Concurrent Sessions - D. The State of Maine’s Water Resources
- Distinguishing urban biogeochemistry: the fingerprints of urbanization on dissolved organic matter quality in Maine USA – Thomas Parr
- Lake Management Strategies for Internal Phosphorus Reduction in China Lake – Bjorn Lake
- Show me the money: Quantifying natural capital and green infrastructure in Maine – Ethel Wilkerson
Distinguishing urban biogeochemistry: the fingerprints of urbanization on dissolved organic matter quality in Maine USA
Thomas Parr, University of Maine
Presentation available (pdf format)
Abstract: Conversion of land cover to urban use is an accelerating global phenomenon. From 2000-2030 the increase in population will expand urban land cover by an estimated 1,527,000 km2. This increasing urban footprint induces a suite of biogeochemical changes impacting stream ecosystem structure, function, and services.
To understand this impact, we examined the seasonal abundance and composition of dissolved organic matter (DOM), nutrients, and common cations in 116 small streams along a gradient of urbanization (0-60% watershed impervious cover, IC), in Maine, USA. Dissolved organic carbon concentration showed no clear relationship to watershed urbanization. UV/Visand fluorescence metrics of organic matter composition indicate a shift from humic compounds to smaller more labile compounds with increasing urbanization. Fluorescence indices further show a shift in DOM source from allochthonous toward autochthonously derived compounds. Concentrations of base cations (Ca2+, Mg2+, K+, Na+) increased with increasing impervious cover. An Na:Cl ratio of 1 suggests that road salt applications may be responsible for mobilizing base cations into streams. There was a strong negative relationship between humic-like DOM components and Ca2+ (R2=0.3-0.5, p<0.01) across streams. Incubations of DOM samples amended with CaCl2 showed strong flocculation of humic DOM.
Lake Management Strategies for Internal Phosphorus Reduction in China Lake
Bjorn Lake, PhD, Kleinschmidt Associates; Jim Hart, PE, Kennebec Water District; Jeff LaCasse, Kennebec Water District
Presentation available (pdf format)
Abstract: Excess phosphorus (P) in China Lake has been identified as the cause of water quality degradation over the past few decades. To address this problem, three in-lake restoration techniques were investigated: hypolimnetic withdrawal using an existing Kennebec Water District intake, chemical treatment using alum, and optimizing the lake drawdown to increase P export from China Lake. The proposed strategies for internal phosphorus reduction considered economic, regulatory, and environmental constraints. The results of this study show the benefit of both a new drawdown plan and alum treatment. However, hypolimnetic withdrawal is unlikely to significantly increase the export of P from China Lake compared to surficial withdrawals.
This study recommends changing the lake level order to commence the drawdown in October to an over winter lake level target of 191.6 feet NGVD which is 1.5 feet lower than the existing lake level. This change in lake level order will increase the export of P by approximately 200 kg yr-1. This equates to around a fifth of the loading reduction goal for China Lake. In contrast, using the alum strategy, an internal P reduction of 900 to 1850 kg yr-1 for the whole lake is expected. Alternatively, treating just the East and North Basins will result in substantial cost savings ($1.8M) with similar effectiveness (545 to 1115 kg yr-1). The longevity of the alum treatment is expected to last at least 13 years based on previous case studies of other restorations and published sedimentation rates for China Lake.
Show me the money: Quantifying natural capital and green infrastructure in Maine
Ethel Wilkerson, Manomet Center for Conservation Sciences; Austin Troy, Spatial Informatics Groups/University of Vermont; Erin Gray, World Resources Institute
Clean water is not only important to fish and wildlife but critical to public health, local economies, and quality of life in Maine. However, despite the wide-ranging importance of clean water to society the protection of this natural resource is not typically viewed in an economic context. This presentation will summarize two recent studies that quantified the economic value of water resources in Maine as well as a case study of a project that uses a new funding strategy to finance watershed restoration. We will first present the findings of an economic valuation of natural processes for the state of Maine. This study estimated the economic value of ecosystem functions and benefits including regulating disturbance, atmospheric gases, and nutrients and soils, recreation value, and water supply and regulation. This study found that the economic value of the estimated 2.4 million acres of wetlands in Maine tops 5 billion dollars per year. We will also summarize a study that quantified costs of a drinking water supply in Sebago Lake by maintaining adequate forest cover to supply clean water and building a new and upgraded drinking water treatment plant. This ‘green versus gray’ infrastructure analysis found that protecting forests and incentivizing sustainable forest management had a 60% cost savings over building a new drinking water treatment plant. In addition, we will present a case study of the Clear Water Carbon Fund, a program that uses carbon offset market as a strategy fund watershed restoration in three watersheds in Maine.