In October 2018, we released a report prepared for us by the EcoLogix Group: Protecting the Source and Maintaining Water Affordability. We released the report publicly and presented findings to stakeholders and the public on 10/25/18. You can view a pdf of the report here & the powerpoint presentation can be viewed here.
It is well known that forests and trees provide the first line of defense and foundation for protecting water quality and drinking water. When combined with effective treatment and spill prevention, protecting and increasing forest and tree canopy cover is a key element in the Multiple Barrier approach to public health protection for drinking water supplies. A new report, prepared by the EcoLogix Group for the Maryland Sierra Club, presents a review of data on the relationship between forest and tree canopy loss and stream health in three Montgomery County watersheds immediately upstream from the Potomac Water Filtration Plant water intake: Watts Branch; Muddy Branch; and Seneca Creek.
The report found a loss of tree canopy based on a review of data covering the period 2009-2014. A review of the literature confirms that forested areas are associated with the lowest sediment loadings per acre, and the highest stream biological ratings, compared with other land uses and land cover types. Conversely, within the Piedmont area of the Chesapeake Bay watershed where these watersheds are located, developed areas have been shown to account for a higher total sediment load than agriculture, even though they occupy a smaller area. The report also reviews the potential water quality benefits and numerous co-benefits of forest and tree canopy strategies, compared with two currently planned "gray infrastructure" solutions, at a combined cost of $240 million, for which debt payments would add 2.6% to current water rates. These are projects designed for the single purpose of handling sediment in the water treatment process, at a significant cost, which may make it easier to treat in the short term, but do not prevent or reduce pollution in the contributing watersheds.
Further data is needed in order to monitor and model the sediment pollution trends related to forest loss in the study area, to better quantify the relationship between land cover and sediment pollution trends. Further work is also needed to explore opportunities for forest and tree-canopy strategies, as a basis for estimating actual costs, benefits, and co-benefits of these strategies for the Counties and for the mid-Potomac drinking water supply that serves the entire Washington Metropolitan Area.