Effects of Nutrient Enrichment in the Nation's Estuaries: a Decade Of

effectsEXHIBIT of nutrient enrichment10 (AR in L.3)the nation’s estuaries: a decade of change

Overall eutrophic condition unique feature, as all other regions have at least one estuary with a high rating. One system was classified • This is the least impacted region; no North as having moderate high eutrophic conditions, with Atlantic systems had high overall eutrophic chlorophyll a and nuisance/toxic blooms as the major condition (OEC). contributing symptoms. • The majority of systems had a moderate or low OEC. One notable characteristic in systems of this • There was some cause for concern for region is the annual occurrence of nuisance/toxic chlorophyll a and macroalgae. blooms, which cause shellfish bed closures. However, • Toxic offshore blooms which leave cysts (potential for systems such as Massachusetts, Cape Cod, Saco, future blooms) were an emerging issue. and Casco Bays, these blooms originate offshore and are advected into the systems. For this reason, the nuisance/toxic bloom rating for these systems The North Atlantic region is the least eutrophic has been adjusted to low since the blooms do not region in the nation, with the majority of systems originate within the system. An emerging issue is the having moderate or low overall eutrophic condition possibility that these blooms, mostly of Alexandrium (Figure 4.3a-b). Furthermore, no estuaries in this spp., may eventually originate within estuaries, due to region recorded high overall eutrophic condition—a cysts that have settled in the estuarine sediments.

Figure 4.3. (a) Map of overall eutrophic condition (OEC) and (b) the combination of individual eutrophic symptoms which constitute OEC ratings in the North Atlantic region. a) Overall eutrophic condition

1. St. Croix R./Cobscook Bay 2. Englishman Bay 3. Narraguagus Bay 4. Blue Hill Bay 5. Penobscot Bay 6. Muscongus Bay 7. Damariscotta River 1 8. Sheepscot Bay 9. Kennebec/Androscoggin R. 10. Casco Bay 2 11. Saco Bay 3 12. Wells Bay 13. Great Bay 14. Hampton Harbor Estuary 4 15. Merrimack River 5 16. Plum Island Sound 17. Massachusetts Bay 18. Boston Harbor 6 9 7 19. Cape Cod Bay Eutrophic condition and trends 20. Waquoit Bay 8 10 High: symptoms generally occur periodically or persistently and/or over extensive area. 11 Moderate high: symptoms generally occur less 12 regularly and/or over medium to extensive area. Moderate: symptoms generally occur less 13 regularly and/or over medium area. 14 Moderate low: symptoms generally occur episodically and/or over small to medium area. 15 16 Low: few symptoms occur at more than minimal levels. 17 0 50 100 18 Unknown: Insufficient data for analysis. Kilometers Miles 0 25 50 19 Symptoms improved since 1999 assessment. No change in symptoms since 1999 assessment. 20 Symptoms worsened since 1999 assessment. Insufficient data to show trend.

42 EXHIBIT 10 (AR L.3) Chapter 4 • regional summaries • north atlantic

The overall confidence in the assessments for this vegetation (SAV) were low in all eight systems for which region is low due to almost a third of the systems there were data. (eight) having inadequate data for assessment. Where data were available, confidence is moderate to high. Changes in eutrophic condition since the 1990s Overall eutrophic conditions worsened in two systems, Eutrophic symptom expressions improved in three systems, and did not change in five Systems with moderate or moderate high overall when compared to the 1999 report (Figure 4.3a-b). eutrophic condition were characterized by having one Chlorophyll a changed in more systems than any of high symptom expression, which in this region was the other symptoms, showing improvements in four most often chlorophyll a and macroalgae. systems and worsening conditions in three systems. Of While most estuaries had one high symptom the data available, dissolved oxygen displayed the least expression, the majority of symptom expressions were amount of change. low. For the primary symptoms, chlorophyll a was Of particular interest is the improvement of expressed as low in seven of the eleven estuaries for eutrophic condition in Boston Harbor, which had which the symptom was reported. Similarly, moderate high eutrophic status in the 1990s, but macroalgae symptom expressions were low in five of currently has a rating of low. All symptom the ten reported estuaries. For the secondary improvements were attributed to sewage treatment symptoms, dissolved oxygen problems were low in all upgrades and the move of the wastewater outfall from twelve systems, and losses of submerged aquatic the harbor into Massachusetts Bay.

b) Overall eutrophic condition & eutrophic symptoms a Overall eutrophic condition Overall confidence expression Chlorophyll Macroalgae Dissolved oxygen Nuisance/toxic blooms SAV Estuary

1. St. Croix R./Cobscook Bay 2. Englishman Bay 3. Narraguagus Bay 4. Blue Hill Bay Eutrophic condition 5. Penobscot Bay in 2004 6. Muscongus Bay High Moderate high 7. Damariscotta River Moderate 8. Sheepscot Bay Moderate low 9. Kennebec/Androscoggin R. Low

10. Casco Bay Insufficient data 11. Saco Bay Overall confidence expression in 2004 12. Wells Bay High 13. Great Bay Moderate 14. Hampton Harbor Estuary Low 15. Merrimack River Change in eutrophic condition since 1999 16. Plum Island Sound assessment 17. Massachusetts Bay Improved 18. Boston Harbor No change 19. Cape Cod Bay Worsened 20. Waquoit Bay Insufficient data

43 effectsEXHIBIT of nutrient enrichment10 (AR in L.3)the nation’s estuaries: a decade of change

Future outlook surfaces, and fertilizer use. For all systems, an • There was a bleak outlook for future conditions; increase in coastal population (affecting land use most systems for which an evaluation was made distribution and subsequent nutrient loads) is likely were expected to worsen in the future. to augment nutrient loads from all of these sources. • The future outlook has not changed from the Though it is premature to make conclusions about early 1990s. the accuracy of the 1999 assessment’s future outlook, in six out of nine systems (for which comparison could be made), actual changes trended in the same The overall future outlook for the North Atlantic direction as predicted. Worsening conditions due region predicts worsening conditions. Eutrophication to increased nutrient loads are expected in Boston symptoms were predicted to worsen in nine of the Harbor, Great Bay, Plum Island Sound, and Cape Cod assessed systems and to improve in only two (Figure Bay (Figure 4.4). Conversely, loads to St. Croix River/ 4.4). For the nine systems expected to worsen, Cobscook Bay and Massachusetts Bay are expected to nutrient loads are anticipated to increase due to decrease due to improvements in onsite septic tanks, wastewater treatment, urban runoff, onsite septic storm water management, restoration of eroding tanks, combined sewer overflow (Cape Cod Bay stream beds, and a reduction in salmon aquaculture. only), atmospheric deposition, increasing impervious These changes are expected to occur by 2020.

Figure 4.4. Future outlook in 2004 and comparison with 1999 future outlook.

Future outlook in 2004 Future outlook comparisons

Future Actual change Future outlook in eutrophic outlook in 2004 condition in 1999 (1999–2004)

1 Estuary 1. St. Croix R./Cobscook Bay 2 2. Englishman Bay 3 3. Narraguagus Bay 4 4. Blue Hill Bay 5 5. Penobscot Bay

6 6. Muscongus Bay 9 7 7. Damariscotta River 8 10 Future outlook 8. Sheepscot Bay 9. Kennebec/Androscoggin R. 11 Large deterioration 10. Casco Bay 12 Small deterioration 11. Saco Bay 13 No change Small improvement 12. Wells Bay 14 Large improvement 13. Great Bay 15 16 Insufficient data 14. Hampton Harbor Estuary 17 Change in eutrophic 15. Merrimack River 18 condition since 1999 16. Plum Island Sound assessment 19 Improved 17. Massachusetts Bay 0 50 100 No change 18. Boston Harbor Kilometers 20 Miles Worsened 19. Cape Cod Bay 0 25 50 Insufficient data 20. Waquoit Bay

44 EXHIBIT 10 (AR L.3) Chapter 4 • regional summaries • north atlantic National Oceanic and Atmospheric Administration Oceanic Atmospheric and National Fishing boats tied up at the Portland Marine Trade Center in Portland, Maine. Monitoring use impairments is important to understanding how eutrophication influences commercial and recreational fishing.

Assessment of Estuarine Trophic Status (ASSETS) (combination of WWTP and sewer overflow), and There were seven systems for which anASSETS rating urban runoff. However, this information was available (combination of influencing factors, overall eutrophic for only five of the twenty systems. condition, and future outlook) could be made. Two Use impairments were reported for six systems systems were rated as good (Boston Harbor, Blue Hill (Damariscotta River, Great Bay, Hampton Harbor, Bay), four were rated as moderate (St. Croix River/ Boston Harbor, Cape Cod Bay, Waquoit Bay) with Cobscook Bay, Great Bay, Massachusetts Bay, and the most frequently noted impairment being shellfish Waquoit Bay), and one as poor (Plum Island Sound). harvesting. Other impacts include recreational and commercial fishing and fish consumption, aesthetics, Impaired uses and swimming. There does not seem to be a clear correlation • Three systems had impaired livingresources. between the level of overall eutrophic condition and • Causes of impairments were reported as river input, impacts to living resources. For instance, Waquoit wastewater treatment, combined sewer outflow, Bay (moderate OEC) had considerably impacted urban runoff, fertilizer, and onsite septics. living resources while St. Croix River/Cobscook • Six systems had human use impairments (primarily Bay, also with moderate overall eutrophic condition, shellfish harvesting, and recreational and had no impacts. This is likely due to the quantitative commercial fishing). nature of the OEC rating and the qualitative nature • There were no clear correlations between overall eutrophic condition and impacts to living resources. of use impairment reporting (i.e., these impairments occurred during the time period, but degree of impairment was not noted). The difference could Living resources were identified as being considerably also reflect the subtlety that nuisance/toxic blooms, impaired in only one estuary (Waquoit Bay), a result which may be advected from offshore, are in many of onsite septic tanks and fertilizer. Two additional North Atlantic systems not considered a result of systems reported moderate to slight impacts eutrophication. Therefore a comparison between (Boston Harbor and Great Bay) due to river inputs, the two is difficult. All systems with some level of wastewater treatment, combined sewer overflow eutrophic condition reported impairments.

45 effectsEXHIBIT of nutrient enrichment10 (AR in L.3)the nation’s estuaries: a decade of change

Potential management concerns The nutrient sources noted as the causes of impairments to living resources were combined sewer overflow, wastewater treatment, onsite septic tanks, urban runoff, fertilizer use, and river inputs. Atmospheric inputs were also noted as a cause for changes in load during the past decade. All of these warrant management attention given that they are also reported as potential causes of future nutrient increases and worsening conditions.

Data gaps and research needs

Monitoring Approximately one third of the systems included in this region had insufficient data for assessment. It is recommended that there be an emphasis on better regional monitoring of all indicators, submerged /University of Maryland Center for Env. Science) Boicourt,Kate Env. for of Maryland ( NOAA /University EcoCheck Center aquatic vegetation and macroalgae in particular. This A volunteer taking water samples to monitor for toxic bloom includes improved assessments of nutrient inputs species of algae in Penobscot Bay, Maine. from rivers, groundwater, and aquaculture so that the causes of observed problems can be identified and addressed. A monitoring program should provide a unified approach for sampling and analyzing Management indicators (i.e., macroalgae) in all systems, including The survey should be adjusted to accurately reflect annual sampling with more intensive sampling during relative conditions in different systems. Participants seasons that are problematic (i.e., summer). at the NEEA workshop noted that the assessment method should be improved so that the relative Research conditions among systems in this region would be A better understanding of circulation dynamics is more accurately reflected. For instance, they argued needed in these systems. Also, improved estimates that despite the improvements to Boston Harbor, of population growth and land use impacts and the eutrophic conditions of Great Bay are still better distribution are needed in order to make accurate than those of Boston Harbor, contrary to the results projections about future conditions. For systems of the survey. It is important that the relative ratings with seasonal population changes, more research accurately reflect conditions since this will impact the is needed in order to assess the effects of winter- prioritization of systems needing management and summer population changes on eutrophic conditions thus the application of scarce resources to improve in estuaries. Finally, improved macroalgal monitoring conditions. For the most part the systems in this and assessment techniques are recommended. region are not presently highly impacted.

46 nationalEXHIBIT estuarine eutrophication 10 (AR assessment L.3) update Great Bay

SUMMARY In Great Bay, increases in dissolved inorganic nitrogen have occurred over the past 20 years. Increases in chlorophyll a and turbidity have been identified with augmented eutrophication in the inner estuary. As a result, eelgrass biomass has declined by 70% in the last 10 years and the occurrence of nuisance macroalgae is becoming more evident.

Influencing Factors Eutrophic Conditions Any level nitrogen input and Primary symptoms high but low to moderate problems with more serious susceptibility (good ability secondary symptoms still not to dilute and flush being expressed. nutrients). Future Outlook ASSETS Rating Nutrient related symptoms Assessment of Estuarine observed in the estuary are Trophic Status based on the likely to substantially three factors evaluated in worsen. NEEA.

Influence/eutro/future Unknown Low Mod Low Moderate Mod High High Reliability and Confidence

ASSETS Unknown High Good Moderate Poor Bad Unknown Low Moderate High EUTROPHIC CONDITION Great Bay Overall Eutrophic Condition of Great Bay 1.0 Tidal Fresh - 0% Mixing - 49% Seawater - 51%

High Moderate Moderate High High Primary

0.6 Moderate Low Moderate High Primary Moderate 0.3 Low Moderate Low Moderate High Low Primary

0 Low Secondary 0.3 Moderate Secondary 0.6 High Secondary 1.0 1.0 Symptom Expressions Unknown

Low/No Problem (0-0.3)

Moderate Low

0.6 Moderate (0.3-0.6) Inputs Symptom Expressions No Moderate High Nitrogen Load Problem Low Moderate High Unknown Flag High (0.6-1.0) Phosphorus Load Chlorophyll a 0.3 Overall Primary &Secondary Symptom Expression Value Dissolved Oxygen Expressions

Overall Eutrophic Water Color Secchi Condition Chl a Low 0 Macroalgae Chl a Moderate

Chl a High Nuisance/Toxic Bloom

Chl a No Entry/ SAV Primary Symptoms Secondary Symptoms Unknown/Flag WATERSHED AND ESTUARY CHARACTERISTICS Estuary Landuse / Population Watershed Details / Input Loads Area (km2) 47 Urban (km2) 477 (19.2%) Area (km2) 2,555 Tidal fresh zone area (km2) 0 Agriculture (km2) 202 (8.1%) Mean elevation (m) 102 Mixing zone area (km2) 23 Forest (km2) 1,740 (70%) Max. elevation (m) 470 Saltwater zone area (km2) 24 Wetland (km2) 65 (2.6%) Watershed: estuary ratio 54.4 Volume (1,000 x m3) 177,660 Range (km2) 3 (0.1%) TSS (tonne y-1) 48,800 Depth (m) 3.78 Barren (km2) 0 (0%) DIN (kg y-1) 905,000 Tide Height (m) 2.38 Total (km2) 2,486 (0%) DIP (kg y-1) Unknown Residence Time (d) 1 Population 236,203 TSS/est. area (tonne km-2 y-1) 1,038 Popn: est. area ratio 5,026 DIN/est. area (kg km-2 y-1) 19,255 DIP/est. area (kg km-2 y-1) Unknown A16