Monetizing Urban Runoff from the Perspective of MS4 Agencies and Stormwater Management Decision Making
Urban runoff has historically been viewed by lawmakers, regulators, municipal agencies, and the general public as a waste stream. And even though the water quality of urban runoff has improved over the last 25 years through the Clean Water Act and implementation of regulations and municipal programs, urban runoff has not been fully utilized as a resource. But now during periods of regional and statewide water scarcity in California, every source of water is examined for its feasibility of use. Desalination has become the primary cost valuation benchmark when examining potential water sources. Treatment and use of urban runoff could even be cost effective in the right situations. Increased pumping of groundwater and environmental flow reductions are used to mitigate reductions in available surface water for municipal and agricultural supply. Storage and reuse or urban runoff could provide additional benefits in long-term protection of water supply and aquatic life. In assessing the value of stormwater in the context of a water resource there are many factors that affect its value including but not limited to water quality, treatment costs, conveyance costs, storage costs, open space value, wildlife improvements, groundwater recharge, and applicable water rights. These factors are identified and discussed in the context of different regions of California.
MS4 agencies will have increased opportunities over the next decades to eliminate waste streams and improve the revenue balance when considering larger projects and long term land use planning. Coordination with watershed and infrastructure planning activities and the Integrated Regional Watershed Management Plans (IRWMP) could provide these long-term opportunities. The primary mechanisms for capturing the value of urban runoff are 1) treatment and localized infiltration to groundwater basins 2) onsite capture and reuse 3) wheeling of water rights to downstream users, and 4) reductions in waste management costs and discharge regulatory compliance costs. These options are evaluated in terms of long term costs and benefits to identify the value of stormwater necessary to fund such programs. Additionally the necessary changes to the water rights and NPDES permitting programs to allow better use of urban runoff are identified and discussed.