FINAL Commonwealth of the Northern Mariana Islands Integrated 305(b) and 303(d) Water Quality Assessment Report Chalan Piao Beach, Saipan Division of Environmental Quality August 2012 Authors: Clarissa T. Bearden, Derek Chambers, Ryan Okano Maps by Yubert Alepuyo & Ken Cochrane <This page left intentionally blank> FINAL Commonwealth of the Northern Mariana Islands Integrated 305(b) and 303(d) Water Quality Assessment Report Division of Environmental Quality August, 2012 Authors: Clarissa T. Bearden, Derek Chambers, Ryan Okano Maps by Yubert Alepuyo & Ken Cochrane <This page left intentionally blank> Table of Contents ACKNOWLEDGEMENTS............................................................................................................ 1 A. EXECUTIVE SUMMARY .................................................................................................... 3 B. BACKGROUND .................................................................................................................... 5 B.1. Scope of Waters in the Integrated Report ........................................................................ 5 B.2. Water Pollution Control Program .................................................................................. 10 B.2.1. DEQ Wastewater and Erosion Control Program .................................................... 10 B.2.2. DEQ Nonpoint Source Pollution Control Program ................................................ 11 B3. Special State Concerns and Recommendations ............................................................. 12 C. SURFACE WATER MONITORING AND ASSESSMENT .............................................. 13 C1. Monitoring Program....................................................................................................... 13 C1.1 Surface Water Quality Monitoring Programs........................................................ 13 C1.2 Biological Monitoring Program............................................................................. 14 C1.3 Other Data Used..................................................................................................... 16 C2. Assessment Methodology .............................................................................................. 19 C2.1 Designated Uses and CNMI Water Quality Standards .......................................... 19 C2.2 Water Body Segmentation - Watershed Approach................................................ 22 C2.3 USEPA’s CALM Assessment Categories ............................................................. 22 C2.4 Assessment Criteria – Coastal Waters .................................................................... 25 C2.5 Assessment Criteria – Fresh Surface waters (Streams and Lakes/Ponds) .............. 27 C3. Assessment Results ........................................................................................................ 29 C3.1 TMDL Development Status................................................................................... 29 C3.2 Removal of Waters from the 303(d) List............................................................... 30 C3.3 Coastal Water Quality............................................................................................ 32 C3.4 Rivers/Streams Water Quality ............................................................................... 37 C3.5 Lake/pond Water Quality....................................................................................... 37 C4. Wetlands Program.......................................................................................................... 38 C5. Public Health Issues ....................................................................................................... 41 C5.1 Beach Water Quality Issues................................................................................... 41 C5.2 Public Water Supply/Drinking Water Use Reporting............................................ 42 D. GROUND WATER MONITORING AND ASSESSMENT ............................................... 44 D.1 Overview of Ground Water Contamination Sources ..................................................... 44 D.2 Overview of State Ground Water Protection Programs................................................. 46 D.2.1 Well Drilling and Well Operation Regulations ...................................................... 46 D.2.2 Wastewater Disposal Regulations........................................................................... 47 D.2.3 Underground Storage Tank Regulations................................................................. 47 D.2.4 Underground Injection Control Regulations........................................................... 47 D.2.5 Safe Drinking Water Regulations ........................................................................... 47 D.2.6 Other Monitoring Events/Programs........................................................................ 48 D.3 Summary of Ground Water Contamination Sources (all CNMI) .................................. 49 D.4 Summary of Ground Water Quality............................................................................... 51 D.5 Summary of Ground Water-Surface Water Interactions................................................ 54 E. PUBLIC PARTICIPATION ................................................................................................. 55 F. REFERENCES ..................................................................................................................... 57 I. APPENDIX I: Water Body Information for Commonwealth of the Northern Marianas Islands ........................................................................................................................................... 61 II. APPENDIX II: Detailed 305b Listing of CNMI Waters..................................................... 72 II.1. COASTAL WATERS.................................................................................................... 74 II.2. LAKES AND PONDS ................................................................................................... 82 II.3. WETLANDS.................................................................................................................. 83 II.3. STREAMS ..................................................................................................................... 85 III. APPENDIX III: TMDL Priority Listing (303(d) List) ..................................................... 86 IV. APPENDIX IV: Selected Monitoring Data Used in 2012 Listing Determinations, by Water Segment.............................................................................................................................. 91 IV.1. Microbiological Data...................................................................................................... 91 *Note: Only one of the 11 monitoring locations from Segment 23 had over 10% exceedance rate however, there is such a strong historical record of attainment for both enterococci and biocriteria that it was not placed on the impaired list. IV.2. Dissolved Oxygen Data 96 IV.2. Dissolved Oxygen Data.................................................................................................. 97 IV.3. Biocriteria monitoring Results ..................................................................................... 102 IV.4. Lake Susupe monitoring data (Segment ID: 18LAK; Susupe) ................................... 106 Tables Table B-1. Atlas Description of the Commonwealth of the Northern Mariana Islands ................ 6 Table B-2. Class A Marine Waters in CNMI ................................................................................ 7 Table C-1. Designated Use terminology as used in this report.................................................... 20 Table C-2. Selected CNMI Water Quality Criteria................................................................ 21 Table C-3. EPA "CALM" Reporting Categories......................................................................... 22 Table C-4. Assessment Criteria for Coastal Waters .................................................................... 27 Table C-5. Assessment Criteria for Fresh Surface Waters .......................................................... 28 Table C-6. Size of Surface Waters Assigned to Reporting Categories, 2012 Assessment Results ....................................................................................................................................................... 29 Table C-7. Segment/Pollutant Combinations Removed from CNMI's Previous Section 303(d) List ................................................................................................................................................ 32 Table C-8. Ocean coasts - Designated Use Support Summary.................................................... 33 Table C-9. Size of Ocean Coast Waters Impaired by Causes...................................................... 33 Table C-10. Size of Coastal Waters Impaired by Sources........................................................... 33 Table C-11. Rivers/streams Designated Use Support Summary........................................... 37 Table C-12. Lake/pond Designated Use Support Summary........................................................ 38 Table C-13. Freshwater Wetland Designated Use Support Summary......................................... 39 Table C-14. Assessment Methodology for Wetlands, using HGM Functions ............................ 40 Table C-15. 303(d) Listing for