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Depressional Wetland Index for Placer County Conservation Program

Project Overview

ECORP has supported the development of the Placer County Conservation Program (PCCP) since its inception as an extension of the Placer Legacy program. Since the early 2000s, ECORP staff have been members of the County’s Biological Working Group, the team responsible for developing the PCCP. Major components of the PCCP to which ECORP contributed include a Depressional Wetland Index and a Cultural Resources Management Plan (CRMP).

Building a Comprehensive Depressional Wetland Index

The depressional wetland index enables County planners to identify, delineate, and manage sensitive wetland resources within the Planning Area of the PCCP. Working with Salix Consulting and County staff, ECORP built a model called the Depressional Landscape Wetland Index for this purpose. The model identifies enclosed topographic areas and linear flow paths that may indicate the presence of regulated wetlands and Waters of the United States. ECORP processed 261,000 acres of U.S. Geological Survey (USGS) and U.S. Forest Service (USFS) lidar data into raster-gridded Digital Elevation Models (DEM) for use in the development of the Depressional Landscape Wetland Index. The resulting model represents the highest resolution and most comprehensive wetland geospatial mapping exercise in western Placer County.

Depressional Wetland Model Utilization and User Training

The Depressional Wetland Index programmatically identifies enclosed topographic areas likely to be basin-type features such as ponds, seasonal wetlands, vernal pools, and similar features that hold water due to enclosed topography and impermeable soils.

Linear wetlands convey water across the landscape and can be either perennial or seasonal (e.g., creeks, intermittent drainages, and swales). ECORP developed automation tools enabling Staff to model the topographic enclosures and linear wetland flow paths. These tools aid in remote sensing of wetlands and wetland habitats using lidar data inputs. ECORP has developed PCCP-specific models and has used available wetland delineation data in Placer County to test and tune the models.

As a component of this project, ECORP developed the Depressional Lands Wetland Index Consistency Review Manual (Manual) and training for County Planning Staff. The Manual instructs County Staff in interpreting remote sensing tool data, enabling them to assess existing conditions in the PCCP baseline land cover dataset. The Manual includes a discussion of aerial photograph interpretation, hillshade and lidar interpretation, and implementation of ECORP’s Depressional Landscape Wetland Index. The Manual and training provide examples and practical applications for the Depressional Wetland Index within the PCCP area.

Cultural Resources Management Plan Development

The County engaged ECORP to develop a Cultural Resources Management Plan (CRMP) to guide compliance with Section 106 of the National Historic Preservation Act (NHPA), the California Environmental Quality Act (CEQA), and revised County codes to reflect the cultural resources procedures for the PCCP. Used with the depressional wetlands index, County Staff can manage sensitive and protected wetlands and the cultural resources these areas may contain.

Ongoing Support and Development of the Placer County In-lieu Fee Program

In addition to supporting the County with the PCCP, our regulatory experts have aided clients in negotiating the PCCP processes and policies with County Staff as they continue to develop, leading to a deep understanding of the program.

We have a solid working relationship with Placer Conservation Authority Staff responsible for implementing the Program. Additionally, we have been working closely with the state and federal resource agencies on developing and implementing the In-lieu Fee (ILF) program for the Placer Vineyards Specific Plan, a foundational document for the PCCP ILF.

Environmental Consulting Services Provided:

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