There are many substantial differences between the Sooke and Shawnigan watersheds.
The vast majority of the Sooke watershed is owned by one entity, the Capital Regional District, and as such is protected through bylaws that restrict access and development. The Shawnigan watershed contains numerous industrial, institutional and residential developments. These developments, which include logging, transportation systems and construction, have altered the hydrology of the watershed.
Additionally, many of Shawnigan’s waterfront properties have ineffective or non-existent sewage-treatment facilities. It is also worth mentioning that some dock systems on Shawnigan are built of chemically treated wood materials, which pollute the lake. Many Shawnigan landowners have also removed the natural vegetation and introduced lawns and gardens, likely supported by chemicals and fertilizers that end up in the water.
Finally, pollution is also generated by the large number of internal-combustion engines operating on the lake surface itself.
While the Sooke watershed is controlled and preserved by the CRD, the Shawnigan watershed has many users who, by their own actions, are polluting their water supply.