Supporting research and documents for evaluating the large scale alternatives are available on the Tidal Wetland Project web page:

Transcription

1 Supporting research and documents for evaluating the large scale alternatives are available on the Tidal Wetland Project web page: Hydrology, Habitats and Water Quality Largay, B. L., K. Johnson, Philip Williams and Associates and E. McCarthy, Management of Tidal Scour and Wetland Conversion in Elkhorn Slough: Partial Synthesis of Technical Reports on Large-Scale Alternatives: Hydrology, Geomorphology, Habitats and Engineering, Water Quality. June Key Species Griffith, Katie A Pickleweed: factors that control distribution and abundance in Pacific Coast estuaries and a case study of Elkhorn Slough, California. Elkhorn Slough Technical Report Series. McCarthy, Erin Sea otters: factors that control distribution and abundance in Pacific Coast estuaries and a case study of Elkhorn Slough, California. Elkhorn Slough Technical Report Series. McCarthy, Erin Harbor seals: factors that control distribution and abundance in Pacific Coast estuaries and a case study of Elkhorn Slough, California. Elkhorn Slough Technical Report Series. Nelson, P. A., Kramer, S., Brown, J Selected Flatfish: factors that control distribution and abundance in Pacific Coast estuaries and a case study of Elkhorn Slough, California. Elkhorn Slough Technical Report Series. Palacios, Sherry Eelgrass: factors that control distribution and abundance in Pacific Coast estuaries and a case study of Elkhorn Slough, California. Elkhorn Slough Technical Report Series. Ruegg, Kristen Selected shorebirds: factors that control distribution and abundance in Pacific Coast estuaries and a case study of Elkhorn Slough, California. Elkhorn Slough Technical Report Series., Kerstin Olympia oyster: factors that control distribution and abundance in Pacific Coast estuaries and a case study of Elkhorn Slough, California. Elkhorn Slough Technical Report Series., Kerstin Selected large benthic infaunal invertebrates: factors that control distribution and abundance in Pacific Coast estuaries and a case study of Elkhorn Slough, California. Elkhorn Slough Technical Report Series.

2 Policy and Economics Kildow, J. and L. Pendleton Elkhorn Slough Restoration Policy and Economics Report. Reports on sedimentation and geomorphology: Geomorphology Working Group, Statement of agreement on the Future Extent of Depositional Intertidal Habitats. Burke Watson, Elizabeth. Summary of findings from the deployment of sediment tiles at Elkhorn Slough. Burke Watson, Elizabeth. Summary of Moro Cojo Slough historic habitats. Burke Watson, Elizabeth. Dating recent sedimentation rates in healthy marsh at Elkhorn Slough using Pb-210 and Cs-137 dating methods. Spear, B., Smith, D., Van Dyke, E., & Vaage, L. (2010) Twenty-nine years of geomorphic change at Elkhorn Slough, California. Prepared for Elkhorn Slough National Estuarine Research Reserve. The Watershed Institute, California State University Monterey Bay, Publication No. WI , 54 pp.

3 Hydrology Outcomes Summary of data from Philip Williams and Associates et. al tidal range (compared to existing conditions) 125% 100% 75% 50% 25% Year 10 0% 1943 No Action New Inlet Low Sill High Sill Parsons Low Sill, Parsons peak velocity (compared to existing conditions) 125% 100% 75% 50% 25% 0% 1943 No Action New Inlet Low Sill High Sill Parsons Low Sill, Parsons Year % 100% 75% 50% 25% tidal prism (compared to existing conditions) 0% 1943 No Action New Inlet Low Sill High Sill Parsons Low Sill, Parsons ratio of tidal volume to tidal prism, related to residence time (units of days) No Action New Inlet Low Sill High Sill Parsons Low Sill, Parsons

4 Habitat distributions Summary of data from Philip Williams and Associates et. al Habitats deep subtidal 600 shallow subtidal 400 intertidal mudflat 200 salt marsh 0 Existing No Action New Inlet Low Sill High Sill Parsons Year 10 Habitats deep subtidal 600 shallow subtidal 400 intertidal mudflat 200 salt marsh 0 Existing No Action New Inlet Low Sill High Sill Parsons Habitats deep subtidal 600 shallow subtidal 400 intertidal mudflat 200 salt marsh 0 Existing No Action New Inlet Low Sill High Sill Parsons

5 Extent of various habitats Summary of data from Philip Williams and Associates et. al tidal marsh (acres) Year No Action New Inlet Low Sill High Sill Parsons intertidal mudflat (acres) Year No Action New Inlet Low Sill High Sill Parsons 1500 shallow subtidal habitat (acres) Year No Action New Inlet Low Sill High Sill Parsons 1500 deep subtidal habitat (acres) Year No Action New Inlet Low Sill High Sill Parsons

6 Habitat Outcomes continued Summary of data from Philip Williams and Associates et. al % tidal marsh habitat: compared to No Action at same interval 100% 75% 50% Year 10 25% 0% No Action New Inlet Low Sill High Sill Parsons 0% -25% -50% -75% -100% -125% intertidal mudflat habitat: compared to No Action at same interval No Action New Inlet Low Sill High Sill Parsons Year 10 Geomorphology Outcomes Summary of data from Philip Williams and Associates et. al tidal scour (cubic meters per year) 125, ,000 75,000 50,000 25,000 0 No Action New Inlet Low Sill High Sill Parsons Low Sill, Parsons to Year 10 Year 10 to

7 Geomorphology Outcomes Summary of data from Philip Williams and Associates et. al The relative magnitude of components of the sediment budget described by PWA: The sediment required to sustain tidal marsh, the very large accommodation space for sediment that resulted from past tidal scour and subsidence, and the effect of Large Scale Alternatives on the sediment budget of the estuary. Reduction in tidal scour relative to No Action over 50 years (blue) Sediment required to sustain the relative elevation of existing habitats over 50 years (white) Tidal scour since 1947 and subsidence in Parsons Slough (black) 6,000,000 5,000,000 cubic meters 4,000,000 3,000,000 2,000,000 1,000,000 0 Sustain habitats: sea level +3 mm/y Sustain habitats: sea level +7 mm/y Past main channel scour Parsons subsidence No Action New Inlet (sediment retained) Low Sill (sediment retained) High Sill (sediment retained) Parsons (sediment retained) Summary of Alternatives Objective No mouth action RANKING OF ALTERNATIVES Parsons Low Sill High Sill Mouth Reroute reduce tidal scour preserve salt marsh

8 SUMMARY OF BIOLOGICAL CHARACTERIZATIONS AND RANKING OF ALTERNATIVES SPECIES or GROUP Eelgrass IMPORTANCE increases fish and invertebrate biodiversity, traps sediment HISTORICAL TRENDS Since preeuropean Last 50 years times ABUNDANCE IN Lower estuary Upper estuary No mouth action RANKING OF ALTERNATIVES Parsons Low Sill High Sill Mouth Re-route decrease? increase XX Pickleweed traps sediment; supports food webs through detritus; may improve water quality similar decrease XXX XX Olympia oyster harvested by humans; increases fish and invert diversity; may increase water quality decrease?? X XX Fat innkeeper, ghost shrimp, gaper, butter harvested by humans,?? XXX X and littleneck clam eaten by sharks, rays, flatfish Jackknife clam?? X XXX Flatfish harvested commercially and recreationally; affect estuarine food webs?? XXX XX Willet, Long-billed Curlew, Marbled increase? stable? XXX XX popular with birdwatchers; Godwit affect estuarine food webs Least Sandpiper increase? decrease? XX XXX Harbor seal popular with recreational? increase XXX XX visitors; affect estuarine Sea otter food webs? increase XXX XX

9 CONCERNS RAISED FOR DIFFERENT SPECIES WITH LARGE-SCALE MANAGEMENT ALTERNATIVES NO MOUTH ACTION DECREASED MOUTH SIZE decrease in sediment depth in subtidal channel increased extent of habitat with strong marine influence (sandy sediments, strong currents) increased eutrophication (diurnal oxygen fluctuation, chlorophyll concentration, macroalgal mats) decreased extent of intertidal mudflat habitat increased temperature increased barrier to movement between estuary and Monterey Bay decreased extent of habitat with strong marine influence (sandy sediments, strong currents) Eelgrass X X Pickleweed Olympia oyster X X X Ghost shrimp and littleneck clam Fat innkeeper, gaper & butter clam X X X X X X Jackknife clam X X X Flatfish X X X Willet, curlew, godwit X X Least Sandpiper X X X Harbor seal X X X Sea otter X X X X To download full report for any taxon, google "Elkhorn Slough Technical Report". The top hit should be the page where they are all posted. If you have suggestions for changes to the reports, please them to Kerstin (kerstin.wasson"at"gmail.com) by July 12. Please include concrete support for any suggested changes, such as literature citations or reference to a robust dataset availble in a technical report.

10 Summary of rankings related to water quality issues Process No Mouth Action Ranking of Alternatives Parsons Low Sill High Sill Mouth Reroute Nitrate Ammonium Eutrophication Hypoxia Hydrogen sulfide

11 A B C D E F G H SUMMARY OF POLICY CONSIDERATIONS AND RANKING OF ALTERNATIVES Policy Variables IMPORTANCE CASE LESSON LEARNED BC, SN, MB Number of landowners/abutters Number and type of agencies involved Cost of project Complexity and uncertainty of outcome Timing and Time Frame Potential impact on stakeholders Types and number of permissions Increases the number of legal approvals and potential owner's impacted. The greater the number of permissions and approvals needed, the more time and money and problems. The higher the costs the need fo stronger justification for expenditures and the more difficult to put funds in place in a timely fashion Raises stakeholder/agency questions and probability of unintended events Delays and time to get underway could compromise outcomes. If impacts are significant economically or socially, this increases the need to find ways of ameliorating them Some permits are more difficult and time consuming. Permits are the most difficult part of the process. Seek approvals early so can get underway while while waiting for others Building on public lands or impacting lands of multiple owners add to time and difficulty(bc) Avoid the ACE (NS)(MB) No mouth action Parsons Low Sill High Sill Mouth Reroute High costs require ACE Lead which can create larte problems of timing and coordination. (NS) Compleixty g with Corps and many agencies led to delays, higher costs,etc (all) Delays from ACE created problems and sunk project (MB) The significance and number of impacts created challenges which were overcome. (BC) which were not overcome (MB) e.g. sediment movements that exceed AC limits (MB) (BC)(MB) RANKING OF ALTERNATIVES Note the rankings in juxtaposition with the other scientist rankings

12 ACTIVITIES LIKELY TO BE AFFECTED FOR DIFFERENT USERS WITH LARGE-SCALE MANAGEMENT ALTERNATIVES NO MOUTH ACTION Sediment delivery to nearby beaches increased extent of habitat with strong marine influence (sandy sediments, strong currents) Bacterial contamination/i ncreased eutrophication (diurnal oxygen fluctuation, chlorophyll concentration, macroalgal decreased extent of intertidal mudflat habitat DECREASED MOUTH SIZE navigability by small craft and kayaks from Moss Landing Harbor into the slough? increased barrier to movement between estuary and Monterey Bay/Distributio n of wildlife, fish, birds decreased extent of habitat with strong marine influence (sandy sediments, strong currents) Kayaking/Canoeing X X X Bird watching X X X X Hiking X X Recreational Fishing X X X X X Recreational Boating X X X Commercial Fishing X X Power Plant X X Harbor Activities X X X Tours (and supporting business) X X X X Wildlife viewing X X X X Beach going X X X X Other local businesses X X X If you have suggestions for changes to the reports, please them tojudith Kildow (judy@oceaneconomics.org) by July 12. Please include concrete support for any suggested changes, such as literature citations or reference to official reports, laws, etc..

13 Activity Commercial Fishing CPFV Recreational Fishing in Estuary Recreational Fishing in the Surrounding Bay Kayaking Bird Watching Otter Watching Alternative 1 (No Action) Positive (increases in mudflat areas and improved water quality) Positive (increases in mudflat areas and improved water quality) Alternative 2 (New Inlet) (decreased mudflat, no connectivity between Slough and harbor) (decreased mudflat, no connectivity between Slough and harbor)? (could be positive, as no (increased expected change in water quality) residence time of water in the Slough, leading to decreased water quality) Alternative 3a (Low Sill) Unclear (more quality compared with Alt. 2, decreased connectivity between Slough and harbor. But, increase in mudflat areas) Unclear (more quality, decreased connectivity between Slough and harbor. But, increase in mudflat areas) Unclear (more quality but increase in mudflat areas) Alternative 3b (High Sill) (more quality compared with Alt. 2, more severe decreased connectivity between Slough and harbor, decreased mudflat) (more quality, more severe decreased connectivity between Slough and harbor, decreased mudflat) (more qualilty, decrease in mudflat areas????? Positive (increases in navigable areas; but what about effect of salt marsh loss, since survey responednts reported liking to kayak near marsh?) Positive (increases in mudflat areas and improved water quality) Positive (increases in subtidal and mudflat areas and improved water quality) Unclear (increased navigable area but loss of salt marsh and increased water velocity. Also decreased water quality) (decreases in mudflat and therefore prey and primary habitat, reduced visitor access during construction, decreased water quality) (decreases in mudflat and therefore prey, no connectivity between harbor and Slough, reduced visitor access during construction, quality) (more quality, potential navigation barrier between harbor and Slough) Unclear (more quality but increase in mudflat areas. Also potentially reduced visitor access during construction) Unclear (decreased connectivity between harbor and Slough, reduced visitor access during construction, more impaired water quality. But, increase in mudflat) (more quality, larger navigation barrier between harbor and Slough) Alternative 4 (Parsons Slough) Positive (increases in mudflat) Positive (increases in mudflat areas) Neutral? Unclear (Alt 4 will likely result in lower tidal velocities downstream, so it depends on kayaker preferences for water conditions) (more Unclear (potentially quality, decrease reduced visitor in mudflat areas, access during potentially construction but reduced visitor increase in access during mudflat area) construction) (decreases in mudflat and therefore prey, more severe decreased connectivity between harbor and Slough, reduced visitor access during construction, more impaired water quality) Neutral (otters do not use this area)

14 Activity Beach Going Harbor Operations Power Plant Operations Alternative 1 (No Action) Unclear (no major change in beaches?) Neutral (little change in tidal exchange and sediment retention) Neutral (little change in tidal exchange and sediment retention) Alternative 2 (New Inlet) (temporary decrease in sand deposition on beach near new inlet, reduced visitor access during construction, quality) (increased dredging costs, reducted visitor access during construction) (increased dredging costs, eutrophication) Alternative 3a (Low Sill) (reduced visitor access during construction, more impaired water quality) (increased dredging costs but less than Alt 2, reducted visitor access during construction) (increased dredging costs but less than Alt 2, eutrophication) Alternative 3b (High Sill) (reduced visitor access during construction, more impaired water quality) (increased dredging costs but less than Alt 2, reducted visitor access during construction) (increased dredging costs but less than Alt 2, eutrophication) Alternative 4 (Parsons Slough) Unclear (deposition of formerly sequestered sediment onto local beaches but reduced visitor access during construction) Unclear (Alt 4 will increase sediment in the Slough main channel but this is expected to be exported by natural processes. Also reducted visitor access during construction) Unclear (Alt 4 will increase sediment in the Slough main channel but this is expected to be exported by natural processes)

15 Tidal Wetland Program Meeting June 23 rd, 2010 Joint Science Panel/Strategic Planning Team This represents a summary of the survey responses regarding the large-scale decision process. This information will be used to communicate the range of opinions in the Science Panel and Strategic Planning team, as well as identify information gaps that must be filled before a decision-making process can proceed. Number of survey respondents: 34 Responses about which of these four questions were most important: Will it work? 64.7% What are the risks? 70.6% What are the trade-offs? 79.4% Can it be done? 32.4% Opinions on future tidal exchange in Elkhorn Slough Opinions on future water quality in Elkhorn Slough

16 Estuarine dependent species Estuarine endemics Long term sustainability Water quality Regional importance Risk Migratory shorebirds Eelgrass Project feasibility Climate change resilience Listed species Large benthic inverts Reduction of tidal prism Large charismatic animals Historical conditions Sea otters Salt marsh conversion Maintenance costs and requirements Loss of soft sediment Subtidal channel erosion Aesthetics Freshwater/saltwater gradients Recreational access Flatfish Reversibility Bank erosion The risk of mouth closure Olympia oysters Effect on sediment supply Tidal brackish marsh habitats Political support Incremental projects Navigation in the harbor Community economics Risk of liability to project sponsor Harbor seals 0% 10% 20% 30% 40% 50% 60% 70% 80% 90%

17 Additional values that were suggested: The Trade off of No Action Eutrophication Porter/Blohm 'marsh' continued mosaic with representation of and connectivity between multiple estuarine habitat types Project flexibility - bang for the buck and the one that can provide the most function Restoration of natural processes Sediment flux -- net inputs and output balance Cost effectiveness Knowledge of the ecological function of each habitat as it pertains to Elkhorn Slough, not elsewhere. changes in benthic productivity that might respond to changes in nutrient residence time Having good scientific data BEFORE the project starts to understand changes Cost feasibility Food web and prey availability changes Biodiversity Oxygen This goes with Feasibility: Funds set aside for adaptive management, or preparing for corrective actions if threshold is met Benthic macroalgae North Marsh Areas where clarification was needed in order to rank values: Temporal impacts of any of these vs. permanent loss or degradation Residence/flushing time Risk of mouth closure re: ES historical ecology How would be determine or measure climate resilience? Tidal brackish marshes: we don't have any, do we? Risks of mouth closure - It happens many years? I would need more info on Qs 3 and 4, tradeoffs b/n tidal exchange and water quality

18 Values (Ranked by number of votes) Presented information Information needs for decision Estuarine dependents Estuarine endemics Water quality (Changes in benthic prod.; eutrophication) Johnson Long-term sustainability Regional importance Eelgrass Migratory shorebirds Risk Johnson Project feasibility (Cost) Kildow Resilience to climate change Large charismatic animals Reduction of tidal prism PWA/Largay Large benthic inverts Listed species Historical conditions Sea otters Salt marsh conversion PWA/Largay Maintenance cost & requirements Loss of soft sediment (Sediment flux) PWA/Largay Aesthetics Subtidal channel erosion PWA/Largay Flatfish Recreational access Freshwater/brackish gradients Effect on sediment supply PWA/Largay Olympia oysters The risk of mouth closure Bank erosion PWA Reversibility (Flexibility) Political support Kildow Tidal brackish marsh habitats Incremental projects (Porter/Blohm, North Marsh) Navigation in the harbor Harbor seals Risk of liability to project sponsor Community economics Kildow Habitat mosaic Restoration of natural processes Biodiversity Food web changes Baseline data (Knowledge of ecologic function)