TABLE OF CONTENTS

• Figures
  • Figure 1 Location Map of the four lakes
  • Figure 2 Monitoring Sites and Water Withdrawal Points for each lake
• Tables
  • Table 1 Provisional Water Quality Objectives for the four Lakes
  • Table 2 Recommended Routine Water Quality Monitoring for the four Lakes
• Preface
• Introduction
• Hydrology
• Water Use
• Water Quality
• Water Quality Objectives
• Water Quality Monitoring

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 study was requested in late 1981 by the Planning Department of the Regional District of Bulkley Nechako. With the support of the Skeena Region of the Ministry of Environment, the sampling required was completed in 1982. This report summarizes and interprets the data collectd to November 1982.

The original goals of the study were to assess the trophic state of the lakes, and identify the major sources of phosphorus (the nutrient limiting algal growth). It would then be possible to propose water management strategies designed to suggest watershed development guidelines for either septic tank/tile field or sewer systems.

Since the study was initiated the Water Management Branch has developed methods of setting water quality objectives based on water use. Pertinent water quality objectives are therefore included in this report and are designed to protect the most sensitive water uses.

HYDROLOGY

Kathlyn and Seymour Lakes had the highest flushing rates (0.9/year) and 1.1/year, respectively) while Tyhee and Round Lakes had much lower flushing rates (0.2/year and 0.3/year, respectively).

WATER USE

Kathlyn and Tyhee Lakes receive the greatest recreation pressure. There is a public beach on the west side of Kathlyn Lake, while Tyhee Lake has a Provincial Campground (see figure 2).

The lakes have a mixture of coarse and sports fish. Rainbow and cutthroat trout are found in all the lakes. Burbot is caught in Round and Tyhee, while pygmy whitefish is caught in Tyhee Lake. The lakes are occassionally stocked with rainbow trout, but because the coarse fish have not been removed, survival rates of trout are low and fishing pressure on the lakes is light.

The coarse fish were to be removed in 1983 from Seymour Lake by the Fish and Wildlife Branch, and restocked with rainbow trout, but the plans have been indefinitely postponed.

WATER QUALITY

Surface water temperatures approached 20 degrees Celcius in mid-summer. Bottom temperatures (below the thermocline) did not exceed 8 degrees C. Winter temperatures ranged from 1 degree C below the ice to 3-4 degrees C at the bottom of the lakes. Spring overturn occurred in late April or early May, while fall overturn occurred by late October.

The lakes had similar dissolved pxygen conditions. Concewntrations were high in the surface waters throughout the year. Anoxic conditions persisted below the thermocline except for brief periods following spring or fall overturn when oxygen was mixed throughout the watwer column.

The hardness ans alkalinity of Kathlyn and Seymour Lakes were quite low. Although the lakes were not considered sensitive to acid rain, the results were typical for well flushed lakes with volcanic bedrock throughout the watershed. The hardness and alkalinity of Round and Tyhee lakes were 3 to 4 times higher than in the other lakes. A lower flushing rate and deep glacial soils caused the higher mineral concentration.

Based on nutrient concentrations, the lakes were considered eutrophic, Kathlyn being the least eutrophic, Round Lake the most. The major source of phosphorus (the key nutrient causing eutrophic conditions) for Kathlyn Lake was the drainage from the adjacent airport area. High concentrations of phosphorus from fire retardant (diammonium phosphate) used by the Ministry of Forests was draining into the lake. The major source of phosphorus in Round and Tyhee Lakes was the lake sediments. The source of phosphorus causing the eutrophic conditions in Seymour Lake could not be determined from the 1982 data. Further sampling in 1984 by the Waste Management regional office in Smithers will attempt to identify the sources of phosphorus to Seymour Lake.

The contribution of phosphorus from septic tanks was found to be of minor importance to the annual phosphorus budget for each lake.

Lake management strategies have been developed for Kathlyn, Round and Tyhee Lakes. The programs are designed to reduce the lake phosphorus concentration to levels where the nuisance algal blooms and the concomitant poor water quality associated with eutrophication, are eliminated. No management strategies are presented for Seymour Lake because the causes of eutrophication are not yet known.

Diversion of the airport runoff containing diammonium phosphate (the fire retardant used by the BC Ministry of Forests) would reduce the annual phosphorus input to Kathlyn Lake by approximately 50 percent. Installation of aeration systems (either destratification or hypolimnetic) in Round and Tyhee Lakes would eliminate or substantially reduce the release of phosphorus originating from the sediments, reducing the phosphorus loading by approximately 50-60 percent in both lakes.

Additional watershed development should not be permitted until the lake management strategies outlined above are implemented, and the present eutrophic conditions are improved. Watershed development could then proceed on a restricted basis without compromising future water quality. Proper management of the watershed should include setback regulations for septic tank tile fields, and restrictions on the number of new dwellings within each watershed.

Developments should have a minimum 50 m tile field setback on soils with a good ability to renovate septic tank effluent through phosphorus adsorption. On soils determined to have moderate ability, developments should have a 100 m tile field setback and on poor soils they should have a 300 m setback. The setbacks should apply around the lake shore and inflow creeks or streams.

The soils around Kathlyn Lake are considered good for phosphorus adsortption except for the Moricetown-Slug soils on the south and east shore of the lake. Seymour Lake is also surrounded by soils considered to be well suited to adsorb phosphorus. Only the Barrett soils on the south shjore and the Ormund-Pinkutt soils on the west shore are considered poor.

Watershed development should be restricted to 35-55 new units on septic tanks (proper tile field setbacks assumed), or 200-350 new units on sewer (with discharge outside the watershed) in either the Kathlyn or Round Lake watersheds.

Tyhee Lake was considered slightly more sensitive to watershed development. Development should be restricted to 25-45 new units on septic tanks (with proper tile field setbacks) or 250-300 new units on sewer (with discharge outside the watershed). A range of development is suggested for each watershed to give the Regional District flexibility in choosing the appropriate levels of development.

Seymour Lake does not have any development guidelines because the present causes of eutrophication are not known, and lake management strategies designed to improve water quality can not be formulated.

WATER QUALITY OBJECTIVES

The objectives are based on preliminary working criteria for water quality and on available data on ambient water quality, waste discharges, water uses and limnological characteristics. The objectives will remain provisional until receiving water monitoring programs provide adequate data, and the Ministry has established approved water quality criteria for the characteristics of concern.

The objectives can be considered as policy guidelines for resource managers to protect water uses in specified water bodies. For example, they can be used to draw up waste management permits and plans, regulate water use or plan fisheries management. They can also provide a reference against which the state of water quality in a particular water body can be checked.

Water quality objectives have no legal standing and their direct enforcement would not be practical. This would be due to the difficulty of accurately measuring contaminants in receiving water and attributing the contamination exceeding the objective to particular sources for legal purposes, and thus of proving violations and their causes. Hence, although water quality objectives should be used when determining effluent permit limits, they should not be incorporated as part of the condition in a waste management permit.

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 waterbodies and for water quality characteristics which may be affected by man's activity, now and in the future.

The designated water uses proposed for all four lakes are: domestic water supply, industrial water supply, water-contact recreation. irrigation water supply and aquatic life.

Only the fecal coliform and turbidity objectives are applied to Seymour Lake for two reasons. First, the causes of eutrophication are not known and lake management strategies have not been developed, and second, the present water quality does not meet the water quality objectives set for the other lakes. Should the causes of eutrophication be irreversible, a re-evaluation of the designated water uses of Seymour Lake would be required and water quality objectives would be set for these re-defined uses.

The objectives are designed to protect all of the designated water uses, but they are based on the protection of drinking water supplies and water contact recreation such as swimming, the two most sensitive uses for the variables of concern.

Two water quality objectives are proposed for fecal coliform bacteria. The first objective is proposed for all lakes to ensure that no water treatment, in addition to disinfection, is required for drinking water. The second is to ensure safe recreation on the beaches in Kathlyn and Tyhee Lakes.

The provisional water quality objective for fecal coliform bacteria near or in water intakes is: not more than 10% of at least 5 samples from each site in any 30-day period, should have a fecal coliform density greater than 10 MPN/100 mL (i.e., the 90th percentile should be less than or equal to 10 MPN/100 mL).

The provisional objective for fecal coliforms bacteria samples taken at public beaches during summer months is: not to exceed a running log mean of 200 MPN/100 mL, calculated from at least 5 weekly samples taken during the recreation season, nor shall more than 10% of samples during any 30-day period exceed 400 MPN/100 mL.

Nuisance algal growth in lakes, as measured for example by chlorophyll-a, is usually the result of excessive phosphorus in a lake. Algae can cause taste and odours in drinking water, aesthetic problems, poor water clarity and hypolimnetic oxygen depletion which results in loss of fisheries habitat and possible winter or summer kill situations.

A provisional water quality objective for total phosphorus is proposed which will reduce the mean summer chlorophyll-a concentration to 0.004 mg/L. This reduction will change the state of the lakes to mesotrophic from eutrophic. The objective is a total phosphoris concentration of 0.015 mg/L for Kathlyn, Round and Tyhee Lakes. An objective cannot be proposed for Symour Lake until the causes of eutrophication are understood and means for reversal are known. The total phosphorus objective applies at spring overturn to the average of at least 3 samples taken near the surface, at mid-depth and near the bottom, at mid-lake. The objective for phosphorus is not presently being met in any of the lakes, but should be attaunable if the watershed management guidelines outlined are implemented and successful.

Turbidity can be caused by algal growth or suspended sediment resulting from erosion. Turbidity caused by algae growth will not be a problem unless the water quality objective for phosphorus outlined above is exceeded. The provisional turbidity objective for all four lakes is an average of 1 NTU and a maximum of 5 NTU. The objectiove is set to ensure that the water quality is suitable for domestic water supply (the most sensitive use) with no water treatment in addition to disinfection (i.e., no removal of turbidity or suspended residues is required). The objectives for turbidity are being partially met and should be attainable in the long term following the successful implementation of the watershed management guidelines outlined above.

The water use most sensitive to colour is drinking water supply. The provisional water quality objective for colour is a maximum of 15 True Colour Units, measured in any discrete sample of lake water taken near or in a drinking water intake. It is applicable to Kathlyn, Round and Tyhee Lakes. On average, the colour values in Kathlyn, Round and Tyhee Lakes were slightly above the colour objective, but Seymour Lake well exceeded the objective. In Kathlyn, Round and Tyhee Lakes reduction of the phosphorus concentrations and algal biomass, following implementation of the lake management techniques, may reduce the colour values. However, it can not be predicted that the colour will be reduced to the level of the water quality objective. Seymour Lake had a more distinct colour than the other lakes. It was a colour typical of bogs, although not as brown. It is not known if the colour originated from within the lake or from the watershed.

WATER QUALITY MONITORING

Because of physical and chemical similarities between Round and Tyhee Lakes, comprehensive water quality monitoring is only required in Tyhee and Kathlyn Lakes. Only limited monitoring is proposed for Round and Seymour Lakes.

TABLES