Eutrophication

Almost all living creatures in rivers, lakes, estuaries and the coastal ocean depend on phytoplankton for sustenance, directly or indirectly. Phytoplankton in turn are dependent on sunlight, macro-nutrients (such as nitrogen, phosphorus, and silica), and micro-nutrients (such as iron) for their growth. However, excess levels of nutrients can stimulate phytoplankton growth to excessive levels, which in turn can have adverse impacts on pelagic and benthic organisms (via reduced dissolved oxygen levels), or promote the development of toxic or nuisance algal blooms, commonly known as harmful algal blooms or HABS.

HydroQual (and its predecessor firm Hydroscience) has a long history in development and application of mathematical models for the evaluation of the inter-relationships between nutrients, phytoplankton biomass, primary production, and dissolved oxygen. This experience has included studies of lacustrine, riverine, estuarine, and coastal systems. The water quality constituents of interest typically include: phytoplankton biomass, nitrogen, phosphorus, silica, organic carbon, and dissolved oxygen. While HydroQual often uses its in-house eutrophication modeling system, it is familiar with publically available eutrophication codes such as WASP, EFDC, CE-QUAL-W2, and QUAL2E. The resulting models have been used by managers of water quality and living resources to develop nutrient reduction programs and goals, assess outfall relocation and nutrient TMDLs.

Specifically, HydroQual provides services relating to eutrophication in the following areas:

• Identification and compilation of data resources and needs
• Design of field monitoring programs
• Selection and application of appropriate watershed/sewershed and receiving water models
• Identification and evaluation of management alternatives necessary to attain water quality goals and standards
• Visualization of field data and model computations
• Presentation of study results to environmental regulators and stakeholders