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Lake San Marcos Biological Investigations

water flowing over a dam

Quick Facts:

  • Key Services: Biological Assessments, Biological Investigations, Hydrological Investigations, Stormwater Sampling, Litigation Support
  • Regulatory Nexus: 303-d listed nutrient impaired water (Clean Water Act)
  • Lake Area: 56 acres
  • Watershed Area: 18,450 acres

Project Summary:

For more than seven years, Great Ecology has conducted biological and hydrological investigations of Lake San Marcos, a 303(d)-listed nutrient-impaired water body in Southern California, in fulfillment of Investigative Order. No. R9-2011-0033 (Order) and in support of ongoing mediation and litigation.

Great Ecology staff have worked closely with the lake owner, Citizen’s Development Corporation (CDC), Regional Water Board (RB), public agency defendants, and the lake homeowner community to characterize the site through field sampling and laboratory analyses. We have collected and submitted the following data to the Regional Water Board, using the appropriate scientific sampling techniques: monthly water quality monitoring data; sediment nutrient flux results; fish, phytoplankton, and zooplankton monitoring; dry and wet weather stormwater data; bathymetric survey results; an assessment of lake vegetation; upstream biomonitoring data; reports detailing in-lake pilot study efforts to reduce phosphorus via alum and Phoslock application and associated permitting documentation for these efforts; and annual water level budgets for the lake’s Water Rights license.

Great Ecology used this data to develop a lake management strategy to address both water and nutrient-associated issues. Additionally, Great Ecology developed the Investigation Work Plan, Sampling and Analysis Plan (SAP), Quality Assurance Program Plan (QAPP), and Health and Safety Plan (HASP) associated with the Order and subsequently approved by the RB in 2012.

Currently, Great Ecology is serving as an expert witness providing a "rebuttal" expert opinion for litigation involving the lake and developing extensive watershed modeling to support outside experts.

News Articles:

"Monitoring the Muddy Waters of Lake San Marcos" - Alison St John, KPBS - San Diego

San Marcos, CA