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recognize silt as a water pollutant, and detention ponding is used to control sedimentation from the erosion of land developments, particularly during the construction period. State flood control laws, such as in Virginia, have been interpreted broadly to allow for the inclusion of the requirement for detention ponds to control flooding. Assessment of a drainage fee has been used by several cities in Colorado (e.g., Arvada and Boulder) to pay for the construction of drainage facilities. The legislation is structured so that the assessment is dependent upon the area and stormwater runoff rates. In Arvada, as an incentive for illdividual land developers to reduce the rate of storm water runoff from their property, the assessment procedure was made flexible so that land developers could reduce the amount of their assessments by providing stormwater detention facilities. Zoning laws as they pertain to storm water drainage and flooding, are primarily structured to specify the minimum amount of drainage protection needed in various areas. For instance, flood protection structures or sufficient storage volume for a 100-year storm might be required for a development near the flood plain of a river, while for a development remote from a flood plain a 2-year frequency rain may be specified for design of the system of collector storm sewers. Also, flood plain zoning regulations may prohibit permanent development within the flood plain that would reduce the capacity of the flood plain for natural storage of flood waters. Most local building codes do not require detention storage, although some public agencies, e.g" the Denver Urban Renewal Agency, require that rooftop storage be incorporated into the design of buildings. Those jurisdictions that mention rooftop detention storage of rainfall in their building cod e s specify various standards of construction including maximum water depth on a roof, roofslope, size of roof drainage leaders and the number of leaders for a given roof area. At least one national building code, the Building Officials and Code Administrators, International, has developed standards for detention storage of rainfall on roofs. In most instances, the power to adopt and enforce laws governing detention of stormwater lies within the established powers of cities and counties. Because drainage regulation on a regional, total-watershed basis may prove to be more effective in solving drainage problems than institutional arrangements that are limited by political boundaries, regional drainage authorities may become more popular in the future. The creation of these authorities and the definition of their powers would require state enabling legislation in each instance. In a study done by the American Public Works Association in 1966, it was found that 53 percent of all communities in the United States larger than 250,000 population had established drainage districts and that more than one-half of the remaining 47 percent had authority to do so. Survey Results: The types of legislation used to require and regulate on-site stormwater detention storage facilities were revealed in a survey of about 500 public agencies and 130 engineering firms across the United States and Canada. Responses were received from 230 agencies and 40 engineering firms. Legislative and/or administrative action was reported by about 60 local public agencies. The method of requiring and regulating on-site detention of runoff by those agencies is shown in Table I, Survey of Studies Made and Action Taken. TABLE 1 Survey of Studies Made and Action Taken by Local Jurisdictions in Requiring and Regulating On-Site Stormwater Detention Facilities Rel!lllation bv means of: Studies Made Yes No Positive Action Taken Yes No Subdivision Regulations 31 Building Code 11 Zoning Ordinance 12 Other Statutory Requirements 18 Administrative Regulations 36 Source: APWAStudy 1972 115 30 122 12 121 9 117 18 106 43 141 138 133 131 132 Studies were made by some jurisdictions and some adopted either legislation or 13