Courtesy of BBMWD

Benefit to Water Quality – Effects on water quality and nutrient cycling was characterized by several monitoring projects focused on water and sediment quality in the Lake immediately after alum application (Berkowitz and Anderson, 2006; Godwin-Saad, 2005) as well as in subsequent years (Anderson and Makefield-Schmuck, 2006; Anderson and Paez, 2007). Figure 2-6, from Anderson and Paez (2007), shows the rapid and substantial decrease and subsequent return of soluble reactive phosphorus (SRP) flux from bottom sediments following alum application in 2004. In the year prior to alum application, herbicide addition resulted in a substantial release of SRP from decaying plant matter. Lakewide SRP fluxes ranged from 10 to 20 mg/m2/day. After the 2004 pilot alum addition, SRP fluxes dropped rapidly to less than 5 mg/m2/day lake wide. By 2005, SRP fluxes had climbed somewhat in the eastern side of the Lake. By 2006, SRP fluxes had increased above 2004 levels in all sections of the Lake. They were below pre-2004 levels in the western segment (Station 1), but very near 2004 levels in the eastern segments (Stations 6 and 9). Along with the measureable decrease in SRP fluxes, water column nutrient concentrations and chlorophyll-a concentrations were reduced, and water clarity was improved. Lake pH was slightly depressed (from 7.9 down to 7.2) during application, and returned to within 2 percent of pretreatment levels after three weeks. This range is within the Basin Plan water quality objective established for pH (range of 6.5 to 9.0). The conclusion of BBMWD as expressed by Godwin-Saad (2006) was that substantial benefits accrued from the alum application with no evidence for a threat to water quality.

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Figure 2-6. Soluble Reactive Phosphorus Flux from Sediments in Big Bear Lake, 2002 to 2006. Site 1 is closest to the Dam, on the West Side of the Lake. Site numbers increase from west to east. Figure taken from Anderson and Paez (2006).

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Cost Information –The cost estimate provided by Sweetwater Technology was $753,000 to apply 700,000 gallons of alum (Heather Boyd, Personal Communication on April 7, 2010). That figure does not include the cost of sales tax, data collection or reporting.

Opportunities to Enhance Current Activities – In 2006, a follow-up Proposition 13 grant application was submitted for an enhanced alum addition project. The project was not supported by Regional Board staff, based on concerns that alum addition could have negative impacts on aquatic life. One specific issue raised by the Regional Board was the concern that alum application would cause an exceedance of the water quality objective for aluminum in receiving waters. There is no adopted numeric water quality objective for aluminum in the state of California. There is a narrative prohibition on toxic substances present in toxic amounts that the Regional Board staff may choose to interpret using the best available science. Regional Board staff has indicated that in the absence of a site-specific objective they would apply the federal criteria for aluminum (USEPA, 1998). The federal criterion for aluminum is 87 µg/L as a four-day average, and 750 µg/L as an instantaneous maximum. This is a perplexing constraint, as ambient aluminum concentrations in natural waters routinely exceed these limitations, owing to the presence of approximately 12 percent aluminum by weight in the earth’s crust. Nonetheless, concerns over aluminum toxicity due to amorphous hydroxides in natural waters are valid – naturally occurring aluminum in mineral form is different from the form applied as alum. Accumulation in sediments may be a more serious concern than water column toxicity, by simply degrading benthic habitat. Depending on application rates, there is a concern expressed by Regional Board staff that floc formations on the bottom (Figure 2-7) could disrupt benthic organisms. Given these concerns, widespread alum addition in Big Bear Lake may face regulatory hurdles in the foreseeable future, despite the proven benefits to phosphorus reduction1. More targeted, strategic alum application, as described below, may still be an option.

Figure 2-7. Floc Formations Settle to the Bottom of a Jar Test Photo courtesy Mr. Jeff Herr, Brown and Caldwell

1 Mr. Jeff Herr, Brown and Caldwell’s National Practice Leader for Stormwater Treatment Technologies, reports that concerns over alum effects on water column and sediment quality may not be well founded. During his peer review of this report, Mr. Herr commented that alum treatment is a common practice that leads to generally improved conditions in the water column and the benthos.

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There are alternatives to alum. One such product, Phoslock®, relies on lanthanum impregnated in bentonite clay to immobilize phosphorus by forming of the highly insoluble lanthanum-phosphate compound, rabdophane. Additional product information is available at http://www.phoslock.com.au/. Preliminary cost information is available for this product; however detailed cost estimates for Phoslock® and other alternatives would be developed in the initial stages of implementing this Plan. Note that this is not an endorsement or recommendation for this specific product. Rather, it is noted that given the success of the alum addition and concerns over toxicity, alternative products should be explored. Any chemical treatment may raise the concern of accumulation in lake sediments over time, depending on the dosage rate and frequency. For that reason, an enhancement to explore would be a more strategic approach that targets focused areas, during specific critical times, and then follows up with a small amount of dredging to remove the flocculant and the upper layer of organic-rich sediments from the treatment area. Critical times and locations that could be important to address include: . After application of an herbicide, as seen in 2003 to 2004 . Near the mouths of tributaries after a storm; and . In upstream detention basins during small to moderate storm events. All three of those activities could to greater or lesser degrees, augmented with silt curtains, such as the one shown in Figure 2-8. Systems for automated dosing could also be installed in detention basins. For all of these operations, important constraints, in addition to protecting water quality by obtaining and complying with all permits, would be protecting public safety and avoiding nuisance to recreation.

Figure 2-8. Example of a Silt Curtain Containing Sediment Impacts from a Lakeside Construction Project in North Carolina. Photo Courtesy Marshal Taylor, Brown and Caldwell

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The benefit of this approach, compared to dredging, is that it uses the past decade of learning to target times and places where we suspect inputs of SRP will have the greatest impact. In particular, the observations of both academic researchers (Kirby; Date unknown) and USACE planners (URS, 2007a; URS, 2006b) described in Section 2.2.2 above point to new sediments as a source of SRP that can feed the eutrophication cycle in Big Bear Lake. If so, that would make sense from a geochemical standpoint as well. Phosphorus tends to bind to sediments (Goldberg and Sposito, 1984) and also flocculants such as Phoslock® (Ross et al., 2008) better at pH 5 to 7 than at pH 8 to 9. Stormwater would be closer to pH 7, whereas Lake water is buffered closer to pH 8.5; therefore, as watershed sediments are swept into the lake, the increase in pH would cause phosphorus to desorb, which would add a pulse of SRP to the Lake. This is a management hypothesis (or question) based on information provided from the past decade, $12 million worth of investment in pilot studies, and some basic geochemical principles. The management question is: “Can we get more effective SRP removal from watershed inputs if we apply a reasonable amount of effort to contain SRP impacts to the margins and remove them quickly by dredging?” The significance of the question is that through lessons learned, it may be possible to develop an alternative that involves small-scale, short-term, strategic dredging projects that are only a modest increase above current levels. This is by no means certain to be a cost-effective solution, but it is worth exploring.

2.2.4 Aeration and Destratification

Current Activities – Currently, BBMWD uses both an aerator and a destratifier on the west end of the Lake between the old submerged dam and boom (Figure 2-9). The aerator draws water from about 12 feet under the lake surface, injects air into the water, and shoots it up at the rate of 125 million gallons every 24 hours. The aerator only operates within the epilimnion of the Lake. The destratifier, on the other hand, has diffuser pipes running across the lake bottom. A compressor supplies air from the shore to the diffusers. BBMWD can choose between using the aerator and the destratifier based on a number of factors. For example, the destratifier helps break up ice formation near the dam; it can also be used to cool the Lake near the dam when air temperatures are lower than water temperatures. At times, it can be used to lift nitrogen and ammonium up into the photic zone to be biologically processed during non-critical times. (Mike Stephenson, Personal Communication on March 24, 2010).

Benefits to Water Quality – Since aeration and destratification were implemented in 2004, there have been no fish kills in the Lake that could be attributed to low DO (there was a fish kill in 2005 that Regional Board staff attributed to dredging). Lake managers have a range of tools to improve temperature, DO, and to some extent, nutrient fluxes in a localized area. Bringing oxygen in to the deeper water through aeration and destratification helps accelerate aerobic processing, which helps the reservoir “burn off” sediment organic carbon that fuels Lake eutrophication. The benefit to water quality can be seen by comparing July 2000 DO profiles to July 2009 profiles, approximately four years before and four years after commencing aeration and destratification management. DO in bottom waters was at zero in July 2000, compared to 3 to 4 mg/L in July 2009 (Figure 2-110); however, the sediment oxygen demand of the Lake appears to be considerable compared to the oxygen inputs from the current management techniques. A month later, in August 2009, DO dropped to zero east of the area being managed by the aerator (Figure 2-11). The aerator affects about a 40-acre area (Michael Stephenson, Personal Communication, March 25, 2010). Although the management activity appears to have successfully created a habitat refuge for fish, low oxygen conditions persist in bottom waters and likely contribute to ongoing release of phosphorus from sediments.

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Figure 2-9. Location (Upper) and Close-up View (Lower) of the Aerator on the West End of Big Bear Lake Photos Courtesy Michael Stephenson, BBMWD

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7/20/2000 Dissolved Oxygen (mg/L) 0 1 2 3 4 5 6 7 8 0

20 Boom Line Papoose 30 West Ramp Depth (Feet) 40 Observatory Juniper Point 50

7/17/2009 Dissolved Oxygen (mg/L) 0 1 2 3 4 5 6 7 8 9 0

20 Boom Line Papoose 30 West Ramp Depth (Feet) 40 Observatory Juniper Point 50

Figure 2-10. July Dissolved Oxygen Profiles in Big Bear Lake in 2000 and 2009. The Lake was slightly deeper in 2000 compared to 2009 (note bottom depths at Boom Line). The Lake had essentially zero dissolved oxygen in the bottom waters in July 2000, prior to implementing of aeration and destratification, as compared to 3 to 4 mg/L in 2009.

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8/14/2009 Dissolved Oxygen (mg/L) 0 1 2 3 4 5 6 7 8 0

20 Boom Line Papoose 30 West Ramp Depth (Feet) 40 Observatory Juniper Point 50

Figure 2-11. August 2009 Dissolved Oxygen Profiles in Big Bear Lake East of the aerator, dissolved oxygen can still fall to zero in bottom waters

Cost information – Operating cost is another factor in selecting between the aerator and the destratifier. The aerator costs approximately $80 per 24 hours use. Actual use varies from year to year. Last year, the annual O&M on the aerator for electricity totaled $11,000 (Michael Stephenson, Personal Communication on March 25, 2010). The destratifier can be operated for a fraction of this cost.

Opportunities to enhance current activities – The need appears to be for more oxygen in the bottom waters. This would be a logical next step in the event that, over time, it is discovered that current management activities are not sufficient to attain responsal targets established by the TMDL. The USACE report proposed removing the legacy burden of organic carbon by dredging; however, it may be possible to remove an equivalent amount of organic carbon more efficiently through aerobic metabolism. The challenge is to introduce enough oxygen into the bottom waters while allowing the lake to stratify to maintain cooler waters at depth. An effective solution may be hypolimnetic oxygenation of the bottom waters.

2.2.4.1 Overview of Hypolimnetic Oxygenation This subsection presents a brief overview of example hypolimnetic oxygenation projects to support some concepts discussed in the report. Four main types of hypolimnetic oxygenation systems (HOS) are typically used (Beutel, 2002). Table 2-3 below provides general comparison among several hypolimnetic oxygenation technologies discussed below.

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Table 2-3. Comparison of Hypolimnetic Oxygenation Technologies

Capital Cost 2 O&M Cost 3 System (million dollars) (dollars per day) Advantages Disadvantages Submerged contact Very high oxygen transfer efficiency. Need for a submerged pump and chamber with pure chamber (e.g., Speece cone). ~1.0 ~850 Oxygen discharged horizontally over oxygen 4 sediment-water interface. System efficiency independent of lake depth. Side-stream Low operating cost compared to on- Need to construct 175-foot deep oxygenation with shore chamber. System efficiency u-tube Pumping required. deep pure oxygen independent of lake depth. Oxygen U-tube and Not reported ~1000 released and maintained closer to horizontally water/sediment interface discharging bottom diffuser Bubble plume No pumping. By pumping air through the Oxygen released above and diffuser deep-water diffusers, it can also be used as away from sediment-water oxygenation without ~1.0 ~1000 destratification system. Good horizontal interface. System efficiency Speece cone distribution of oxygen. decreases with lake depth. May impact thermal stratification. Linear diffuser Good horizontal distribution of oxygen. System efficiency decreases with oxygenation lake depth. Oxygen released above and away from sediment- Not reported Not reported water interface. System can impact thermal stratification.

1) Table taken in part from Beutel (2002) 2) Capital costs are based on a system with 5 tons per day of oxygen input. Such a system is expected to be adequate for a mesotrophic to eutrophic lake/reservoir roughly 50,000 acre-feet in volume. 3) Operating costs assume liquid oxygen cost of $150/metric ton and energy costs of $0.10/kWh. 4) Because of its extremely high efficiency in dissolving oxygen gas into hypolimnetic water, the lowest operating costs are associated with a submerged contact chamber.

Submerged contact chamber oxygenation – consists of a submerged cone-shaped contact chamber (such as a Speece cone see Figure 2-12) mounted on the lake bottom. A submersible pump draws water from the hypolimnion and directs it into the top of the cone. Oxygen supplied from an on-shore facility is injected at the cone’s top. The oxygenated water is discharged through a horizontal diffuser pipe, which creates a horizontally directed, oxygen-rich plume that flows over the bottom sediments. Note that placing the contact chamber on the bottom increases the transfer efficiency because water can carry more dissolved oxygen when it operates at the higher pressure found at depth.

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Figure 2-12. Conceptual Diagram of a Speece Cone

Side stream oxygenation – hypolimnetic water is pumped onto shore, injected with oxygen (such as inside a deep-shaft U-tube chamber), then discharged back into the hypolimnion through a submerged pipeline connected to a diffuser.

Bubble plume oxygenation – works by injecting pure oxygen through a dense group of diffusers at the lake bottom. Oxygen bubbles dissolve into a surrounding plume of rising water. The oxygenated plume then detrains and spreads out horizontally below the thermocline, with mixing induced by Coreolis forces and wind-induced circulation.

Linear diffuser deep-water oxygenation – consists of an extensive network of linear bubble plume diffusers (soaker hoses) that release fine oxygen bubbles that rapidly dissolve into the overlaying water column as the bubbles rise. Oxygen is added several feet above the bottom and rises away from the bottom.

2.2.4.2 Oxygen Gas Supply Options Oxygen suppliers and/or owners use several technologies generated for providing oxygen to a hypolimnetic oxygenation system (HOS). The choice of onsite generation or trucked–in purchased liquid oxygen is governed by a project’s location, electric power availability, and local ability to maintain mechanical equipment. On-site generation is preferable to trucking in liquid oxygen for remote sites or accessible only over rural roads. Commercial liquid oxygen can be produced with various processes. The most widely used of these is cryogenic air separation (as described in CALFED [2003]). Large refrigeration units cool air to oxygen’s condensation temperature (-275 ºF). It can then be separated from the nitrogen and shipped in liquid form or generated onsite where the demand is sufficiently large. Because of the massive refrigeration units required, cryogenic methods require a large facility that may cost tens of millions of dollars. Such systems also require large utility power connections. Most often, cryogenic methods are intended to produce more valuable liquefied gases, such as nitrogen and argon, which generate liquid oxygen as a side product. This market characteristic can keep liquid oxygen price low if the use is located near an accessible point of production. A non-cryogenic method for oxygen gas production is membrane gas separation. This process requires dense ceramic materials known as “ion transport membranes.” When heated to high temperatures, these membranes ionize oxygen molecules in the air using electrons that have migrated to the outer side of the membrane. The oxygen ions then pass through the wall of the ceramic membrane. Once inside, the oxygen ions release the electrons which form a stream of pure oxygen. The ions migrate back to the outer edge,

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which allows the process to continue. This method is also expensive to install initially, and it consumes large quantities of electricity, just like the refrigeration process. A third method is pressure swing absorption (PSA). PSA systems are typically used where oxygen demand is less than about 40 tons per day. In a PSA system, compressed air is directed into a tank filled with a medium that selectively adsorbs nitrogen, with the purified oxygen passing through for use in the HOS. When the medium becomes nitrogen saturated, compressed air is diverted into a parallel adsorption vessel. Then, when the first adsorption vessel vents to atmosphere, the adsorbed nitrogen desorbs and the medium regenerates, ready for a repeat cycle. Separated oxygen typically has a purity of up to 95 percent. This technology is often used to generate oxygen on site in lieu of trucking in liquid oxygen.

2.2.4.3 Four Examples of Hypolimnetic Oxygenation Systems (HOS) Table 2-4 summarizes four hypolimnetic oxygenation projects implemented in various lakes and reservoirs in the western United States. Some brief, relevant details noted on each project follow. For comparison, it helps to note that Big Bear Lake is approximately 3,000 acres, intermediate to Newman Lake and Camanche Reservoir. The eastern portion of Big Bear Lake is about the same size and has similar depth to Newman Lake. The western portion of Big Bear Lake below 40 feet in depth is similar to Upper San Leandro Reservoir in surface area. The surface area of the deepest portion (below 50 feet) near the boom line and the old dam is closer to that of Indian Creek Reservoir. The surface area and volume of the smallest pocket in Big Bear Lake, between the old and new dams, is much smaller than Indian Creek Reservoir.

Table 2-4. Summary of Hypolimnetic Oxygenation Projects

Year HOS Area Volume Oxygenation Construction Annual O&M Waterbody (State) Constructed (acres) (acre-ft) Technique Cost (millions) Cost Submerged Newman Lake contact chamber 1992 1200 23,000 Not available Not available (WA) 1 oxygenation— Speece cone Submerged Camanche Reservoir contact chamber 1993 7622 431,000 $1.2 $40,000 (CA) 2 oxygenation— Speece cone

Upper San Leandro Diffuser deep- Reservoir 2002 744 37,980 water oxygenation $1.1 $30,000 (CA) 2 with soaker hoses

Submerged Indian Creek Reservoir contact chamber 2009 110-159 1,500 – 3,100 $0.84 $10,000 (CA) 4 oxygenation— Speece cone 1 From Beutel (2002) 2 Personal Communication, Rod Jung, East Bay Municipal Utility District, March 2010\ 3 Personal Communication, Ivo Bergsohn, South Tahoe Public Utility District, March 2010.

Newman Lake (Washington) Newman Lake began experiencing cyanobacterial blooms in the late 1960s and early 1970s as a result of internal phosphorus recycling that accounted for nearly 80 percent of the 3,000 kg annual load. In the 1980s, the community initiated a restoration program that led to a coordinated plan of watershed controls, alum treatments, and a hypolimnetic oxygenation system (Moore and Christensen, 2009). Working in concert with

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a dual-port, microfloc alum injection system, the program reduced phosphorus levels from above 50 µg-P/L to an average of 21 µg-P/L over the past seven years. The algae community has shifted from cyanobacteria to a more diverse population that includes diatoms, and green and golden-brown algae. The project is regarded as a successful HOS example used in conjunction with external watershed load control programs and an in- lake treatment technology to manage eutrophication effectively in a lake surrounded by a developing watershed with significant forestry uses. Oxygen in the Newman Lake system is manufactured on-site in two molecular sieve oxygen gas generators that capture oxygen from the atmosphere. The oxygen gas is then compressed and piped to the submerged contact chamber. Highly oxygenated water is discharged horizontally into the hypolimnion through a 46-m- long diffuser pipe. For scoping purposes, this would be a good example to understand the construction and operating cost of a surface oxygen generation system, and the design and performance issues associated with a diffuser pipe.

Camanche Reservoir (California) East Bay Municipal Utility District (EBMUD) owns and operates this reservoir. In this case, EBMUD added HOS not to benefit reservoir users but rather to avoid fish kills in the Mokelumne River and Mokelumne River Fish Hatchery downstream. Low or absent DO in Lake Camanche resulted in low dissolved oxygen, sulfide, and ammonia in reservoir releases. The watershed also has a mining impacts history. Positive hypolimnion DO was planned to counteract possible sediment trace metal mobilization. Post-operation water quality monitoring indicate that after operation of the hypolimnetic oxygenation system, fall hypolimnetic orthophosphate levels dropped from 200 µg-P/L prior to treatment to less than 50 µg-P/L after oxygenation. Oxygen demand dropped off after initial startup by about 50 percent. EBMUD staff thinks these results are from sediment oxygen demand (SOD) depletion. Electricity now accounts for about 65 percent of O&M costs (as of 2010). In-lake facilities include a 12-ft-diameter, 23-ft-high submerged Speece cone; 170-hp submersible pump with 35 cubic foot per second (cfs) capacity and 150-ft outfall diffuser with 100 2-inch diameter ports. Oxygen is supplied from an on-shore 13,000-gallon liquid oxygen storage tank. The rated output is up to 15,000 ppd oxygen. More detail on this project is readily available for scoping purposes.

Upper San Leandro Reservoir (California) EBMUD also owns and operates this reservoir. Unlike Camanche Reservoir and Newman Lake, this small drinking water reservoir is located in a protected watershed, with access to the lake by permit only; therefore, watershed load programs are presumably near maximum effectiveness. Because the small lake has little natural mixing, compressor is used to spread the oxygen. This adds another $15,000 to the annual O&M cost. The diffuser piping extends 8,500 feet along the centerline of the reservoir. An evaporation facility below the dam converts trucked–in liquid oxygen from an onsite 6,000-gallon storage tank to gaseous oxygen for the HOS.

Indian Creek Reservoir (California) South Tahoe Public Utility District (STPUD) owns and operates the Indian Creek Reservoir (ICR) HOS Project. Indian Creek reservoir has a history of nutrient loading due to the past practice of discharging treated municipal wastewater into the lake. The system uses oxygen generated onsite by a PSA oxygen purification system to feed a Speece cone located at the lake’s deepest point. A submersible pump circulates water through the cone. The annual O&M cost assumes operation for six months per year, average electrical costs of $1,000 per month and six hours per week for operations logging and regular maintenance. Note that these are preliminary findings, as the system was only constructed in 2009. This would be a useful project to follow to better understand the time frame for effecting significant change in a relatively small water body with significant SOD and phosphorus loading, such as the deepest portion of Big Bear Lake. The ICR HOS is a direct response to an order from the Regional Water Quality Control Board (RWQCB) to lessen algae

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blooms, suppressed DO, and fish kills within the lake. STPUD also hopes to improve recreational fishing since trout will have a colder oxygen-rich area near the lake’s bottom.

2.2.4.4 Summary and Conclusions about HOS HOS is a viable technology for addressing eutrophication and low dissolved oxygen in natural lakes and man- made reservoirs. Several examples are discussed above that provide a range of lake sizes, oxygenation techniques, and reasons for installing an HOS.

2.2.4.5 Summary of Management Options for Aeration and Oxygenation Of all the alternatives discussed, this one has received the most detail because it has shown the most success and has the most certainty of success should enhancements be necessary. Figure 2-13 summarizes the key concepts related to current and potential future operations to maintain and enhance DO levels in the lake through mechanical means. One important feature of the Lake under the current condition that should be considered is the presence of the old dam, which creates a pocket of water in front of the new dam that is somewhat isolated from the rest of the Lake. Stratification could be different in the pocket behind the old dam. The condition of the locks, which were reportedly left open when the old dam was submerged, is unknown. Divers have reported seeing debris obstructing the western side. It is unknown whether the eastern opening is blocked by silt or other debris. This is important pre-design information for an HOS, to understand how oxygenation on the east side would or would not affect low DO on the west side. It could also create an opportunity for a small pilot that evaluates an HOS in the very small water body between dams. The expected benefit of an HOS is that, over time, the unconsolidated organic layer at the bottom of the lake would be metabolized, and replaced with a crust of iron-manganese oxides. This oxide crust would be a barrier to phosphorus diffusion upward from deeper, anoxic sediments. The amount of oxygen and length of time to overcome existing sediment oxygen demand would need to be evaluated in a pre-design study.

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Figure 2-13. Current and Potential Future Operations to Manage Dissolved Oxygen in the Western Portion of Big Bear Lake

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2.2.5 Other Possible Activities There are also valuable lessons to be learned from management actions that have been considered but not implemented. For example: . Cloud seeding using silver iodide was considered in 2004 as an enhancement to water management and Lake stabilization. The concept was tabled over concerns that silver iodide could be a pollutant of concern. Cloud seeding using silver iodide is a common practice in the arid west; the basis for water quality concern expressed by interested citizens was not clear from the public record of the 2004 discussion. . A second, larger alum treatment project was proposed in 2006. Funding was not granted for the project, based on SARWQCB concerns over aluminum effects on water quality. Alum addition is a common practice in eutrophic lakes around the United States. There should be enough nationwide experience to evaluate the potential for impacts to water or sediment quality, without resorting to development of a site- specific water quality or sediment quality objective for aluminum. Alum is a valuable tool that should not be overlooked. In the Newman Lake case study discussed above, alum injection was used in conjunction with the HOS to achieved desired levels of water quality. . Portions of Sand Creek have been stabilized in the past to reduce erosion and downcutting, thereby reducing sediment loads to the Lake from this tributary. The most recent proposed project to complete bank stabilization in Sand Creek was not carried out, in part because of concerns expressed by the SARWQCB staff. Opportunities to reduce sediment transport through channel maintenance and improvement should continue to be explored. . Existing detention basins can be enhanced to reduce sediment and nutrient transport to the Lake. However, detention basin maintenance has been inhibited by resource agency concerns over the growth of willows in the basins, which then provide habitat to flycatchers and other special status species. It would be helpful to resolve how detention basins can be constructed and operated so that they provide the needed water quality protections without becoming permanent habitat areas that cannot be properly maintained. Ultimately, a mosaic of nutrient reduction strategies will be needed to remove Big Bear Lake from the 303(d) list of impaired water bodies. The most effective programs (e.g., lake level stabilization, aquatic weed eradication, fishery management, aeration, maintenance dredging, fire prevention and other erosion control measures) are already well-established and local stakeholders are strongly committed to continuing such efforts. In addition, a number of previous remediation initiatives (e.g., stream bank stabilization, cloud- seeding, alum application, enlarged sediment trapping basins, etc.) that were deferred in order to address various state and federal regulatory concerns, may be reconsidered if conditions warrant. An adaptive management approach is essential to dealing with the reality that some mitigation projects succeed, some fail, and some never get off the ground. The lessons learned over the last 10 years must be carefully considered as new strategies (e.g. silt containment curtains or oxygenation systems) are being proposed and evaluated for implementation.

2.3 Recommendations The findings in the previous section set the stage for a brief set of recommended actions in this closing section. After bringing together the findings into a single alternatives screening matrix, a three-staged implementation plan is proposed.

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2.3.1 Alternatives Screening The findings about each management activity are compiled into a preliminary screening matrix (Table 2-55) The table simply asks of each potential enhancement to existing activities: . What would it cost to build? . What would it cost to operate and maintain? . How likely is it to do any good? . Are there any concerns or constraints? . What are the next steps to advance the alternative? The answers to the last question set up, in part, the schedule of activities to be carried out in Stage 1 of the Plan. The two approaches that show the most promise for success are: . Construction and operation of an HOS. This activity would implement the Load Allocation for nutrient releases from the in-lake legacy of nutrient-rich sediments; and . Enhanced management of watershed sediment inputs to the margins, by improving existing detention basins, deploying of silt curtains around tributaries during wet weather, use of alum, Phoslock®, or other lake treatment chemicals, and strategic dredging to remove nutrients and sediments contained by these measures. This activity would implement the Wasteload Allocation for nutrient releases that are attributed to regulated dischargers or dischargers such as the Forest Service who operate under a Memorandum of Agreement, such as the Forest Service. An HOS would get directly at the cause of the problem: a large, legacy reservoir of sediment oxygen demand in the Lake sediments. The capital cost is potentially as much as forty-fold lower than a massive dredging project to attain the same ends. Based on experiences in other lakes, there is a reasonably high degree of certainty that the system would show significant improvements over current practices. Although the operating costs are approximately 10-fold higher than the current aeration operating costs, the system would likely provide commensurately large benefits. Experience in other lakes indicates that the operational cost may decline over time as the legacy reservoir of sediment oxygen demand is consumed. The rate of recovery of the Lake may depend in part on the rate at which oxygen is introduced using the HOS. Therefore, progress toward attainment of water column targets using this approach may depend in part on the available budget for HOS operation. Concurrent with pre-design and analysis of an HOS, techniques for management along the margins would be pilot tested, detention basins would be enhanced, and approaches using silt curtains and/or limited flocculant application and follow-up dredging would be explored. This alternative likely has lower startup costs compared to HOS design and construction costs. Similar to the HOS, the operating costs of sediment management along the margins can be increased or decreased depending on the level of effort and available funding resources. There is not enough information available at present to determine which approach (HOS or management on the margins) is the most cost-effective, or whether a combination of the two would be needed to attain all causal and response targets established by the TMDL. Therefore, the schedule of activities includes initial steps of pre-design evaluation of the HOS, as well as pilot testing of management on the margins techniques.

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2.3.2 Sediment Disposal and Beneficial Re-use: Planning for the Future Finally, a scoping process would be initiated to consider whether it would be beneficial to develop a master plan for sediment disposal and beneficial re-use. Maintenance dredging can reasonably be expected to proceed at the same pace, and remove sediments gradually, 10,000 to 20,000 cy per year, which roughly balances the long-term average sediment input that comes in sudden pulses. This means that there is a need for one to two million cy of sediment disposal/reuse capacity over the next 100 years. If a clear path to cost- effective sediment re-use were established, the cost savings on planning and executing dredging projects could enable strategic dredging projects that go somewhat beyond the needs of maintenance dredging. The extra work proposed is not intended to be massive, remedial dredging. Rather, the need is to enable some dredging to create capacity (by digging holes) near the tributaries during dry periods to enable sediment containment during wet periods. This would potentially increase dredge volumes by two-fold over current activity levels. Sediment disposal appears to be one of the biggest cost and constructability challenges to pulling ahead of maintenance dredging. There has been a use or disposal available from year to year for sediments that need to be dredged to keep marina access open under variable water levels. It could help build planning efficiency if there were a master plan that created a need for sediment. That way, the 10,000 to 20,000 cy of sediment per year that discharges into the Lake becomes a resource, not a problem. The concept is to keep the impact on costs incremental compared to the projects that benefit recreation - and therefore pay for themselves. Such a master plan would evaluate the programmatic impacts and benefits, and seek a path that results in net environmental benefit. The plan could consider the benefits of developing a mosaic of habitat types. For example, more contouring, as was done in the east end deepening project, would gradually eliminate shallow habitat where the milfoil grows. It could be replaced with either deep water habitat where sediment is removed, or adjacent freshwater wetlands where dredged sediment is piled to establish grades significantly above the Lake surface at most times, except for the highest lake levels. This concept is similar to the island refuge concept proposed by USACE in its draft feasibility evaluation report. This evaluation would entail many considerations – for example, how would circulating water to keep the wetlands alive affect the water master account because of evaporation losses? It would take engineering to stabilize the banks with the right kind of vegetation or hard gabions to support a steep slope. It would also require resource agencies and BBMWD agreeing to the concept that the proposed mosaic of habitat types would be a net environmental benefit. And most importantly, this would only work if the vision for the landscape is something the community wants.

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Table 2-5. Screening Matrix for Enhancements to Existing Activities Approximate Approximate Construction Recurring Cost Cost Concerns or What is Needed to Activity ($ millions) ($ thousands) Likelihood of benefit Constraints Advance this Option Hypolimnetic 10 to 40/yr; • Proven in other lakes • Ongoing O&M • Feasibility Evaluation oxygenation could be as • May be most effective way Cost • Design and permitting much as to remove/isolate legacy • Could promote • Funding arrangement for 0.5 to 2 100/yr, organic carbon that fuels invasive aquatic construction and O&M depending on eutrophication invertebrates. design and operation Phoslock or • Unproven in Big Bear Lake • Need more • Vendor quotes for other • Likelihood of benefit high information on Phoslock (in progress) alternative to toxicity • Review of Phoslock alum Unknown, likely • Phoslock binds toxicity same order of Not applicable SRP, but is not • Research on other magnitude as a flocculant, so flocculant alternatives alum will not isolate • Permit from regional fine sediments Board in place • Pilot testing Margin • Unproven in Big Bear Lake • Obstructions to • Peer review of concept management • Precedents in other Lakes navigation • Cost scoping through silt • Creation of • Pilot testing curtains, flood hazard flocculants, Unknown at • and dredging n/a General present messiness of working in wet weather • Blocking fish passage Sediment • Would provide planning • Programmatic • CEQA/NEPA Scoping Re-use and certainty for dredging EIS/EIR would • Community shoreline projects be required outreach/visioning master Unknown – Unknown – • Could provide shoreline • Community planning depends on depends on amenities, wetland or marsh acceptance ambition ambition habitat unknown • Planned evolution of shoreline habitat could improve recreation, wildlife alum addition • Proven in Big Bear Lake • Impacts to • Site specific objectives 700 – 900, aquatic life, • Special studies accumulation in Not applicable every 3 – 5 • or plan for more limited sediments years usage acceptable to Regional Board Major • Quantifiable reductions • Cost • Not feasible at present Remedial • Evidence for improvement • Disposal/reuse Dredging from pilot test • Noise Project 10 to 40 n/a • Shoreline contouring could • Air Quality reduce nuisance plant • Habitat habitat disturbance

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For all the tools in the adaptive management toolbox – water management, destratification, aeration, oxygenation, dredging, lake treatment, and Best Management Practices (BMPs) upland – it will take energy to maintain what is essentially a metastable situation. The goal is to find the most efficient approach, the one that fights entropy the least. It has to cost something to maintain the resource, but costs be contained by looking for the most efficient solutions. So the proposal for the sediment re-use master planning process is a step toward a more efficient way to move sediment out of the Lake. The attraction of creating wetlands is rehabilitating the nutrient processing capacity of the landscape, and at the same time starving other areas of sediment where it creates navigational problems and nuisance plant habitat. There is a precedent for this in the San Francisco Bay Long-Term Management Strategy for Dredged Sediments (LTMS), which addressed the problem of mounding at the Alcatraz disposal site by establishing policies that would enable local wetland restoration projects to use dredged sediments. The suggestion is a planning process that could evaluate and, if feasible, create the need through enabling policies. Like LTMS, the program wouldn’t have to rely exclusively on wetland creation for sediment disposal. But having that option, among other local re-use projects, could help keep long-term costs down for necessary maintenance dredging and any added increment of water quality dredging.

2.3.3 Updates to Lake Monitoring Plan An in-Lake nutrient monitoring plan has been established by the TMDL (Resolution No. R8-2008-0070). That plan is intended to help assess attainment of causal and response targets established by the TMDL. As new management activities are implemented, it may be necessary to modify the monitoring plan to better enable stakeholders to evaluate effectiveness. Modifications that could be considered include: . Analysis of satellite imagery to produce high-resolution spatial and temporal data on chlorophyll concentrations; . Collection of continuous DO, temperature, and redox potential measurements using installed probes; . Collection of additional cores and measurement of phosphorus by sequential extraction to evaluate chemical forms of phosphorus, distribution within the lake bottom, and changes in the distribution that may result from HOS operation, if constructed; . Measurement of phosphorus concentrations and chemical forms in sediments contained using management on the margins; . Assessment of phosphorus flux rates using the core incubation techniques of Anderson et al (2006); and . Camera inspection techniques to assess the depth of the redox boundary in the area around the HOS, if constructed.

2.3.4 Comprehensive Schedule A conceptual timeline showing past and potential future activities shown in Plate 1 and Plate 2. Two Plates are presented to help understand that the proposed adaptive management activities for the future represent a continuum of events that builds on decades of adaptive management experience in the Lake. It is important to recognize that the variation in climate and Lake levels establish windows of opportunity for different activities. As shown by the diagram of Lake levels in Plate 2, small storm events are opportunities to develop and test small-scale sediment containment projects along the margins. Larger storm events would be windows of opportunity to test larger-scale containment approaches. The prolonged periods of low lake levels present windows of construction opportunity to dredge and beneficially re-use sediments in preparation for the next El Niño cycle that will bring more sediment resources to the Lake.

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A comprehensive schedule of activities is shown in Table 2-6. Stage 1 activities take place over the next 18 months, and involve the planning and scoping activities necessary to implement proposed actions. The Lake Monitoring plan would be updated during Stage 1 along the lines of the conceptual description provided in Section 2.3.3 above. Monitoring will continue during Stage 1 to evaluate whether current activities are sufficient to attain response targets, and whether the causal targets established by the TMDL are appropriate to response targets. In Stage 2, CEQA procedures necessary to enable implementation actions would be completed, cost sharing and compliance crediting agreements would be established, and the revised Lake monitoring plan would be implemented. Enhanced management activities would commence in Stage 3. Table 2-6 shows fixed dates for Stage 1 activities and relative dates for Stage 2 and Stage 3 activities, to make it clear that completion of those activities is contingent on timely and successful completion of earlier activities. The comprehensive schedule shown in Table 2-6 uses color coding to distinguish between activities that are related to program management and monitoring (white cells), activities that implement the Load Allocation for releases from in-lake sediments (blue cells), and activities that implement the Wasteload Allocation for discharges over and above natural background (green cells). Table 4-2 presents the three different types of activities intermingled, arranged sequentially with time. For clarity, Plate 3 shows a Gantt chart that separates the three different types of activities.

2.3.5 Summary and Perspective Task Force members need only to look at the contours of Big Bear Lake to understand what the watershed wants to do to the Lake. Flashy storms will rip down the hillslopes, and bring melted snow, sediment and organic detritus into the Lake. The debris will spread and settle near the tributary mouths, silt in dredged navigational channels, and gradually focus toward the deep end of the Lake. Left unmanaged, the Lake would gradually fill in from east to west, returning at last to the marshy high mountain plain it once was. To maintain the current beneficial uses of the Lake, it will take energy to resist against the natural tendency for a system to degrade over time. The findings in this Plan point to the lowest energy and, therefore, lowest cost approaches to push back against that disorder and degradation. The schedule to impose order will depend on natural events, the rising and falling lake levels, and the unpredictable schedule of climate and weather. The schedule will also depend on human events – how fast people can comprehend, discuss and come to consensus on the path forward. And finally, the schedule will depend on economic events. It is for Task Force members to decide on a sustainable expenditure rate that leaves room for other priorities in your community.

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Table 2-6. Proposed Comprehensive Schedule for Sediment Nutrient Management Plan Implementation Task Estimated Stage Number Task Description Completion Date White background indicates program management and monitoring tasks Blue (lighter) background indicates tasks addressing sediment phosphorus releases from non-point sources within the Lake as identified in the Load Allocation Green (darker) background indicates tasks addressing new phosphorus loads from point sources discharging sediment to the Lake as identified in the WLA

0 1 SARWQCB considers Plan for approval in concept of approach and timeline July, 2010 0 2 BBMWD considers Plan for approval in concept of District commitments September, 2010 1 1 Complete natural background calculations December, 2010 1 2 Develop HOS Pre-design Report July, 2011 Develop Margin Management Strategy to implement WLA for external sources 1 3 July, 2011 Assumption: This would include assessment of costs, feasibility, effectiveness of alternatives to alum 1 4 Update existing Lake Nutrient Monitoring Plan July, 2011 1 5 Based on HOS Pre-Design Report, evaluate probable costs, feasibility, likelihood of achieving phosphorus LA September, 2011 1 6 Identify federal or state grant funding sources to address LA for in-Lake sediment phosphorous releases September, 2011 Decide whether to proceed with HOS design. 1 7 September, 2011 Assumption: Availability of grant funding sources is essential to proceed with design and construction of an HOS. 1 8 Calculate net legacy loads to sediments from discrete urban sources October, 2011 3 months after completion of Stage 2 1 Complete initial CEQA/NEPA scoping of Sediment Re-use Strategy 1 Task 8 Implement revised Lake Nutrient Monitoring Plan 3 months after SARWQCB approval 2 2 Condition: Proceed with this task only if funding available and SARWQCB has approved revised Monitoring Plan. of revised Monitoring Plan 6 months after completion of Stage 2 3 Develop compliance crediting framework and cost-sharing agreements for HOS, Margin Management Strategy 1 Task 2 Complete CEQA necessary to enable Margin Management Strategy 9 months after completion of Stage 2 4 Assumption: Finding of mitigated negative declaration of impacts. If a mitigated negative-declaration cannot be made, full EIR would 1 Task 3 extend this completion date. Complete CEQA on HOS Construction Project Condition: Proceed with this task only if HOS determined to be feasible and effective, funding is available for design, and crediting 12 months after completion of Stage 2 5 framework has been established. 1 Task 2 Assumption: Finding of mitigated negative declaration of impacts. If a mitigated negative-declaration cannot be made, full EIR would extend this completion date.

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Begin implementing Margin Management Strategy 3 months after completion of Stage 3 1 Condition: Proceed with this task only if determined to be feasible and effective and funding is available for implementation, and 2 Task 4 crediting framework has been established. Acquire federal or state grant funding for HOS to address LA for in-Lake sediment phosphorous releases 12 months after completion of Stage 3 2 Assumption: Availability of grant funding sources is essential to proceed with design and construction of an HOS. 1 Task 6 Design HOS 3 months after completion of Stage 3 3 Condition: Proceed with this task only if HOS determined to be feasible and effective, funding is available for design, and crediting 3 Task 2 framework has been established. Construct HOS Condition: Proceed with this task only if HOS determined to be feasible and effective, funding is available for construction and 12 months after completion of Stage 3 4 operation, and crediting framework has been established. 3 Task 3 Assumption: Completion date proposed determined to be feasible through design process. Unanticipated site conditions, permitting, and other factors outside the control of Project Owner would extend this completion date. Complete CEQA for Sediment Re-use Strategy Condition: Proceed with this task only if a viable Project is identified through initial Stage 1 CEQA/NEPA scoping and funding is 24 months after completion of Stage 3 5 available for programmatic EIR/EIS. 2 Task 1 Assumption: Project would be supported by community and resource agencies. Significant opposition or concerns would extent this completion date. Continue implementation of Revised Lake Monitoring Plan to monitor attainment of LA for in-Lake sediment phosphorus loads, Immediately following completion of 3 6 attainment of LA for external loads, and attainment of causal and response targets established by TMDL Stage 3 Task 4 Condition: Proceed with this task only if funding available.

Review TMDL, progress towards attainment of LA, WLA and TMDL targets. 3 7 December 31, 2015 Assumption: There are physical constraints on the recovery rate of the Lake that may extend the attainment timeline.

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BIG BEAR LAKE TMDL ACTION PLAN

3. WET WEATHER STRATEGIES FOR CONTROLLING NUTRIENT INPUTS TO BIG BEAR LAKE

3.1 Introduction This section described describes past and current efforts by the TMDL stakeholders to control sediment transport to the Lake, and provides recommendations for potential future actions to build upon these existing efforts. Efforts to control the release of phosphorous from sediments within the lake itself are described in a separate document. Erosion and sedimentation is a natural process that occurs within watersheds. However, rates of sediment transport may be affected by anthropomorphic activities such as changes in land use, road building, land management practices, or constructed/paved channel sections. To assess the potential for stream channel erosion as a potential sediment contributor to Big Bear Lake and its tributaries, Tetra Tech conducted a channel stability assessment. The assessment includes most of the major drainages to the Lake, including; Grout Creek, Minnelusa Creek, Rathbun Creek, Knickerbocker Creek, Metcalf Creek, Boulder Creek, and Kidd Creek. Results of the study indicated a continuum of stream channel conditions, from stable channels with low sediment delivery potential, to moderately or severely unstable, widening and/or deepening channels that are active sediment sources. As expected, generally the greatest degree of channel instability occurs in the urban/developed areas of the watershed in Rathbun Creek, with lesser degrees of apparent sediment delivery from forested or less-disturbed areas, although there are a few notable exceptions in the upper reaches of Metcalf and Boulder Creek. Hardened channels such as the paved channels in Knickerbocker and East Summit Creek are not sediment sources, but can transport any sediment loads from upstream. Observed watershed conditions indicate that adjacent slopes bare of vegetation may comprise significant sediment sources to the tributaries, as could unpaved roads (Tetra Tech, 2006). The expected outcome of this analysis is to identify a range of possible BMPs and management actions within the Big Bear Lake watershed that could be undertaken to reduce the amount of sediment and associated nutrients (phosphorous) in runoff entering the Lake from both natural and anthropogenic sources.

3.2 Overview of Best Management Practices

3.2.1 Overview of Nutrient Removal Mechanisms Nutrients are inorganic substances, such as nitrogen and phosphorus. They commonly exist in the form of mineral salts that are either dissolved or suspended in water. Primary sources of nutrients in urban runoff are fertilizers and eroded soils. Excessive discharge of nutrients to water bodies and streams can cause excessive aquatic algae and plant growth. Such excessive production, referred to as cultural eutrophication, may lead to excessive decay of organic matter in the water body, loss of oxygen in the water, release of toxins in sediment, and the eventual death of aquatic organisms. Nutrients are primarily transported in the particulate and dissolved phases and have four main mechanisms of control – sedimentation (if associated with suspended sediment), physical filtration, adsorption, and bioaccumulation (Federal Highways Administration [FHWA], 2003).

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Biological uptake and bioaccumulation of nutrients is an important mechanism of nutrient control, which occurs as aquatic plants, algae, microorganisms, and phytoplankton utilize the nutrients as food for growth. Physical filtration is the removal of particulates by passing water through a porous medium, such as soil, sand, gravel, peat, compost, and combinations these. Filtration can be used to remove solids and attached pollutants such as metals and nutrients. Organic filtration media such as peat or leaf compost can also be effective at removing soluble nutrients from urban runoff. Sedimentation is the removal of suspended particulates from the water column by gravitational settling, which is dependent upon the particle velocity, the fluid density, the fluid viscosity, and the particle diameter and shape. Sedimentation can be a major mechanism of pollutant removal in ponds and constructed wetlands. Pollutants such as metals, hydrocarbons, nutrients and oxygen demanding substances can become adsorbed to particulate matter, particularly clay soils. Adsorption is not a common mechanism used in BMPs; however, it can occur in infiltration systems where the underlying soils contain substantial amounts of clay. Dissolved metals and nutrients in stormwater runoff can be bound to the clay particles as storm water runoff percolates through the clay soils.

3.2.2 BMPs for Nutrient Removal A Best Management Practice (BMP) is defined as a “device, practice, or method for removing, reducing, retarding, or preventing targeted stormwater runoff quantity, constituents, pollutants, and contaminants from reaching receiving water” (Strecker et al., 2001). The USEPA defines stormwater BMPs as techniques, measures, or structural controls that are used for a given set of conditions to manage the quantity and improve the quality of stormwater runoff in the most cost-effective manner. BMPs are classified as either structural BMPs, which are systems that are engineered and constructed, or nonstructural BMPs, which are pollution prevention techniques designed to stop pollutants from entering urban runoff (United States Environmental Protection Agency [USEPA], 1999). According to the California BMP Handbooks published by the California Stormwater Quality Association (CASQA) and the California Department of Transportation (Caltrans) Storm Water Quality Handbook: Project Planning and Design Guide, there are a number of BMPs that may be used to remove nutrients from runoff (Table 3.1). Table 3.1 presents the relative effectiveness from CASQA and whether the BMP is considered applicable by Caltrans. A brief description of the rated BMPs is presented in Table 3.2.

Table 3-1. BMPs and Relative Effectiveness1 BMP CASQA Caltrans Bioretention Medium Not Rated Constructed Wetlands Medium Not Rated Drain Inlet Insert ````````````````Not rated No* Extended Detention Basin Low Yes Infiltration Basin High Yes Infiltration Trench High Yes Media Filter Low Yes (Austin-Style Filter Only) Retention/Irrigation High Not Rated Vegetated Buffer Strip Low No Vegetated Swale Low No Water Quality Inlet Low Not Rated Wet Pond Medium Yes (for Dry Weather Flows Only) Wetland Not Rated Yes (for Dry Weather Flows Only) 1 From Caltrans (2004)

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Structural BMPs (Table 3.2) are in place technologies that are employed either at the point of generation, the source, or at the point of discharge, the storm sewer or the receiving water body. These include engineered and constructed systems designed to control the water quantity and quality in the stormwater runoff (USEPA, 1999).

Table 3-2 Description of BMPs (From Sayre et al. 2006)1 BMP Description Intended Use and Impact Removal Mechanism Conditioned soil layers containing a Soil layer and presence of microbes enhance Physical Filtration mixture of detritus, humus, and mineral filtration and the vegetation aids constituent Adsorption and biological complexes in shallow removal Bioretention depressed areas Areas Small areas can be located in medians, parking lot islands, or grassy areas along streets, making these ideal for constricted urban areas Upstream pond with deep water and Remove pollutants through sedimentation, Sedimentation downstream wetland filtration, plant uptake, degradation, biological Bioaccumulation/Biological Imitate natural function of wetlands uptake and conversion Uptake Constructed Utilize aerobic or anaerobic vegetation to Remove metal pollutants through plant Adsorption Wetlands remove pollutants from water uptake, neutralization by carbonates, fastening to substrate soils, metal adsorption and exchange onto algae layers, iron hydroxide formation and sulfates reduction through microbial dissimilation Permanent pool of water Control runoff from impervious area by storing Sedimentation Temporary storage volume above the and releasing it at a slowed rate through an Bioaccumulation/Biological Detention/Wet permanent pool outfall Uptake Pond Shoreline zone planted with aquatic Remove pollutants through settling, Adsorption vegetation infiltration, nutrient uptake, adsorption, and physical filtration Longer, often coupled systems that Detention time is a function of size of outflow Sedimentation facilitate longer detention times for opening with respect to storm event runoff Bioaccumulation/Biological Extended optimal pollutant removal volume Detention Uptake Basin Provides water quality treatment of first flush Adsorption runoff and some reduction of peak flows for small storm events Shallow depression created by Remove fine suspended material by soil Adsorption excavation or berming that captures filtration, dissolved materials by adsorption, stormwater and promotes infiltration into and organic compounds by biodegradation soil Remaining treated runoff passes into Infiltration Utilize chemical, physical, and biological groundwater Basin processes in soils to remove sediments Prevents both water and its contaminants and other soluble constituents from urban from reaching water body runoff Usually limited to roadway interchanges and large residual parcels of land and may not be suitable for dense urban areas Excavated trench lined and backfilled with Diverts and stores runoff until it can infiltrate Adsorption stone to form subsurface basin into soil, usually over a period of several days Infiltration Trench Ideal for small urban drainage areas Most effective with pretreatment included in design, such as vegetated filter strips or grassed swales

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Table 3-2 Description of BMPs (From Sayre et al. 2006)1 BMP Description Intended Use and Impact Removal Mechanism One or more permanent pools of water Pollutant removal efficiency is a function of Sedimentation that enhance particulate settling by pond depth, residence time, drainage area-to- Bioaccumulation/Biological increasing residence time and provide pool volume ratio, and existence of aquatic Uptake Retention conditions for growth of aquatic vegetation Ponds Adsorption vegetation, thereby enhancing filtration, Enhance aesthetics and/or provide metal and nutrient uptake recreational benefits such as parks, soccer fields, and baseball fields Land surface is shaped to direct Removes sediments and increases infiltration Filtration stormwater through a broad, relatively flat Frequently located in medians or along Adsorption Vegetated grassed area Swale shoulders of roads Soil may require preparation to maximize infiltration prior to planting of grass Evenly sloped vegetated areas similar to Remove sediments and increase infiltration Filtration grassed swales Vegetated Often utilized on roadway shoulders and/or Adsorption Buffer Strip Commonly used as a pre-treatment BMP safety zones, but typically require soils with located upstream of other BMPs capable high percolation rates that can efficiently of greater pollutant removal rates infiltrate water over short lengths Utilize settling and surface oil separation Settle out fine and coarse sediment, trapping Filtration mechanisms, and/or filtration, flotation, or debris and trash, and separating oil and Adsorption vortex motion settling and separating grease from runoff mechanisms Water Quality Oil and grease or hydrocarbon trap with a Inlets Designed to allow floatable materials submerged outlet pipe allows these such as Styrofoam “peanuts” used for contaminants to accumulate and to be packaging, and other low-density removed materials to accumulate and be manually removed 1 Wieder, 1988; Henrot and Wieder, 1990; Wildeman et al., 1993; Faulkner and Skousen, 1994; Schueler, 1987; Schueler, et al., 1992; Schueler, 2000; Yu and Kaighn, 1992; National Resources Defense Council, 1999; Schueler, 2000; FHWA, 2003; Caltrans, 2004; Devinny, et al., 2004; USEPA, 1999; USEPA, 2004

3.2.3 Performance Locally According to the CASQA BMP Handbooks there are a number of BMPs that are being utilized successfully in California. Examples of these are as follows:

. Vegetated Swales: Caltrans constructed and monitored six vegetated swales in southern California. The swales were generally effective in reducing the volume and mass of pollutants in runoff. Although there are areas where the annual rainfall was only about 10 inches/yr, the vegetation did not require additional irrigation. Gophers were the biggest problem in most areas, because they created earthen mounds, destroyed vegetation, and generally reduced the effectiveness of the controls for TSS reduction. . Detention Basins: Caltrans constructed and monitored five extended detention basins in southern California with design drain times of 72 hours. Four of the basins were earthen, less costly and has substantially better load reduction because of infiltration that occurred, than the concrete-lined basin. . Media Filters: Caltrans constructed and monitored five Austin sand filters, two Multiple Chamber Treatment Trains (MCTTs), and one Delaware design in southern California. Pollutant removal was very similar for each of the designs; however operational and maintenance aspects were quite different. The Delaware filter and MCTT maintain permanent pools and consequently mosquito management was a critical issue, while the Austin style which is designed to empty completely between storms was less affected. Removal of the top few inches of sand was required at 3 of the Austin filters and the Delaware

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filter during the third year of operation; consequently, sizing of the filter bed is a critical design factor for establishing maintenance frequency. . Bioretention: Bioretention has been used as a stormwater BMP since 1992; however, there are no documented cases in California. Bioretention has been used successfully in urban and suburban areas in Maryland, Virginia, and North Carolina. . Vegetated Buffer Strips: Caltrans constructed and monitored three vegetated buffer strips in southern California and is currently evaluating their performance at eight additional sites statewide. These strips were generally effective in reducing the volume and mass of pollutants in runoff. Even in the areas where the annual rainfall was only about 10 inches/yr, the vegetation did not require additional irrigation. One factor that strongly affected performance was the presence of large numbers of gophers at most of the southern California sites (although this may be less of an issue in the Big Bear Lake Watershed). The gophers created earthen mounds, destroyed vegetation, and generally reduced the effectiveness of the controls for TSS reduction. . Constructed Wetlands: The City of Laguna Niguel in Orange County has constructed several wetlands, primarily to reduce bacteria concentrations in dry weather flows. The wetlands have been very successful in this regard. Even though there is not enough perennial flow to maintain the permanent pool at a constant elevation, the wetland vegetation has thrived. . Wet Pond: Caltrans constructed a wet pond in northern San Diego County (I-5 and La Costa Blvd.). Largest issues at this site were related to vector control, vegetation management, and concern that endangered species would become resident and hinder maintenance activities. . Infiltration Basins: Infiltration basins have a long history of use in California, especially in the Central Valley. Basins located in Fresno were among those initially evaluated in the National Urban Runoff Program and were found to be effective at reducing the volume of runoff, while posing little long-term threat to groundwater quality (EPA, 1983; Schroeder, 1995). Proper siting of these devices is crucial as underscored by the experience of Caltrans in siting two basins in Southern California. . Infiltration Trenches: Caltrans constructed two infiltration trenches at highway maintenance stations in Southern California. Of these, one did not operate to the design standard because of average soil infiltration rates lower than those measured in the single infiltration test (the facility took longer than 72 hours to drain, but still drained within 96 hours and there was no mosquito breeding). This highlights the critical need for appropriate evaluation of the site. Once in operation, little maintenance was required at either site. Until recently, little consideration has been given to the effect of climate on BMPs. Most BMPs require modifications; others are considered unacceptable in arid and semi-arid regions (Table 3.3) (Schueler, 2000). Big Bear Lake and its tributary watersheds can be considered semi-arid because they have distinctive wet and dry seasons. The Big Bear Lake area receives an average of 21.15 inches of rain (61.8 inches of snowfall measured at lake level) (National Weather Service).

Table 3-3. Modifications for BMPs in Arid and Semi-Arid Watersheds (from Schueler 2000) BMP Semi-Arid Watersheds Arid Watersheds Preferred Acceptable Require multiple storm extended detention Extended Detention Ponds Require a dry or wet forebay ponds, stable pilot channels, and a dry forebay Limited Use Not Recommended Requires supplemental water Constructed Wetlands Evaporation rates too great to maintain wetland Use of submerged gravel wetlands can help plants reduce water loss

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Table 3-3. Modifications for BMPs in Arid and Semi-Arid Watersheds (from Schueler 2000) BMP Semi-Arid Watersheds Arid Watersheds Preferred Preferred Use a mix of coarse and fine media to prevent Media Filters Requires greater pretreatment premature clogging and ensure sufficient Excludes pervious area treatment Limited Use Not Recommended Unless irrigated For pollutant removal, but rock berms and Vegetated Swales Rock berms and grade control essential to grade control needed for open channels to prevent erosion in open channels prevent channel erosion Major Modification Major Modification No recharge for hotspot land uses No recharge for hotspot land uses Infiltration Basins Treat no pervious area Treat no pervious area Multiple pretreatment Multiple pretreatment Soil limitations Major Modification Major Modification Requires no irrigation Use runoff to supplement irrigation Better pretreatment Bioretention Areas Use xeriscaping plants Treat no pervious area Avoid trees Xeriscape plants or no plants Replace mulch with gravel Replace mulch with gravel

3.2.4 Nutrient Removal Efficiencies All BMPs have limitations based on the drainage area served, available land, cost, desired pollutant removal efficiency, and site-specific factors such as soil type, slope, and depth of groundwater table (USEPA, 1999). When properly designed, BMPs can effectively remove a wide range of pollutants from urban runoff when (Table 3-4). The pollutant removal efficiency of a BMP depends on numerous site-specific variables, including the size, type and design of the BMP; the soil types and characteristics; the geology and topography of the site; the intensity and duration of the rainfall; the length of antecedent dry periods; climatological factors such as temperature, solar radiation, and wind; the size and characteristics of the contributing watershed; and the properties and characteristics of the various pollutants (USEPA, 1999). Table 3-4 summarizes the average percent nutrient removal efficiencies from literature for the BMPs listed above. Note that the pollutant removal efficiencies listed in this table are relative and based on specific research projects, and are provided for guidance and planning purposes only. Agencies choosing to implement structural BMPs such as the ones listed in the table may wish to perform BMP effectiveness monitoring to measure the actual performance of their facilities.

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Table 3-4. Nutrient Removal Efficiencies (%) for Select BMPs1 Nitrogen as Nitrate Total Kjeldahl Nitrogen Total Nitrogen Phosphorus Ortho- BMP (NO3-N) (TKN) (N) (P) Phosphate Bioretention Area 29 43 29 13 -218 Constructed Wetland 49 24 35 58 28 Detention Basin 78 35 46 60 Extended Detention Basin 38 40 39 49 -22 Infiltration Basin (with subdrain) 65 58 62 66 N/A Infiltration Trench (with subdrain) N/A 55 55 38 N/A Media Filter -58 49 38 52 18 Retention Pond 49 42 46 48 N/A Vegetated Swale 33 10 58 36 -2 Vegetated Strip 24 38 31 21 -76 Water Quality Inlet 15 N/A 15 15 27 Wet Basin 45 26 26 40 -116 1 Data presented in this table were compiled from the following studies: Wang et.al. 1981, Kercher et.al. 1983, Yousef et al. 1985, Martin and Smoot 1986, Hogland et al. 1987, Schueler 1987, Harper 1988, Yu and Benelmouffok 1988, Dorman et.al. 1989, City of Austin (1990, 1995), Kahn et al. 1992, Schueler et al. 1992, Seattle Metro and Washington Department of Ecology 1992, Stewart 1992, Yu and Kaighn 1992, Goldberg 1993, Harper and Herr 1993, USEPA 1993, Yu et al. (1993, 1994), Prince George's County Department of Environmental Resources (PGDER) 1993, Bell et al. 1995, Horner and Horner 1995, Koon 1995, Gain 1996, Pitt 1996, Young et al. 1996, Pitt et.al. 1997, Glick et.al. 1998, Greb et.al. 1998, Lief 1999, USEPA 1999, Davis et.al. 2001, California Department of Transportation 2002, Davis et.al. 2002, FHWA 2003, CASQA 2003, California Department of Transportation 2004 N/A – Not Available

3.2.5 Nonstructural and Operational BMPs Nonstructural BMPs are institutional and pollution prevention practices designed to prevent or reduce pollution. These include public education and awareness, strategic planning and institutional controls, pollution prevention practices and procedures (such as street sweeping), regulatory controls, and development and planning controls (such as low-impact development) (USEPA 1999, Taylor and Fletcher 2007). A brief definition of these five types of nonstructural BMPs follows (from Taylor and Fletcher 2007): . Development and planning controls – using town planning instruments to promote low impact development principles in new developments, such as decreasing the area of impervious surfaces. . Strategic planning and institutional controls – using strategic, city-wide urban stormwater quality management plans and secure funding mechanisms to support the implementation of these plans. . Pollution prevention procedures – particularly practices undertaken by stormwater management authorities involving maintenance, these include maintenance of structural BMPs and the stormwater drainage network, and elements of environmental management systems (such as procedures on material storage and staff training on stormwater management). . Public Education and Awareness – targeted media campaigns, training programs, and stormwater drain stenciling programs. . Regulatory controls – enforcement of local laws to improve erosion and sediment control on building sites, the use of regulatory instruments such as environmental licenses to help manage premises likely to contaminate stormwater and programs to minimize illicit discharges to stormwater.

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Within these five types of controls, the American Public Works Association (APWA) developed a list of nonstructural BMPs (1992). Costs associated with these are presented in Section 5. . Ordinances/Regulatory Controls: • No Littering Ordinance – Litter laws stipulate that anyone caught littering will be fined, and while laws are in place, there is a need for far more vigorous public education and enforcement. Prohibits littering and would control household and restaurant paper, plastics, and glass. • Pet Waste Ordinance – similar to litter laws, pet waste ordinances stipulate that anyone caught not picking up after their pet will be fined; however, this requires vigorous public education and enforcement. This would require owners to clean up after their animals and properly dispose of waste, controls coliform bacteria and nitrogen/urea. . Pollution Prevention Procedures: • Chemical Use and Storage Ordinance – APWA determined that a program to control the use and storage of chemicals would be similar in scope and cost to that for litter or pet waste. Works to prevent pollutants from entering storm drains by controlling hazardous and harmful chemicals, oil, and grease. • Spill Prevention Ordinance – Works to prevent pollutants from entering storm drains by controlling hazardous and harmful chemicals, oil, and grease. • Improved Street Sweeping – The APWA report determined that sweeping should be improved by increasing its frequency. More recent research results suggest that more frequent sweeping with traditional brush machines produces only a modest improvement. However, changing to vacuum sweepers is effective, and can remove up to 50 percent of particulate pollutants. When catch basin screens are used, street sweepers, even older style sweepers, can remove additional material that would otherwise enter storm drains. Reduce potential for clogging storm drains with debris with potential for oil and grease control. • Improved Cleaning of Catch-Basins – During dry periods, storm drains collect trash from illicit dumping and wind blown litter. Sediments also accumulate in the drains and channels. Releases to the streams and lake could be reduced by a full program of storm drain cleaning. . Public Programs: • Recycling Programs – APWA predicted less trash would be discarded if convenient recycling programs were in place. This would control household and restaurant paper, plastics, and glass. • Public Education Programs – Developing public support for stormwater quality control and explaining the need for citizen action is vital to its success. These include billing inserts, news releases, radio, school programs and pamphlets. • Vacant Lot Cleanup Programs – Prevents debris from accumulating on lots and eliminates sources of hazardous waste. • Prevent Illicit Discharges – APWA determined that vigorous efforts would be needed to find and eliminate illicit discharges to the storm drain system. This would reduce the pollutant load entering the storm drains.

3.3 Project Approach

3.3.1 Review of BMP Documents In early 2004, during the development of the dry season nutrient TMDL, several stakeholders (Big Bear Municipal Water District, the City of Big Bear Lake, and Big Bear Mountain Resorts) submitted letters to the Regional Board detailing their efforts in improving and protecting water quality. In general, the Big Bear

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Municipal Water District’s efforts have been more focused on erosion and sediment control projects (construction of sediment basins, stream bank stabilization, and storm drain system improvements). The City of Big Bear Lake’s program is organized around municipal public works-type activities such as street sweeping, catch basin cleaning, storm drain improvements, and litter removal. The resort is focused on drainage control and erosion and sediment control. A summary of these efforts is presented in Table 3-5.

Table 3-5. Summary of Best Management Practices (BMPs) in Place in 2004 Agency BMP Description Date Effectiveness Cost Successful – Big Bear Municipal Big Bear Lake, Conducted in Alum pilot project additional Prop 13 $327,000 Water District (MWD) Aquatic plant control 2003 funding of $500,000 Cleaned annually by Rathbun Creek, near Bear Mountain Ski Big Bear Municipal 2 sediment catchment Constructed in Elm Street and Resort, Approximately Water District (MWD) basins mid 1980s Moonridge Road 6,500 cu.yd. removed since installation Constructed in Big Bear Municipal 3,000 cu.yd. catchment Cleaning Rathbun Creek mouth early 1990s Unknown Water District (MWD) basin costs: $34,912 Cleaned in 1998 Has not required Big Bear Municipal 9,000 cu.yd catchment Rathbun Creek mouth, 2000 cleanout (prior to $90,000 Water District (MWD) basin on lake bottom 2004) Sand Canyon Channel, Rathbun Creek, with San Overall cost: Stabilized channel banks Bernardino County Provided erosion Big Bear Municipal $278,771 with placement of rocks Flood Control District, October 1997 control and protection Water District (MWD) MWD cost: and planting vegetation East Valley Resource for Sheephorn Road Conservation District, $32,200 and City of Big Bear Lake Sand Canyon Channel, Rathbun Creek, with San Replaced 2 storm Overall cost: Bernardino County Big Bear Municipal culverts and a portion of Between 1997- Provided bank $377,849 Flood Control District, Water District (MWD) Teton Road, bank 2000 stabilization MWD cost: East Valley Resource stabilization Conservation District, $185,000 and City of Big Bear Lake Snow Summit Ski Bank stabilization below Area cleaned out box culvert, placed riprap Near confluence of Big Bear Municipal culvert, and filter fabric along Summit and Rathbun 2000 $15,500 Water District (MWD) stream bank and Creeks Prior to project, streambed culvert capacity was less than 50% Targets Lakefront homeowners, explains Big Bear Municipal Shoreline Erosion methods of control, Periodically Unknown Water District (MWD) Control Pamphlets MWD helps with permitting process

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Table 3-5. Summary of Best Management Practices (BMPs) in Place in 2004 Agency BMP Description Date Effectiveness Cost Used for any disturbed Big Bear Mountain Installation of soil area: tree removal, Periodically, any Resorts (Bear protection measures, trenching, run time an area is Unknown Mountain and Snow such as jute matting or shaping, other disturbed Summit) other fabric construction Intervals determined Ditches can erode, Big Bear Mountain by steepness and resorts are using Cross Ditching to prevent Resorts (Bear width of slope and soil geocloth through the water run off (rilling) on Mountain and Snow composition, typically length of such ditches all ski runs Summit) 1-2 feet deep and at to prevent further 80-85o angles erosion Metal inlet feeding a corrugated box culvert, typically 12" Big Bear Mountain Overside drains installed by 10' to 20' Resorts (Bear at the end of cross Unknown Mountain and Snow From overside drains, ditches Summit) water flows through the forest cover into the main canyon drainage areas Culvert systems collect The culvert systems Larger culvert Big Bear Mountain water from cross ditches run longitudinally systems require Resorts (Bear running toward the center within ski runs and debris rakes to Mountain and Snow of the run, and route it have drop inlets about prevent blockage Summit) into the culvert below every 100 ft during flooding. The silt collection Big Bear Mountain Silt collection dams and capability ranges from Resorts (Bear Clean runoff prior to basins installed at the few square yards to Mountain and Snow leaving site base of the resort several hundred yards Summit)

Geocloth is installed at Big Bear Mountain right angles to water flow Increases the silt Resorts (Bear (blinds) within catch collection capability of Unknown Mountain and Snow basins, channels and the device Summit) cross ditches Of over 1,000 cubic yards of debris and Street Sweep four-lane snow cinders removed annually. Sweeper: portion of Big Bear Initiated in These are tested for $141,236.30 City of Big Bear Lake Street Sweeping Boulevard December 1999, heavy metal and continues annually and sweep 658 curb petroleum product miles of roadway Annual Cost: content and are then $20,000 disposed of in the appropriate manner Daily monitoring and Staff Litter and Trash 3000 hours of staff City of Big Bear Lake removal of trash and Pick up time litter Annual inspection and Staff spent 160 hours City of Big Bear Lake cleaning of 135 drainage hydro-vactoring 80 of 2003 Unknown culverts these culverts

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Table 3-5. Summary of Best Management Practices (BMPs) in Place in 2004 Agency BMP Description Date Effectiveness Cost Sand Canyon Channel, Rathbun Replaced 2 storm Creek, with San Overall cost: culverts and a portion of Bernardino County Between 1997- Provided bank City of Big Bear Lake $377,849 Teton Road, bank Flood Control District, 2000 stabilization stabilization East Valley Resource Conservation District, and MWD City of Big Bear Lake

3.4 Interview Findings Brown and Caldwell conducted interviews with members of the Task Force to determine the current status of BMP programs and other actions in the watershed that serve to reduce sediment loads to Big Bear Lake.

3.4.1 City of Big Bear Lake The City of Big Bear Lake is the only incorporated municipality within the Big Bear Lake watershed, and is a Copermittee under the San Bernardino County Municipal NPDES permit. The City, home to some 6,000 residents, extends along the southern end of the lake. The City continues to implement all of the BMPs and activities described in the City Manager’s letter of February 2004. The main difference is that they have increased their efforts in controlling sediment from construction projects. Currently, all construction projects (regardless of size) within City limits are required to prepare a Water Quality Management Plan (WQMP) to eliminate sediment discharges into the lake. Lakefront properties are required to install and maintain permanent erosion and sediment control BMPs such as gravel- lined basins and drainage ways. Also, construction sites within 200 feet of sensitive water bodies must submit Category WQMPs (more stringent WQMPs that must include backup calculations that demonstrate the BMPs are adequate to prevent sediment discharge). Each property owner must sign a maintenance agreement that is recorded against their property. The maintenance agreement provides the City with the legal authority to issue Notices of Violation to the property owner if they fail to maintain the BMPs, or repair the problem at the property owner’s expense. The City is actively seeking grant funding for flood control and stabilization projects in Sand Canyon and along Rathbun Creek. The City already has plans for two specific projects, but has not been able to proceed due to a lack of funds. The proposed projects are designed to increase infiltration by installing coarse gravel and rock that provide subsurface reservoir capacity. These are significant projects ($50-100 million). There is an existing pond located on private property within the drainage way of Rathbun Creek that was formerly served as a trout fishing operation (it is now out of business). The City believes that the pond is actually functioning as a sediment trap and does not have a negative impact. There is a defunct ski area formerly known as Snow Forest, located approximately 2 miles west of Snow Summit, above Pine Knot Rd. The US Forest Service has constructed a number of sediment basins along the foot of the mountain below this area to control sediment prior to discharging to Knickerbocker Creek. According to the City, the basins work very well.

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3.4.2 San Bernardino County Flood Control District The San Bernardino County Flood Control District (District) is the principal Copermittee under the San Bernardino County Municipal NPDES permit. The District participates in the Big Bear Lake Nutrient TMDL Task Force on behalf of the County (although the District is technically a separate agency from San Bernardino County, the two agencies share a common Board of Supervisors/Directors). The District has jurisdiction over certain designated drainage channels and associated access roads within the watershed, including: . Knickerbocker Creek . Cameron Storm Drain (tributary to Knickerbocker Creek) . Grout Creek (portions) . Sand Canyon Creek . Van Dusen Creek The District has historically constructed and maintained several in-stream detention basins (e.g., Sand Canyon Channel, Rathbun Creek) in conjunction with Big Bear Municipal Water District and the City of Big Bear Lake. The District also performs maintenance in its channels on demand (e.g., if there are complaints of erosion or damage).

3.4.3 San Bernardino County The County of San Bernardino has jurisdiction over the unincorporated areas of the watershed, which includes the communities of Fawnskin (north shore) and Big Bear City (southeastern shore). Like the City of Big Bear Lake and the Flood Control District, the County is a Copermittee under the San Bernardino County Municipal NPDES permit. The County is primarily responsible for permitting and inspecting new development and redevelopment areas. During the preconstruction phase, developers and contractors are required to obtain permits for Erosion and Sediment Control Program and WQMP, which details how the applicant intends to control erosion and sediment in runoff from the site. During the construction phase, the County inspects the sites and the BMPs employed at the site. Post construction, the County continues to conduct field inspection of the BMPs to ensure they are functioning properly. Currently, all construction projects (regardless of size) within the County’s jurisdiction are required to prepare a WQMP to eliminate sediment discharges into the lake. Each property owner must sign a maintenance agreement that is recorded against their property. The maintenance agreement provides the County with the legal authority to issue Notices of Violation to the property owner if they fail to maintain the BMPs, or repair the problem at the property owner’s expense.

3.4.4 US Forest Service The United States Forest Service (San Bernardino National Forest) owns the majority of the land area within the Big Bear Lake watershed (37 square miles). There are approximately 1250 miles of roads within the forest (check how much of this is in the BBL watershed) that the Forest Service is responsible for maintaining. Most of these roads are earthen access and fire roads that may be a source of erosion and sedimentation. However, based on a literature review conducted by Robert Taylor, improvements to earthen roads (drainage and erosion control) can reduce erosion sediment delivery by as much as 70 percent. During Fiscal Years 2008-10, the annual road maintenance budget allocated by the USFS Regional Office is $157,000, which equates to approximately $125 per mile. Beginning in FY08, the US Congress appropriated $90 million in funding to address issues associated with legacy roads in National Forests throughout the US.

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Specifically, this money was designated for “urgently needed road decommissioning, road and trail repair and maintenance, associated activities, and removal of fish passage barriers, especially in areas where Forest Service roads may be contributing to water quality problems in streams and water bodies which support threatened, endangered or sensitive species or community water sources (HR 2996, Title III, USDA Forest Service).” In FY08, San Bernardino National Forest received $390,000 to reform the road, add overside drains and culverts and a rock cap along Forest Road 2N13 near Grout Creek. Subsequently, in FY09, the Forest received $360,000 for improvements to Polique Canyon Road. This project involved improving the roadway surface to reduce erosion and installing better drainage control. Both of these projects were located in the Big Bear Lake watershed. This year, the Forest received a $700,000 grant under the American Reinvestment and Recover Act (ARRA) for decommissioning nearly 600 illegal openings and unauthorized trails along 18 miles of roads within the watershed.

3.4.5 Big Bear Mountain Resorts The Big Bear Lake watershed has two popular ski and snowboard resorts operated under a permit with the San Bernardino National Forest, Snow Summit and Bear Mountain. In 2002, the two resorts merged and are operated jointly as Big Bear Mountain Resorts. The resort has a full-time erosion and sediment control program in place to keep sediment from running off the ski slopes and into the lake. They spend approximately $30,000 annually on erosion control products and more on labor to install and maintain them. The most intense efforts are conducted in the spring and summer, when snowmelt is occurring. The resort continues to implement all of the measures described in the 2004 letter, along with new special projects as issues arise. For example, they recently constructed a barrier between the auxiliary parking lot and Rathbun Creek at Bear Mountain Resort using boulders wrapped with geofabric. The barrier is approximately one-third of a mile long. During summer 2008, Big Bear Mountain Resorts constructed a 700-foot culvert extension at Bear Mountain to route drainage from the base area. The project, which cost $60,000, included the reconstruction of a retaining wall and bank stabilization in Rathbun Creek. The resort has also modified their snow plowing at Bear Mountain such that they pile snow into the center of the auxiliary parking lot instead of the perimeter to prevent entrained sediment from entering the creek after the snow melts. Since 2004, the resort has constructed 3 new sediment basins at Snow Summit. One of the basins was constructed as a mitigation project associated with the Construction of a new beginners’ ski area which required removal of an older US Forest Service sediment basin. The resort replaced this basin, added another one, and constructed an additional basin half way up the ski hill. Additionally, the resort has optimized the operation of one of its largest sediment basins, which captures runoff from the west and central areas of Snow Summit, by adding a submersible skimmer pump that improves settlement of particulates and enables faster drainage of the basin. The resort uses its extensive snowmaking systems at both Bear Mountain and Snow Summit year-round to provide dust control and irrigation for erosion control revegetation. In addition, they use straw mulch to protect seed on hillsides during the plant establishment period.

3.4.6 California Department of Transportation The California Department of Transportation (Caltrans) District 8 operates and maintains highways in the watershed, including Highways 18 and 38. Caltrans maintenance conducts regular street sweeping, slope repair/erosion control, and snow and ice control in order to keep the highways open to the travelling public. However, due to a lack of available right-of-way, Caltrans has conducted relatively few BMP projects to

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control runoff quality flowing to the Lake. Caltrans implemented one significant BMP project at the Fawnskin Maintenance Station where a biofiltration strip was installed to treat runoff from approximately 50 percent of the parking lot prior to discharge into the Lake.

3.5 Implementation of BMPs

3.5.1 Opportunities and Constraints According to the City of Big Bear Lake, the largest constraint on implementing new BMPs and management actions is cost, and the City is actively pursuing grant funding to support many of its efforts (and has succeeded in getting several grants for this purpose). In the event that funding becomes available, the City would consider implementing the following recommendations: . Stream bank stabilization projects in Sand Canyon and along the lower reaches of Rathbun Creek to provide erosion control and enhance infiltration . Construction of additional curb and gutter and storm drain system infrastructure to enable better maintenance (e.g., street sweeping, vactor cleaning of catch basins) and move water through hardened surfaces instead of earthen conveyances The Flood Control District noted that there is one potential improvement project planned for Knickerbocker Creek, in which there is a portion of the creek that has exacerbated erosion that could be controlled in order to limit sediment loss. The District also noted that there is an improved section of the Creek that the District may gift to the City of Big Bear Lake. Other than that, the District is not aware of any other treatment BMP or erosion control projects planned to be conducted in the watershed. The Forest Service has identified opportunities for further improvements to forest roads and has requested $612,000 in FY10 legacy funding from the Federal government for Forest Road 2N10 – Mill Road near Metcalf Creek and North Creek (Boulder Bay area). Most, if not all agencies have noted that a major constraint on their ability to expand their BMP programs and activities is the availability of funding. In addition, both Caltrans and the Flood Control District have noted that limited right-of-way restricts their ability to physically construct BMPs. Specifically, Caltrans’ right- of-way is limited to a narrow strip adjacent to Highways 18 and 38, and the Flood Control District right-of- way is limited to the channels within their jurisdiction. Both Caltrans and the Distinct also pointed out that land ownership in the watershed is not always contiguous. Big Bear Mountain Resorts believes that they are doing everything possible to control erosion from their facilities.

3.5.2 Costs During the Caltrans BMP Retrofit Pilot Program (2004), the incurred costs of constructing and operating the BMPs in the pilot study were documented in detail (Table 3-6). The actual construction costs were reviewed on a site-by-site basis by a technical workgroup that included water quality specialists, construction managers and design engineers. The construction costs for the BMPs were normalized by water quality volume rather than by tributary area to account for the significant differences in design storm depth used for sizing the controls in different parts of the study area and for the differences in the runoff coefficient at each site (Caltrans, 2004). The cost values have been adjusted for inflation and current 2010 rates.

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Table 3-6. BMP Costs Adjusted for Inflation (From Caltrans 2004)1 Adjusted Construction Annual Life- Average Adjusted Cost/m1 of the Design Adjusted O&M Present Value Cycle BMP Type (No. of installations) Construction Cost Storm Cost O&M Cost/m1 Cost/m1 Wet Basin (1) $591,366 $2,283 $22,393 $596 $2,879 Multi-chambered Treatment Train (2) $363,482 $2,473 $8,454 $226 $2,698 Oil-Water Separator (1) $169,209 $2,598 $1,042 $28 $2,626 Delaware Sand Filter (1) $303,515 $2,522 $3,838 $103 $2,624 Storm-Filter (1) $402,702 $2,073 $10,049 $269 $2,342 Austin Sand Filter (5) $320,203 $1,908 $3,838 $103 $2,011 Biofiltration Swale (6) $76,250 $992 $3,627 $98 $1,089 Biofiltration Strip (3) $83,133 $986 $3,627 $98 $1,084 Infiltration Trench (2) $192,748 $967 $3,508 $94 $1,060 Extended Detention Basin (5) $227,806 $778 $4,115 $109 $888 Infiltration Basin (2) $204,559 $487 $4,115 $107 $593 Drain Inlet Insert (6) $488 $13 $1,451 $38 $51 1 Original cost data were in 1999 dollars. Present value costs are adjusted to 2010. An estimate of costs for source control (non-structural) BMPs has been prepared by the APWA (1992). Their analysis includes ten source control measures with cost data, which have been adjusted for inflation and current 2010 rates (Table 3-7). Their cost data did not include engineering, administration, land acquisition, or permitting costs, which could increase the capital costs by 30 to 50 percent (APWA 1992).

Table 3-7. Source Control Costs Adjusted for Inflation (from APWA 1992) O&M Cost Source Control Description Capital Cost (present value) Billing inserts, news releases, radio, school Public education $313,820 $403,259 programs, pamphlets Controls household and restaurant paper, plastics, Litter Control $31/trash receptacle $25/acre/trash and glass Controls household and restaurant paper, plastics, $549,185/300,000 per Recycling Programs $313,820 and glass capita Prohibits littering, Controls household and restaurant Potential to be self- No Littering Ordinance $31,382 paper, plastics, and glass supporting through fines Requires owners to clean up after their animals and Potential to be self- Pooper Scooper Ordinance properly dispose of waste, controls coliform bacteria $31,382 supporting through fines and nitrogen/urea Works to prevent pollutants from entering storm Spill Response Plan drains by controlling hazardous and harmful $31,382 N/A chemicals, oil, and grease Prevents debris from accumulating on lots and Self-supported by fines to Vacant Lot Clean Up N/A eliminates sources of hazardous waste lot owners Prohibit illegal and illicit connections Reduces pollutant load from entering the storm $3/acre Self-supported by fines and dumping into storm drains drains Identify, locate, and prohibit illegal or Halt hazardous and harmful discharges, whether $3/acre (1 monitor every $78 illicit discharges into storm drains intentional or negligent 5 square miles) Reduce potential for clogging storm drains with Street Sweeping N/A $1.30 debris with potential for oil and grease control

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The APWA defines five levels of BMPs that might be workable, with the appropriate level depending on the stringency of discharge requirements and the success of the individual measures. Level 1 is the institutional and non-structural controls. BMP Level 2 is a combination of Level 1 and increased maintenance of existing minor and moderate structural source controls (which primarily were constructed for flood control). BMP Level 3 is a combination of BMP Level 2 and construction of additional minor and moderate structural source controls. BMP Level 4 is a combination of BMP Level 3 and construction of detection basins or wetlands. BMP Level 5 is a combination of BMP Level 4 and construction of advanced treatment processes to remove metals, microorganisms, and nutrients. The capital and operation and maintenance (O&M) costs for these five levels, are presented in Table 3-8. The cost values have been adjusted for inflation since the publication of the study and the present value was calculated with current 2010 interest rates. Note that the costs provided in the table below are provided for informational purposes only and were derived from a nationwide survey that mainly considered metropolitan areas considerably larger than those in the Big Bear Lake Watershed. Additional surveys and research could be performed in the future to adapt this nationwide study to refine cost information especially for the Big Bear Lake Watershed.

Table 3-8. BMPs Costs Adjusted for Inflation (From APWA 1992) O&M Cost Best Management Practice Capital Cost (present value) BMP Level 1 Institutional Source Controls No Littering Ordinance $859,482 $1,289,224 Pooper Scooper Ordinance $859,482 $1,289,224 Chemical Use/Storage Ordinance $859,482 $1,289,224 Recycling Programs $8,594,825 $15,040,944 Public education $8,594,825 $11,044,350 Vacant Lot Clean Up $859,482 $1,289,224 Spill Prevention Ordinance $859,482 $1,289,224 Non-structural Source Controls Program to prevent illicit discharges $21,435,682 $267,946,023 Street Sweeping $0 $4,447,904 Increased cleaning of storm drains $0 $112,537,330 TOTAL $42,922,745 $417,462,670

BMP Level 2 BMP Level 1 $42,922,745 $417,462,670 Minor Structural Controls Improve Diversion Channels $0 $64,307,045 Improve Grass Swales $0 $64,307,045 Improve Natural Channels to Reduce Erosion $0 $16,076,762 Plant Vegetative Controls on Exposed Soils $0 $1,339,730,115 Minor Structural Discharge Elimination Methods Increase Maintenance for Recharge Areas $0 $8,038,380,689 Increase Maintenance for Porous Pavements $0 $107,178,410

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Table 3-8. BMPs Costs Adjusted for Inflation (From APWA 1992) O&M Cost Best Management Practice Capital Cost (present value) Moderate Structural Controls for Floatables/Oils Removal Increase Maintenance for Parking Lot Oil/Grease Separators $0 $1,071,784,092 Increase Maintenance for Parking Lot and Rooftop Runoff Storage with $0 $1,178,962,502 Outlet Protection TOTAL $42,922,745 $12,298,189,328

BMP Level 3 BMP Levels 1 & 2 $42,922,745 $12,298,189,328 Moderate Structural Controls for Floatables/Oils Removal Construct Parking Lot Oil/Grease Separators $9,646,056,827 $9,646,056,827 Construct Parking Lot and Rooftop Storage with Outlet Protection $21,703,627,860 $10,610,662,510 TOTAL $20,000,000,000 $20,700,000,000

BMP Level 4 BMP Levels 1, 2, & 3 $31,392,607,431 $32,554,908,664 Major Structural Controls for Floatables/Oils Removal Construct Detention Basin with Outlet Protection $700,282,925 $599,350,376 Construct Wetlands Treatment Area $0 $0 TOTAL $32,092,890,358 $33,154,259,040

BMP Level 5 BMP Levels 1, 2, 3, & 4 $32,092,890,358 $33,154,259,040 Major Structural Controls for Floatables, Metals, Microorganisms,

and Nutrient Removal Add Lime Precipitation, Filters, and Chlorination/Dechlorination to $47,102,142,990 $107,283,717,281 Detention Basins Add Lime Precipitation, Chlorination/Dechlorination to Wetlands $0 $0 TOTAL $79,195,033,348 $140,437,976,322

3.6 Conclusions Over the past 10 to 15 years, numerous efforts have been conducted to control the sediment nutrient loading to Big Bear Lake from the tributary streams. These included operational and institutional source controls, as well as structural BMPs (such as the two constructed catch basins at the mouth of Rathbun Creek). The recently-approved San Bernardino County NPDES Permits states that “The proposed plan shall identify recommended short and long-term strategies for control and management of sediment and dissolved and particulate nutrient inputs to the lake to the extent that the permittees are responsible for these inputs over and above that which would occur naturally.” As such, Table 3-9 presents opportunities for short-term (i.e., next 2-3 years) and long-term strategies that may be considered in the watershed with funding being the biggest constraint.

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With respect to short-term strategies, the MS4 Copermittees within the Big Bear Lake Watershed should implement all of the required activities listed in Order R8-2010-0036 in accordance with the deadlines listed within that Order. Additionally, Caltrans should continue to implement the requirements in its existing and next generation Statewide Stormwater Permit., and the Forest Service should continue to pursue funding and implement projects to control erosion and sedimentation from forest roads within the watershed.

Table 3-9. Short-Term Strategies to Control Particulate Nutrient Inputs to Big Bear Lake Implementing Agency(ies) Strategy or Project Implementation Schedule Big Bear Municipal Water District Third grade educational curriculum on lake water quality Ongoing City of Big Bear Lake Develop and implement a Local Implementation Plan (LIP) for July 29, 2011 County of San Bernardino City’s/County’s jurisdiction Implement all applicable program elements including but not limited to the management programs, monitoring programs, implementation plans and appropriate BMPs outlined in the Municipal Stormwater Management Plan and the LIP; review and revise policies and City of Big Bear Lake ordinances as necessary; obtain public input for any proposed major changes to its storm water management program and implementation As per schedule in LIP County of San Bernardino plans; inspect, clean, and maintain the MS4 systems within its jurisdiction;; maintain up-to-date GIS-based MS4 facility maps; and prepare and submit to the Principal Permittee in a timely manner all required information necessary to develop a unified Annual Report for submittal to the Executive Officer of the Regional Board. Designate at least one representative to the Management Committee and attend at least 7 out of the 8 Management Committee meetings per year; conduct, and/or coordinate with the Principal Permittee to conduct, any surveys and/or characterizations needed to identify pollutant sources from specific drainage areas; review and comment on all plans, strategies, management programs, monitoring programs, as developed to comply with the Order; participate in committees or subcommittees formed to address storm water related issues to comply with the Order; respond to or arrange for responding to emergency situations such as accidental spills, leaks, illegal discharges/illicit connections, etc. to prevent or reduce the discharge of pollutants to storm drain systems and City of Big Bear Lake Waters of the U.S.; pursue enforcement actions as necessary within its jurisdiction for violations of storm water ordinances, prohibitions on illicit As per schedule in LIP County of San Bernardino connections and illegal discharges, and other elements of its storm water management program; track, monitor, and keep training records of all personnel involved in the implementation of its LIP; track and monitor operation and maintenance of post-construction BMPs installed in areas within the jurisdiction; prior to accepting permanent connections to its MS4 from entities outside its jurisdictional authority, notify these entities in writing of General Stormwater Permit post-construction standards and the regulatory requirements for control of pollutants in MS4 discharges (including relevant requirements from the MSWMP and Water Quality Management Plan), where feasible, and consistent with the MEP standard.; and track and monitor operation and maintenance of post-construction BMPs installed in areas within the jurisdiction. Continue to conduct street sweeping of Caltrans highways within the watershed. Revised statewide permit and Statewide Stormwater Caltrans Ongoing Management Plan anticipated to be approved in late 2010 or early 2011 may include additional provisions. The Forest Service has applied for FY10 legacy funding from the Implementation likely beginning US Forest Service Federal government for Forest Road 2N10 – Mill Road near Metcalf during FY 2010 Creek and North Creek (Boulder Bay area).

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Identified long-term opportunities within the Big Bear Lake Watershed, given appropriate funding are presented in Table 3-10.

Table 3-10. Long-Term Strategies to Control Particulate Nutrient Inputs to Big Bear Lake Implementing Agency Strategy or Project Implementation Schedule Stream bank stabilization projects in Sand Canyon and along the To be determined – timing contingent on City of Big Bear Lake lower reaches of Rathbun Creek to provide erosion control and availability of grant funding enhance infiltration

Construction of additional curb and gutter and storm drain system infrastructure to enable better maintenance (e.g., street sweeping, To be determined – timing contingent on City of Big Bear Lake vactor cleaning of catch basins) and move water through hardened availability of grant funding surfaces instead of earthen conveyances

To be determined – timing contingent on Additional erosion and sediment control along forest roads within US Forest Service availability of future legacy funding and the watershed other funding

Constraints In addition to funding, which is a concern for nearly all stakeholders, Caltrans and the Flood Control District both stated that limited right-of-way is an additional constraint as it restricts their ability to physically construct BMPs. Though funding is a constraint, BMP design and implementation guidance is not an issue. Caltrans and CASQA provide detailed design guidance documents and interactive tools on their websites. Reducing the sediment nutrient loading to Big Bear Lake from the main tributaries will be a process of finalizing efforts, evaluating the benefit of potential opportunities, identifying potential opportunities that are achievable given current constraints, and coordinating efforts jointly with the agencies.

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Use of contents on this sheet is subject to the limitations specified at the end of this document. S01255.Revised Draft_Big Bear LakeTMDL Action Plan 8-26-2010.docx

BIG BEAR LAKE TMDL ACTION PLAN

4. NUISANCE AND NOXIOUS AQUATIC PLANT MANAGEMENT PLAN

This section describes activities carried out by Big Bear Municipal Water District (BBMWD) control the spread of nuisance and noxious aquatic plants.

4.1 Introduction BBMWD has been working to eradicate invasive aquatic plants for many years. Initially relying on mechanical harvesting technology, BBMWD has recently shifted to using aquatic herbicides that targets only Eurasian Watermilfoil. This program has proven highly successful is now an integral part of BBMWD's long-term lake management strategy. Rather than interfere with or duplicate the on-going weed control program, the stakeholders named in the TMDL have elected to partner with BBMWD. The Water District will continue to take primary responsibility for acquiring and applying appropriate aquatic herbicides to eradicate Eurasian Watermilfoil. The other Task Force agencies will be responsible to conduct the monitoring and submit the reports required to demonstrate that the weed control program is implementing the Nuisance and Noxious Aquatic Plant Management Plan (NAPMP) as required by the TMDL. It is envisioned that the Aquatic Plant Management Plan will be updated every three years in accordance with the Regional Board's TMDL review schedule. BBMWD will conduct annual reconnaissance surveys to determine when and where to apply aquatic herbicides. The other agencies named in the TMDL will document these efforts in an annual report and will perform a more comprehensive survey of aquatic vegetation every five years to evaluate progress toward meeting the long-term targets for macrophyte coverage in the lake. All of aforementioned responsibilities will be codified in a contract between the various stakeholders after the Regional Water Quality Control Board approves this Aquatic Plant Management Plan. Native aquatic plant communities are an integral part of the lake environment as they provide food, shelter, and nesting sites for many fish, waterfowl and smaller animals. Rooted aquatic plants also stabilize shorelines, reduce sediment suspension, and improve water quality by absorbing excess nutrients from the water column (Gibbons, et al., 1999). Invasive aquatic vegetation can create nuisance conditions by altering the structure of the lake's ecosystem. In particular, noxious freshwater weeds can crowd-out native plants thereby destroying aquatic habitat. Invasive plants spread rapidly and create dense monocultural canopies that result in decreased water mixing, reduced oxygen exchange and increase nutrient cycling (AERF, 2005). The scientific literature clearly supports the value of maintaining diverse aquatic and semi-aquatic ecosystems. A healthy community of native aquatic plants supports fish and wildlife by providing habitat, food, breading areas, water oxygenation and refuge from predators (AERF, 2005). It is well-established that the excessive growth of invasive aquatic plants also impairs recreational opportunities in Big Bear Lake (TMDL Technical Report, 2005). Large stands of noxious species such as Eurasian Water Milfoil and Coontail foul boat propellers restrict access to shoreline swimming and interfere with sport-fishing activities.

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Use of contents on this sheet is subject to the limitations specified at the end of this document. S01255.Revised Draft_Big Bear LakeTMDL Action Plan 8-26-2010.docx Section 4: Aquatic Plant Management Plan Big Bear Lake TMDL Action Plan

Therefore, it is in the best interest of both the public and the environment to establish and implement a plan to reduce the adverse effects of nuisance and noxious aquatic plants in Big Bear Lake to the maximum extent practicable. The goal of this document is to describe that plan.

4.1.1 NAPMP Objectives The TMDL adopted by the SARWQCB enacted targets for minimum acceptable levels of coverage by native plant species in the lake (Table 4-1).

Table 4-1. Big Bear Lake Nutrient TMDL Response Targets for Aquatic Plants Indicator Target Value Macrophyte Coverage – 30-40% on a total lake area basis; to be attained by 2015 for dry hydrological (calculated as a five year running average based on conditions and by 2020 for all other hydrological conditions measurements of peak macrophyte growth). Percentage of Nuisance Aquatic Vascular Plant Species - 95% eradication on a total area basis of Eurasian Watermilfoil and any other (calculated as a five year running average based on invasive aquatic plant species; to be attained no later than 2015 for dry measurements of peak macrophyte growth). hydrological conditions and by 2020 for all other hydrological conditions

The TMDL requires dischargers in the Big Bear Lake watershed to develop and implement a plan describing the specific means by which the aforementioned targets will be achieved. The plan must evaluate the applicability of various in-lake treatment technologies to control noxious and nuisance aquatic plants. The plan must include a description of the monitoring needed to track plant diversity, coverage and biomass. The plan must also describe how the resulting data will be used to assess compliance with the numeric targets identified in the TMDL. In January, 2010 the Regional Board enacted similar requirements in the NPDES permit governing stormwater discharges in the Big Bear Lake watershed. That permit obligates the dischargers to submit a draft plan by February 26, 2010. This document is intended to fulfill that requirement. The NAPMP is one of several initiatives to improve water quality and protect beneficial uses in Big Bear Lake. Other plans and efforts are underway to reduce the internal and external nutrient loads that indirectly encourage the growth of invasive plant species. The focus of the NAPMP is on describing the more direct measures that will be used to eradicate nuisance and noxious aquatic weeds in the lake.

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4.1.2 Problem Statement Big Bear Lake is an important water supply reservoir and recreational resource. It is moderately productive in terms of nutrient concentration, planktonic algae, and vascular aquatic plants, both rooted and non-rooted. Until 2004, two aquatic macrophytes, Eurasian Watermilfoil (Myriophyllum spicatum, EWM) and Coontail (Ceratophyllum demersum) dominated the shorelines and littoral zone of Big Bear Lake and directly interfered with many of the lake’s designated beneficial uses. Aquatic plant interference with recreational uses was evidenced by the number of calls received by the BBMWD from lake users and dock owners complaining about problems caused by aquatic plants. Prior to the summer of 2003, BBMWD staff indicated that the BBMWD received two to three phone calls each day during the summer from dock owners complaining about the presence of aquatic plants (Sheila Hamilton, personal communication). Examples of other problems reported included: 1) propellers of boats and jet skis entangled or clogged by aquatic plants, 2) swimmers entangled in aquatic plants and 3) fishing impeded by aquatic plants. The impact of excessive aquatic plant growth on other beneficial uses of the lake is more ambiguous. Dense aquatic macrophyte beds can negatively impact lake water quality characteristics (e.g., dissolved oxygen, temperature). In the early 1970s, the noxious and invasive aquatic plant, Eurasian Watermilfoil, began to interfere with recreational uses of the lake. Although a native aquatic plant in California, Coontail was also deemed a nuisance and invasive plant species as it also developed into extremely dense stands in the lake. Both Eurasian Watermilfoil (EWM) and Coontail continued to expand and displace the native/natural aquatic plant communities within the lake system. By the summer of 2000, an aquatic plant vegetation survey determined that 781 acres of the 2,971 surface acre lake exhibited excessive growth of EWM and Coontail (ReMetrix, 2001). In 2002 and 2003, large-scale aquatic herbicide applications designed to target EWM and Coontail were successful in significantly reducing the aerial coverage and relative density of these aquatic plants. During the 2004 growing season, the prior aquatic herbicide treatments combined with extremely low lake levels (i.e., -17 feet below full pool) enabled Curlyleaf pondweed (Potamogeton crispus) to become the dominate plant within the lake. Then, in the winter of 2005, record amounts of rainfall delivered 39,000 acre-ft of water to Big Bear Lake and essentially re-filled the water body. However, an aquatic plant survey in 2005 discovered that EWM was re-establishing in many locations throughout Big Bear Lake. From these and other observations, it was concluded that EWM as well as other aquatic plants may require a continuous management program in order to protect the beneficial uses of the lake. Since then, annual surveys indicate that regular herbicide treatments have reduced EWM to 288 acres in 2008 and 183 acres in 2009. The short-term aquatic plant control/management efforts are specifically directed at EWM. The long-term aquatic plant management goals will include efforts to support recolonization of the lake by native plant species. The primary means by which re-vegetation will occur is through the use of aquatic herbicide application(s) to control the overgrowth of noxious aquatic plant species. Modern herbicides are highly selective and target only the EWM without harming desirable native species. This will provide the space necessary for the recovery of native aquatic plant species.

4.2 Background This section provides an overview of the nuisance and noxious aquatic plants recently and historically observed in and around Big Bear Lake, the historical aquatic plant management efforts, a water body description of Big Bear Lake, and a discussion of recent lake water quality status.

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4.2.1 Aquatic Plant Species in Big Bear Lake According to Leidy (2006), the historical record indicates that several aquatic plants, including both EWM and Coontail, were common in Bear Valley Reservoir (now Big Bear Lake) prior to and during the height of resort development in the valley. Specifically, Parish (1917) noted that EWM and Coontail were present in abundance. The shallow impoundment that comprised the Bear Valley Reservoir created optimum conditions for the dispersal of aquatic plants. Therefore, the expansion of aquatic macrophytes occurred long before there was any significant development in the watershed (Leidy, 2005). A 1979 report by the California Department of Fish & Game provides early documentation regarding the aquatic plant species observed and the overall status of aquatic plants in Big Bear Lake (Siegfried et al., 1979). In the 1977 to 1978 time period, a total of eight (8) aquatic plant species were identified in Big Bear Lake. With the exception of EWM and Curlyleaf Pondweed, each of the aquatic plant species identified were considered native to Southern California (Hickman, ed., 1993). Table 4-2 provides a list of the species identified and where reported, the corresponding dry biomass measurements made. The report indicates that in the 1970s, EWM and Coontail were present in Big Bear Lake in abundance. The study did not include a quantitative biomass evaluation of Coontail, but clearly stated that at that time Coontail dominated the aquatic macrophyte community of the lake over all other species (Siegfried et al., 1979).

Table 4-2. 1977-1978 Aquatic Plant Species and Biomass In Big Bear Lake Dry Biomass Species Common Name (g/m2) Native or Exotic (c) Most Abundant (b); Ceratophyllum demersum Coontail/Hornwort (a) Native Biomass not Measured Native to California, but not Potamogeton filiformis Slender-leaved pondweed (a)(d) 304.2 native to Bear Valley Elodea Canadensis American elodea (a) 114.8 Native Myriophyllum spicatum Eurasian Watermilfoil 74.7 Exotic. Native to Eurasia Identified in the Report; Native to California, but not Myriophyllum sibiricum Northern Water Milfoil (a) Biomass not Measured native to Bear Valley Potamogetan crispus Curlyleaf pondweed 47.5 Exotic. Native to Eurasia Polygonum amphibium Not Identified in the Swamp knotweed (a) Native var. emersum Report Polygonum amphibium var. Identified in the Report; Smartweed Native stipulaceum Biomass not Measured Notes: (a) These plants are considered native aquatic plant species in Southern California (Jepson Manual), but not necessarily Bear Valley. (b) Was observed as the most abundant aquatic plant in Big Bear Lake, although no attempts to measure biomass were made. (c) Re-created and referenced from Table 3 in Leidy (2006). (d) Leidy (2006) proposed a possibility for miss identification of Potamogeton filiformis. A 2005 aquatic plant survey conducted by AquaTechnex, LLC in Big Bear Lake identified the following aquatic plant species and relative abundance (Table 4-3):

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Table 4-3. 2006 Aquatic Plant Species and Relative Dispersion In Big Bear Lake Relative Native or Species Common Name Dispersion Exotic (b) Ceratophyllum demersum Coontail/Hornwort (a) 1 of 300 pts Native Native to California, but not native Potamogeton filiformis Slender-leaved pondweed (a)(c) 97 of 300 pts to Bear Valley Elodea canadensis American elodea (a) 6 of 300 pts Native Found in the lake, but not Myriophyllum spicatum Eurasian Watermilfoil reported with native plant survey Exotic. Native to Eurasia results. Not observed, but potentially Native to California, but not native Myriophyllum sibiricum Northern Milfoil (a) also present in Big Bear Lake to Bear Valley Potamogetan crispus Curlyleaf pondweed 16 of 300 pts Exotic. Native to Eurasia Polygonum amphibium Swamp knotweed (a) Not observed by the survey Native var. emersum Polygonum amphibium var. Smartweed (a) 56 of 300 pts Native stipulaceum Chara sp. (d) Chara 27 of 300 pts Native/Macro-algae Notes: (a) These plants are considered native aquatic plant species in California (Jepson Manual), but not necessarily Bear Valley. (b) Re-created and referenced from Table 3 in Leidy (2006). (c) Leidy (2006) suggested a possibility for misidentification. (d) Chara is not a vascular aquatic plant, but is a macro-algae. The 2005 aquatic plant survey indicates that the same aquatic plant taxa present in Big Bear Lake almost three decades ago are still present today. However, the early aquatic herbicide applications (i.e., those in 2002 and 2003) and the water level fluctuations (2004 vs. 2005) shifted the relative abundance of certain aquatic plant species. This shift was the desired outcome of the aquatic herbicide applications. A recent report by Leidy (2006) suggests that some ambiguity regarding species composition exists. Specifically, Leidy (2006) indicates that a misidentification may have occurred for the Potamogetan filiformis (Slender-leaved pondweed). Using the Jepson Manual, the Leidy report (2006) also identifies two other species of pondweeds that are native to the Bear Valley (i.e., Potamogeton natans and Potamogeton pectinatus), but which were not noted by the Siegfried et al., 1979 study or the 2005 AquaTechnex, LLC survey. Additionally, Leidy’s research and review of historical documents infers that Northern Water Milfoil (Myriophyllum sibiricum) could potentially be present in Big Bear Lake. Finally, there also appears to be some potential confusion regarding the variety of Polygonum amphibium (Swamp knotweed vs. Smartweed) found in Big Bear Lake. According to Leidy (2006), both varieties are potentially present. The observations of Leidy (2006) suggests that historically there is potentially some uncertainty about aquatic plant species identification, however, this plan will resolve these problems by providing for the collection of voucher samples in conjunction with the aquatic plant monitoring efforts. Coontail and the exotic species, EWM, have been present in Big Bear Lake since the early 1900s. Coontail and EWM have been present in nuisance and invasive densities since the 1970s. Prior to aquatic herbicide applications, aquatic plant monitoring efforts and aquatic plant harvesting records indicated that the percent dominance of EWM had substantially increased from 1978 to 2001. Aquatic herbicide applications in 2002 and 2003 specifically targeted EWM and Coontail and reduced their percent dominance relative to other aquatic plants. Other aquatic plant taxa can be important indicators of stressed or recovering conditions, particularly the pondweeds (Potamogeton spp.) and waterweeds (Elodea canadensis). According to the Jepson Manual (Hickman, ed., 1993), Potamogeton crispus is “uncommon” in California and must be considered non-

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native. Curlyleaf pondweed is more indicative of eutrophic conditions, compared to the other pondweed species and often attains nuisance densities in lake in which it becomes established (Dr. Mary Ellen Harris, personal communication). The recently identified (2005) submersed aquatic plant communities throughout Big Bear Lake are presently limited to the presence of only six different species of aquatic plants. Submersed aquatic macrophytes included: 1) Eurasian Watermilfoil, 2) Coontail, 3) American Elodea (Elodea canadensis), 4) Curlyleaf Pondweed (Potamogeton crispus), 5) Slender-leaf Pondweed (Potamogeton filiformis) and 6) Smartweed (Polygonum amphibium var. stipulaceum). Waterstargrass has been identified in the recent past (2001, 2002), but was not identified by the 2005 aquatic plant survey. It is expected that similar comprehensive surveys will be needed approximately every 5 years to reassess the relative abundance of desirable and undesirable aquatic plant species.

4.2.2 Historical Aquatic Plant Management Efforts Beginning in the early 1980s, the BBMWD implemented an Aquatic Plant Harvesting Program to control problems resulting from excessive aquatic plant growth. At the height of the aquatic plant harvesting program, the BBMWD operated up to four aquatic weed harvesters and one Aquamog for the purposes of removing aquatic weeds from the lake during the growing season (i.e., from May to September). The Aquatic Plant Harvesting Program could cut and maintain a maximum of approximately 240 to 250 acres of aquatic plants each growing season. Each harvester could hold two to three tons (wet weight) of harvested aquatic plants per trip so that a range of 1,500 to 4,500 wet tons of plant material would be mechanically removed from Big Bear Lake each year. Harvesting efforts were focused in areas of high recreational use, such as public boat launch ramps and private docks. As time passed, it became apparent that harvesting efforts were no longer sufficient to protect the lake’s recreational beneficial uses directly affected by the non-native and nuisance aquatic macrophytes (EWM and Coontail). By the year 2000, the BBMWD harvesting records indicated that the combined presence of EWM and Coontail constituted 94 percent of the total aquatic plant biomass found in the lake. Further, these aquatic plants occupied 781 acres of the lake’s littoral zone, which is approximately 91 percent of the entire littoral zone and more than 25 percent of the total surface area (normalized to full pool) of Big Bear Lake (ReMetrix, 2001). Note: For purposes of this estimation, the total littoral zone area is assumed to be 850 acres of lake bottom for water depths ranging from 0 to 18 feet at full pool. The littoral zone is defined as “the shallow zone along the shore of a lake; that portion of a water body extending from the shoreline lakeward to the greatest depth occupied by rooted aquatic plants” (Holdren, C., W. Jones, and J. Taggart, 2001). Recent hydroacoustic aquatic plant data clearly showed that aquatic plants in Big Bear Lake occupy water depths from 0 to 18 feet, and that the densest stands of aquatic macrophytes are located in water depths ranging from 0 to 10 feet. Additionally, in 2002, estimates of average aquatic plant biomass were high, ranging from 306 g/m2 to 651.9 g/m2 during the growing season. Again, nearly all of this biomass was due to the dense stands of either EWM and/or Coontail. The BBMWD understood that an alternative means of reducing the excessive growth of non-native (i.e., EWM) and nuisance (i.e., Coontail) aquatic plant species could be achieved by the proper use of an aquatic herbicide. Application of an aquatic herbicide would result in a substantial reduction in the biomass of the targeted non-native and nuisance aquatic plants. In 2002, the BBMWD initiated a campaign to reduce the presence of EWM and Coontail (Ceratophyllum demersum) through aquatic herbicide applications to select areas of Big Bear Lake. The aquatic herbicide treatment technology selected was a fluridone-based aquatic herbicide formulation known as SONAR®. The 2002 Aquatic Herbicide Application treated a total of 270 littoral zone acres of EWM and Coontail. The 2003 Aquatic Herbicide Application treated an additional 144 littoral zone acres of these same plants, for a

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total of 414 acres treated in two consecutive years. Additionally, aquatic macrophyte hydroacoustic survey data and biomass samples were collected both prior to and after aquatic herbicide applications so that treatment success could be evaluated. Unfortunately, these aquatic plant monitoring data were generally limited to only herbicide-treated areas of the lake. Pre- and post-treatment assessments of aquatic plant biomass surveys were performed within the aquatic herbicide treatment areas. These pre- and post-treatment vegetation assessments demonstrated the success of aquatic plant herbicide applications in treated areas of Big Bear Lake. As mentioned previously, the results indicated that plant species composition did not change much in a short-term period, despite vegetation control measures and water level changes. However, the changes in biomass and percent dominant plant species (by dry weight) were dramatic for pre- and post-treatment comparisons. The overall biomass of the invasive and nuisance species decreased by at least 85 percent within all herbicide treatment areas. The exotic species, the EWM, and the nuisance species, Coontail were clearly the dominant species prior to treatment, and the least dominant post-treatment. Increases in the presence and biomass of the Curlyleaf Pondweed were observed in 2004 (319h Report, 2004). However, Curlyleaf Pondweed is also an exotic, non-native aquatic macrophyte. In addition, a 2005 lake-wide survey of aquatic plants discovered that EWM was still present in Big Bear Lake and that its re-growth was occurring in many areas of the lake. This discovery led the BBMWD to conclude that efforts to eradicate and control EWM must be continued into the future. Since 2008, a new herbicide (Renovate OTF) has proven to be effective to reduce dense stands of EWM. During the summer of 2009, 183 surface acres were treated and the nuisance plant conditions were eliminated for the remainder of the recreational season. Additional control measures may be needed to prevent some native species, such as Coontail, from creating nuisance conditions.

4.2.3 Pilot Programs to Eradicate Eurasian Water Milfoil In Big Bear Lake, the interference of excessive aquatic plant growth on the recreational beneficial uses of Big Bear Lake was managed by performing a pilot application of aquatic herbicides over two years (2002 and 2003). The aquatic herbicide applications, in conjunction with decreased lake water levels, were shown to effectively control the excessive aquatic macrophyte growth and substantially decrease the amount of plant biomass occupying the littoral zone (BBMWD, 2004). However, the extensive plant biomass reductions also eliminated a storage reservoir for nutrients during the growing season (BBMWD, 2004). Aquatic plant removal also increased entrainment of nutrients, thus contributing to an increase in water column nutrient concentrations. Finally, the use of aquatic herbicides released a significant amount of nutrient-rich organic materials (in the form of decaying plant tissues) to the water column and lake sediments (Berkowitz and Anderson, 2005). In turn, these actions could have resulted in increased nutrient availability and more frequent algal blooms. Each of the above management measures acted to shift the lake’s steady state equilibrium from a clear, aquatic macrophyte-dominated system toward a more turbid, algal-dominated system. Therefore, additional control measures will likely be needed to reduce nutrient releases from lake- bottom sediments. These measures are described in a separate plan to be submitted to the Regional Board in April, 2010.

4.3 Noxious and Nuisance Aquatic Plant Monitoring Program A systematic means of monitoring the status of aquatic plants in Big Bear Lake is a critical component for measuring the success of the APMP. Long-term aquatic plant monitoring data regarding aquatic plant locations, species composition, relative density and relative percent abundance are needed to develop adaptive management.

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4.3.1 Aquatic Plant Monitoring Approach A comprehensive survey will be performed to characterize the abundance, diversity and relative percent coverage of aquatic vegetation in Big Bear Lake. The Monitoring Program will utilize three stages of monitoring. These stages are: Stage 1 - Littoral Circumventing, Stage 2 – Littoral Transecting, and Stage 3 - Management-specific Monitoring. These stages are described in greater detail below (see Section 3.4). In short, Stage 1, Littoral Circumventing provides for aquatic plant monitoring parallel to the shoreline of the lake. Stage 2, Littoral Transecting provides for aquatic plant monitoring perpendicular to the lake shoreline. The combined use of Stage 1 and Stage 2 aquatic plant monitoring provides a systematic and repeatable means for assessing the overall status of aquatic plants in Big Bear Lake. Stage 3 monitoring provides a means for locating specific plants of interest (i.e. Eurasian Water Milfoil). For all aquatic plant point observations, the GPS coordinates; lake surface elevation, water depth, aquatic plant species, plant relative density, and relative plant abundance will be recorded. In addition, voucher samples of each aquatic plant species identified by Stage 1 and Stage 2 surveys will be taken for taxonomic identification verification. Voucher specimens will be sent to the U.S. Army Corps of Engineers, Lewisville, Texas or U.C. Davis for verification. After verification, voucher specimens will be returned to the BBMWD to provide an aquatic plant library of species found within the lake.

4.3.2 Aquatic Plant Monitoring Schedule The comprehensive lake vegetation survey will be performed every five years at the peak of the growing season. In addition, an annual Stage 3 reconnaissance-level survey will be performed each spring to identify areas that require herbicide treatment. Regular lake patrols and data from public call logs will be used to schedule follow-on spot treatments throughout the summer months. More frequent surveys are unnecessary because the lake ecosystem changes very slowly. Moreover, the proposed schedule fits well with the TMDL triennial review process. Baseline surveys were performed in 2006. Therefore, the next comprehensive analysis will be conducted in the summer of 2011. The results will be submitted to the Regional Board as part of the next annual report due in February of 2012. The dischargers named in the TMDL will be responsible for contracting the comprehensive lake vegetation surveys (Stage 1 and Stage 2 sampling and the BBMWD will provide on the water support services and office/computer use to the consultant for data processing). BBMWD will be responsible for performing the annual reconnaissance-level pre-treatment surveys, conducting the daily lake patrols and recording the public call logs. In addition, BBMWD will be responsible for maintaining all the records required by the California Department of Pesticide Regulation related to the herbicide applications.

4.3.3 Aquatic Plant Monitoring Parameters Stage 1 Littoral Circumventing is simply the point visual observation of aquatic plants through use of a single rake sample or visual observation tube at 1.5 m water depth approximately every 100 m parallel to the shoreline. Since the perimeter of the Big Bear Lake shoreline averages 30,000 m in distance, observations taken at every 100 m parallel to the shoreline will result in approximately 300 points of observation. At every visual observation point, the following will be recorded: . Sample date and sample time; . Location of each sampling point by GPS coordinates; . Water depth and lake surface elevation; . Presence or absence of aquatic plants; . Aquatic plant species (if plants are present);

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. Relative aquatic plant density (if plants are present); and, . Relative percent abundance of each aquatic plant species. If aquatic plants are present, each aquatic plant species found on the rake sampling device will be identified, and relative plant densities assessed. Relative plant densities will be assessed by determining the number of plant stems captured by a single rake sample. Relative plant density will be defined as low when 1 to 2 vertical stems are collected from the sediment per rake sample, moderate at 3 to 6 stems per rake sample, high at 7 to 10 stems per rake sample and saturated at 10 or more stems per rake sample. Note: In the case of Elodea canadensis (common Elodea) the relative plant density should be related to area of sediment visible from viewer because of that plant’s growth characteristic. Therefore, low density would be more than 75 percent of sediment surface visible, moderate at 50 percent sediment surface visible, high at 25 percent of the sediment surface visible and saturated at less than 25 percent of sediment surface visible from viewer. If the plants have canopied and have extensive growths on the water surface, as is often the case for EWM, that area shall be classified as saturated. After relative percent density is determined, the relative percent abundance of each species will also be recorded. When there are 10 or fewer stems retrieved by the rake sampler, relative abundance will be determined by counting the number of stems of a given species and then dividing by the total number of stems observed. When there are more than 10 stems per rake sample, the relative abundance will be determined simply by estimating the species stem count distribution in 10 percent increments. The process of determining relative aquatic plant abundance should be fairly simple based on the low number of species observed within the lake over the past two decades. If species cannot be identified at the time of sampling, a sample will be obtained for later identification with the appropriate plant keys. It should be noted that relative aquatic plant density and abundance information can later be translated to numbers that correspond to area coverage. For example, a single rake will sample a known surface area (approximately 0.2 to 0.3 m2 area). Similarly, the viewing area at 1.5 m water depth is approximately 0.3 m2 when using a 0.15 m viewing tube. The information associated with each rake sample, can then be converted to a square meter area. The recorded GIS data will adhere to the following protocols: 1. GPS data will be collected using a Global Positioning System (GPS) unit with differential correction using a satellite-based augmentation system (SBAS). Corrected GPS measurements will be within 1-meter (m) horizontal accuracy. 2. GPS data will be reported using NAD83 datum coordinates (decimal degrees, five (5) decimal places), northing, easting, and UTM Zone 11. Other information recorded will include sample date, time, water depth (m), aquatic plant species, relative aquatic plant density, and relative species abundance. 3. GPS data will be post-processed and converted into a geographic information system (GIS) shapefile compatible with an ArcGIS 9.X Platform. All metadata shall compiled with FGDC standards. 4. Post-processed ASCII format file containing aquatic plant transect data, GIS compatible shapefile with metadata will be produced. 5. Raw survey notes recorded during survey shall be included in metadata file. Stage 2 Littoral Transect monitoring will be conducted by first locating a station previously established by the Stage 1, Littoral Circumventing monitoring. Transect lines will be spaced approximately 400-m to 500-m apart and run perpendicular to the lake shoreline. Observation points along the transect lines will record the same aquatic plant data as recorded during Stage 1 efforts and will be collected at the 1.5 m, 2.5 m, 3.5 m, and 4.5 m water depths. Data at the 1.5 m water depth point will not be re-collected (as it was already collected during the Stage 1 efforts however, the GPS coordinates will be used to locate the starting point of each transect line. The length of each transect line (i.e., from the 1.5 m data point to 4.5 m data point) will be

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influenced by the slope of the lake bottom. Shorter transect lengths will indicate steeper lake bottom slopes, while longer transect lengths will reflect lake bottom slopes more gentle in nature. The littoral transect monitoring will provide approximately 75 separate transect lines for Big Bear Lake. Again, the same aquatic plant information will be recorded at each observational station as described in the Stage 1 sampling. At every sample rake point and/or visual observation point, the following will be recorded: . Sample date and sample time; . Location of each sampling point by GPS coordinates; . Water depth and lake surface elevation; . Presence or absence of aquatic plants; . Aquatic plant species (if plant are present); . Relative aquatic plant density (if plants are present); and, . Relative percent abundance of each aquatic plant species. If aquatic plants are present, each aquatic plant species found on the rake sampling device will be identified, and relative plant densities assessed. Relative plant densities will be assessed by determining the number of plant stems captured by a single rake sample. Relative plant density will be defined as low when 1 to 2 vertical stems are collected from the sediment per rake sample, moderate at 3 to 6 stems per rake sample, high at 7 to 10 stems per rake sample and saturated at 10 or more stems per rake sample. Note: In the case of Elodea canadensis (common Elodea) the relative plant density should be related to area of sediment visible from viewer because of that plant’s growth characteristic. Therefore, low density would be more than 75 percent of sediment surface visible, moderate at 50 percent sediment surface visible, high at 25 percent of the sediment surface visible and saturated at less than 25 percent of sediment surface visible from viewer. If the plants have canopied and have extensive growths on the water surface, as is often the case for EWM, that area shall be classified as saturated. After relative percent density is determination, the relative percent abundance of each species will also be recorded. When there are 10 or fewer stems retrieved by the rake sampler, relative abundance will be determined by counting the number of stems of a given species divided by the total number of stems observed. When there are more than 10 stems per rake sample, the relative abundance will be determined simply by estimating the species stem count distribution in 10 percent increments. The process of determining relative aquatic plant abundance should be fairly simple based on the low number of species observed within the lake over the past two decades. It should be noted that relative aquatic plant density and abundance information can later be translated to numbers that correspond to area coverage. For example, a single rake will sample a known surface area (approximately 0.2 to 0.3 m2 area). Similarly, the viewing area at 1.5 m water depth is approximately 0.3 m2 when using a 0.15 m viewing tube. The information associated with each rake sample, can then be converted to a square meter area. The recorded GIS data will adhere to the following protocols: 1. GPS data associated with transects will be collected using a Global Positioning System (GPS) unit with differential correction using a satellite-based augmentation system (SBAS). Corrected GPS measurements will be within 1-meter (m) horizontal accuracy. 2. GPS data will be reported using NAD83 datum coordinates (decimal degrees, five significant figures), northing, easting, UTM Zone 11. Other information recorded will include sample date, time, water depth (m), aquatic plant species, relative aquatic plant density, and relative species abundance. 3. Observations will be collected from the 2.5-m, 3.5-m, and 4.5-m water depths along each transect. In addition, secchi disk depth will be recorded at the 4.5-m depth.

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4. GPS data will be post-processed and converted into a geographic information system (GIS) shapefile compatible with an ArcGIS 9.X Platform. All metadata shall compiled with FGDC standards. 5. Post-processed ASCII format file containing aquatic plant transect data, GIS compatible shapefile with metadata will be produced. This file will also include data on the length of each transect from the 1.5-m starting point to the 4.5-m ending point. 6. Raw survey notes recorded during survey shall be included in metadata file.

4.3.4 Aquatic Plant Biomass Sub-Sampling After the completion of Stage 1 and Stage 2 aquatic plant monitoring, aquatic plant total biomass samples will be collected at 24 randomly selected sampling points. The 24 total biomass sampling points will be randomly selected based upon the distribution of relative plant density categories (i.e., low, moderate, high, and saturated). For example, if 50 percent of the monitoring points were categorized as low relative plant density and the remaining 50 percent of the monitoring points were categorized as high relative plant density, then 12 total biomass samples would be randomly selected from the monitoring points labeled as low relative plant density and the other 12 samples from points labeled as high relative plant density. Total biomass samples will be collected using the quantitative rake sampling method. Both wet and dry mass measurements will be recorded. The purpose for collecting the total biomass data is to ensure the ability to estimate nutrient loads from aquatic plant senescence in the future. Stage 3 Management-Specific Monitoring. Stage 3 monitoring will employ a visual reconnaissance and, if needed, a point-intercept method, to better document the locations and surface area coverage of Eurasian Water Milfoil. The location and relative aquatic plant density information will then be used to make decisions regarding the location of treatment areas via the use of map polygons (See Section 5.0). The areal size of the polygon and average water depth within the polygon treatment area will provide the information needed for aquatic herbicide applications. If utilized, the objective of the point-intercept approach for aquatic plants is to generate point observation measurements at regularly spaced locations within a given area. For Big Bear Lake, the suggested spacing interval will be approximately every 20-m horizontally within the 5m-depth (18-feet) contour. These points can be found in the field using GPS and GIS equipment. Under Stage 3 monitoring, areas located for EWM eradication and control efforts will most likely be dominated by EWM. All GPS coordinates and geographic information system (GIS) shapefiles will be managed as already described.

4.3.5 Equipment Equipment required for the emergent and aquatic plant monitoring efforts include the following: . GPS Unit with software downloadable to GIS format; . Standard Rake Sampler (15-inches in length); . One View Tube; . Boat; and . Miscellaneous field supplies. Design of the quantitative rake sampler will follow Gibbons and Gibbons, 1985 or similar device.

4.3.6 Data Management For aquatic plant monitoring, all of the field information will be overlaid on the most recent bathymetric map for Big Bear Lake for mapping and analysis purposes. All data will be captured when taking the GPS

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coordinates. Data dictionaries will be created in the Trimble DGPS unit used for field locations. The data collected will be directly downloaded for use into the GIS after post-processing of the GPS coordinates. A map will then be produced that shows aquatic plant species and locations as well as aquatic plant relative density information. The selected contractor for aquatic plant monitoring activities will provide the monitoring results in both hard copy and electronic formats. All data will also be available in Microsoft® Excel spreadsheets. Ultimately, the Big Bear Lake Beneficial Use map and/or priority management/regulatory areas will also be overlaid on the aquatic plant maps to highlight areas in need of aquatic plant management action.

4.4 Aquatic Plant Numerical Index The SARWQCB staff have expressed an interest in development of a numerical index of aquatic plant communities. In an attempt to develop a tool to aid in future aquatic plant management decisions as well as track the relative environmental habitat value of aquatic plant communities, a preliminary Aquatic Plant Numerical Index (APNI) system was developed. This Aquatic Plant Numerical Index utilizes the data collected during aquatic plant monitoring under Stage 1 and Stage 2 efforts and translates that data to numerical values to allow an unbiased means of assessing the need for aquatic plant management activities in the lake. The index is based on presence or absence of native or non-native species, relative species composition, and relative density as described in the monitoring protocol given in the previous section. This subsection provides an example of how surveillance data provided by the BBMWD can be used by the SARWQCB and others to calculate APNI values. Although coverage area can also be incorporated into this type of aquatic plant index, for Big Bear Lake the potential littoral zone area is highly variable from location to location due to water level fluctuations from year to year (see TetraTech, 2004). A vertical variation of 17 feet below normal full pool elevation leads to littoral area instability within a given location and transitional plant community structure. Most importantly, the vertical instability of the water surface elevation makes year-to-year comparison based on area difficult. To overcome this variability in euphotic littoral area, two aquatic plant index numbers will be produced. One will use data collected following the Stage 1 littoral circumventing monitoring method and the other from the Stage 2 littoral transect monitoring method. Aquatic plant index based on Stage 1 data will characterize the shoreline community and an aquatic plant index based on Stage 2 data will characterize the shallow bays within the lake. This will allow relative assessment of aquatic plant community structure and environmental habitat status independent of area. The index number is calculated by assigning a number value to the collected field data at each observation station (Table 4-4). The series of numbers in Table 8 is totaled to produce the index number at that location or observation station. To calculate an average index number within a specific zone, the index number is added to every index number within the zone of interest and then divided by the number of observation locations used to generate an average index number for that zone. “Zones of interest” will be established using GIS systems and during the process of evaluating the utility of the Aquatic Plant Numerical Index. At this time, it is anticipated that “zones of interest” will be established within Boulder Bay, Metcalf Bay, Grout Bay, the eastern side of Eagle Point. “Zones of interest” will also be established along rectangular stretches adjacent to the Big Bear Lake shoreline.

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Table 4-4. Aquatic Plant Index Value Assignments Data Species Value Composition Value Density Value Species Plants 1 Present Plants 0 Absent 0 if absent, 1 if between 1 and 2 stems per rake sample, 2 if between 1 if present, 0 if 1 if present, Native 3-6 stems per rake sample, 3 if between 7-10 stems per rake sample, absent 0 if absent and 4 if more then 10 stems per rake sample. 0 if absent, and 1 if 5% or less, 0 if absent, 1 if between 1 and 2 stems per rake sample, 2 if between 0 if absent, 2 if 5-25%, 3 if 25-50%, and 4 if Non-Native 3-6 stems per rake sample, 3 if between 7-10 stems per rake sample, more than 50% of the plant 2 if present and 4 if more then 10 stems per rake sample community composition

Table 4-5 presents an example of the numerical index assignment and calculation based on Stage 1 or Stage 2 monitoring for a good habitat aquatic community and one that would be prioritized for management action.

Table 4-5. Examples of Aquatic Plant Index Calculation Balanced Aquatic Plant Community Data Species Value Composition Value Density Value Total Values Species Present 1 1 Absent 0 0 Native 1 1 1 3 Non-Native 0 0 0 0

Index Number 4

Aquatic Plant Community in need of

management action Data Species Value Composition Value Density Value Total Values Species Present 1 1 Absent 0 0 Native 1 1 1 3 Non-Native 2 4 4 9

Index Number 13

Using the Aquatic Plant Numerical Index approach, the threshold for aquatic plant management action is based on the presence and density of non-native species and the adverse impacts that native plants may have on recreational lake uses when plant densities become too dense. If utilized in the future, this preliminary Aquatic Plant Numerical Index will be modified to incorporate the Beneficial Use Map.

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Under the preliminary index system, the non-native plant presently of concern within Big Bear Lake is EWM. However in the future, management of other non-native and native aquatic plant species may be necessary depending on their locations and densities as well. For example, although not currently a problem in Big Bear Lake, the native Coontail may again attain nuisance status and require management activities. Table 4-6 provides an example of the preliminary Aquatic Plant Numerical Index relationship to potential aquatic plant management actions for a specific targeted zone. It is unlikely that the BBMWD would rely on this APNI to guide management actions. Rather, surveillance data would be provided to the SARWQCB, who could then calculate APNI values as one among several indicators of overall Lake health.

Table 4-6. Aquatic Plant Index Number versus Management Actions Index Number Management Action 0 Consider introduction of native aquatic plants 1-4 No action 5 Control action if index score due to non-native plants 6 Control action needed but low priority 7-9 Control action necessary 10-13 Immediate control with maximum intensity

Other means of assessing aquatic plant interference with the lake’s recreational uses will include: 1) keeping records of the number of people that require lake patrol assistance due to aquatic plants, 2) documenting complaints about lake navigability, and 3) documenting complaints from dock owners.

4.5 Aquatic Plant Control Strategies Eurasian watermilfoil is a submersed, rooted, perennial dicot that is submersed except for the upper flower- bearing portions. Native to Eurasia and North Africa, the history of the spread of this species in the United States is unclear due to its initial confusion with a phenotypically similar species, Northern milfoil (M. sibiricum). According to AERF (2005), this plant is now considered one of the worst aquatic weeds in North America. EWM is a highly aggressive invasive aquatic species. Its rapid growth rate enables this milfoil to cover water surfaces and form thick underwater stands. Such rapid growth displaces the native vegetation over a few years. EWM is tolerant of low water temperatures and can begin spring growth earlier than other aquatic plants. EWM spreads by the dispersal of plant fragments into water currents in lakes and reservoirs.

4.5.1 Eradication Treatment Technologies This nationally pervasive and potentially detrimental noxious aquatic weed has been intensively studied to identify effective control techniques (CDA, 2000; AERF, 2005). The treatment technologies currently utilized for EWM include the following:

Mechanical – Mechanical control of EWM has been identified as a short- to medium-term strategy deployed for small to moderate infestations. Mechanical controls established for EWM include: 1) Hand pulling, 2) Harvester, 3) Rototiller and 4) Cutter. The advantages of using harvesters are that it immediately opens up harvested areas and removes the upper canopy and shade-producing portion of the plants. However, a disadvantage of harvesting is that fragments of EWM are left in the water and these fragments contribute to the re-growth and re-spreading of the plant. Secondly, the literature shows that harvesting impacts fish and insect populations by removing them in the harvested plant material. Thirdly, cutting plant stems too close to the bottom of the lake results in re-suspension of sediments and nutrients. Finally, the operation of harvesters is a fairly expensive endeavor. The BBMWD utilized both harvesters and rototiller control methods for over

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20 years. Despite their long history of efforts using these methods, EWM continued to expand in the lake. Also, the BBMWD has verified the expenses associated with harvesting activities. Physical – Methods of physical control used for EWM include employment of: 1) Benthic Barriers, 2) Dredging, 3) Drawdown, and 4) Shading. The use of benthic barriers and/or shading is limited by both size, treating no more than 1.0 acre per site, and the absence of selectivity. Dredging is extremely expensive, while drawdown is counter to the BBMWD’s overall lake management mission.

Herbicide – According to the AERF (2005), the use of herbicides for the control of invasive and nuisance plant species represents one of the most widely used and effective management options available. Specifically, herbicide control of aquatic weeds is often the first step in a long-term integrated control program. Further, no herbicide product can be labeled for aquatic use if it has more than one in a million chance of causing significant harmful effects to human health, wildlife, or the environment (AERF, 2005). There are many herbicides available for the control of EWM. Since EWM is a dicot, it is amenable to selective control using herbicides that specifically target this group. Aquatic herbicides used in Big Bear Lake against EWM include various formulations of Sonar (active ingredient = Fluridone) and Renovate OTF (active ingredient = Triclopyr). These aquatic herbicides are classified as systemic herbicides. Systemic herbicides are translocated throughout the plant and are slower acting, but they often result in mortality of the entire plant. Sonar formulations can be selective for EWM alone, however, in order to achieve selectivity for EWM alone, herbicide application rates and plant responses must be examined on a site-specific basis. Fortunately, according to the Sonar manufacturer (SePro), EWM is one of the most sensitive aquatic plant species controlled by this product. Unlike Sonar formulations, Renovate OTF is selective for EWM alone, independent of the applied dosage. Other plant taxa found in Big Bear Lake are not adversely affected by treatment with this product.

4.5.2 Control Objectives for Non-native Aquatic Plants The main purpose of the Aquatic Plant Management Plan is the continued eradication of Eurasian Water Milfoil. BBMWD will rely on aquatic herbicides to achieve this objective. The aquatic herbicide used will most likely be a Sonar formulation or Renovate OTF. The BBMWD has the necessary National Pollutant Discharge Elimination System (NPDES) permits required for the application of each of these herbicides. EWM treatment areas will be established after the completion of aquatic plant monitoring activities. Treatment areas will be limited to those locations found to be almost exclusively dominated by EWM with high relative density values. If Sonar is used (but will most likely be Renovate OTF) this approach would minimize the impact of Sonar to sensitive native aquatic plant species (e.g., Common Elodea and Coontail). If Renovate OTF is used, sensitivity of native aquatic plant species should not be an issue, as Renovate OTF is selective for EWM only in Big Bear Lake. All aquatic herbicide applications will be performed in accordance with applicable individual or General NPDES permit specifications by or under the direct supervision of a State licensed applicator.

4.6 Adaptive Response on Plant Management Strategies Ultimately, aquatic plant control is needed for Big Bear Lake to: 1) protect recreational, aquatic life, and wildlife beneficial uses, 2) enhance aquatic habitat that has been degraded by shifts in native plant community structure and/or 3) reduce the density of aquatic plants that lead to water quality declines, such as lowering of dissolved oxygen, or physical densities that limit shelter and food gathering. In the future, the approach to controlling nuisance and noxious aquatic plants in Big Bear Lake will be influenced in part by the large littoral area of the lake and historical plant coverage. The large littoral zone area in need of management leads to the use of herbicides as the most cost effective methodology to manage the

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aquatic plants in the lake. However, the aquatic plant management approach will need to be refined so that when needed, control of EWM alone can be achieved and acceptable approaches for the control of native nuisance aquatic plant species may be developed. Because one goal of the Nutrient TMDL program is to limit EWM to less than 5 percent of the aquatic plant community in the lake, control of EWM will always be a high priority for managing recreational resources in the lake. This Big Bear Lake APMP will incorporate the use of a Beneficial Use Map previously developed by BBMWD. The schedule of NAPMP activities is shown in Table 4-7 below.

Table 4-7. Schedule Of Deliverables No. Description Due Date Responsible Agency Comprehensive Aquatic Vegetation Survey (including Every 5 years beginning in August, 2011. Results 1 voucher specimens, data collection, analysis and submitted with annual report beginning in TMDL Dischargers reporting and integrating results with 3D map) February, 2012 Pre-Treatment Reconnaissance-Level Survey 2 Annually in spring BBMWD (including GIS mapping) Aquatic Herbicide Applications (including required Annually in late spring and bi-weekly spot 3 BBMWD permits, product, personnel, and DPR reporting) treatment throughout the growing season. 4 TMDL Annual Data Reports Annually beginning in February, 2011 TMDL Dischargers 5 Mechanical Weed Harvesting As needed BBMWD

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BIG BEAR LAKE TMDL ACTION PLAN

5. MODEL UPDATE PLAN

This section presents an overview of efforts to update models used in the TMDL.

5.1 Background The TMDL relies heavily on two computer simulation models. One is used to estimate the phosphorus loading to Big Bear Lake in runoff from the surrounding watershed.1 The other model simulates in-lake processes to estimate how phosphorous loads contribute to water quality impairments such as: excess algae, noxious aquatic plants, low dissolved oxygen levels and poor water clarity.2 When the Regional Board sought public comment on the proposed TMDL, several local and state agencies questioned the validity of the watershed and lake models.3 Most of the criticism focused on the fact that the models did not adequately distinguish between natural background sources and man-made sources of phosphorus. In general, the Regional Board acknowledged this deficiency and offered stakeholders the opportunity to revise and update both models as part of the TMDL Implementation Plan. In addition, Tetra Tech, Inc. prepared a technical memorandum recommending more sophisticated models to replace the current computer simulation tools.4

5.2 Regulatory Requirements Task 6 of the TMDL Implementation Plan requires the U.S. Forest Service, the California Department of Transportation (Caltrans), the County of San Bernardino (County), the San Bernardino County Flood Control District (SBCFCD), the City of Big Bear Lake and Bear Mountain Ski Resorts to prepare and submit a Lake Management Plan.5 The purpose of the plan is to identify a coordinated and comprehensive strategy for meeting water quality standards in Big Bear Lake. One required element of the Lake Management Plan is a proposed plan and schedule for updating the watershed nutrient model and the in-lake nutrient model used to support the nutrient TMDL enacted for Big Bear Lake. In January 2010 the Regional Board renewed the Area-wide Urban Storm Water Runoff permit for San Bernardino County (MS4 Permit).6 The MS4 Permit requires the Big Bear Lake MS4 Permittees (the City of Big Bear Lake, the County, and the SBCFCD) to prepare a plan and schedule for updating the existing

1 Big Bear Municipal Water District (BBMWD), Hydmet, Inc., and AquAeTer, Inc. Nutrient budget study for Big Bear Lake using Hydrologic Simulation Program Fortran (HSPF) Model. June, 2003. 2 Tetra Tech, Inc. Final Big Bear Lake WASP model calibration report. June, 2004 3 http://www.waterboards.ca.gov/santaana/water_issues/programs/tmdl/docs/bigbear/03_06_attachment_d.pdf 4 Anderson, W. Tetra-Tech Inc. Memorandum: Big Bear Lake Watershed and Lake Model Plan. Sept. 7, 2007. 5 Attachment to Regional Board Resolution No. R8-2006-0023 (pg. 16 of 18) 6 Regional Board Order No. R8-2010-0036 (adopted 1/29/2010)

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Use of contents on this sheet is subject to the limitations specified at the end of this document. S01255.Revised Draft_Big Bear LakeTMDL Action Plan 8-26-2010.docx Section 5: Model Update Plan Big Bear Lake TMDL Action Plan

Big Bear Lake watershed nutrient model and the Big Bear Lake in-lake nutrient model.7 At a minimum, the plan and schedule must take into consideration additional data and information that are generated as part of the required TMDL monitoring programs previously approved by the Regional Board.8 In addition, the plan must describe how the watershed runoff model will be used to evaluate progress toward achieving the urban WLA for phosphorus during dry hydrological conditions. The MS4 Permittees must select a watershed model that best fits the conditions being modeled and document the basis for that selection including the data evaluation process, and the model calibration/validation process.9 Results from the revised model must be provided to the Regional Board by February 15, 2011. The plan and schedule to update both the watershed nutrient model and the in-lake nutrient model must be submitted to the Regional Board no later than March 31, 2010. This document is intended to fulfill that requirement.

5.3 Objectives and General Approach The nutrient TMDL for Big Bear Lake includes an urban wasteload allocation (WLA) of 475 pounds/year of total phosphorus during dry hydrological conditions. The Regional Board has determined that the MS4 Permittees are already meeting the approved WLA. Therefore this plan does not recommend revise the models used to support that finding.10 Instead, the Permittees propose to continue using the existing HSPF model to demonstrate continuing conformance with the urban WLA during dry hydrological conditions. However, it will be necessary to clarify exactly how the specific thresholds described in the TMDL will be applied (individually or collectively?) to determine whether a given year qualifies as "dry hydrological conditions."11 The staff report supporting adoption of the TMDL indicates that the vast majority of phosphorus loads to the water of Big Bear Lake are coming from sediments and macrophytes already in the lake.12 Consequently, the load allocation (LA) for dry hydrological conditions specifies a reduction in phosphorus from these internal nutrient sources.13 External load dischargers (such as the MS4 Permittees) are responsible for reducing their contributions to these internal nutrient loads.14 However, the extent of their contribution has not been determined. Current nutrient loads from the sediment during dry weather conditions are likely the cumulative product of external phosphorus loads transported to the lake in stormwater runoff and snow melt during moderate and

7 NPDES No. CAS 618036; Section V-D-4-f (pg. 55 of 125) 8 Regional Board Resolution No. R8-2008-0070 (In-lake Monitoring Plan) and Regional Board Resolution No. R9-2009- 0043 (Watershed-wide Nutrient Monitoring Plan) 9 NPDES No. CAS 618036; Section V-D-4-k (pg. 56 of 125) 10 NPDES No. CAS 618036; Section II-F-15-e (pg. 26 of 125) 11 Attachment to Regional Board Resolution No. R8-2006-0023; See Section 1.B.1 12 Boyd, Heather. California Regional Water Quality Control Board – Santa Ana Region. Staff Report on the Nutrient Total Maximum Daily Loads for Big Bear Lake. June 1, 2005 (draft). 13 Attachment to Regional Board Resolution No. R8-2006-0023; See Table 5-9a-e 14 NPDES No. CAS 618036; Section II-F-15-j (pg. 28 of 125)

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wet weather conditions. At the time the TMDL was adopted, there were insufficient watershed and in-lake nutrient data to support development of LAs and WLAs for average or wet hydrologic conditions.15 The Regional Board intends to establish TMDLs, WLAs and LAs for such conditions after collecting sufficient data.16 Until sufficient data become available, it may be necessary to estimate the relative responsibility for addressing internal nutrient load reductions. It may be possible to develop these estimates using the current models, but the models must be adjusted first.

5.4 Planned Updates for the HSPF Model Three significant modifications are planned for the HSPF model in 2010. First, the model will be recalibrated using additional precipitation, stream flow, lake level and water quality data collected since it was originally developed as the permit requires. San Bernardino County has also instituted an on-going program to update land use data for the Big Bear watershed on a regular basis and the HSPF model will be updated accordingly. Results from the updated HSPF model will be compared to similar estimates developed by the U.S. Army Corps of Engineers using different simulation tools to ascertain whether significant differences exist between the models and the cause of such disparities.17 Second, the HSPF model will be re-run after to simulate the conditions of reverting all existing land uses to pre-anthropogenic conditions. For this analysis, we will use the coefficients previously used to represent nutrient shedding, percolation and runoff from undeveloped forest land in the HSPF model. The results should accurately describe the natural background loads that would be discharged to the lake, under a wide variety of meteorological conditions, in the absence of any human development. MS4 Permittees are not responsible for naturally occurring pollutants or flows.18 Third, the HSPF model will be updated to account for various Best Management Practices (BMPs) that have been implemented as part of an effort to reduce external sediment and nutrient loads flowing into Big Bear Lake from the major tributary streams. Examples include the sediment trapping basins in Grout Creek and Rathbun Creek and the load reductions provided by long-term maintenance dredging activities in the lake. Finally, a post-processing subroutine will be added to the HSPF model to refine existing land uses by "ownership." Under the WLA all "Urban" loads are grouped together. But, responsibility varies by jurisdictional authority. Some urban areas are controlled by the City of Big Bear Lake, others by San Bernardino County and, within each of these jurisdictions, is the area managed by Caltrans under a separate discharge permit. For more effective management of the external loads, it would be useful to further subdivide the Urban loads into discrete component sources that better reflect the legal obligations described in the new MS4 Permit.

15 NPDES No. CAS 618036; Section II-F-14 (pg. 25 of 125) 16 Attachment to Regional Board Resolution No. R8-2006-0023; See Section 1.B.1 17 U.S. Army Corps of Engineers – Los Angeles Region. Hydrology Analysis of Major Tributaries to Big Bear Lake. 2007 18 NPDES No. CAS 618036; Section I-D (pg. 7 of 125)

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5.5 Planned Updates for the WASP Lake Model Two modifications are planned for the WASP lake model in 2010. First, the model will be updated to include a decay function reflecting the rate at which soluble reactive phosphorus mineralizes to an inert state. This calculation is essential to determine the legacy phosphorous loads from external sources that remain bioavailable in the lake at any given time. Dr. Michael Anderson at the University of California, Riverside, will be asked to provide a conservative decay function coefficient based on values published in peer-reviewed scientific literature and, where possible, using data from sediment core samples previously collected from Big Bear Lake. Second, the model will be revised to account for the effects of the water quality remediation efforts in Big Bear Lake that serve to reduce internal nutrient loads to some degree. Examples include: the west-end aeration system, carp reduction projects, and aquatic weed control programs Quantifying the effectiveness of such efforts should increase the incentive to implement these and other mitigation strategies designed to improve water quality. Dr. Anderson will also estimate the phosphorus load reduction potential of these efforts using techniques similar to those he developed for similar calculations in Lake Elsinore.19 The updated model will be used to quantify the effectiveness of current and planned BMPs in and around Big Bear Lake. The updated model is expected to provide a basis for establishing the accounting system needed to support a pollutant trading program to address average and wet weather load reductions.

5.6 Tetra-Tech's Recommended Changes to the TMDL Models Tetra-Tech recommended replacing the existing HSPF model with the LSPC (Loading Simulation Program in C++) model. Tetra-Tech also recommended replacing the existing WASP model with the CE-QUAL-W2 model. The rationale supporting these recommendations is provided in Tetra-Tech's technical memorandum dated September 7, 2007 (attached as an appendix to this document). Insofar as the MS4 permittees are already meeting the urban wasteload allocation for dry hydrological conditions, there is no practical benefit to installing new models for the nutrient TMDL currently in force. However, it may be useful to do so before devoting any serious effort toward developing a nutrient TMDL for average and wet hydrological conditions. In the near-term (2010-2015) all available resources are being earmarked to meet existing TMDL obligations, including: implement the two water quality monitoring programs and executing the in-lake sediment nutrient reduction plan. Historically, the cost of model development, calibration and validation has been borne directly by the Regional Board as part of their effort to prepare and approve a TMDL. Given the significant financial commitment required to implement the monitoring programs and lake management plan, the MS4 Permittees lack sufficient funding to assume the state's traditional responsibility for developing TMDL models. By deferring the decision whether to develop new models, the MS4 Permittees are not conceding the question of whether the existing models are adequate for the next phase of TMDL development. At present, there is insufficient data to make that determination. In addition, it is uncertain whether creating a more sophisticated model would measurably improve the stakeholders' ability to develop and implement the BMPs needed to improve water quality in Big Bear Lake. As with the ongoing monitoring programs and the forthcoming in-lake sediment nutrient reduction plan, the TMDL Task Force will implement an adaptive management strategy when deciding whether to update the

19 Anderson, M.A. Predicted Effects of Restoration Efforts on Water Quality in Lake Elsinore: Model Development and Results. March, 2006.

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computer simulation models. Therefore, the MS4 Permittees propose to continue using the HSPF and WASP models, after making the adjustments described earlier, until the working relationship between these models and the nutrient management strategy for Big Bear Lake is more thoroughly understood. The Task Force will continue to work with Regional Board staff if they elect to develop new lake or watershed runoff models representing the average and wet hydrological conditions.

5.7 Schedule for Updating Existing TMDL Models Table 5-1 describes the specific tasks and deliverables that will be accomplished during the next 12 months.

Table 5-1. Model Update Tasks for 2010 Task Description Date 1 Transmit new data to Tetra-Tech June, 2010 2 Recalibrate HSPF model to new data Sep., 2010 3 Recalibrate WASP model to new data Nov., 2010 4 Estimate natural background loading Dec., 2010 5 Report results of new model runs Feb., 2011 6 Estimate range of Chlorophyll-a likely to result from natural background loads Mar., 2011 7 Estimate phosphorus decay coefficient June, 2011 8 Add phosphorus decay coefficient to WASP Aug., 2011 9 Develop post-processing land use tool Sep., 2011 10 Calculate net legacy loads to sediments from discrete urban sources Oct., 2011 11 Develop spreadsheet for net load accounting Dec., 2011 12 Report results of new model runs Feb., 2012 13 Model update plan for 2012-13 (if needed) Mar., 2012

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6. LIMITATIONS

Report Limitations This document was prepared solely for the Big Bear Lake Nutrient TMDL Task Force in accordance with professional standards at the time the services were performed and in accordance with the contract between SAWPA (who administers contacts on behalf of the Task Force) and Brown and Caldwell, dated February 17, 2010. This document is governed by the specific scope of work authorized by the Task Force; it is not intended to be relied upon by any other party except for regulatory authorities contemplated by the scope of work. We have relied on information or instructions provided by the Task Force and other parties and, unless otherwise expressly indicated, have made no independent investigation as to the validity, completeness or accuracy of such information. Further, Brown and Caldwell makes no warranties, express or implied, with respect to this document, except for those, if any, contained in the agreement pursuant to which the document was prepared. All data, drawings, documents, or information contained in this report have been prepared exclusively for the person or entity to whom it was addressed and may not be relied upon by any other person or entity without the prior written consent of Brown and Caldwell unless otherwise provided by the Agreement pursuant to which these services were provided.

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