Canadian Cataloguing in Publication

Hall, R. A.
Sechelt Area: Pender Harbour water quality assessment and objectives

[Vol. 2] constitutes technical appendix.
Includes bibliographic references.
ISBN 0-7726-1571-3

1.  Water quality - British Columbia - Pender Harbour.
I.  British Columbia.  Water Management Division. II.  Title: Pender Harbour Water Quality Assessmernt and Objectives.


TD227.B7S42 1992    363.73'942'0971131    C92-092210-4

TABLE OF CONTENTS

• Canadian Cataloguing in Publication Data
• Summary
• Figures
  • Figure 1. Location of Pender Harbour
  • Figure 2. Pender Harbour Study Area
  • Figure 3. Pender Harbour Sampling Sites
• Tables
  • Table 1. Provisional Water Quality Objectives for Pender Harbour
  • Table 2. Maximum Concentration of Total Ammonia Nitrogen for the Protection of Saltwater Aquatic Life
  • Table 3. Average 5 to 30 Day Concentration of Total Ammonia Nitrogen for the Protection of Saltwater Aquatic Life
  • Table 4. Polycyclic Aromatic Hydrocarbon (PAH) Sediment Objectives for Pender Harbour
    (micrograms/gram dry weight)
  • Table 5. Recommended Water Quality Monitoring for Pender Harbour
• Preface
• Introduction
• Hydrology and Oceanography
• Water Uses
• Waste Discharges
• Water Quality
• Water Quality Objectives
• Monitoring Recommendations

SUMMARY

The main water quality concerns in Pender Harbour relate to leachate from septic tile fields and agricultural runoff, as well as sewage effluent and other contaminants originating from boats. These sources have caused elevated fecal coliform levels that have resulted in shellfish harvesting closures but primary-contact recreation is not currently at risk. The extent to which the waters and sediments are impacted by other contaminants such as heavy metals is largely unknown until additional monitoring can be conducted. Nutrient enrichment is not considered to be a significant threat in Pender Harbour.

FIGURES

PREFACE

Water quality objectives are prepared for specific bodies of fresh, estuarine and coastal marine surface waters of British Columbia as part of the Ministry of Environment, Lands and Parks' mandate to manage water quality. Objectives are prepared only for those waterbodies and water quality characteristics that may be affected by human activity now or in the near future.

Water quality objectives are based the BC approved and working criteria as well as national water quality guidelines. Water quality criteria and guidelines are safe limits of the physical, chemical, or biological characteristics of water, biota (plant and animal life) or sediment which protect water use. Objectives are established in British Columbia for waterbodies on a site-specific basis. They are derived from the criteria by considering local water quality, water uses, water movement, waste discharges, and socio-economic factors.

Water quality objectives are set to protect the most sensitive designated water use at a specific location. A designated water use is one that is protected in a given location and is one of the following:

• raw drinking water, public water supply, and food processing
• aquatic life and wildlife
• agriculture (livestock watering and irrigation)
• recreation and aesthetics
• industrial water supplies.

Each objective for a location may be based on the protection of a different water use, depending on the uses that are most sensitive to the physical, chemical or biological characteristics affecting that waterbody.

Water quality objectives routinely provide policy direction for resource managers for the protection of water uses in specific waterbodies. Objectives guide the evaluation of water quality, the issuing of permits, licences and orders, and the management of fisheries and the province's land base. They also provide a reference against which the state of water quality in a particular waterbody can be checked, and help to determine whether basin-wide water quality studies should be initiated.

Water quality objectives are also a standard for assessing the Ministry's performance in protecting water uses. While water quality objectives have no legal standing and are not directly enforced, these objectives become legally enforceable when included as a requirement of a permit, licence, order, or regulation, such as the Forest Practices Code Act, Water Act regulations or Waste Management Act regulations.

Water quality objectives are established to protect all uses which may take place in a waterbody. Monitoring (sometimes called sampling) is undertaken to determine if all the designated water uses are being protected. The monitoring usually takes place at a critical time when a water quality specialist has determined that the water quality objectives may not be met. It is assumed that if all designated water uses are protected at the critical time, then they also will be protected at other times when the threat is less.

The monitoring usually takes place during a five week period, which allows the specialists to measure the worst, as well as the average condition in the water.

For some waterbodies, the monitoring period and frequency may vary, depending upon the nature of the problem, severity of threats to designated water uses, and the way the objectives are expressed (i.e., mean value, maximum value).

INTRODUCTION

The purpose of this report is to assess the current water quality of Pender Harbour and to develop water quality objectives for use by resource managers. A detailed technical appendix was prepared and forms the basis for the conclusions presented in this report.

HYDROLOGY and OCEANOGRAPHY

During months of heavy rain, flushing in Pender Harbour is accelerated due to the entrainment of saltwater by outflowing freshwater (known as "estuarine-type circulation"). The watershed area for the harbour is 58 km² and the months of November through March have the heaviest rainfalls, with monthly freshwater inputs averaging in excess of 7 x 10⁶ m³/month. This is a significant volume in comparison with the total volume of the harbour of approximately 35 x 10⁶ m³. Estuarine-type circulation models predict that such inputs can result in a flushing time of 6 days or less. Combining this with the predicted tidal flushing time of 3 days results in a combined median flushing time of 2 days or less duing the winter months.

WATER USES

The fisheries resources of Pender Harbour are diverse and encompass important recreational and commercial fish stocks. Several streams entering the head of the inlet support spawning populations of coho and chum salmon as well as cutthroat and rainbow trout. Chinook salmon, rockfish, perch and herring are all known to frequent the harbour and crabs constitute a well-used recreational fishery. Clams and oysters are abundant in several areas, although these shellfish are currently subject to a harvesting closure due to excessive fecal coliform levels.

Waterfowl are also important users of Pender Harbour with a variety of species overwintering in the surrounding area. A number of locations in the harbour serve as feeding areas for these birds.

Pender Harbour supports very little industrial/commercial activity in the harbour other than the marinas catering to boat-owners and sport fishermen. There is only one waterfront fish processing plant currently in operation, although a number of commercial fishing vessels continue to utilize the harbour's mooring facilities. There is also one active oyster lease in Pender Harbour.

WASTE DISCHARGES

Although most homes and businesses around Pender Harbour are serviced by septic tanks with tile fields, local soils are generally poorly suited for the renovation of septic tank effluents. As a result, some effluent leachate reaches the harbour and contributes to nutrient and bacterial loading. Small agricultural enterprises at the eastern end of the harbour are also a source of fecal contamination.

Boats are a significant source of bacterial loading to the harbour. Their sewage discharges tend to be concentrated and, since most boats tend to moor or anchor in relatively shallow water, localized areas of elevated coliform levels can be expected to occur. Boats are also a potential source of a number of metals and fuel-related contaminants. It is expected that these materials may exist at elevated concentrations, particularly in the sediments surrounding large docks or marina facilities.

WATER QUALITY

Septic field leachate, agricultural runoff and boat discharges are also sources of nutrient (nitrogen and phosphorus) loading to the harbour. Background variability is so great and the receiving volume of the harbour is so large, that nutrient inputs are not anticipated to significantly impact water quality in the harbour. The possibility does exist that deeper waters in the harbour may trap and concentrate nutrients over a period of time, and this may cause brief pulses of enrichment during periods of complete mixing of the harbour.

Bargain Bay, which forms a southern appendage to Pender Harbour, has generally superior water quality due to better flushing. Only very localized areas of this bay surpass shellfish growing criteria and at no time is primary-contact recreation compromised. Nutrient enrichment problems are not expected in this bay.

Non-bacteriological water quality data for Pender Harbour are extremely sparse, but there is slight evidence of possible heavy metal contamination, particularly of the sediments. This is consistent with other reports of metal contamination in association with large numbers of boats. Metals of concern include copper, zinc, lead and iron. There are currently insufficient data to draw any firm conclusions related to these metals in Pender Harbour. Although no ambient data are available, tributyl tin and polycyclic aromatic hydrocarbons are also of some concern in the harbour because of their known linkage with boats.

Dissolved oxygen levels are somewhat depressed in Pender Harbour, but this is expected in an enclosed bay with restricted flushing.

WATER QUALITY OBJECTIVES

Water quality objectives have no legal standing and are not directly enforceable. They can be considered as policy guidelines for resource managers to protect water uses in the specified water bodies. They will guide the evaluation of water quality, the issuing of permits, orders and licences and the management of the fisheries and of the Province's land base. They will also provide a baseline reference against which localized water quality can be compared and decisions for basin-wide water quality studies assessed.

Depending on the circumstances, water quality objectives may already be met in a water body, or may describe water quality conditions which can be met in the future. To limit the scope of the work, objectives are only being prepared for water bodies and for water quality characteristics which may be affected by man's activity now and in the foreseeable future.

The designated water uses for Pender Harbour are for the protection of aquatic life, harvesting of shellfish (in Bargain Bay only), and primary-contact recreation. Water and/or sediment objectives have been proposed for the following characteristics of concern: microbiological indicators, nitrogen, copper, zinc, lead, iron, tributyl tin, polycyclic aromatic hydrocarbons and dissolved oxygen. Oil and grease films are recognized as nuisance conditions that should be minimized to the greatest extent possible.

Most objectives correspond to approved or working provincial criteria for water quality. Exceptions include the objective for microbiological indicators which has been modified to conform to the new Health and Welfare Canada criteria to protect primary-contact recreation (geometric mean of less than or equal to 350 enterococci/L). Sediment objectives as given in Table 1 for copper, zinc, lead and polycyclic aromatic hydrocarbons are based on objectives developed for Burrard Inlet, since Provincial sediment criteria are not available. There are also no Provincial criteria for tributyl tin, so this objective has been set at a maximum of less than or equal to 0.001 micrograms/L in accordance with the Canadian Water Quality Guidelines.

MONITORING RECOMMENDATIONS

The recommended monitoring program is based on technical considerations. Regional priorities and considerations may limit or expand this program.

TABLES