Stormwater draining from streets and arroyos in the Albuquerque area carries trash, bacteria and chemicals that pollute the Rio Grande. Typically, as urban growth expands, impervious surfaces replace areas of native soil and vegetation. The Albuquerque region has expanded from the valley to the mesas, foothills and mountains since this photo was taken in 1935.
As the land was paved, non-point source pollution has increased, carried by stormwater into the Rio Grande. The loss of aquatic habitat is a result.
The Albuquerque area’s “first flush” of stormwater produces a “very high level of E.coli, at 50,000 ppm.” Dr. Bruce Thomson, UNM, at the 2013 Water Conservation Conference.
Local governments work to decrease pollution levels with public information campaigns, such as the “Poop Fairy” poster campaign in Bernalillo County. Canine waste is a major contributor of bacteria in the region’s stormwater; human and bird waste are also significant. Inorganic pollutants from oils are also causing problems.
Green Infrastructure and the EPA – UPDATE December 2014
The US Environmental Protection Agency recognizes the connection between impervious (paved) surfaces and pollution in local waterways. The EPA, which administers the Clean Water Act, encourages changes in stormwater management approaches using Green Infrastructure (GI) and Low Impact Development (LID). Generally, that means less emphasis on “grey infrastructure” such as channelized arroyos and storm sewers, and more on practices that slow, spread, and sink stormwater on site.
The agency has designated the Middle Rio Grande sub-basin as a pilot area for a watershed-based Municipal Separate Storm Sewer System permit. The new “MS4 Permit” challenges local agencies to adopt stormwater control practices that provide the most environmental results and community benefits. The MS4 permit involves about 18 government jurisdictions and institutions, including the City of Albuquerque, Bernalillo County and AMAFCA (a flood control authority).
With more direction forthcoming from the EPA, Green Infrastructure is gradually becoming a standard practice of landscape architects, permaculture designers and developers. Many practitioners view GI, which includes rainwater harvesting techniques, as common sense solutions to other problems. Stormwater is viewed as a resource, not a problem or a waste product. On a large scale, the challenges are formidable, and flood control and Rio Grande water supply requirements to downstream users are important public issues.
This site features photos of several GI techniques, including catchment basins, swales, berms and trees. Permeable pavements, green roofs, and rainwater storage with tanks and underground cisterns are also in the mix of GI.
What is allowed?
People at workshops with Querencia Green have asked what they can do with the rainwater that falls on their property. In the State of New Mexico, the Office of the State Engineer has provided one statement on its website: the Rainwater/Snowmelt Harvesting Policy.
The New Mexico Office of the State Engineer supports the wise and efficient use of the state’s water resources and, therefore, encourages the harvesting, collection and use of rainwater from residential and commercial roof surfaces for on-site landscape irrigation and other on-site domestic uses. The collection of water harvested in this manner should not reduce the amount of runoff that would have occurred from the site in its natural, pre-development state. Harvested rainwater may not be appropriated for any other uses.
Local Government Regulations shift toward Green Infrastructure
The City of Albuquerque and Bernalillo County have adopted or updated ordinances that affect new development, beginning a policy shift toward green infrastructure and rainwater harvesting practices.
Bernalillo County requires water conservation with options for conserving outdoor as well as indoor water use. Today, “Building permit applications for all new Commercial and Large Multi-Family Development on more than 1 acre shall include a fully and properly completed Commercial Outdoor Water Conservation Plan and Site Plan that includes three of the following seven outdoor water conservation measures related to landscaping.” Three of those options are green infrastructure techniques: passive water harvesting (earthworks), collected and stored rainwater (tanks and barrels), and “Precipitation Supported Plant Material” (native and other water-wise plants).
In 2012, The City of Albuquerque revised its Drainage Ordinance to require new developments to “manage the runoff from precipitation from 90th Percentile Storm Events.” The amount of rainwater from such a storm event in this region is .44 inches (nearly half an inch). This type of storm event can cause pollution problems when it is the first of the rainy season: the “first flush” contains the highest concentration of pollutants in urbanized areas. (On average, only five rain days have half an inch rain or more annually.)
Infiltration into soil and water harvesting are listed as techniques for capturing, slowing, and utilizing this stormwater on site.
Property owners need to apply for a permit from the City if they intend to move 500 cubic feet or more of earth on their site while installing earthworks.
As we adapt to the need for reducing pollutant loads in urban stormwater runoff, more Low Impact Development strategies should emerge, include planning, zoning and design standards that control stormwater runoff discharges to mimic pre-development runoff conditions. Low impact development can involve cluster development and maximize the amount of permeable area, leaving some land in natural conditions.
Local residential and civic projects can demonstrate how to slow and spread rainwater, while saving potable water and energy, and growing native plants. Neighborhood champions and residents are part of the solution, helping local governments comply with the new stormwater permit standards and creating demand for incentives and programs that create benefits in our neighborhoods.