Chetco Estuary and Boat Basin Water Quality Monitoring

Transcription

1 Chetco Estuary and Boat Basin Water Quality Monitoring Executive Summary The South Coast Watershed Council monitored the Chetco Estuary and Boat Basin to determine oxygen conditions in the basins, effectiveness of the aerators in the Sport Boat Basin and nutrient sources and their effects on algae growth. Dissolved oxygen as low as 5.5 mg/l, was found in the most stagnant areas in late summer 2002 and spring 2003 near the bottom. Large diurnal oxygen and ph fluctuations are expected because the algal cycle is promoted by high temperatures, abundant sunlight and nutrients coming from several tributaries that drain into the basins. To date, dissolved oxygen levels below the state standard were detected in May at or near the bottom of the most stagnant areas. The effectiveness of the aerators in the Sport Boat Basin in raising DO levels was not adequately evaluated with the sampling design that was used. Elevated phosphorus and biochemical oxygen demand that could result from the decomposition of organic matter were monitored in the basin in August The highest nitrate concentration was found in February 2003 in the Commercial Boat Basin, with the highest values at the south end, probably influenced by the drainage of Buried Pipe and Tuttle Creek. By May 2003, an algae bloom was consuming nutrients and the nitrate concentration was lower at the south end of the Commercial Boat Basin. Also in May the ocean was high in nitrates (0.24 mg/l) and phosphorus (0.07 mg/l) probably due to upwelling. The relative load and duration of nitrates from ocean upwelling and from the tributaries flowing into the basins is unknown, however as long as nitrates are the nutrient limiting algae growth, both will contribute to algae blooms. Tributaries flowing into the south end of the Commercial Boat Basin contributed a load of 8.1 kg/day of nitrogen compared to 0.5 kg/day from tributaries flowing into the Sport Boat Basin in February. When phosphorus is available, these nitrate loads may enrich the basin enough to provoke an early algae bloom. Further sampling will help clarify the role that tides, diurnal, seasonal and inter-annual variability play in determining the water quality in the estuary. Continuous sampling of dissolved oxygen and ph will allow characterization of the peak magnitude and duration of impairment during the summer months. Aerators can be evaluated by continuous dissolved oxygen monitoring while they operating and while turned off. To better assess changes to the N:P ratio during the algae bloom, chlorophyll a and nutrient (Total Kjedahl Nitrogen or Orthophosphate) tests can be included. To reduce the algae growth and improve the summer water quality in the basins, alternatives include constructing bioswales on tributaries to absorb nutrients, and improving the water circulation in the basins. An outreach/education program and pilot projects to demonstrate the value of vegetated areas and wetlands may also improve the water quality in the Chetco Estuary and Boat Basin. 1

2 Executive Summary... 1 Introduction... 3 Background... 3 Methods... 5 Results and Discussion... 9 Estuary and Boat Basins... 9 Temperature, Salinity, Turbidity and ph... 9 Dissolved oxygen (DO) and Biochemical Oxygen Demand (BOD): Total Phosphorus and Nitrate + Nitrite Tributaries to the Boat Basins Temperature, conductivity, turbidity and ph: Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD) Total Phosphorus (TP) and Nitrate + Nitrite Nutrient Loads Conclusions Recommendations Acknowledgements References Appendices Appendix A: Notes from Birgit Knoblauch s Interview of Jim Waldvogel, Sea Grant Extension Agent Appendix B: Sampling Schedules and Comments on Sampling Conditions Appendix C: Detailed Sampling Methods Appendix D: Field Forms Appendix E: Quality Assurance and Quality Control Appendix F: The Manning Formula Appendix G: Temperature, Salinity, Dissolved Oxygen Profiles Appendix H: Water Clarity and Wave Height Appendix I: Flows and Nutrient Loads

3 Introduction This report presents the results of water quality monitoring in the Chetco Estuary and the Port of Brookings-Harbor Sport Boat Basin (SBB) and Commercial Boat Basin (CBB) from August 2002 to May The major concerns in the Boat Basins are low dissolved oxygen levels, poor water circulation, excessive summer algal growth, nutrient inputs and periodic fish mortality. After conducting a study of the SBB in 1999, the Corps of Engineers recommended that aerators be installed to improve circulation and improve oxygen levels. The Corps measured nitrate concentrations of 0.68 and 0.20 mg/l from two tributaries flowing into the basins, but in the Sport Boat Basin, nitrates were non-detectable (<0.05 mg/l) in October The South Coast Watershed Council and OSU Extension Service initially developed a monitoring plan to assess dissolved oxygen conditions in the SBB and determine if the aerators were effective. The study was expanded after Russ Crabtree, Port of Brookings- Harbor Manager, suggested that the CBB had more severe DO, algae, and fish mortality problems. Nutrient conditions and other water quality parameters were sampled from tributaries flowing into the basins, the ocean, the Chetco, and within the Sport and Commercial Boat Basins. This monitoring was intended to improve the understanding of water quality in the Chetco Estuary for the Port of Brookings-Harbor and its users. Since estuaries are very diverse and provide a unique habitat for aquatic species, it is important to address tidal, diurnal, seasonal and inter-annual variability in water quality, as well as how algae respond to nutrient inputs. Background Estuaries are transitional zones, where fresh and saltwater come together, providing a highly productive habitat for many aquatic species. Density differences cause water to stratify into a top layer of fresh, oxygenated water and a bottom layer of saltwater with less oxygen. Dissolved oxygen is a fundamental requirement for maintaining aquatic life and is increased by wave action, water circulation, and photosynthesis, but is decreased by respiration and decomposition of organic matter. Less oxygen is dissolved at higher temperatures and in saline water. Dissolved oxygen concentrations less than 5.0 mg/l create hypoxia that leads to biological stress of aquatic organisms. Death may result from anoxia if dissolved oxygen levels drop below 2.0 mg/l. Masses of anchovies spawn in the ocean and move into estuaries to feed (Appendix A). The timing depends on ocean conditions (particularly upwelling nutrients) and their reproductive cycle, often between June and August. In the summer, phytoplankton bloom in the presence of warm temperatures, sunlight, and nutrients. Zooplankton feed on phytoplankton, and in turn, anchovies feed on zooplankton. Because anchovies school in masses, they need adequate dissolved oxygen to survive. Their masses can create hypoxia and even anoxia, causing mortality within 24 hours (Waldvogel, 2002, pers. comm.). Anchovies usually feed in the surface, but freshwater is lethal, so if freshwater flows 3

4 increase once they are in the Boat Basins, they may be trapped. Oxygen levels are also affected by the diurnal cycle of phytoplankton and algae, water temperature, wind conditions, and wave action. During 2001, there were two episodes of anchovy mortality in the Port of Brookings-Harbor and elsewhere along the coast (Waldvogel, 2002, pers. comm.). The transition between spring and summer ocean conditions, from southwest winds and rains to northwest winds and clear days, may be quantified based on an average date of April 6th (Data and plot by Robert Emmett, cited by Logerwell et al., 2003). In 2001, the onset of wind-induced upwelling was unusually early. It is likely that oceanderived nutrients not only fueled an abundance of anchovies, but also fed high algal biomass in the Boat Basins. Nutrients play an important role within an estuary. Estuaries are generally rich in nutrients, which are required for production the base of the food web that supports aquatic species. Excessive nutrients result in increased algal growth, decomposition of organic matter, reduced oxygen and ultimately eutrophication. Anoxic conditions in the benthos can cause release of phosphorus normally bound up in bottom sediments ( Algal growth is optimal when the ratio between Nitrogen and Phosphorus (N:P) is between 10:1 and 16:1. Whichever nutrient is more limited determines whether algae respond to additional nutrient inputs. Small additions of the limited nutrient can cause large increases in algae production. Most Oregon rivers are phosphorus limited (reference), but in estuaries nitrogen is more typically limiting to algal production (Howarth and Marino, 2006). Estuaries tend to be nitrate limited, but can be phosphate limited in cases of excessive nitrate input. 4

5 Methods Chetco Estuary and Boat Basin were sampled in 2002 on August 2 nd, September 9 th, September 17 th (tributaries only), October 17 th (basin only) and in 2003 on February 26 th and May 21 st. Chetco Estuary/Boast Basin Study August 2002-May 2003 Chetco near Brookings USGS gage Discharge, cfs 1000 Daily Avg Samples Aug 29-Aug 26-Sep 24-Oct 21-Nov 19-Dec 16-Jan 13-Feb 13-Mar 10-Apr 8-May Sample sites included eight estuary and boat basin sites, as well as five tributaries flowing into the basins (Table 1). Sites BH005 and BH006 were identified as established by the Army Corps of Engineers for their 1999 samples. Water quality parameters included temperature, conductivity/ salinity, ph, turbidity, dissolved oxygen (DO), biochemical oxygen demand (BOD), nitrate + nitrite and total phosphorus. Secchi disk readings for water clarity were recorded daily in the Sport Boat Basin during September and October. Estuary and basin sites were sampled from a boat by lowering a bridge bucket to the desired depth. Nutrient, DO, BOD, turbidity and ph samples were taken at mid-depth, except for DO and BOD sampled from the bottom at the more isolated, stagnant sites during September, October and February. Tributaries emerging from pipes were sampled by hand. Sampling schedules and comments on conditions during sampling are included in Appendix B. Sampling and field parameter testing details are provided in Appendix C, and field forms in Appendix D. Temperature, salinity and DO were profiled during three runs/day with YSI DO and salinity meters every 0.5 meter in depth. DO meter readings on profiles were systematically higher 5

6 than Winkler titrations from grab samples (Appendix E). Therefore only one set of DO profiles is presented to illustrate changes with depth and tidal cycle. Samples were collected from tributaries flowing into the Boat Basins on 9/17/02 during a first flush storm. All samples were collected between 11:45 and 13:10. September 17, 2002 Cumulative Rainfall Brookings AgriMet Station Precipitation, inches :00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 Nutrient samples collected in August and September 2002, were analyzed by Neilson Research Corporation (Environmental Testing Laboratory), whereas samples collected in October, February and May were analyzed by Watershed Council staff at the City of Gold Beach Public Works Department laboratory facility. Samples from this project were among the first to be tested by the Watershed Council, and include a mix of high quality, unknown quality and poor quality results (Appendix E). October results for total phosphorus are suspect, with poor precision due to an issue with reproducibility on the Spectrophotometer that was later remedied. For nitrate+nitrite, low range concentrations reported in February have poor precision, but it is probable that differences between the ocean and boat basin are real. Anions present in estuarine samples can cause interference and incomplete recovery nitrate+nitrite. One Boat Basin sample was spiked during the watershed council analysis, and resulted in complete recovery. To calculate nutrient loads, tributary flows were estimated by timing the filling of a bucket of known volume. When flows were too high for the bucket method, flow height, pipe slope and diameter was measured to calculate flows by the Manning equation (Grant & Dawson, 1997). A and R are obtained from tables using the coefficient between flow height and pipe diameter (Appendix F). Q = A R S n Q = flow rate A = cross sectional area of flow R = hydraulic radius (cross sectional area divided by the wetted perimeter) S = slope of the hydraulic gradient n = Manning coefficient of roughness dependent upon material of conduit 6

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8 Table 1. Sampling Sites and Location # Site Name Location Purpose 1 BH005 (from Corps of Engineers 1999 report) Northern SBB pipe, next to ramp Check WQ and nutrients, Corps study showed high nitrogen 2 BH006 (from Corps of Engineers 1999 report) Southern SBB pipe, next to ramp Check WQ and nutrients, Corps study showed high phosphates 3 Donovan Pipe at barge slip area Check WQ and nutrients 4 Buried Pipe Pipe at the SE end of the CBB Check for nutrients 5 Tuttle Creek Pipe at the SW end of the CBB Check for nutrients 6 Parking Lot Pipes from the SE parking area that drain into the CBB Check for turbidities and nutrients at first storm event 7 Sport Boat Basin North (SBB-N) Between the four aerators Look at aerators effectiveness 8 Sport Boat Basin South (SBB-S) South of the SBB docks, west For comparing with SBB-N from Eureka Fisheries 9 Commercial Boat Basin North (CBB-N) Open place near the shrimp processing facility Check WQ and nutrients and to compare with CBB-S 10 Commercial Boat Basin Mid (CBB-M) At the end of Commercial dock G Check WQ and nutrients and to compare with CBB-S 11 Commercial Boat Basin South (CBB-S) Between Buried Pipes and Tuttle Creek Check WQ and nutrients and influences by southern pipes 12 / Opening The port entrance Check WQ from the ports outflow 13 Chetco Middle of the stream, next to the To compare with WQ of basins fish processing area 14 Chetco / Between the jetties To compare with WQ of basins 8

9 Results and Discussion Estuary and Boat Basins Temperature, Salinity, Turbidity and ph Salinity and temperature profiles from August 2 nd and September 9 th revealed a high salt content with no distinct halocline or thermocline and therefore indicate that the estuary is dominated by ocean water during low river flow (Appendix G). Temperatures were only 1 2 C (2 4 F) warmer on top than at the bottom and salinity differences were around 4 ppt in August and even less in September. In contrast, during high winter flows on the Chetco, stratification is common. As flows decrease, the fresh water layer becomes thinner until it mixes completely. Stratification resulted in an increase of up to 5 C (9 F) in temperature and up to 22 ppt in salinity. During each of the three daily profile runs (Appendix G), temperatures at the river site were less than or equal to 16 C (61 F). This is consistent with a longitudinal survey of the estuary on the afternoon of 8/3/01, showing temperatures at 1 foot depth declining from 20.6 C near the Harbor water intake to 15.3 C at the Boat Basin entrance (Kocher and Cavenass, 2001, pers. comm.). The survey was conducted during the Low High to High Low ebb tide while mainstem Chetco temperatures were increasing. In 2004, continuous recording thermometers were deployed in the Chetco upstream of the estuary. Figure x illustrates maximum and minimum temperatures for each day. At the furthest downstream site, the 7-day average of daily maxima was 77.4 F (25.2 C). Minimum temperatures did not decline below 64 F (17.8 C) for most of the summer, thus creating a relatively inhospitable environment for juvenile salmonid rearing. Water clarity at the SBB-S during September and October seem to be influenced by the wave height, with higher visibility occurring during periods of lower wave height (Appendix H). need to test this statement statistically. The ocean site was more turbid than the river during February and May sampling events, and was also richer in nutrients. Because Chetco runoff is mixing at the ocean site, it is uncertain whether the higher turbidity results from turbulence at the mouth or from wind-induced upwelling of nutrients from deep water ocean sources. In May, after a long period of decreasing flow, higher nitrate concentrations in the ocean probably indicate upwelling (consistent with the timing shown in Figure 1). Nutrient 9

10 availability in late spring allows the growth of phytoplankton which results in higher basin turbidity. During late summer/fall, ph values ranged from , and in February, declined to , which is a normal response to the ph of rainfall (Table 1). Discuss why elevated ph may be harmful to aquatic organisms. Violations of the state standard at 8.5 were detected mostly in the summer in the afternoon. Dissolved oxygen (DO) and Biochemical Oxygen Demand (BOD): DO was highest ( mg/l) in late summer, presumably due to higher temperatures, salinities and more algal photosynthesis. The and Chetco sites always had the highest DO, due to their greater wave action and better water circulation. In summer, lower ocean swells may reduce circulation, which together with higher temperatures and adequate nutrient input can enhance algae, increasing diurnal DO fluctuations. September and February sampling events had lower DO values in the morning and higher towards the afternoon, which is a normal diurnal fluctuation. Natural fluctuations of oxygen occur due to daily cycles in photosynthesis and respiration. Oxygen is higher in the afternoon during photosynthesis and lower in the early morning after oxygen-consuming activities have been going on for more than eight hours (Maryland Department of Natural Resources, 2003). May samples had high DO in the morning and lower DO towards the afternoon, following a low tide. Chetco Boat Basin Dissolved Oxygen with Tidal Cycles Dissolved Oxygen (mg/l) :27 SBB-N SBB-S CBB-M 12:30 18: Tide (ft) Tide :48 7:12 9:36 12:00 14:24 16:48 19:12 21:36 Time of Day 10

11 Chetco Boat Basin Dissolved Oxygen with Tidal Cycles :59 7 Dissolved Oxygen (mg/l) SBB-N SBB-S CBB-M CBB-N CBB-N CBB-M 7:55 CBB-S SBB-S CBB-S SBB-N SBB-N CBB-N SBB-S CBB-S 20: Tide (ft) Tide :48 7:12 9:36 12:00 14:24 16:48 19:12 21:36 Time of Day Note: bottom samples are red circled Chetco Boat Basin Dissolved Oxygen with Tidal Cycles :30 7 Dissolved Oxygen (mg/l) SBB-N SBB-N CBB-S SBB-S CBB-N CBB-S CBB-M SBB-N CBB-S SBB-N CBB-S Tide (ft) : Tide :48 7:12 9:36 12:00 14:24 16:48 19:12 21:36 Time of Day Note: bottom samples are red circled 11

12 Chetco Boat Basin Dissolved Oxygen with Tidal Cycles Dissolved Oxygen (mg/l) SBB-N SBB-N CBB-S SBB-S CBB-M CBB-S SBB-N CBB-N SBB-N CBB-S CBB-N SBB-S SBB-N SBB-N CBB-S CBB-S 18: Tide (ft) Tide 11: :48 7:12 9:36 12:00 14:24 16:48 19:12 21:36 Time of Day Note: bottom samples are red circled Low DO can appear after low tides in the bottom of the most stagnant areas (SBB-N & CBB-S), especially when low wave heights and well-established halocline limit water mixing or exchange. In May, the lowest DO levels (5.5 mg/l) in the SBB-N and CBB-S near the bottom were less than the estuarine standard of 6.5 mg/l. In October there was no difference in DO between mid and bottom samples in these same areas, probably because of large swells that allowed better water mixing and circulation in the basins. DO differences near (SBB-N) and away from the aerators (SBB-S) are difficult to attribute to the aerators, since the ocean has more influence on DO levels at the second site. More strategic sampling, with the aerators in this area turned on and off is needed to assess their effectiveness in raising dissolved oxygen in the Sport Boat Basin. Increased organic material from decaying algae is present in the summer. This extra organic matter has to be decomposed by microorganisms, increasing their population and activity, and thus creating an additional pressure on DO, and therefore raising the BOD. In August BOD levels were between mg/l, while in fall and winter all BODs were < 1.1 mg/l. The origin of the elevated BOD, whether created in the basins by algae production (autochthonous) and/or imported to the basin from the ocean (allochthonous) is unknown. Monitoring BOD in basins and at different ocean sites during the summer could provide sufficient information understand the origin of the organic matter. Total Phosphorus and Nitrate + Nitrite Total phosphorus (TP) was highest in late summer and fall and lowest in the spring (Table 1). In August and September, TP was mainly present in the CBB, increasing towards the CBB-S, where more algal mats had accumulated. High TP values on August 2 nd in the Chetco (0.09 mg/l) are considerably higher than July and September values measured by DEQ at Chetco at second bridge (0.01 mg/l). Tidal exchange between the Boat Basins with high 12

13 TP and organic matter and the Chetco, could account for the difference. Alternatively, it is possible that the August sample was contaminated with bottom sediments. The highest ocean TP was measured in May (0.07 mg/l) and is likely influenced by ocean upwelling. Phosphates in Estuary and Basin 0.14 mg/l SBB-N SBB-S CBB-N CBB-M CBB-S 0 Aug Sep Oct Feb May Date The highest nitrates were detected in February in the CBB. Tributaries at Buried Pipe and Tuttle Creek were likely sources, since the ocean was an order of magnitude less (0.10 mg/l), and nitrates increased from the north to the south end of the basin. Nitrates in Estuary and Basin 0.3 mg/l SBB-N SBB-S CBB-N CBB-M CBB-S 0 Aug Sep Oct Feb May Date Note: Non-detected values are plotted as 0 mg/l 13

14 Also in February, nitrates in the SBB were similar to the ocean, and only half the concentrations measured in the CBB. In May, the ocean had the highest nitrate concentrations, more than double those found in the CBB. The pattern in the CBB is reversed, with the lowest values at CBB-S not only furthest away from the ocean influence, but also where the highest densities of algal mats were observed. Accumulation of algal mats appears to be a physical as well as a biological process, resulting from onshore winds and obstacles to surface circulation within the Boat Basins. Nitrate + nitrite was less than the detection limit (0.05 mg/l) in September and remained low in August and October ( mg/l). It is suspected that algae are using all available nitrate in the basin during the summer and fall (reference). 14

15 Table 1. WQ Results from the Chetco Basin and Estuary Corps 8/2/2002 9/9/ /17/2002 2/26/200 3 Site Time Depth (m) Temp (C) Temp (F) Salinity (ppt) ph Turb (NTU) DO (mg/l) DO% Sat BOD (mg/l) Total P (mg/l) Nitrates (mg/l) North Sport Basin 0.05 ND Chetco 0.05 ND North Sport Basin 10: South Sport Basin 10: Composite Sport 10: ND Commercial Basin 11: * Composite Commercial 12: Basin Opening 8: Chetco 8: :12 11: * < ND 0.08 North Sport Basin 7: ND ND North Sport Basin 10: South Sport Basin 7: ND ND South Sport Basin 10: Commercial Basin North 8: ND Commercial Basin North 8: Commercial Basin Mid 8: ND Commercial Basin Mid 9: Commercial Basin South 9: ND Commercial Basin South 9: Basin Opening 11: Chetco 11: ND ND 11: ND ND North Sport Basin 16: < North Sport Basin 16: Commercial Basin Mid 16: Commercial Basin Mid 16: Commercial Basin nr Buried 17: North Sport Basin 8: North Sport Basin 10: North Sport Basin 10:

16 5/21/2003 North Sport Basin 15: South Sport Basin 11: Commercial Basin North 12: Commercial Basin Mid 11: Commercial Basin South 9: Commercial Basin South 11: Commercial Basin South 11: Commercial Basin South 16: Basin Opening 10: Chetco 15: Chetco 16: : : North Sport Basin 8: North Sport Basin 8: North Sport Basin 11: North Sport Basin 11: North Sport Basin 14: North Sport Basin 14: South Sport Basin 10: South Sport Basin 10: Commercial Basin N 11: Commercial Basin N 11: Commercial Basin Mid 12: Commercial Basin S 8: Commercial Basin S 8: Commercial Basin S 12: Commercial Basin S 16: Commercial Basin S 16: Basin Opening 9: Chetco 13: <0.05 9: : *not measured, estimated 16

17 Tributaries to the Boat Basins Temperature, conductivity, turbidity and ph: Temperatures from all tributaries draining water into the boat basins ranged from C (50-60 F), with the lowest values in February, corresponding to the cool season (Table 2). Specific conductivity ranged from 70 to 1511 and was highest in BH006 and Buried Pipe tributaries. The pipe at BH006 is corroded, and drains not only a large parking area, but also a boat cleaning station, explaining the variability in dissolved minerals. The outlet of the Buried Pipe is under saltwater at most tides. Turbidity ranged from 1 to 535 NTU and was highest during the first flush storm runoff from pipes draining the parking lots and during the highest flows in BH005, Donovan Creek, Buried Pipe and Tuttle Creek. On days with no storm runoff, the highest turbidities usually occurred in BH006 and Donovan Creek, but the limited flows from these tributaries are unlikely to have much effect on turbidity in the boat basins. ph values were between 7.0 and 8.4 and BH006 always had the highest ph. This ph range is similar to that found in the Chetco. ph tended to decline in the winter, and increase during summer sampling runs. Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD) DO ranged between 9.0 mg/l and 10.8 mg/l, with the lowest values recorded in BH006. There are no clear seasonal changes, but late summer and fall DO samples had around 98% saturation whereas February samples were lower and ranged from 89-96% saturation. BOD was highest in BH006 in August (5.8 mg/l) and September (9.5 mg/l), while BODs in all the other tributaries were less than 1.2 mg/l. This indicates more biological activity or potential contaminants in this pipe, but since its flow is small, it is probably not a major influence on the SBB. In February all BOD samples were < 0.7 mg/l, comparable to the Chetco sample (0.3 mg/l). Total Phosphorus (TP) and Nitrate + Nitrite Total phosphorus contributions from all of the tributaries were low during most of the sampling events. During the first flush of the rainy season on September 17th, TP was elevated to between 0.17 and 0.36 mg/l. In August and September, all sites had values averaging approximately 0.06 mg/l, except for non-detectable levels in Donovan Creek. February TP levels were < 0.04 mg/l and May levels were < 0.02 mg/l at all sites. Nitrate+nitrite concentrations were consistently high ( mg/l) on Buried Pipe and Tuttle Creek, especially during sample events in August, February and May. Buried Pipe and Tuttle Creek also have the highest flows (see next section). One sample from the Buried Pipe, collected during the first flush storm, was mixed with estuarine water (of high conductivity). Nitrate was nondetected in this sample. 17

18 Total Phosphorus in Pipes mg/l BH005 BH006 Donovan Buried Tuttle Date Note: Non-detected values are plotted as 0 mg/l Nitrates in Pipes mg/l BH005 BH006 Donovan Buried Tuttle Date Note: Non-detected values are plotted as 0 mg/l 18

19 Table 2. WQ Results from Tributaries to the Boat Basins Site Time Flow, gpm Temp (C) Temp (F) Cond. ph Turb. NTU DO (mg/l) DO% Sat BOD (mg/l) Total P (mg/l) Nitrates (mg/l) 5/21/2003 2/26/ /17 9/17/2002 9/9/2002 8/2/2002 Corps BH BH BH005 12: BH006 12: Donovan Creek 7:57 200* ND 0.72 Buried Pipe 13:23 56* Tuttle Creek 8: ND 1.00 BH005 7: ND BH006 7: ND 0.41 Donovan Creek 8: ND 0.39 Buried Pipe 9: Tuttle Creek 11: BH005 12:50 200* BH006 12: Donovan Creek 13:00 300* Buried Pipe 13:10 200* 16, ND Tuttle Creek 11:45 500* SE Parking Lot 12:30 20** 130** Buried Pipe 17: < BH005 13: BH006 14: Donovan Creek 8: Buried Pipe 15: < Tuttle Creek 9: BH005 11: BH006 12: Donovan Creek 9: Buried Pipe 12: < Tuttle Creek 8: * estimated ** Average value 19

20 Nutrient Loads Table 3. Nutrient Loads from All Tributaries Total Phosphorus (g/day) Total Phosphorus (lbs/day) Sampling Date Nitrate (g/day) Nitrate (lbs/day) lbs of Urea/day Nitrate loads decrease towards the summer and generally total phosphorus loads only increase during high runoff events (Table 3). The highest nitrate load was found in February (9.9 kg/day) which might enrich the basin enough to provoke an early algae bloom, especially since the tributaries with the highest loads enter the most stagnant area in the CBB-S. In February the CBB-S pipes contributed 8.1 kg/day and the SBB pipes only 0.5 kg/day. Flows and loads are tabulated by tributary in Appendix I. g/day Phosphorus Loads in Pipes BH005 BH006 Donovan Buried Tuttle Date Nitrate Loads in Pipes g/day BH005 BH006 Donovan Buried Tuttle Date

21 Conclusions In spring, as water temperature and sun light increase, algae began to grow and use nutrients. The highest nitrates were detected in February in the Commercial Boat Basin. Tributaries at Buried Pipe and Tuttle Creek were likely sources, since the ocean was an order of magnitude less (0.10 mg/l), and nitrates increased from the north to the south end of the basin. Evidently, nitrogen loads from the tributaries, particularly Buried Pipe and Tuttle Creek, are available prior to the average onset of wind-induced ocean upwelling. These nutrients may prolong the period of algae production in the early spring, as well as later into the summer. During years with later or weaker upwelling than in 2002 or 2003, the relative importance of these sources of nitrate would be greater, particularly in the Commercial Boat Basin. Algae production depends on temperature, sunlight, and nutrients. For phytoplankton, the optimal ratio between nitrogen and phosphorus is 16:1, and for ephemeral macroalgae is x:x (reference). Understanding the changing abundance of these nutrients and which of them limits algal production, may be used manage and reduce the algal biomass. Assuming that nitrogen is at least as high as the nitrate+nitrite concentration (which ignores any particulate or organic fractions), an N:P ratio may be calculated for the Boat Basins during the growth season. In February, N:P in the Commercial Boat Basin increased from 8 to 11 to 14, from the site closest to the ocean to the south end near the tributaries. This seems to indicate that reducing the nitrogen contribution from the tributaries could result in a less optimal N:P ratio, and reduce the algal biomass. Nutrient inputs may be encouraging algae production in the basins which exacerbates diurnal fluctuations in DO and ph and increases BOD values after algae decomposes. This study detected dissolved oxygen levels as low as 5.5 mg/l near the bottom of the north end of the Sport Boat Basin and 6.5 mg/l at the south end of the Commercial Boat Basin.. These lower DO sites are furthest from the Boat Basin entrance, and are more stagnant. The lowest levels were detected during May when the aerators are turned off. Although these levels violate the state standard for estuarine waters, they are not as low as expected. Corps of Engineers profiles (1999) in the north end of the Sport Boat Basin measured 4.5 mg/l at the north end of the Sport Boat Basin at the of August. At this time, they also detected dissolved oxygen as low as 4.7 mg/l in the Chetco. However, due to complex relations among time of day, tidal cycle, and season, the minimum value and duration of DO impairment is yet to be determined. Grab samples in the summer were only collected at one time of day, in the top and bottom layers. In order to fully evaluate the effect of algae growth on dissolved oxygen, 24-hour diurnal cycles need to be recorded at different tidal stages. Continuous recording dissolved oxygen, temperature, and salinity sensors may be deployed over 24-hour periods, at intervals through the spring-fall. ph exceeding the state standard of 8.5 was detected at the river site in September and May. Peak ph values tend to occur later in the afternoon than our samples. Continuous recording ph sensors would be needed to determine the duration of ph impairment. Tributaries to the boat basins are lower in ph. The effectiveness of the aerators in the Sport Boat Basin in raising DO levels was not adequately evaluated with the sampling design that was used. The two sites selected to be closer and further away from the aerators, SBB-N and SBB-S, differed in the degree of tidal influence on their oxygen levels. Knowing that large masses of schooling fish such as sardines, anchovies, and herring periodically move into the Boat Basin changes ones perspective about adequate dissolved oxygen levels. Diurnal 21

22 fluctuations in dissolved oxygen and ph have not been adequately examined. The highest density of algal biomass, where the most extreme fluctuations may be expected is associated with the location of the highest nitrate loads from tributaries. Dissolved oxygen stress renders some proportion of the Boat Basin stressful during current conditions, and it is clear that this proportion may expand rapidly when the wrong combination of waves, water temperature, fish density, and fresh water flow is present. In addition, continuous dissolved oxygen measurements on other South Coast estuaries have shown that morning fog extends the period of respiration, which allows dissolved oxygen to continue to decline for a longer period of time. Recommendations Estuary processes are complex making them difficult to analyze for water quality, because of their tidal, diurnal, seasonal and inter-annual variability. Additional monitoring during different spring upwelling conditions will better clarify the variability in nutrient sources and dissolved oxygen response. The maximum diurnal range for dissolved oxygen in other South Coast estuaries tends to occur in the mid- to late summer months. Continuous recording sensors will provide critical information on the duration of dissolved oxygen stress from algae respiration. BOD grab samples are also helpful for comparing ocean, river, and Boat Basin conditions. Grab samples for nutrients in north, midand south positions within the Commercial Boat Basin were particularly useful. Chlorophyll a samples would provide another check on the trophic state of the Boat Basins, and track phytoplankton abundance with tributary and ocean nutrient inputs. DO profiles should be measured in the SBB-N in summer in order to evaluate the effectiveness of the aerators. The profiles may be measured between two aerators from the dock, while operating and when they are turned off. - discuss the results of this effort in 2003 Abundance, growth rates, and diversity of aquatic species supported by the estuary could be tracked along with dissolved oxygen stress and algal density. ODFW could be involved in these evaluations. Excessive algae growth in the Port of Brookings-Harbor is a chronic summer problem that affects not only aquatic species, but also commercial and recreational activities. The algae problem will vary in intensity from year to year, but activities to diminish nitrate loads will need to be ongoing. Among the factors that could be addressed (water temperature, sunlight, or nutrients), nitrate reduction appears to have the best chance of success. Improving vegetative uptake of nitrate, as well as reducing fertilizer additions within the watersheds of Buried Pipe and Tuttle Creek should be pursued. Opportunities for increasing the contact time between water and riparian or wetland vegetation should be assessed. Bioswales can reduce the nutrient load in the water by filtration through wetland plants and conversion of nutrients to both gaseous forms (that are then lost in the atmosphere). Bioswales accomplish this by aerating and increasing the residence time of the water so that plants and microorganisms may transform nutrients to other forms before they reach the estuary.. An outreach/education program and pilot projects to demonstrate the value of vegetated areas and wetlands could be developed to reduce the contribution of nitrates from the watersheds. the program could also build awareness of the boundaries of the watersheds affecting the boat basin, and provide incentives for using alternatives to fertilization. 22

23 Creating better connectivity between the basins, the river and ocean will help to improve circulation, as well as dissolved oxygen conditions in the basin. Alternatives to the current basin entrance have been proposed to reduce the effects of ocean swell on the docks and boat. Assessments of these alternative configurations should consider potential effects on algal biomass, dissolved oxygen and conditions leading to fish mortality. In 2001, fish mortality had serious economic, as well as ecological effects on the Port (Crabtree, 2002, pers.comm.). Acknowledgements This Water Quality Monitoring project was conducted primarily by Cindy Myers (South Coast Watershed Council), Frank Burris (Oregon State University Extension Service) and Birgit Knoblauch (Experience International Trainee). Funding was obtained from the Port of Brookings-Harbor, EPA Rural Sustainability Grant, Oregon Watershed Enhancement Board, Chetco Watershed Council, Oregon State University Sea Grant and Cal-Ore Enhancement. Experience International and Siskiyou National Forest were responsible for creating the internship that allowed the South Coast Watershed Council to benefit from Birgit s enthusiastic and capable presence. We appreciate the contributions of Dick Laskey, Chetco Watershed Council, for providing his boat and fuel for sampling, and recording daily Secchi disk measurements for the study. Sampling would not have been possible without the help of our volunteers: David de Lucca, Andy Gross, Liesl Coleman, Aaron Fitch, Kai Druzdzel, Matt Swanson, Morgan Kocher, and employees of the Port of Brookings-Harbor. References Grant D. & Dawson B Isco Open Channel Flow Measurement Handbook. Fifth Edition. Lincoln: Isco, Inc. Howarth, R.W., and R. Marino Nitrogen as the limiting nutrient for eutrophication in coastal marine ecosystems: Evolving views over three decades, Limnol. ogr., 51(1, part 2), Maryland Department of Natural Resources Dissolved Oxygen in Coastal Bays. NOAA National Buoy Data Center. Station St. Georges. Historical Data. Oregon Coastal Atlas Chetco Estuary. 23

24 US Army Corps of Engineers Port of Brookings/Harbor, Oregon. Sport Boat Basin. Evaluation of Aeration System Application. Copy of Study. U.S. Environmental Protection Agency (EPA) Mid-Atlantic Integrated Assessment. Estuaries. Waldvogel, Jim Anchovies in Oregon and California Estuaries, Agriculture & Natural Resources. Sea Grant Extension. Crescent City. CA. Personal Communication. 24

25 Appendices Appendix A: Notes from Birgit Knoblauch s Interview of Jim Waldvogel, Sea Grant Extension Agent - There are great masses of anchovies in the. They come into estuaries depending on ocean conditions (currents and food) and their reproductive cycle, this occurs often between June and August. - Anchovies are everywhere, only a small amount comes into the harbors to feed, or sea lions and seals chase them into the basins. - They usually spawn off shore and not in the harbors - In summer, higher temperatures create more algae (phytoplankton) and with a further input of nutrients and sun light they bloom, which attracts more zooplankton that feeds on algae. - Anchovies feed on zooplankton that is mainly available in the summer. They form masses and hang out in harbors mainly to feed. - Anchovies need big amounts of oxygen to survive and since they hang out in masses, they can create hypoxia and even anoxia and die within 24 hours. - Fresh water also kills anchovies within 24 hours. - The major reasons of anchovy die offs are: o High populations of anchovies come into the basin to feed and create too much pressure on the oxygen o Phytoplankton cycle (creating extremer diurnal DO fluctuations, due to higher temperatures and higher photosynthesis or respiration) o Temperatures and specific wind conditions (higher temperatures hold less oxygen and winds have great influence in temperatures and wave action) o Fresh water - There have been two anchovy die offs in the Port of Brookings-Harbor in Anchovies usually feed in the surface, this can cause a problem if the sweet water is present and traps them in the basins. They have no place to escape in the shallow water and consume all the oxygen around them. - There is a normal phytoplankton cycle in estuaries, which is necessary and important for the organisms that live in them. It is normal to have a certain algae growth and the extreme diurnal fluctuations of DO in summer. It is normal to have an algae die off after the summer. - Ones anchovies die, this normal cycle is altered for at least 2 months. With the decaying anchovies, a great amount of hydrogen sulfide is produced which can even corrode boat paint. The nutrient input from the decaying mass rises, having different effects in the WQ and on estuary organisms. This disturbance or alteration of the normal cycle has evidently no effect on the phytoplankton cycle and WQ of the next year. Comments on DO and BOD data: - High DO in August because of more photosynthesis by algae or because of increased boat activity in the summer (they are moving and stirring up the water, acting like aerators) - DO drop in September and October since algae are dieing off - BODs are affected by the nutrient cycle. (I say: high BOD maybe because of nutrients and optimum temperature conditions for microorganisms. They get more active in this period and use up more oxygen) Comments on aerators: - They might create more oxygen for the fish - They might create more algae instead of decreasing 25

26 Appendix B: Sampling Schedules and Comments on Sampling Conditions Sampling Schedule Site Name 7:00-10:00 10:00 13:00 13:00 15:00 15:00 18:00 SBB-N Profile DO, BOD, ph, Turb, ¼ nutrients Profile Profile SBB-S Profile DO, BOD, ph, Turb, ¼ nutrients Profile Profile Other SBB ¼ nutrients Other SBB ¼ nutrients Port entrance Profile, ph, Turb Profile Profile CBB Profile DO, BOD, ph, Turb, ¼ nutrients Profile Profile Other CBB-N ¼ nutrients Other CBB-M ¼ nutrients Other CBB-S ¼ nutrients Chetco Profile, DO, BOD ph, Turb Nutrients Profile Profile Chetco Profile, DO, BOD, ph, Turb Nutrients Profile Profile BH005 Flow, temp, ph, turb, cond, DO, BOD, nutrients BH006 Flow, temp, ph, turb, cond, DO, BOD, nutrients Donavan Buried Pipe Tuttle Creek Flow, temp, ph, turb, cond, DO, BOD, nutrients Flow, temp, ph, turb, cond, DO, BOD, nutrients Flow, temp, ph, turb, cond, DO, BOD, nutrients 26

27 Sampling Schedule Location 7:00-8:00 8:00 9:30 9:30 10:30 10:30 13:00 13:00 15:30 15:30 18:00 SBB-N Prof., temp, DO, Profiles, DO, Profiles, DO, temp BOD, ph & turb temp Nutrient SBB-S Prof., temp, DO, Profiles, DO, Profiles, DO, temp BOD, ph & turb temp Nutrient CBB-M Prof., temp, DO, Profiles, DO, Profiles, DO, temp BOD, ph & turb temp Nutrient CBB between 2 Prof., temp, DO, Profiles, DO, Profiles, DO, temp southern pipes BOD, ph & turb temp Nutrient CBB by shrimp Prof., temp, DO, Profiles, DO, Profiles, DO, temp BOD, ph & turb temp Nutrient Port entrance Prof., temp, DO, Profiles, DO, Profiles, DO, temp BOD, ph & turb temp Nutrient Chetco Prof., temp, DO, Profiles, DO, Profiles, DO, temp BOD, ph & turb temp Nutrient Chetco Prof., temp, DO, Profiles, DO, Profiles, DO, temp BOD, ph & turb temp Nutrient Buried Pipe BH005 BH006 Donovan Tuttle Creek Flow, temp, ph, turb, cond, DO, BOD, nutrients Flow, temp, ph, turb, cond, DO, BOD, nutrients Flow, temp, ph, turb, cond, DO, BOD, nutrients Flow, temp, ph, turb, cond, DO, BOD, nutrients Flow, temp, ph, turb, cond, DO, BOD, nutrients 27

28 Sampling Schedule Location 7:30-9:00 9:00 13:30 14:30 17:30 SBB-N Profile, DO & BOD bottom Prof., DO & BOD mid + bottom, ph, turb, nutrients Profile, DO & BOD bottom SBB-S Profile Prof., DO & BOD mid, ph, turb, nutrients Profile Port entrance Profile, ph, turb Profile Profile CBB-N Profile Prof., DO & BOD mid, ph, turb, nutrients Profile CBB-M Profile Prof., DO & BOD mid, ph, turb, nutrients Profile CBB-S Profile, DO & BOD bottom Prof., DO & BOD mid + bottom, ph, turb, nutrients Profile, DO & BOD bottom Chetco Profile Profile Chetco Prof., DO & BOD mid, ph, turb, nutrients Profile Prof., DO & BOD mid, ph, turb, nutrients Profile, DO mid BH005 BH006 Donovan Buried Pipe Tuttle Creek Flow, temp, ph, turb, cond, DO, BOD, nutrients Flow, temp, ph, turb, cond, DO, BOD, nutrients Flow, temp, ph, turb, cond, DO, BOD, nutrients Flow, temp, ph, turb, cond, DO, BOD, nutrients Flow, temp, ph, turb, cond, DO, BOD, nutrients 28

29 Sampling Schedule Frank + Birgit Frank + Cindy Birgit +Liesl + Kai Location 7:30-9:00 9:00 13:30 14:30 17:30 SBB-N Profile, DO & BOD mid, DO Prof., DO & BOD mid + Profile, DO & BOD mid, DO bottom bottom, ph, turb, nutrients bottom SBB-S Profile Prof., DO & BOD mid, ph, turb, nutrients Profile CBB-N Profile Prof., DO & BOD mid, ph, turb, nutrients Profile CBB-M Profile Prof., DO & BOD mid, ph, turb, nutrients Profile CBB-S Profile, DO & BOD mid, DO Prof., DO & BOD mid + Profile, DO & BOD mid, DO bottom bottom, ph, turb, nutrients bottom Chetco Profile Prof., DO & BOD mid, ph, turb, nutrients Profile Chetco Prof., DO & BOD mid, ph, turb, nutrients Profile Profile, DO mid Port entrance Profile, ph, turb Profile Profile BH005 Flow, temp, ph, turb, cond, DO, BOD nutrients BH006 Flow, temp, ph, turb, cond, DO, BOD nutrients Donovan Buried Pipe Flow, temp, ph, turb, cond, DO, BOD nutrients Flow, temp, ph, turb, cond, DO, BOD nutrients / nutrient at RV Park Flow, temp, ph, turb, cond, DO, BOD nutrients / other nutrients next to pipe 29