Results from the 2017 Water Quality Monitoring Program

Transcription

1 Results from the 217 Water Quality Monitoring Program

2 As part of a larger project, this summer the BWC conducted water sampling throughout the Belleisle Bay to get a baseline of data and determine the overall health and potential areas of concern or inputs (full report ready Winter 218). Water quality sampling was conducted at 8 sample sites throughout the Belleisle Bay at 5 different time points in the 217 field season June to August (Figure 1). In the field, water temperature, conductivity, ph, dissolved oxygen, turbidity, and Secchi disk depth were determined. Water samples were also collected and sent to a lab to determine the E. coli, nutrients, and various metal concentrations for the full dataset, please contact the Belleisle Watershed Coalition (belleislewatershed@gmail.com or info@belleislebay.ca). Figure 1: Map of the 8 sampling sites throughout the Belleisle Bay. Field Parameters Water temperatures, ph, conductivity, dissolved oxygen, turbidity, and Secchi disk depth are determine on the spot in the field and are thus classified as field parameters and are presented in the section below. Water Temperature The temperature of the water is very important water quality parameter as it greatly influences aquatic habitat, particularly fish habitat. Salmonid species, such as Atlantic salmon and Brook 1 P a g e

3 trout, are quite sensitive to high water temperature (above 22 C). Not only does high water temperatures stress fish out, it also affects the amount of dissolved oxygen in the water; which can equally put stress on fish. The water temperatures recorded over the summer in the surface water of the Belleisle Bay showed that temperatures started out around 2 C and increased over the summer as expected (Figure 2a). Large open waterbodies like the Bay are expected to reach high water temperatures due to solar warming of the exposed water surface; especially during a dry summer such as this summer. The values recorded represent the top portion of the water column and is likely that deeper waters would be significantly cooler resulting in fish moving into these deeper areas of the Bay and not a loss or degradation of aquatic habitat. Conductivity Conductivity is the measurement of the water s ability to conduct an electrical current and is measured in microsiemens per centimetre (µs/cm). The conductivity was stable over the majority of the field season but spiked in the August sampling time points (Figure 2b). This spike is likely due to the lower water levels resulting in increased dissolved ions within the Bay. Groundwater has more dissolved ions when compared to surface water and during low-flow periods groundwater infiltration into streams and brooks maintains base flow. These watercourses then feed the Bay, resulting in increased groundwater fractions and could result in a spike of conductivity. ph ph is the measurement of how acid or basic a substance is and ranges from (very acidic) to 14 (very basic) with 7 being neutral. The Canadian Council of Ministers of the Environment (CCME) guidelines for the protection of aquatic life states that the ph of freshwater should range between 6.5 and 9. All ph readings collected over the summer field season in the Bay where within the recommended range for ph (Figure 2c). Dissolved Oxygen The dissolved oxygen or DO is the amount of oxygen dissolved into the water and is a key water quality parameter as it is crucial to aquatic life. Dissolved oxygen has an inverse relationship with water temperature meaning that as the water temperature increases the dissolved oxygen concentrations decreases. For this reason, both DO and temperature become some of the most common water quality parameters. The DO concentrations in the Bay remained within the recommended range, even with increased surface water temperatures in late July and August (Figure 2d). The CCME guideline for dissolved oxygen in freshwater is greater than 9.5 mg/l for early life stages and greater than 6.5 mg/l for all other life stages; as shown by the two red lines on Figure 2d. 2 P a g e

4 ph Dissolved Oxygen (mg/l) Temperature ( C) Conductivity (µs/cm) Figure 2: Graphs of field parameters (temperature - a; conductivity - b, ph - c, and dissolved oxygen with CCME guidelines in red - d) from 8 sample sites throughout the Belleisle Bay over 5 time points in P a g e

5 Water Clarity The water clarity was measured by two different parameters turbidity and Secchi disk depth (Figure 6). Figure 3: A photograph of the Secchi disk being lowered into the water (left) and a vile filled with water to be used for a turbidity reading. Turbidity Turbidity is the measurement of the water s opacity, not to be confused with colour, and is measured by an instrument that passes light through the sample to determine the turbidity in Nephelometric Turbidity Units (NTU). The turbidity can be effected by many things, most likely sediment runoff (brown water), however any particulate in the water such as pollen, microscopic algae, and bacteria can also increase the turbidity. The turbidity readings in the Bellesisle Bay over the summer period were well within expected values (Figure 6). At most of the sites, the highest reading was the first time point (June 26) which is not surprising given the rainy spring and high freshet the probability of sedimentation movement would be high. 4 P a g e

6 Turbidity (NTU) Figure 4: Turbidity (NTU) readings from all 8 sampling site in the Belleisle Bay over 5 time points in 217. Secchi Disk Depth The Secchi disk is used to determine a depth from the surface in which the disk can still be seen and is used to track changes in the clarity of the water (ie. depth of the disk). The deeper sites within the Bay (3, 6, 7, and 8) had a Secchi disk depth between 2 and 4 meters on average. The other sites (1, 2, and 4) are in shallower areas and the disk reached to the bottom on all sampling occasions. Overall, these results suggest that the Bay has very clear water with the potential for good sunlight infiltration into the water column. Lab Parameters To determine the E. coli, nutrients, and metals concentrations samples were sent to RPC in Fredericton and the results are presented in the sections below. E. coli E. coli or Escherichia coli is a bacteria common in the intestinal track of warm-blooded animals including humans. It can also cause serve sickness in humans when ingested and is therefore commonly tested to ensure recreational contact with the water is safe and is monitored diligently in drinking water sources to ensure the water is safe for human consumption. The CCME guideline for E. coli in recreational waterbodies is on average 2 MPN/1 ml or 4 MPN/1 ml in a single sample. As seen in figure 5, the E. coli concentrations for all samples collected were well below any guideline limits. The highest concentrations at all sites except 4 was determined to be in June and is likely due to the large freshet and land-based runoff during the rainy Spring. The highest E. coli concentration at site 4 was 67 MPN/1 ml on August 22; this site is probably due to very low water levels and high water temperature in Earle Cove allow the bacteria to grow at peak growth rates. 5 P a g e

7 E. coli (MPN/1 ml) June 26 July 17 July 26 August 11 August 22 Figure 5: E. coli concentrations from all 8 sampling site throughout the Belleisle Bay over 5 time points in 217. Nutrients Nutrients are vital in aquatic environments and dictate the amount of plant life (algae, cyanobacteria, emergent and submergent vegetation) that the waterbody can sustain. In the aquatic environment, Phosphorus is the most limiting and therefore small increased can support a spike in plant growth. The other common nutrient in aquatic systems is Nitrogen or Nitrate (NO 3 ) however it is less limiting than Phosphorus. Phosphorus Phosphorus was measured as total Phosphorus meaning that the sample was digested and both free or orthophosphate and bound Phosphorus are captured in the reported concentration. Currently, there is no CCME guideline for the amount of Phosphorus in a waterbody however, there is framework to determine next steps to restore, protect, or enhance the water quality. The data collected this summer could be a starting point for this framework in the future. Analyzing the data collected over the summer places the Bay as mesotrophic or mid-range in the classification scale. On average, the first three sites had higher Phosphorus concentrations compared to the other site (Figure 6). This trend is likely due to the water depth; shallower water is generally has more nutrients and plant life due to the ability of sunlight to reach the bottom and wave action mixing with substrate to increase the nutrient concentration. 6 P a g e

8 Nitrate (N mg/l) Total Phosphorus (P mg/l) Jul-17.5 Figure 6: Phosphorus concentrations over 5 time points in 217 at all 8 sampling site in the Belleisle Bay. Nitrate Similar to Phosphorus, the Nitrate concentration varied over the summer but never truly spiked or had concentrations that would cause concern (Figure 7). The CCME guidelines state that the Nitrate concentrations in freshwater should not exceed 13 mg NO 3 /L for the protection of aquatic life however at that concentration the water would be able to support a large amount of plant growth. Natural sources of Nitrogen or Nitrate include sediment and rocks; anthropogenic (human caused) sources include fertilizers, farm runoff (manure), and septic discharge Jul-17.2 Figure 7: The Nitrate (N mg/l) concentration over the 5 time points at all 8 sampling site in the Belleisle Bay. Metals A total of 31 metals were analyzed as part of the water quality monitoring program this year. The most common metals and the highest concentration of metals were the common groundwater 7 P a g e

9 metals Iron, Manganese, Magnesium, and calcium. These metals varied over the field season as groundwater seepage into the Bay and watercourses fluctuated. Other more toxic metals such as Arsenic, Cadmium, and Lead were all at or slightly above detection limits of the lab and therefore at a safe concentration. The one notable spike in metals was in respect to Sodium and is caused by the tidal fluctuations in the Bay. Conclusion The data represented here was collected as a one-year grant provided by the Environmental Trust Fund and as such gives a snapshot of water quality of the Belleisle Bay. In the future, it is recommended that this sampling continue to track changes and determine if this year s results are typical or abnormal for the Bay. In short, the data collected over the field reveals fairy good water quality for both aquatic life and recreational opportunities. As with most waterbodies and watercourses, it is recommended to increase good vegetation buffers between development and the water (ie: vegetated shorelines and riparian areas around brooks) to trap sediment, reduce erosion, and uptake nutrients in order to protect and enhance the water quality of the Bay - for more detailed results and recommendations see the ETF report ready winter P a g e