Water Glossary

Best Management Practices (BMPs)

Economically feasible conservation practices and land and water management measures that minimize adverse impacts to the chemical, physical and biological characteristics of waterbodies. BMPs may include a wide range of structural and non-structural practices to be implemented in association with land disturbance, development and construction activities.

Buffer

An area adjacent to a waterbody where land development or disturbance is restricted. When disturbance or development is permitted within this area, best management practices or other mitigation should be used to minimize adverse impacts to the waterbody.

Check Dams

Small, temporary constructed dams across a swale or drainage ditch, to slow the velocity of flowing water and minimize erosion.

Development

All activities involving earth disturbance and requiring a building or grading permit, including but not limited to, commercial or industrial developments, single or multi-family housing, construction of structures, road and driveways, and installation of utilities.

Direct Discharge

A flow of water into a lake, wetland, or perennial stream from a development site, which has not passed through a water quality improvement device designed to either percolate the flow into the subsurface or otherwise remove sediments and other pollutants.

Disturbance

The mechanical removal or compaction of natural soil, fill, rock and/or any combination thereof; or placement or stockpiling of fill; or clearing of trees and vegetation for the purpose of constructing roads, structures, or other site improvements.

Diversion

A channel, embankment, culvert, or other manmade structure constructed to divert water from one area to another.

Drainage Plan

A plan that describes how stormwater will drain from a development site and measures taken to control these flows. The Drainage Plan addresses water quantity issues; however, a Stormwater Quality Control Plan can also be developed as part of the Drainage Plan. These standards are primarily focused on water quality issues. Additional drainage requirements may be required in other sections of local codes and regulations. Specific requirements for Drainage Plans should be identified in those sections.

Erosion and Sediment Control Plan

A plan to minimize erosion and sedimentation resulting from construction activities. The plan should include basic information about the site; planned construction activities and best management practices (BMPs) taken to minimize on-site erosion and transport of sediment off- site during construction.

Filtration

The movement of water through a device (such as a straw bale barrier, filter fence, or sand/gravel bed, for example) for the purpose of removing sediment and other particles that would otherwise be transported by the water.

Final Grade

Final ground surface profile at a development site immediately prior to permanent site revegetation, sodding and or placement of structures.

Floodplain

A low area of land adjacent to a stream or other water course which is subject to flooding and overflow of water during a flood. Often the floodplain is delineated on the basis of the 100-year flood, which is the flood event that has a 1-percent chance of being equaled or exceeded in any given year. A base flood may also be referred to as a 100-year storm and the area inundated during the base flood is sometimes called the 100-year floodplain.

Impervious Surfaces

The area of a site which allows only minimal infiltration and percolation, such as a constructed or natural surface which will allow surface runoff equal to or greater than ninety percent (90%) of the applied water.

Infiltration

The movement of water through the soil surface into the soil, as distinguished from “percolation.”

Intermittent Stream

A channel of water or stream which does not generally flow continuously during the entire calendar year. The criteria used to identify an intermittent river, stream, reservoir, or pond are the same as those used by the US Geological Survey, and are shown as intermittent water features on the US geological Survey 7.5 Minute Series Topographical maps.

Mining Operations

The development or extraction of a construction material from its natural occurrence on land. Mining operations are regulated under the Mined Lands Act of 1976.

Mitigation

Measures taken to reduce adverse impacts to waterbodies resulting from land development or disturbance and to minimize potential future impacts associated with such activities.

Natural Drainage

A natural channel that collects and transports stormwater and other surface water flows without design or construction by man. Natural drainages, or drainageways do not include best management practices (BMPs) such as grass-lined swales, wetland channels, or similar measures.

Percolation

The movement of water through soil and into the subsoil.

Perennial Stream

A channel of water or stream that flows continuously during all of the calendar year as a result of groundwater discharge or surface runoff. The term does not include intermittent or ephemeral streams.

Riparian Zone

That transition area between aquatic and terrestrial (upland) environments influenced by the high water table associated with a stream or river. Plant types typically associated with the riparian zone include but are not limited to cottonwoods, willows, alders, aspens, and chokecherry. Natural riparian areas are commonly recognized by the combination of high species diversity, high species densities, and high productivity.

Registered Professional Engineer

An individual registered as a professional engineer by the State of Colorado Department of Regulatory Agencies, when such registration is based on a background of civil engineering duties and training related to drainage and erosion control.

Sediment Basin

A primary sediment control structure designed, constructed and maintained, which slows down water runoff to allow sediment to settle out over a period of twelve (12) hours.

Sediment

Any material transported or deposited by water, including soil and debris or other foreign matter.

Silt or Filter Fence

A temporary sediment barrier consisting of a filter fabric stretched across and attached to supporting posts and entrenched.

Stormwater Management Plan

A written plan to minimize pollutants in stormwater discharged from construction sites as required under the Colorado Discharge Permit System (CDPS) General Permit for Stormwater Discharges Associated with Construction Activity. This plan includes a site description and map, identifies best management practices for implementation at the site and identifies maintenance and inspection requirements for these best management practices.

Stormwater Quality Control Plan

A plan to control pollutants transported in stormwater prior to pollutants entering waterbodies. Stormwater quality control plans in the context of these regulations refer to post-development stormwater flows, rather than stormwater flows under construction conditions. Stormwater Quality Control Plans should be based on best management practices (BMPs) such as avoiding direct discharge into waterbodies, minimizing directly connected impervious areas, and use of detention ponds, and other BMPs.

Superfund

Superfund is the name given to the environmental program established to address abandoned hazardous waste sites. It is also the name of the fund established by the Comprehensive Environmental Response, Compensation and Liability Act of 1980, as amended (CERCLA statute, CERCLA overview). This law was enacted in the wake of the discovery of toxic waste dumps such as Love Canal and Times Beach in the 1970s. It allows the EPA to clean up such sites and to compel responsible parties to perform cleanups or reimburse the government for EPA-lead cleanups.

Straw Bale Barrier

A temporary sediment barrier consisting of a row of entrenched and anchored straw bales.

Twenty-five (25) year, Twenty-four (24) Hour Storm

An occurrence of precipitation that can be expected to be equaled or exceeded once every twenty-five years (on an average). This event has a four percent (4%) chance of occurring during any given year. Duration, such as twenty-four hours, is usually associated with such an event to define the time period over which the precipitation falls. The rainfall volumes and durations for various storm frequencies are provided in “NOAA Atlas 2, Precipitation – Frequency Atlas of the Western United States,” volume III – Colorado, NOAA 1973.

Water Quality Control Facilities/Devices

Structural and nonstructural measures having the purpose of filtering sediments and pollutants from surface flows, diverting surface flows, inducing percolation, and/or controlling the volume and velocity of flowing water. Such devices include, but are not limited to, the following: sediment ponds, drywells, berms, grassed drainageways, sediment traps, detention ponds, drop structures, filter silt fences, culverts, embankments, check dams and straw bale barriers.

Water Quality Control Plan

A detailed plan submitted to the local government that includes a qualified professional engineer’s certification that the project as proposed will meet the water quality control standards as set forth in these standards.

Waterbody

Waterbody means a wetland, perennial or intermittent river, stream, lake, reservoir, or pond, whether natural or artificial. The following water features are excluded: irrigation and roadway drainage ditches; artificial lakes and ponds which are not tributary to state waters or are created and used for the primary purposes of agricultural activities or stormwater treatment and development water features less than 0.5 acre in surface area. A “perennial” river, stream, reservoir or pond is one that normally holds water or flows continuously during all of the calendar year as a result of groundwater discharge or surface runoff. An “intermittent” river, stream, reservoir or pond is one that is shown as an intermittent water feature on the U.S. Geological Survey 7.5 Minute Series Topographical Maps.

Wetlands

Those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs and similar areas (33 CFR Part 328.3(b)). For the purposes of these regulations, wetlands do not include areas that are saturated solely by the application of agricultural irrigation water. Manmade lakes or ponds built for the purpose of detaining runoff are not considered wetlands in the context of these regulations. The criteria for delineating wetlands are those used by the Army Corps of Engineers.