Prepared Pursuant to Washington Department of Ecology Centennial Clean Water Fund Grant No. G0400195
“Fisher/Carpenter TMDL Implementation”
Skagit Conservation District
Table of Contents
1 Introduction 3
1.1 Location of the Study Area 3
1.2 Policy Background 3
1.3 Purpose of the Study 3
2 Watershed Delineation 4
2.1 Boundaries 4
2.2 Topography 4
3 Land Use 7
3.1 Relevant Historical Land Use 7
3.2 Existing Land Use/Zoning 7
4 Soils 12
4.1 Soils Description 12
5 Geohydrology 15
5.1 Aquifer 15
6 Surface Water Hydrology 17
6.1 Description of Sub-basins 17
6.2 Impervious Surfaces 22
6.3 Flow 24
6.4 Channel Morphology 25
6.6 Key Hydrologic Structures and Fish Passage Blockages 32
7 Water Quality 32
Water Quality Standards 33
7.2 SCD’s In-House Water Quality Monitoring Program 33
7.3 SCD’s Stream Team Citizen Water Quality Monitoring 36
7.4 Sources of Water Quality Degradation 36
7.5 Quality Assurance / Quality Control 40
8 Fish and Wildlife Habitat 43
8.1 Species Inventory 43
8.2 Evaluation of Habitat Quality 44
8.3 Endangered Species Act 45
1.1 Location of the Study Area
The Fisher/Carpenter Creek Watershed is located in southwest Skagit County and northwest Snohomish County, Washington. The watershed’s several upland tributaries, manmade drainage channels, and natural slough drain an area of approximately 25.5 square miles, located between the communities of Mount Vernon and Stanwood, Washington.
1.2 Policy Background
Section 319 of the Federal Clean Water Act requires states to identify water bodies, which, without control of non-point source pollution, cannot attain applicable water quality standards. In response to this Federal mandate, the Washington Department of Ecology funded local initiatives to identify and rank such water bodies and to develop action plans for addressing non-point source pollution.
A related provision of the Federal Clean Water Act, Section 303(d), requires states to identify water bodies that do not attain the relevant water quality standards. Further, states must develop plans for limiting the total point source and non-point source pollution discharges to such water bodies, in order that water quality standards can be attained. Fisher/Carpenter is identified in Department of Ecology’s 1998, 303(d) listings as a water body that, without control of pollution, cannot attain the State of Washington Water Quality Criteria for temperature and fecal coliform bacteria (Department of Ecology 1998). Department of Ecology’s revised 303(d) listing includes dissolved oxygen and fecal coliform (Department of Ecology 2004). The Department of Ecology has not formulated a plan for regulating “total maximum daily loads” of pollution in Fisher/Carpenter Creek to meet State water quality parameters (i.e., temperature, dissolved oxygen and fecal coliform). This characterization will define and describe in detail the physical and political characteristics of the Fisher/Carpenter Watershed. It will provide the base for development of a plan that will address and regulate total maximum daily loads of pollution in the watershed.
1.3 Purpose of the Study
The goal of this project is to protect, restore, and enhance the water quality, quantity, and fish and wildlife beneficial uses of the Fisher/Carpenter basin in order to meet State Water Quality Standards for temperature, fecal coliform bacteria, and dissolved oxygen as part of the total maximum daily load. A slate of community supported restoration and/or enhancement projects will be developed which, when implemented, will improve water quality, provide more consistent stream flows, restore some historic hydrologic function and support fish and wildlife habitat.
The characterization project area, Fisher/Carpenter Creek Watershed, is a 16,320-acre (25.5 square miles) watershed that drains into the south fork of the Skagit River on the southwestern edge of Skagit County, Washington (Figure 2.1). The Fisher/Carpenter Creek Watershed extends 8.1 miles in a north to south orientation, is 3.7 miles wide, and is bounded by the 10-foot Hill Ditch levee on the west side, the City of Mount Vernon and Little Mountain to the north, Big Lake to the east, and the Pilchuck Creek Watershed to the south. The majority of the watershed (14,325 acres or 87 percent) is located in Skagit County. The remaining 1,955 acres or 13 percent is located in Snohomish County. The Fisher/Carpenter Creek Watershed was defined by standard watershed delineation techniques using topography and field investigations to identify areas that affect flow direction.
The topography of the Fisher/Carpenter Creek Watershed ranges from mean sea level (MSL) to approximately 1,700’ above MSL and has primarily three distinguishing topographic features: the alluvial flats of the Skagit River Delta, a long north-south trending ridge that peaks at 1,727-foot high Devils Mountain, and associated rolling uplands. Several creeks drain the watershed, including English, Carpenter, Stackpole, Lake Ten, Sandy, Johnson, and Bulson (collectively known as the “Carpenter Creek” system), and Starbird, Fisher and Little Fisher Creeks (collectively known as the “Fisher Creek” system) (Figure 2.2).
Water from the Carpenter Creek system flows into Hill Ditch, where it combines with flows from the Fisher Creek system to form Fisher Slough. Fisher Slough drains to the south fork of the Skagit River through a large tidegate located about a mile south of the town of Conway, Washington.