If you guys aren't already familiar with it, you should look up the Okanagan Lake Action Plan - in short, the issues with the lake's productivity have been noted for decades now and a more detailed look at the how and why then anywhere else in BC. Amongst other things the irrigation control dams on pretty much every tributary act as Phosphorus sinks, thus the lake has lots of Nitrogen but very low Phosphurus and this nutrient imbalance has greatly decreased the primary productivity in the lake. Add to this the ill-fated mysis introduction, over use of water in the Valley and large-scale habitat loss due to uncontrolled lakeshore and tributary development and it should be not surprise to anyone that the lake isn't producing the fishery it could be.
The OLAP is a road map but there has to be the funding in place to put it into action, which of course there isn't. Small one off pieces get taken on as various grants or redirected fine money become available but, such small scale, one-off piece meal work clearly isn't being effective.
Ukee