Horizon consultants are expert at conducting stream and watershed assessments for a variety of objectives, including identifying and analyzing flooding risks, evaluating erosion and sedimentation issues, characterizing habitat and species needs, complying with regulatory requirements, creating maintenance solutions, and developing restoration approaches.

Our team of geomorphologists, hydrologists, ecologists, botanists, wildlife and fish biologists, and water quality specialists are knowledgeable across traditional discipline boundaries and can conduct comprehensive and integrated resource assessments working together or alone.

We have experience evaluating watersheds and developing watershed assessment reports and management plans. Our experience includes evaluating erosion and sediment source areas, water quality source problems, runoff generation, and stormwater management opportunities. We provide our clients with recommendations for managing sediment, including developing sediment basins, beneficial reuse of sediment, and reservoir sediment dredging and management.

The Horizon team is also experienced in developing vegetation management plans for watersheds, including fuel reduction and fire risk reduction plans.

We are comfortable assessing the full range of fluvial systems from small creeks to large rivers. Our work includes hydrologic and streamflow evaluations, geomorphic process studies (sediment textural analysis, sediment transport, hydraulic conditions, etc.), streambank stabilization analysis, as well as geomorphic form analysis (channel shape, instream complexity and habitat features, planform and cross-section analysis). We are particularly skilled at understanding and characterizing how a particular stream reach or segment functions within the overall watershed and identifying the constraints and opportunities of working with that segment.

Our consultants are skilled and experienced with conducting a range of hydrologic analyses including watershed rainfall-runoff analysis, statistical analysis of long-term hydrologic data, water balance evaluation, and streamflow analysis.

In addition to using available historic hydrologic data, we frequently install stream gauges and sediment monitoring instruments to characterize local conditions in real time.

Horizon staff are adept at both field-based and desktop geomorphic and hydrologic evaluations. We have conducted sediment source, texture, transport, and depositional analyses, and estimated watershed-based sediment yields as well as local stream sediment transport rates. With our technical understanding of erosion and sedimentation, we can help our clients develop watershed, stream maintenance and management solutions. Example solutions include developing or maintaining sediment basins, beneficial reuse of sediment, and reservoir management for sediment.

Horizon also has deep experience analyzing instream geomorphic conditions and streambanks as a basis to develop ecologic enhancement, restoration, or stable streambank designs. We are expert at translating habitat needs into workable stream designs that are sustainable for the longer-term and future dynamic cycles of erosion and sedimentation. We help our clients find solutions that provide a stable streambank environment, maintain or enhance ecologic conditions, and that are ultimately permittable with regulatory agencies.

Horizon is an industry-recognized leader in developing stream and channel maintenance programs for its flood district, municipal and county public works, and water supply agency clients. We have developed award-winning programs known for their practical implementation, clear guidance, and environmental compliance solutions. Most of our maintenance programs focus on sediment management, vegetation management, streambank stabilization, water quality protection, ecologic enhancement, impact avoidance, trash removal, public safety, and fire risk reduction in watersheds and other public facilities.

Our approach begins with understanding our clients’ objectives and maintenance needs. From there, we conduct hydrologic, water quality, vegetation and habitat assessments to clarify maintenance priorities or understand regulatory constraints. We partner with engineers who specialize in channel design and bank stabilization if designs and specifications are needed. We can develop operation and maintenance manuals that support the environmental permitting and CEQA process and, at the same time, provide clear direction to staff who conduct maintenance activities.

Horizon has earned the trust of numerous clients and has successfully work with the following agencies and organizations to help develop routine maintenance programs:

• Sonoma County Water Agency
• Napa County Flood Control and Water Conservation District
• Contra Costa County Public Works Department
• San Mateo County Public Works Department
• Zone 7 Water Agency
• San Jose Water Company
• Alameda County Water District
• Vallejo Public Works Department
• Santa Clara Valley Water District
• S. Army Corps of Engineers
• Regional Water Quality Control Boards
• California Department of Fish and Wildlife
• S. Department of Fish and Wildlife
• National Marine Fisheries Service
• Bay Conservation and Development Commission

Horizon’s team of consultants includes Professional Wetland Scientists who are expert in formally delineating wetlands and characterizing the fundamental hydrologic, soil, and vegetation aspects of wetlands. Typically, this involves conducting water balance evaluations, estimating the roles of surface water, soil water, groundwater, plant water, evapotranspiration, and other inputs and outputs to the water balance at the wetland site. We incorporate historic data and install instruments to collect real-time hydrologic data to form the basis of our wetland studies.

Our understanding of wetland hydrology is matched by our knowledge of wetland soils and vegetation. Horizon scientists have experience across the full range of wetlands in California including high Sierra meadows, foothill vernal pools, valley floodplains, hillslope seeps and springs, estuary and coastal tidal wetlands. This deep familiarity with naturally occurring wetlands informs Horizon’s wetland restoration and design practice.

Horizon is experienced in developing and implementing water and sediment quality sampling and analysis programs to support client needs. We are well versed in the requirements of the Federal Clean Water Act (CWA) and the State of California Porter-Cologne Water Quality Control Act and can assist our clients in interpreting water and sediment quality results to comply with federal and state regulations. In addition to conducting technical analyses, we also help our clients evaluate potential water and sediment quality impacts for CEQA/NEPA purposes and achieving permit compliance.

Our staff specializes in crafting best management practices that meet client needs while also satisfying water quality regulations. In addition to sediment sampling and analysis programs, we have successfully developed water quality monitoring programs for short-term and long-term construction, restoration, and habitat enhancement projects. We have also developed and implemented sediment dredging and reuse plans for lakes, wetlands, streams, and flood control channels.

Horizon has successfully worked with the State Water Resources Control Board and the State’s Regional Water Quality Control Boards for projects involving CWA Section 401 water quality certification, CWA Section 303(d) – Impaired Waterbodies and Total Maximum Daily Loads, National Pollutant Discharge Elimination System compliance, and Waste Discharge Requirements.

• Municipal Stormwater Permit Compliance
• Green Infrastructure and Low-Impact Development
• Operation and Maintenance Plans and Inspections
• Stormwater Pollution Prevention Plans, Inspections, and Reporting

Horizon offers expertise in stormwater compliance and permitting. We help our clients understand stormwater regulations and requirements and keep their programs compliant and successful.  We prepare stormwater guidance manuals, operation and maintenance plans, hydromodification management measures, and stormwater pollution prevention plans for construction sites. We support our municipal clients with annual stormwater reporting and help our public agency clients integrate practical approaches to comply with stormwater requirements.

We understand the full lifecycle of green infrastructure and low-impact development facilities (planning, design, construction, maintenance, reporting, etc.) and have many years of experience working with multi-disciplinary teams for individual agencies and countywide stormwater programs. Where appropriate, we can take programs beyond simple permit compliance, and develop multi-benefit projects that integrate water quality protection with groundwater recharge, flood control, urban greening, or water conservation objectives.