Massachusetts Estuaries Project Estuarine Restoration and Management
Nitrogen Loading & Management Thresholds: Menemsha Pond - Squibnocket Pond Estuarine System
MEP Technical Team: B.L. Howes, R.I. Samimy, D.R. Schlezinger, E.M. Eichner, T. Ruthven, S. Kelly, J. S. Ramsey
Towns of Chilmark and Aquinnah Wampanoag Tribe of Gay Head Town Workshop August 23, 2018 Massachusetts Estuaries Project Natural Resource Restoration/Management • A partnership between – DEP/EOEA (regulatory, TMDL’s) – SMAST/UMassD (science, assessment & modeling) – with S.E. Mass. Municipalities, Barnstable County, Regional Planning Agencies (Cape Cod Commission, MVC, SRPEDD), USGS, EPA, DMF • Purpose: to develop nitrogen thresholds and target loads to support management planning FOCUS: Major Problems Facing Embayments Throughout SE Mass
• The primary threat to South Coast and Cape Cod Estuaries:
increased nutrient loading from watersheds to estuaries, resulting in wholesale decline in habitat health.
Estuaries - Status
•A loss of >65% of seagrass habitat world-wide and >50% in s.e. Mass. •In s.e. Massachusetts, >50% of benthic animal habitat is impaired-degraded. •Almost all estuaries in s.e. Mass have some impairment. Embayment Nutrient Related Health:
Degradation of Estuaries and Bays by nutrient enrichment is primarily through Nitrogen from surrounding watersheds.
Over-Fertilization results in declining health: Phytoplankton Blooms and turbid waters Loss of eelgrass beds Decline in benthic animal populations, fish & shellfish Low Oxygen in bay waters, fish kills, possibly odors Macro-algal accumulations At highest levels loss of aesthetics
5 What is needed to restore our estuaries?
Nitrogen management is the only way to restore degraded estuarine habitat and to prevent future habitat degradation.
Nitrogen management must focus primarily on control of watershed nitrogen inputs and maximizing tidal flushing. Massachusetts Estuaries Project Estuaries Status Complete
Planned
Underway Future 89 Estuaries__ 81 Embayments 8 Salt Marshes
70 Nitrogen-done 9 Bacterial-done Field Data >95%
7 Linked Watershed-Embayment Management Modeling Approach used for MEP Key Aspects:
Site-specific Data-driven Approach with numerous validation steps Not a “push button model” but an “Approach” consisting of a series of models linked by scientists, conducting necessary reality checks and sub-routines; Watershed N Loading Module distributed to Municipalities & their consultants at no cost Future access for use in watershed planning through SMAST Municipal Service Center. Linked Watershed-Embayment Approach
Stream Flow - N Load Watershed Delineation Model Tide Elevation Bathymetry Recycled N Currents Watercolumn N Watershed N Loading Model
Hydrodynamic Total Nitrogen Model Model
D.O., Eelgrass Infauna Surveys
Thresholds Development (N Target)
Linked Watershed-Embayment Approach
Stream Flow - N Load Watershed Delineation Model Tide Elevation Bathymetry Recycled N Currents Watercolumn N Watershed N Loading Model
Hydrodynamic Total Nitrogen Model Model
D.O., Eelgrass MassDEP Infauna Surveys TMDL
Thresholds Development MassDEP (N Target) CWMP 10 Massachusetts Estuaries Project Estuaries
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? ? ? ? To Be Determined MEP Threshold Completed Towns of Chilmark, Aquinnah, and Wampanoag Tribe of Gay Head MENEMSHA POND – SQUIBNOCKET POND EMBAYMENT SYSTEM
Nutrient Related Water Quality Monitoring: Collaborative Effort b/w MVC + SMAST + MassDEP 604b Program 2000-2012(for modeling) Setting N Loading Targets for Management
MENEMSHA POND – SQUIBNOCKET POND N-THRESHOLD DEVELOPMENT Watershed N Loading to Estuary
Watershed N Load to Bay = N Sources - N Sinks + N Storage
-- Sources: wastewater, fertilizers, agriculture, impermeable surfaces, natural surfaces, atmosphere, etc. -- Sinks: denitrification within wetlands, aquifer transport, surface water ecosystems, well withdrawals -- Storage: sorption, aquifer transport, biomass accumulation, etc. Menemsha Pond – Squibnocket Pond Embayment System: Watershed Delineation
Sub-watershed delineations (87) for the MEP Watershed Land-use Analysis
Total Watershed Load: Menemsha - 77% Squibnocket - 33%
Parcel by parcel analysis Menemsha Pond Land Use Loads 0% 6% 3% 0% Atmos Deposit to Estuary 12% 47% 7%
40%40% 81%81%
4%
Overall Load Locally Controllable Load Wastewater Agricultural Water Body Animals Surface Area
Turf Fertilizers Impervious "Natural" Surfaces Surfaces
Squibnocket Pond Land Use Loads
Atmos Deposit to Estuary 1% 73% 14% 7%
78%78%
3% 17% 17% 5%
0% 2% OverallLoad Overall Load Locally Controllable Load
Wastewater Landfill Water Body Surface Area Turf Fertilizers Impervious "Natural" Surfaces Surfaces
Watershed Future Potential Development
Increased TN Load at Build-Out under Current Zoning: Menemsha – 18% Squibnocket – 28% MEP STREAM GAUGING PROGRAM: 3 Major Surfacewater Inflows (2006-2007)
Verification of Watershed Delineation
Measured flows are within 4-6 % of calculated flows based on watershed delineation MEP Hydrodynamic Analysis Bathymetric Survey, Tide Gauges, (exchange and circulation) Model Gridding, Modeling MEP Hydrodynamic Analysis:
Tidal Range (pump) Offshore & Pond
MP1 = V. Sound MP5 = Squibnocket MEP Hydrodynamic Analysis: Model Validation: Tidal Flow Thru Inlet of Menemsha Creek Menemsha Pond – Squibnocket Pond Water Quality Model Valication Modeled versus Measured (Salinity)
RMS error = 1.1 ppt
Model Calibrated with site-specific data, then Independently Validated Menemsha Pond – Squibnocket Pond Water Quality Model Validation Modeled versus Measured (Total Nitrogen)
R2 = 0.98 RMS error = 0.03 mg/L
Model Calibrated with site-specific data, then Independently Validated MEP Watershed- Embayment Nitrogen Model Menemsha- Squibnocket Ponds Present Conditions Variation in TN Gradient through INSERT AVI a Tidal Cycle Total Nitrogen (mg/L) Gradient Calibrated-Validated Linked Model
Present Buildout Embayment-Specific Critical Nitrogen Loading Thresholds
Primary Components: 1) Dissolved Oxygen Record (summer, bottom water) 2) Eelgrass & Macroalgae (distribution & abundance) 3) Benthic Animal Communities (habitat quality) 4) Water Quality Long-term Records MEP Oxygen & Chlorophyll-a Autonomous Recorders Summer 2007 and 2012
Minimum 30 day Continuous Time-series Record Menemsha Pond Dissolved Oxygen (bottom water)
Stress to Infaunal Animals Menemsha Inner (west basin)
Stonewall Pond
Stress to Infaunal Animals Menemsha Pond Chlorophyll-a (bottom water)
Menemsha Inner >10 ug/L indication of habitat impairment
Stonewall Pond
>10 ug/L indication of habitat impairment Squibnocket Pond Dissolved Oxygen (bottom water)
Squibnocket (west basin) Stress to Infaunal Animals
Squibnocket (south basin)
Stress to Infaunal Animals Squibnocket Pond Chlorophyll-a (bottom water)
>10 ug/L indication of habitat impairment Squibnocket (west basin)
>10 ug/L indication of habitat impairment
Squibnocket (south basin) Historic Eelgrass Distribution SMAST/MEP 2007 - field verified Menemsha Pond Eelgrass Loss 1951-2006 = 25% MEP Habitat Assessment: Benthic Animal Communities
29 Total Locations Sampled November 2007 11 locations in Squibnocket Pond MEP: Assessment of Benthic Habitat Health
Total Total Species Weiner Sub- Station Actual Actual Calculated Diversity Evenness Embayment ID Species Individuals @75 Indiv. (H') (E) Menemsha Pond
Menemsha Creek MEN 1,5,21 25 1566 15 3.35 0.73 Menemsha Main Basin MEN 7,9,10,18,19,22-24 20 609 15 3.12 0.73 Nashaquitsa Pond MEN 14,15,16 17 871 11 2.56 0.63 Stonewall Pond MEN 12, 13 14 1444 9 2.19 0.57 Squibnocket Pond
Squibnocket Main Basin SQB 1-8,10,13,15,16 9 430 6 1.72 0.55
Highest habitat quality diversity is >3 and evenness (~0.7). Lowest habitat quality diversity is <1 and evenness (<0.5). Massachusetts Estuaries Project:
Assessment of Habitat Health
Menemsha-Squibnocket Embayment System
Menemsha Menemsha Nashaquitsa Stonewall Squibnocket Health Indicator Channel Main Basin Pond Pond Pond Dissolved Oxygen H1 HI1 HI1 MI2 MI/SI3 Chlorophyll H4 H/MI5 MI6 MI/SI7 H/MI5 Macroalgae H8 H/MI9 H8 H8 H/MI10 Eelgrass H11 H/M11 SI12 SI12 --13 Infaunal Animals H14 H15 MI16 MI16 MI17 Overall: H18 H/MI19 MI/SI20 SI21 MI22
Primary metric in:
Menemsha Pond = eelgrass
Squibnocket Pond = benthic animals
Status: High to Moderate Quality Habitat
Threshold Concentration:
Sentinel Stations (average MEN-4,5,8,9,10) TN = 0.350 mg/L (eelgrass)
(average SQB-1,2,3,4) TN = 0.500 mg/L (infauna) Present TN Concentration:
(average MEN-4,5,8,9,10) TN = 0.355 mg/L
(average SQB-1,2,3,4) TN = 0.789 mg/L
Protection Goals: Restoration of Eelgrass and Infauna Habitat Linked Watershed-Embayment Approach Implementation Planning . Monitoring Stream Flow - N Watershed Delineation Model Tide Elevation Load Updates . Bathymetry Currents Recycled N (20-30 yr phased process) Watercolumn N Watershed N Loading Model
N Hydrodynamic Total Nitrogen Model Model Management Scenarios D.O., Eelgrass Infauna Monitoring
Surveys MassDEP Thresholds and Model Development TMDL Updates (N Target) & CWMP Revised Targets & Implementation Plans
Nitrogen Management Options for Estuaries Generally via CWMP and TMDL Processes:
Hydrodynamic options • Tidal flushing/circulation enhancement & management Natural attenuation options • Nitrogen source location to maximize natural attenuation • Wetland/riparian zone restoration to increase attenuation • Pond restoration to create zones of natural attenuation Nitrogen source reductions • Fertilizer education Wastewater options (what, where, how much) • Centralized and decentralized systems Restoration Approach Based on MEP Modeling
Menemsha Main Basin + Nashaquitsa Pond
• < 20 percent load reduction to achieve threshold Squibnocket Pond
• Threshold NOT achievable through load reduction
• Must increase exchange significantly, increase tidal prism 20-25 times
42 How long does this take?
• Recovery of estuarine systems is relatively rapid. Significant recovery of animal populations and habitat and water quality within 3-5 years.
• Implementation is a local and municipally driven effort, which requires significant funding. Time-line? Massachusetts Estuaries Project for Estuarine Restoration
Questions & Discussion
SMAST SMAST Sheri Caseau Brian Howes Ed Eichner John Ramsey Christine Seidel Roland Samimy Sara Sampieri Sean Kelley William Wilcox David Schlezinger Jen Benson Trey Ruthven David White Mike Bartlett Liz Hunt
Dale Toner Interns TNC