The Card Brook Watershed covers 4,217 acres, beginning with its headwaters in western Lamoine and Hancock. A little more than half of this acreage is in Ellsworth, where these tributaries meet in a large wetland between Route 1, Main Street, High Street, and the City’s border. From the wetland, Card Brook flows under High Street (near Pizza Hut) and Water Street and into the Union River near Indian Point.
Card Brook Water Quality
Water quality monitoring done by the Maine Department of Environmental Protection (DEP) in August 2006 at two sites on Card Brook—one above High Street and the other below Water Street—has shown that the stream does not meet water quality standards for bacteria, dissolved oxygen, and aquatic life for a Class B stream. This data labels 1.2 miles of Card Brook as an impaired water body.
Now that Card Brook is on the State’s list of impaired water bodies, the State has been required under Section 303(d) of the Clean Water Act to establish a Total Maximum Daily Load (TMDL) for the stream. The TMDL is a calculation of the maximum amount of a pollutant that the particular water body can receive and still safely meet water quality standards. It is the responsibility of the City of Ellsworth to implement the TMDL in the coming years and work to improve the brook’s water quality.
Why is Card Brook impaired?
It is likely that multiple types of nonpoint source pollution are impacting the water quality of Card Brook. Nonpoint source pollution—as opposed to a “point source” of pollution such as a pipe running from a parking lot into a stream—is gathered up from the landscape as rainwater and snowmelt flow to lower elevations and eventually into a water body. When this stormwater falls on undeveloped land or other porous surfaces, its rate of flow is slowed down, much of it percolates into the soil, and any impurities are somewhat filtered out. However, when stormwater falls on impervious surfaces such as roads, parking lots, roofs, and compacted soils, it flows until it reaches a pervious surface or a water body, collecting pollutants along the way. In a heavily developed area such as the part of High Street through which Card Brook runs, a significant volume of water and any pollutants present quickly run off of building roofs, the parking lots, sidewalks, and roads and into the stream.
This “urban residue” picked up by stormwater includes:
To account for all of these potential nonpoint source pollutants, the DEP has chosen to use % impervious cover as a single “surrogate” pollutant that represents stormwater volume and all nonpoint sources in the calculation of the TMDL. The percentage comes from the area of the watershed which is covered by impervious surfaces relative to the total area of the watershed. The TMDL has established a target of 6% impervious cover in the Card Brook Watershed to improve water quality. Currently, 7% of the watershed is covered by impervious surfaces.
Though it may seem that 1% is a small difference, the DEP has calculated that reducing impervious cover by that amount will result in a 14% reduction in stormwater runoff volume and associated pollutants. This reduction does not need to be accomplished by literally removing 1% of the watershed’s impervious surfaces—instead, applying Best Management Practices (BMPs) and Low Impact Development (LID) techniques to problem areas will help eliminate the impact that the 1% impervious cover has had on water quality.
The City must implement the TMDL for Card Brook, which includes identifying specific sources of stormwater runoff, addressing these issues with BMPs and LID, and providing for the prevention of future degradation through improved stormwater control ordinances.
The City will also apply for federal funding to create a Watershed Management Plan under Section 319 of the Clean Water Act. Watershed Management Planning works to actively involve all stakeholders in the process of planning for the long-term improvement and protection of water quality.
On January 25th, 2012 the City held a joint workshop of the Planning Board, City Council, and Card Brook Watershed stakeholders to begin a discussion on Card Brook’s water quality and impaired status, introduce attendees to the successes of LID techniques in other watersheds, and set the stage for pursuing funding to create a long-term Watershed Management Plan. The workshop featured presentations from LaMarr Clannon of Maine Nonpoint Education for Municipal Officials (NEMO) and Maine DEP Stream Specialist Melissa Evers.
View the Maine NEMO presentation, “Water Quality and Low Impact Development.”
View the Maine DEP presentation, “Impervious Cover/Stormwater TMDL.”
Learn more about the TMDL from the DEP: "Card Brook TMDL Summary."
View a map of the Card Brook Watershed.
October 2013 Maine Townsman Article: Best to Get Ahead of ‘Impaired’ Waterways
Maine Stormwater Best Management Practices Manual – Maine DEP
Low Impact Development – U.S. EPA
Responding to an Impervious Cover-Based TMDL – University of Connecticut Center for Land Use Education and Research
Handbook for Developing Watershed Plans to Restore and Protect Our Waters – U.S. EPA
UNH Stormwater Center – University of New Hampshire