Maine Stormwater Conference

Watershed Management

Tuesday, November 17

Presentations from the 2015 Conference are available here.

8:30 – 10:00
Session IV – What’s up in the Creek: An Update on the Long Creek Restoration Effort

8:30 – 10:00
Panel Discussion
Long Creek Watershed Management District staff and experts will provide a status update on the efforts to restore Long Creek. Learn about restoration successes and challenges and where future efforts will be focused.

10:30 – 12:00
Session V – Expanding the Toolbox: Approaches to Watershed Assessments

10:30 – 11:00
The Ability of Streams to Withstand the Effects of Urbanization
Tom Danielson, Maine Department of Environmental Protection

The Biological Monitoring Program completed its study of the effects of impervious cover (IC) in watersheds on Maine’s stream algae and macroinvertebrates. The risk of not attaining Class AA/A biological criteria increases in the range of 1-3 percent IC. Between 3-6 percent IC, there is an increased risk of not attaining Class B biological criteria. Finally, there is an increased risk of not attaining Class C biological criteria in the range of 10-15 percent IC. The location of IC in a watershed matters. In general, watersheds with development close to the streams had poorer quality macroinvertebrate  communities than streams with intact riparian corridors. Although IC is commonly used as a surrogate for urban development, IC is only one of many factors that influence urban stream conditions. In addition to IC, stream quality is determined by the condition of riparian corridors, flood plains, in-stream habitat, stream bank stability, water flow, water temperature, habitat fragmentation or isolation, specific conductance, nutrient enrichment, and toxic chemicals. IC can influence many of the factors listed above, but natural conditions and non-IC stressors also influence the factors listed above and ultimately determine how resilient a stream is to IC. A stream may be more resilient if the other factors are favorable to healthy aquatic communities. In contrast, some streams may be more susceptible to IC if the other factors are not favorable to healthy aquatic communities. In general, resource managers should be cautious about focusing watershed protection and restoration plans only on IC.

11:00 – 11:30
A Method for Subwatershed Prioritization: Sebago Lake and the Water Quality Index
Kate McDonald, Cumberland County Soil & Water Conservation District

Sebago Lake is Maine’s deepest and second largest lake, a popular recreation destination, and is used by the Portland Water District (PWD) to provide drinking water to nearly one in six Maine residents. It’s also surrounded by a 450 mi2 watershed, which is dotted with other popular lakes. The water quality of the lake is so outstanding that it is exempt from the filtration requirements of the federal Safe Drinking Water Act.

In the past 15 years more than a dozen “319” projects – watershed surveys and subsequent erosion control projects funded in part under Section 319 of the Clean Water Act – have been completed in Sebago Lake subwatersheds. Generally a subwatershed was chosen for work primarily because there were citizens and/or organizations interested rather than to address the most important problems. The PWD offered cash and in-kind match to these projects under the philosophy that improvements anywhere in the watershed benefit the lake. Recent policy changes initiated by EPA require that a Watershed-based Plan be completed as a prerequisite to eligibility for 319 funds. Unfortunately, the recommended methodology for a watershed-based plan isn’t feasible for such a large watershed.

The PWD partnered with the Cumberland County Soil and Water Conservation District and others to evaluate each of the 50 subwatersheds and rank them in order of importance to the overall water quality of Sebago Lake. The method took into account present water quality, water quality trends, land use, and the engagement of local organizations and involved only a limited collection of new field data.

11:30 – 12:00
Defining Maximum Extent Practicable to Meet Watershed-Scale Receiving Water Quality Goals
Renee Bourdeau, Geosyntec; Rob Roseen, Horsley Witten

As current development and redevelopment trends continue to focus on green infrastructure, federal, state and local agencies are setting new rules that require the water quality storm event to remain on site by infiltration, evapotranspiration or reuse to the maximum extent practical (MEP). To meet this requirement, a better understanding of what constitutes MEP would be helpful. The definition of MEP is often left up to interpretation by the designer and the reviewer of each individual project. The use of MEP to allow flexibility in adapting green infrastructure for watershed based planning appears to be extremely beneficial for targeting scarce resources. Typical stormwater management is in many ways opportunistic and driven by redevelopment cycles in which new sites are gradually upgraded over time through change of ownership. Communities are now beginning to consider watershed-scale redevelopment stormwater management for both MS4 and NPDES wastewater permits. Opportunities arise to plan on a watershed scale to identify the most beneficial approach both from cost and water quality benefit to the receiving water. A detailed watershed model was developed in combination with a cost optimization process which seeks to find the lowest cost mix of nutrient control measures through flexible application of a range of land uses. The analyses found the lowest unit cost efficiency for nitrogen management was sized to treat water quality volumes less than a typical 1” water quality volume; however, it can achieve comparable reductions with targeted implementation. The cost optimization ultimately targets high pollutant load land uses and relatively small water quality volumes first (i.e., impervious cover). On the watershed scale, of great significance, is the finding that the cost to meet receiving water quality load reductions does not need to fall entirely on the municipality. Through implementation of local ordinances, the cost for implementation of controls on municipally owned lands (i.e., roads, parks, schools) is significantly less when controls are applied throughout the watershed across a range of land uses and ensure the private land owner shares the load reduction burden. Defining the MEP at the watershed scale allows load reduction goals to be met through implementation of nutrient management strategies throughout the watershed, which are sized and implemented on land uses that provide the highest pollutant load reduction for the least cost. This approach has the potential to allow municipalities and watershed managers to meet regulatory milestones more cost effectively while still achieving load reduction goals.

2:30 – 4:00
Session VI – The Pinch of Salt: Winter Maintenance Impacts on Water Resources

2:30 – 3:00
Pass the Salt, Hold the Liability
Patrick Woodbrey, New Hampshire Department of Environmental Services 

There are more than forty chloride impairments in New Hampshire, and many more urban watersheds that have not been assessed. Due to four chloride-impaired watersheds, the proposed expansion of I-93 from four to eight lanes between Salem and Manchester made salt reduction an imperative. TMDL studies showed that salt reduction ranging from 25 percent to 45 percent was needed to meet water quality standards. Further, in the two largest watersheds, private sector sources contributed 44 percent to 55 percent of the total salt load, far greater than the 9 percent to 10 percent contributed by state highways. Soon after convening, a stakeholder group called the I-93 Salt Reduction Work Group recognized that addressing liability concerns would be essential to achieving salt reduction in the private sector. Since private sector salt applicators in New Hampshire had no professional association and few networking opportunities, New Hampshire DES took the lead in addressing the issue. In 2010, DES drafted a commercial salt applicator certification bill that offered liability protection for commercial salt applicators who followed best management practices and successfully completed training. After four different bills were proposed and killed or retained in the 2010 – 2013 legislative sessions, salt applicator certification/limited liability language was included in the budget bill passed in June 2013. This presentation will describe New Hampshire’s first in the nation commercial salt applicator certification program and its first two winters of results.

3:00 – 3:30
Research and BMP Installation Considerations at a Municipal Snow Dump Facility
James Houle, UNHSC; Dan Bourdeau, Geosyntec 

This presentation will review research data and design considerations for managing winter snow loads at a municipal snow dump facility to maximize pollutant load reductions.

3:30 – 4:00
Between a Rock and a Hard Place: How Bedrock Fracture Affects Chloride Transport
Mark Holden, Maine Department of Environmental Protection

The purpose of this work is to better understand the hydrologic behavior of road salt. Past work has indicated a strong bias in chloride sampling results in residential wells downslope and proximal upslope from the road where salt is seeded in the winter months. This ongoing analysis proceeds with the hypothesis that fracture orientation in bedrock, if steep in dip and with an optimal strike direction, could further enhance the conductivity of the salt solute. Using pre-construction data from the Maine Department of Transportation, the location of each well was precisely located.

Using specific sections of road throughout the state, the chloride data were normalized. The normalized data were then converted to percent.  These percent data were then placed spatially within 30 meter statistical “bins” or groups perpendicular to the road. The middle group was centered on the road. The percent within each spatial group was tallied from upslope to downslope from the road center to 135 meters or greater. By using either the sine of the tangent to the well to road  direction or the cosine of the well to road topographic slope angle, it was possible to separate out the optimal versus non-optimal orientations relative to the regional fracture directions.  The results, shown graphically, demonstrate that 61 to 77% of the asymmetric downslope flow is due to fracture conductivity.

To view speaker bios click here.