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LAKE

ROTORUA

SAURABH I BHANU I JAY

CEPT University


Contents INTRODUCTION CATCHMENT LAND USE AGRICULTURAL /FORESTRY ECOLOGY AND BIODIVERSITY ENVIRONMENTAL ISSUES STRATEGIES REFERENCES


FEATURES • • • • • •

LOCATION

CRATER LAKE FORMED 140000 YEARS AGO SURFACE AREA: 80 SQ.KM CATCHMENT : 507 SQ.KM 11M MEAN DEPTH 45 M MAX. DEPTH

• • • Mokoia Island, Lake Rotorua Reference : EBOP,2004b

Rotorua distt., Bay of Plenty, North Island 38O05’S 176O16’E New Zealand


CATCHMENT

Reference : EBOP,2010/2


BUILT UP NGONGOTAHA

ROTORUA CITY

Source : civildefence.govt.nz


LANDUSE

Reference : EBOP,2010/2


Major industry • • • • •

Forestry and wood processing Tourism Geothermal Research and Development (R&D) Agriculture


Agriculture • Dairy and sheep farming • Horticulture remains a relatively minor industry in the Rotorua District • Rotorua’s economic output is estimated at $2.3 billion per year.


Forestry in Rotorua • Rotorua's forestry sector directly and indirectly employs more than 2,500 people and generates an estimated NZ$250 million of income per year


Biodiversity

Elodea canadensis,

Lagarosiphon major

Egeria densa,

C. denersum

Asterionella spp

Melosira granulata,

M. distans

Mougeotia spp.,

Staurastrum spp.


fauna

G.cotidianus,

Galaxias brevipinnis,

Salmo gairdneri*,

S. trutta,


Environment Issues

Water quality in the Rotorua Lake has been declining for at least 30 to 40 years due to increasing nutrient loads (particularly nitrogen and phosphorus).


Environment Issues

Nutrient load:  Farming (animal waste, fertiliser)  Erosion (both natural and accelerated by land disturbance)  Septic tank effluent  Storm water  Community sewerage schemes  Rainfall  Springs  Geothermal sources  Internal loads from lakebed sediment.


Bloom of Blue-Green Algae "Blue-green algae have the potential to release toxins which can affect health by aggravating hayfever and asthma, causing skin rashes, and even neurological effects such as tingling around the mouth, headaches, breathing difficulties and visual problems," A health warning has been issued for parts of Lake Rotorua and Lake Rotoiti after tests found a bloom of blue-green algae. The Bay of Plenty Regional Council said people should avoid any activity which results in significant contact with the water.  If the water looks discoloured, smells unusual, or if there is scum on the surface of lakes or on the beds of rivers, go somewhere else to swim or do motorsports.

Source: ONE New dated 11/05/2009


REGULATIONS

• Clean Water Act (1970) • State Pollution Control Commission Act (1970) • Clean Waters Regulations (1972) Responsible authorities: • State Government • State Pollution Control Commission


STRATEGY FOR THE LAKES OF THE ROTORUA DISTRICT Action plan under development Urgent actions for Lakes Rotorua and Rotoiti include:  Reviewing storm water management The implementation of best management practices to reduce nutrient loads to the lakes. Upgrading Rotorua City’s central sewage treatment plant to reduce nitrogen loading before it enters the forest irrigation system Completing sewage reticulation of various communities around the lakes


STRATEGY FOR THE LAKES OF THE ROTORUA DISTRICT

Approach to Nutrient Reduction


Sustainable measures • • • •

Protection Use Enjoyment Management


Conclusion Protection of lakes is far more feasible and cost effective than attempting to restore them once they have become degraded


Reference • International Lake Environment Committee • Kotwicki, V. (1986) Floods of Lake Eyre. 99 pp. Engineering and Water Supply Department, Adelaide. Gentilli, J. (1971) Climatic tables for Australia and New Zealand. • Corcoran, D. & Kotwicki, V. Personal communication


Lake Rotoroa, New Zealand