Ministry of Works' engineers and workers who built the Benmore dam would never have dreamt that almost 50 years later the lake they created would become the second most popular in New Zealand for fishermen.
The latest national angler survey undertaken by the National Institute of Water and Atmospheric Research (Niwa) ranks Lake Benmore second only behind Lake Taupo as the most-fished lake in New Zealand.
It also makes it the most popular fishing lake in any fish and game council region - Lake Taupo is administered by the Department of Conservation.
That has come as a surprise to the Temuka-based Central South Island Fish Council, which is responsible for administering freshwater angling at Lake Benmore.
"It's hard to conceive - we thought other lakes such as Lake Wanaka would have ranked ahead," fish and game officer Mark Webb said.
But Mr Webb regarded the survey result as "a good news story", with economic spin-offs for towns in the vicinity.
Kurow-based fish and game officer Graeme Hughes, who has lived in the area for 32 years, was less surprised by Benmore's rapid growth in angling popularity, but still did not expect it to be so highly ranked.
He recalled his father driving from Christchurch to fish the lake when it was filled and the fish population exploded in both size and numbers.
But he never expected it to be so popular almost 50 years later.
The Niwa survey, the third, is carried out every six to seven years on behalf of fish and game councils.
Preliminary results are available to fish and game councils, and the final report has yet to be released.
The huge growth in Benmore's ranking is reflected in the figures.
The lake is open for fishing all year, providing an outlet for anglers outside the normal season.
In the 1994-95 season, angler use of Lake Benmore was estimated at 13,000 angler days, placing it eighth most-fished in New Zealand of the fish and game council-administered lakes (which excludes Lake Taupo).
Ahead of it were Lakes Rotoiti (43,370 anglers days), Rotorua (40,190), Wanaka (25,530), Dunstan (22,250), Wakatipu (21,410), Waikaremoana (20,620) and Hawea (18,820).
In 2001-02, Lake Benmore at 22,000 angler days was ranked sixth, behind Rotoiti (43,080), Hawea (28,160), Wanaka (25,530) and Dunstan (22,250).
In the latest survey over the 2007-08 season, Lake Benmore had jumped to the top of the fish and game council lakes list with 57,000 angler days.
That represents "an immense increase" - 475% - since the first survey was carried out.
And, despite greater fishing, the lake's stocks of brown and rainbow trout and chinook and sockeye salmon are holding their own.
"Complaints of lack of fish that might be expected to accompany such an increase have been absent, indicating the lake was either underutilised previously or the productivity of the fishery has increased to sustain the extra angler attention," Mr Webb said.
Anglers were quick to voice their disappointment if fishing quality fell.
In the early 1990s, they were vocal about the condition of fish during an infestation of shagworm.
"If the fishery was in the same condition it was 10 years ago, we would have been in deep trouble," he said.
In fact, the variety of sports fish has increased.
Salmon from farms on hydro canals above Lake Benmore have escaped into the lake, and the fish and game council has also released chinook salmon, including 22,000 in the latest release, in early 2008.
The resurgence of sockeye salmon over the past three years - the latest population was estimated at more than 8000 - has also added to the food source for trout and chinook salmon.
Acoustic surveys undertaken by Niwa of fish population in the lake, along with returns from the annual Haldon Christmas competition weigh-ins, show fishing has actually improved in recent years, both in terms of numbers and condition.
The acoustic surveys indicate Benmore is one of the South Island's most productive lakes, helped by major spawning rivers such as the Ahuriri, Tekapo, lower Ohau and Twizel, and other smaller streams.
So what is behind the increase in popularity?
Mr Webb and Mr Hughes agree on the cause.
Apart from its continued productivity and a growing word-of-mouth reputation, including with international anglers, the lake is also easily accessible both on foot and in boats.
A wide range of accommodation and services is available close by in towns such as Kurow, Otematata, Omarama and Twizel.
Accommodation ranges from "freedom camping" at reserves along the shores of the lake, offering families cheap holidays and growing in popularity, to well-equipped holiday parks and and luxury level in nearby towns.
The lake also has a good number of public boat ramps.
Boat ownership has increased markedly in recent years, which has encouraged more fishing, and the lake is suitable for a wide range of water-based recreation.
"You can go fishing in the mornings and evenings, then the rest of the day take the kids out on their water toys," Mr Hughes said.
The lake is within easy distance of major urban centres, but still offers the "wilderness experience" with magnificent scenery and, usually, good weather.
It is rarely unfishable.
Even when the rivers flood and discolour the lakes, there is usually still good fishing around its edges.
Canadian angler Donn Holmes can attest to that. This is his seventh visit to New Zealand, and fifth to the Omarama area.
On a recent Sunday, he was fly fishing the lake edge at Pumpkin Point because rivers in the area were running high and dirty.
In about an hour, he had hooked two good brown trout, the heaviest about 2.3kg.
Most of the fishing is by those who hold licences with the Central South Island Fish and Game Council, but the latest survey showed 20,000 angler days were put in by Otago and North Canterbury licence holders.
Mr Hughes thinks the fish and game council has been doing the right thing in terms of managing the lake's fishery.
But the survey results have raised awareness the lake also needs to be closely monitored.
"We have to take even more notice of what is happening to maintain and because of its popularity," he said.
Lake Benmore
Filling started November 30, 1964.
Filling completed January 14, 1965.
Area: 79sq km.
Shore length: 116km.
Volume of water: 2036 million cu m.
Maximum depth: 96m.
Fishery: brown and rainbow trout, sockeye and chinook salmon.
Season: all-year to full-season licence holders.
Limit bag: four sports fish, of which two can be salmon.
Angler days: 1994-95, 13,000; 2001-02, 22,000; 2007-08, 57,000.
