Fish habitat in jeopardy
by Rob Munro
The Daily Courier
September 15, 1997
The future is gloomy for Okanagan Lake kokanee. Even though a ban has been imposed on fishing for the landlocked salmon they may still have trouble surviving because of continued impact on spawning streams.
“I’m getting more and more pessimistic about the situation,” said Bruce Shepherd, senior fisheries biologist with the Ministry of Environment.
“Man wants to live along streams and they want to build right on the bank because it’s a nice environment — until they get flooded. Then, they want to build big walls along the creek.”
Mission Creek is a prime example of what’s wrong.
It’s the largest single source of water for Okanagan Lake and the major spawning stream.
Yet, it’s accommodating a mere 10 per cent of spawning kokanee compared to the 1970s.
Shepherd doesn’t expect it to get any better.
The creek was confined behind dikes after the 1948 flood. A small dam in Mission Creek Park was removed in the 1970s, allowing gravel to wash downstream, filling in spawning areas.
The creek was dredged 10 years ago and again a few weeks ago.
“The dredging in Mission Creek is not going to do the fish any favours,” Shepherd said.
Channels were dug out and spawning gravel put into the stream bed to make it suitable for the fish.
Unfortunately, an unusually heavy rainstorm last week pushed flows to five cubic metres per second from 1.2, washing much of a protective berm into the creek and damaging the prepared spawning beds.
Last year, 23,000 kokanee laid their eggs in Mission Creek while another 12,000 used the man-made spawning channel in Mission Creek Park.
That was up from the previous year, but far below even the 1991 and 1992 runs when the spawning channel was filled to its 20,000-fish capacity.
While that channel isn’t filling to capacity, that doesn’t mean additional spawning channels, further downstream, couldn’t increase the creek’s capacity, Shepherd said.
But land along the creek is privately owned so there’s no room for a spawning channel.
Work on Mission Creek Greenway isn’t helping, Shepherd said.
That project included swapping old creekbed outside the dike — ideal for future spawning channels — for land along the dike.
But Mission Creek isn’t the only problem.
A 1992 study identified seven of Okanagan Lake’s most important spawning streams and recommended their flows be regulated to benefit fish more than humans.
Those included Mission, Bear (Lambly), Peachland (Deep), Powers, Trepanier, Kelowna (Mill) and Vernon creeks.
Since then, Penticton Creek has become more important while Bear and Vernon creeks have dropped off.
Except for Mission Creek, they all have a common deficiency — too little water.
“We could double fish production if we boosted the flows,” Shepherd noted.
But the water in those creeks is being used for irrigation and drinking. The only way to increase fall and winter flows enough to boost spawning would be to build expensive upland dams.
While Shepherd would like more water, the irrigation districts that hold licences on those creeks aren’t the villains.
Peachland administrator Bill Brown pointed out that his municipality pumps water from Okanagan Lake into Trepanier Creek when it dries up in the late summer.
“We pump water uphill for them, at great expense,” Brown noted.
He acknowledged that greater flows would help fish — it’s just that no one has the money to spend on dams.
A third human influence is the level of Okanagan Lake.
“Flood control efforts meant we lost half the shore spawners last spring,” Shepherd noted.
Twenty-five to 75 per cent of kokanee spawn along the lake shoreline.
Because of the huge snowpack, efforts were made to lower Okanagan Lake farther down than usual in the spring.
That work paid off from a flood control perspective — keeping the lake 10 feet below where it could have peaked.
But it destroyed the eggs of half the 10,000 kokanee that spawned along the shoreline.
Because of continued high lake levels, Ministry of Environment officials are struggling to get the lake down to its target level by mid-October when the shore spawning starts.
Ministry engineer Brian Symonds expects to be back on target by the end of September. That means dropping the lake by 18 – 20 centimetres.
He does that by letting out more than 60 cm a second at Penticton — enough water to fill a community swimming pool in one second, but only lowers the lake by 1 – 1.5 cm a day.
Normally, the outflow rate drops to 10 – 15 cm a second by mid-September. That’s essential for sockeye salmon that spawn in the Okanagan River channel below Vaseux Lake.
If they spawn in high water the eggs may dry out when the river drops.
Symonds, therefore, has the challenge of balancing the needs of the kokanee and sockeye. His success at that task depends on how much it rains this fall. Too much precipitation could hurt both salmon runs.