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Natural Resources Division

Manager: Dan Berentson
BIG LAKE DRAINAGE MANAGEMENT PLAN
The Big Lake Drainage Management Plan has been prepared to address stormwater management planning including facilities inventory, problems assessment, solutions development, capital improvements, and stormwater program needs within a 1.9 square mile study area surrounding and local to Big Lake, a developing urban fringe area near Mt Vernon, Skagit County, Washington. The location and extent of the study area and the Big Lake watershed are shown on Figure 1-1 (Chapter 1). This Executive Summary provides a brief synopsis of key findings of the plan. Details of the plan and its recommendations, methods of assessment, database, supporting analysis, assumptions, and results are documented in the various report chapters and appendices.

TABLE OF CONTENTS

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List of Figures

List of Tables (Located within the Management Plan)
  • Table ES-1 Recommended CIP Drainage Improvements and Estimated Implementation Costs
  • Table ES-2 NPDES Phase II Program Elements and Estimated Annual Costs
  • Table 2-1 Summary of Federal, State, and Skagit County Programs, Policies, Regulations, and Standards and Application to Big Lake DMP
  • Table 3-1 Hydrologic Soil Group Classifications and Soil Characteristics
  • Table 4-1 Drainage Facilities Surveyed Inventory Summary
  • Table 5-1 Drainage Complaint Records and Observed Problem Source
  • Table 5-2 Culverts Obstructed by Sediment or Debris
  • Table 5-3 Culverts Obstructed by Damage
  • Table 6-1a Watershed Land Use Summary Tributary to Big Lake Outlet (Expressed as Total Acreage in Watershed)
  • Table 6-1b Watershed Land Use Summary Tributary to Big Lake Outlet (Expressed as Percentage of Total)
  • Table 6-2a Stage, Storage, and Discharge Relationships for Big Lake
  • Table 6-2b Stage, Storage, and Discharge Relationships for Lake McMurray
  • Table 6-3a Big Lake Watershed Peak Flood Flows and Water Surface Elevation Magnitude-Frequency, Existing Land Use
  • Table 6-3b Big Lake Watershed Peak Flood Flows and Water Surface Elevation Magnitude-Frequency, Future Land Use
  • Table 6-4a Big Lake Water Surface Elevation Duration Statistics, Existing Land Use
  • Table 6-4b Big Lake Water Surface Elevation Duration Statistics, Future Land Use
  • Table 6-5 Local Subbasins Runoff Parameters, Existing and Future Land Use
  • Table 6-6 Subbasin Precipitation for Selected Storm Events HEC-HMS Model Calibration/Validation
  • Table 6-7 Subbasin Estimated Peak Discharges for Selected Design Storm Events, Existing and Future Land Use Conditions
  • Table 6-8 Characteristics and Unobstructed Hydraulic Capacities of Perimeter Road and other Major Culverts with 25-Year Peak Flows Comparison
  • Table 7-1 NPDES Phase II Required Program Components and Required Schedule for Implementation
  • Table 7-2 Public Education/Outreach Program Needs Summary
  • Table 7-3 Potentially Illicit Connections
  • Table 7-4 Illicit Discharge Detection and Elimination Needs Summary
  • Table 7-5 SWMP Compliance Assessment and Cost Tracking Needs Summary
  • Table 8-1 Recommended CIP Drainage Improvements and Estimated Implementation Costs
  • Table 8-2 Recommended Study Area NPDES Phase II Components and Estimated Annual Program Costs
  • Table 8-3 Suggested Priorities for Recommended CIP Projects Implementation

Appendices