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Early melt coupled with lack of rainfall caused 2015 water shortage

Lack of June rainfall causes unanticipated drops in water levels

Last year's drought came unexpectedly to water managers in the Okanagan.

Anna Warwick Sears, executive director of the Okanagan Basin Waterboard, said it was simply a strange year that didn't follow normal patterns.

"Last year we didn't have a very heavy snowpack, and it was just warm," Sears said. "No one was really concerned about flooding last year, even with the early melt. The lake level went up, but the managers were more or less able to deal with it. It was high for that time of the year, but it wasn't flooding conditions. The lake filled up faster and earlier than normal, so they had to release water to make room for the June rain, then we didn't get that rain."

Statistically, June is the month where the Okanagan sees the most precipitation. Coupled with higher than usual water levels through May, an average June would have caused real concern for flooding, so water was let out to make room for the June rains. However, June didn't just come in below average in rainfall. It came in far below average, only raining a handful of times, and was unusually hot.

"It wasn't just hot in June, it was also hot in May, so people started irrigating more," Sears said. "When people start irrigating more, they're using more and more water from the reservoirs. Most people started with pretty good reservoirs last year, but when you start using them early, and the hotter it is, the more water you need to irrigate with. Then the rains didn't come in June to relieve the irrigation demand. Then it was hot and dry in July, and we were lucky it cooled down in August. It slowed the irrigation demand, even though it didn't break the drought."

While last year's drought will have little to no impact on water levels this year, Sears noted the ecosystem will be feeling repercussions in the future.

"We were expecting hundreds of thousands of sockeye salmon to come back here into the Okanagan river system," she said. "I think it was only something like ten percent of them that returned, so it had a harsh impact on that. If you hardly have any salmon spawning in one year, then when those little salmon fry emerge, grow up here and go out to the ocean, there won't be many of them that come back. So really, we're going to see the impact four years from now when we see very few salmon come back."

So far this year, Sears isn't anticipating a water shortage. The snowpack in the mountains is currently well above average, and she noted there is no doubt we will go into summer with full reservoirs and lakes. Instead, the question is how fast the melt will be. With such a large snowpack, a fast melt could mean high flow events at Mission Creek and other waterways, which could cause erosion and difficulties for people living nearby. Additionally, waterways that don't have a reservoir above them would be negatively impacted by a fast melt. A fast melt coupled with dry weather would lead to very low stream flows, which is currently a very real concern for fisheries and the Water Board.