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Section 10. Discussion:

• Interpretation of Results

• Conclusions

• Implications of Nitrate Results

• Implications of Fecal Coliform Results

• Recommendations for Land Use Management

Interpretation of Results:

1. The levels of nitrates and fecal coliforms of the creek samples were significantly different. Other parameters could not be significantly differentiated among the sites. This may have been related to the nature of the sites. That is, factors such as the presence of wildlife, vegetation and human waste, as well as other natural sources of nutrients and fecal coliforms may cause significantly different results.
2. Although precipitation for all sites was the same in each sampling period, it was statistically significant that at all sites, a change in precipitation resulted in a change in fecal coliform counts. Increased precipitation lead to higher levels of leaching and increased storm water input into the stream, hence an increase in fecal coliform counts. Site six had the highest level of fecal coliforms. Sites four and five had similar levels of fecal coliforms, and site three had its own distinct level.
3. The combination of precipitation and sampling sites location had a significant effect on the level of nitrates. Precipitation did result in a reduction of nitrate levels, however, the reduction was not significant. This may indicate that there is a permanent source of nitrates in the sampled waters. The level of nitrates at site five was not significantly affected by precipitation. Site six had the lowest level of nitrates, and, sites four and five have their own unique group of results.
4. When the variables were compared between the upstream and downstream locations, sites two and three, on Colwood Creek, there was no significant difference in the levels or concentrations of the variables. This may indicate that there is no significant addition of nutrients or fecal contamination along the creek as it passes through RRU property.
5. There were significant differences in the levels of nitrates and conductivity between the two groundwater sites. High levels of nitrate at site eight could be associated with nutrient inputs from the forest. Then, as the groundwater flows toward the Lagoon, some nitrates are taken up by vegetation. When the precipitation increases, the amount of nutrients from the forest floor that enters into the groundwater increases. Conductivity levels at site seven were higher than at site eight. This indicates the possible intrusion of saline water from the Lagoon into the groundwater. Statistical analysis has shown that precipitation does not significantly influence the level of conductivity. However, the combined factor of precipitation and location does have profound effect on the conductivity.

Conclusions:

The Lagoon inlet contributes some fecal coliforms and nitrate into the Lagoon. However, the levels of nitrate inputs are very low. Fecal coliforms were detected during the inflow period into the Lagoon, but again the levels were low (average less than 100 CFU/100ml). Wildlife or backwash from the sewage outfall may contribute to this.

In regard to the fecal coliform counts in Colwood Creek, there are two points that should be considered. First, according to the City of Colwood Landuse Plan, Colwood Creek provides a main overflow drain for storm sewer runoff from area. Second, a report by Levelton Associates said that the highest fecal coliform counts at an upstream location on Colwood Creek was as high as 1400 CFU/100ml. Whereas it was as high as 800 CFU/100ml near the Lagoon. This report, however, did not mention precipitation levels during the sampling period. As well, there were only two samples taken from each site. Compared to this study, the previous levels of fecal coliforms found were much higher. Similar to the conclusion made in the Levelton report, it is concluded that such high counts are associated with storm water input from the City of Colwood. Septic field tank leakage may also contribute. It was mentioned in the land use plan that high sulfate levels in Glen Lake are related to septic field failure near the area (Colwood, 1997) (Reynolds & McLeod, 1996).

Garden Creek originates on RRU property and feeds into the Lagoon. At site four, the levels of all variables, except pH and temperature, were similar to site three. The pH was more alkaline, and the water temperature was higher. This variation may be natural, due to the fact that the three ponds in the Garden Creek system are very biologically productive. Also, although the levels of fecal coliforms in the water was insignificant, the report by Levelton Associates stated that high fecal coliform counts were detected in pond sediments. This is likely due to the many waterfowl that use the ponds.

At the mouth of the Hatley Creek, site five, the average fecal coliform count was the second highest and nitrate level was the highest among any other sites. There are some small drainage-channels passing behind the Mews and CEDAR buildings that feed into this creek. The Levelton Associates report mentioned that there are a couple septic tanks in this area, and that one of them is no longer used. The report stated that in the soil near the septic field, the total and fecal coliforms were greater than 2,400 MPN/100ml. This is a very high count, and it indicates waste contamination. By combining the results of this previous report with the findings of this study, it was possible to deduce that a septic tank may be failing in this area. Further study is required to investigate this. The area near the shore of the Lagoon has considerable amounts of wildlife activity. An old deer skeleton was found in the vicinity of site five. The fact that precipitation does not affect the level of nitrates may indicate a permanent source. It could be an ongoing problem of leaking septic tanks, natural sources locked in bottom sediments, or continuous sources of wildlife waste that leach as nitrates and nutrients.

Site six represents any inputs from the area near the border of the family resource center, as well as the eastern corner of the abandoned cow pasture. While fecal coliform counts at site six were the highest, the nitrate levels were the lowest among all the sites. On one occasion, a distinctive odor, similar to that of human sewage, was detected upstream from this site near the fence bordering the family resource center. There is no known septic tank near the area that belongs to RRU. The family resource center may have a septic tank or field, but this requires further confirmation. Therefore, the source of fecal coliforms in this area could not be determined at this point. It could be from anthropogenic sources, natural wildlife sources, or both. Low levels of nitrates at site six may indicate that a source of the nitrate levels, such as fertilizers, found at other sites does not exist here.

In conclusion, the nature of the nutrient and fecal coliform inputs from RRU grounds into Esquimalt Lagoon is quite complex. In the south-western part of the property, there is evidence of high nutrient and fecal coliform inputs into the Lagoon. Further study is required to determine the actual source. Conversely, the groundwater did not contain fecal coliforms at the time of sampling. The absence of fecal coliform in the groundwater may be due to the fact that the surficial geology is dominated by glacial outwash sands with a thick, well-oxygenated unsaturated zone unfavorable to the survival and transport of fecal coliform (Weiskel, Howes & Heufelder, 1996). That is, fecal coliforms are primarily transported in the soil through flushing or high amounts of precipitation, above 12.3 cm/day (Bitton & Harvey, 1992). Nutrients that originate from the forest may be mostly used by vegetation as they flow towards the Lagoon.

Implications of Nitrate Results:

Implications of Fecal Coliform Results:

Given that the concentration of fecal coliforms in the Lagoon is not uniformly distributed, and the fact that fecal coliform inputs from fresh water inputs tend to be higher, there are some possible explanations.

First of all, being a migratory bird sanctuary, the Lagoon is frequented by a variety of waterfowl. The resident avian population is higher during the winter, as the Lagoon provides wintering habitat. The normalized twenty-four hour based input of fecal coliforms by ducks, geese, and swans are 109, 107, and 109 cfu respectively (Weiskel, Howes & Heufelder, 1996). Thus, high avian populations during the winter could result in the accumulation of fecal coliforms, primarily in shallow areas. A 1996 study discovered that fecal coliform can be deposited and survive for months in the sub-tidal sediments and sea-wrack (Weiskel, Howes & Heufelder, 1996). In the case of the brackish water of Esquimalt Lagoon, a separate study must be done to quantitatively determine the levels of fecal coliforms surviving in the sediments and any populations of wrack that may exist there. The extent of the survival of pathogenic micro-organisms in the sediments is unknown at this point. A study regarding the populations of migratory birds using the Lagoon would be necessary to provide quantitative analysis and modeling.

Secondly, fecal coliforms originating in fresh water inputs has influenced the water quality of the Lagoon. Although levels found in this study were low, precipitation levels determine the degree of contamination at any one time. Urban runoff containing fecal contaminants from pets, as well as those from wildlife and septic tank leakage are some factors that contribute to the complexity of the matter (Weiskel, Howes & Heufelder, 1996). The results of this study indicated that all streams contain fecal coliforms within their water columns.

Recommendations for Land Use Management:

There are a couple of immediate management recommendations that deal with the issue of water quality of Esquimalt Lagoon:

1. As previously indicated, identifying the sources of fecal coliform and nitrates in Esquimalt Lagoon is a complex matter. The community, including RRU and the City of Colwood, places a high value on Esquimalt Lagoon. Therefore, it is advisable that a collective effort be made to tackle this issue. Rather than waiting for every potential source of fecal and/or nutrient contamination to be identified, everybody with a residence or place of work in the Lagoon’s watershed can do something to ensure that they are not contributing to any contamination of surface or ground waters. This can include activities such as checking septic systems for the leakage and stopping the direct discharge of storm water into Colwood creek. These activities should be encouraged by RRU. This encouragement can include lobbying the City of Colwood and the CRD. This can be done even before a further study is completed to fill in some of the existing knowledge gaps. The precautionary principle should be employed in the management of RRU.
2. In terms of water quality, the use of the Lagoon for primary recreational activities, such as swimming, should be avoided in the winter. In the summer, these activities may be safe, provided recent fecal coliform counts are available for consultation. However, considering the potential for sediments to act as a repository for fecal coliforms, as well as the variable role of waterfowl, it is advisable that primary recreational activities be discouraged until studies of these factors can be completed. Secondary recreational activities, such as canoeing, can take place with a degree of precaution. Signs should be posted warning recreationalists of the dangers of primary contact with the water, and, what precautions should be taken if primary contact accidentally occurs.

To Section 11. Future Study

Index:

1. Introduction
2. History and Land Use
3. Geomorphology
4. Nutrients and Coliforms
5. Red Tides and Fish Kill
6. Hydrocarbons
7. Sample Procedure
8. Analysis Procedure
9. Results
10. Discussion
11. Future Study
12. References
13. Photo Album

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Articles	Projects	Resume	Cartoons	Windsurfing	Paintings	Album