## 3 Results and Discussion
### Optimization of the W1 WQMP - Results and Discussion  
The step to understand the rationale of the WQMP contributed greatly to providing a list of actionable tasks for the optimization of the W1 WQMP. The results from the statistical analysis for the optimization objective: evaluate whether a reduction in sampling frequency, sampling points and number of samples per sampling station (up to three at different depths) which would lead to a loss of information also contributed to the list of actionable tasks. As mentioned in Figure 2, one objective of this lake WQMP was to obtain a spatio-temporal portrait of cyanobacteria, that assesses the cyanobacteria community at different sites and depth throughout the lake and at different times during the ice-free period. The objective was also to find out whether there were any interannual differences. However, the first and foremost objective was to obtain information on the evolution of the eutrophication of the lake. Therefore, at every station (C03, C08, C05, C04, C01 shown in Figure 9) visited at two-week intervals (total of 10 outings every year) from the ice-free season (spring mixing) to fall mixing, a profile of physicochemical and biological parameters was taken at every 0.5 m with a YSI 6600 V2 probe (pH, specific conductivity, temperature, dissolved oxygen, phycocyanin, chlorophyll a and turbidity). In addition, water samples for laboratory analysis of total phosphorous (TP) nitrogen compounds and chloride were also taken at a depth of 1 m, in the meta-limnion and at 1 m from the bottom with a horizontal bottle (when depth permits). These stations were selected in a study conducted prior to the WQMP, the aim at this time was to continue with the same stations considered representative of the heterogenic zones of the lake. The objective of monitoring cyanobacteria was added afterward. The objective was not only to know the distribution of cyanobacteria in the lake but also to determine the locations onshore where they could be observed and sampled for the spatio-temporal portrait. The selection of these stations was first based on an equal spatial distribution around the lake but was then very much influenced by accessibility and permissions to access the lake (SCx in Figure 9). The sampling strategy for cyanobacteria was one sample at the surface (all stations), at the peak of the phycocyanin readings (lake stations) and at 1 m from the bottom (depth permitting - C0x). The sampling was done every two weeks with the other sampling campaign. The results of the analysis proposed by [PERSON] and [PERSON] (2001), showed that there is a relatively consistent factorial structure demonstrating that the distribution of the 29 cyanobacteria species is relatively constant throughout the year and between years The results also show that there is a relatively consistent spatial distribution. For instance, _Planktothrix_ sp. prefers the cold and deep hypolimnion of C08 and C03 (temperature ranging between 6-8 \({}^{\circ}\)C between 10 and 16 m). Species such as _Anabaena_ sp. _Radiocyystis_ sp., _Anabaena_ sp., _Microcytis_ sp., _Aphanothece_ sp., and _Aphanocaps_ sp consistently prefer the epilimnion at all stations, including the shore stations (surface and peak of phycocyanin generally situated in the epilimnion) and _Planktolynthia_ sp. occupies the 4 m zone at station C05, as well as the hypolimnion at 12 m at C08. There is no difference between stations C01 and SC0, as they are very close to each other. The conclusions of this analysis are that either station C01 or SCO could be abandoned and that the sampling frequency (every two weeks) could be significantly reduced. However, before taking a final decision, there are several actionable tasks to be followed which are summarized in Table 1 for the W1 WQMP. Figure 9: Distribution of sampling stations on Lac Saint-Charles (lake). Maximum depth at each station: C03: 17 m, C08: 13 m, C04: 7.5 m, C05: 5 m, and C01: 2 m). Reproduced with permission from [21], APEL, 2019.