Watts Up!
The Watts Branch stream starts in Rockville and enters the Potomac river next to the water intake at the WSSC Water Filtration Plant, carrying every drop of stormwater runoff from its watershed. This stormwater runoff carries sediment and pollutants found along the way and erodes stream channels which add to the sediment load. Therefore, everything we do in this and other Up County watersheds directly adds to our water treatment costs.
In late May, the Montgomery County Group of the Maryland Sierra Club co-sponsored a bus tour of selected sites in the Watts Branch watershed together with Conservation Montgomery and the Watts Branch Watershed Alliance, to explore challenges of protecting our drinking water. Participants in the tour included County Executive Marc Elrich, Rockville Mayor Bridget Newton, the Directors of the Department of Environment, Adam Ortiz, and the Director of Montgomery Parks, Mike Riley and several of their staff members.
Just as watersheds cross political jurisdictions – in this case the City of Rockville and Montgomery County, water within them flows across various kinds of public, private, commercial and residential properties and roadways. This demonstrates the need to use all available tools, break down departmental silos, and engage all sectors in a collaborative process in order to more effectively address runoff problems.
For example, upstream of where the Watts Branch stream intersects with Ambleside Drive, erosion and lateral movement of the stream has exposed two sewer manholes. To stabilize these two short stretches of the stream and install liners in the pipes to prevent sewage leaks, WSSC has built over half a mile of access road at an approximate cost of $750,000 and installed a temporary bridge. In between the exposed manholes there is approximately 2,000’ of eroded stream channel, which also expose Pepco power poles to the stream channel. Restoring the stormwater outfalls and stream channel in between the exposed manholes – while the access road and temporary bridge are in place - would be much more cost-effective than the piecemeal approach, as well as reduce sediment at the drinking water intake, all of which is paid for on our water bills if not through the Water Quality Protection Charge. But WSSC only has a mandate and budget to address exposed pipes to prevent or repair Sanitary Sewer Overflows (SSOs), which is required under a consent decree. To avoid continuing erosion, it will also be necessary to capture and treat stormwater runoff from the source, i.e., upstream roads and land areas that are the primary cause of stream erosion and sediment loads at the water intake. This will require the Montgomery County Departments of Environmental Protection, Parks, Transportation, as well as WSSC, the State Highway Administration and property owners to work together.
The Washington Suburban Sanitation Commission (WSSC) had a proposal, now on hold, to spend approximately $83 million to move their River Road intake pipe to the middle of the Potomac River (known as the proposed mid-river intake). The new intake had been recommended in a 2002 Source Water Assessment (SWA) to avoid the high variability of water quality from Watts Branch during storm events that present challenges for treatment, requiring increased use of chemicals to provide safe drinking water.
However, the runoff is not on hold, and the mid-river intake would not have addressed the increases in sediment loads from Seneca Creek watershed which enters the Potomac a few miles upstream. The SWA had recommended source water protection in the Seneca Creek watershed in addition to the new intake. It is of note that, years earlier, an important justification for establishing the Agricultural Reserve and maintaining rural low-density zoning in the Up County was to protect the public water supply.
Sediment loads from all Up-County watersheds as well as from the Monocacy in Frederick require the addition of treatment chemicals at the Water Filtration Plant resulting in discharges much greater than the loads entering the facility, and in excess of the plant’s discharge permit under the Clean Water Act. A consent decree reached because of a lawsuit originally brought by the Potomac Riverkeeper, joined by the Chesapeake Bay Foundation and the Maryland Department of the Environment requires WSSC to upgrade the capacity of the plant to handle solids, at an estimated cost of $157 million.
Climate change predictions for our area are already producing more intense storm events with larger precipitation amounts. There is no time to waste in capturing stormwater runoff at its source before it reaches the stream and tributaries. Although it may be too late to avoid the cost of upgrading the Water Filtration Plant, we need to ask: what would $240 million, or even just $83 million would buy if invested in nature-based solutions that provide multiple benefits? In addition to protecting and preventing further degradation of water quality, these would sequester carbon, increase resilience to climate change by reducing floods from the increases in intense storms, reduce the urban heat island affect, and improve quality of life.
Watts Branch is a historical legacy. Much of our knowledge about rivers and streams comes from Luna Leopold, a pioneer in the field of fluvial geomorphology, (how water shapes and is shaped by the landscape), who also happened to live in this watershed. Over a 41-year period beginning in 1953, he and colleagues began to record changes in a tributary of Watts Branch, as it transitioned from primarily agriculture to a residential and urbanized watershed. In summarizing three decades of observations he noted that overbank flows increased from two to seven per year as the number of houses increased from 140 to 2060. He observed a widening of stream beds and changes in composition of the materials transported by stream water.
As erosion and flooding carried away trees used as markers, sewer manholes became benchmarks for observing the movement of stream channels. Given the existence of this long-term data set, it would be an ideal watershed in which to develop new, effective restoration practices, and demonstrate what can be done in a deteriorating urban watershed. A total Watts Branch watershed remediation project could become a national model, just as the Ag Reserve is a national model for protecting farmland.
A more detailed version of this article was published by Conservation Montgomery, here. Special thanks to the Watts Branch Tour Committee: Ken Bawer, Sylvia Tognetti, Ginny Barnes, Diane Cameron, Annita Seckinger and Caren Madsen