October 2013
Don't Forget About Your BMP's!
Roads and bridges may be all over the news, but they are
not the only infrastructure impacted by the recent rainfall and
flooding experienced in Colorado. Stormwater systems,
including permanent water quality BMPs, were overwhelmed
in many areas and may no longer function as designed until
they are properly maintained and repaired. In those areas,
sediment and debris removal will be required at all types of
BMPs. Other issues to look for include damaged inlet and
outlet structures, clogged underdrains, erosion and
dead/dying vegetation. Now is the time to inspect
stormwater BMPs, submit damage estimates to FEMA, and make plans to maintain/repair BMPs as soon
as possible.
If you are not sure what to look for or how to perform required BMP maintenance/repairs, consider
attending the Colorado Stormwater Center’s BMP Inspection and Maintenance training workshop on
November 20-21. Details of the workshop are provided below.
Water Law and Low Impact Development (LID)
LID practices are becoming more common in Colorado, however there is still a good deal of confusion
about what is and is not allowable under Colorado's strict water laws. The fact is most LID practices are
allowed, however different regulations pertain to different LID practices. Below is a short synopsis of how
you can develop LID in compliance with Colorado water law.
Disconnect Impervious Areas: The first step of UDFCD’s 4-step process to stormwater quality
management is to minimize directly connected impervious areas (MCDIA). The easiest way to MCDIA is
to direct rooftop downspouts to landscaped, pervious areas; a practice that is allowable under Colorado
water law.
Stormwater Detention and Infiltration Methods: Once runoff becomes “concentrated” (collected) in a
detention or infiltration area (e.g. detention basin, rain garden), several water law regulations become
effective. The first is that any runoff collected in those areas cannot be diverted for “beneficial use”, which
includes using that water to irrigate nearby lawns, gardens, etc. Any runoff captured in detention or
infiltration areas must be released to nearby surface waters or infiltrated into the groundwater within 72
hours of the end of precipitation event. In addition, detention and infiltration areas must be designed to
“minimize consumption from vegetation”.
Green Roofs: Green roofs are allowed in
Colorado, however they must be designed to only
capture precipitation that falls directly onto the
green roof. Runoff from other areas of the
rooftop cannot be diverted to an adjacent green
roof, nor can a green roof store water below the
root zone of the green roof plants.
Rainwater Barrels: In general, rainwater
harvesting in cisterns and barrels for later use is
illegal in Colorado due to water rights law;
however a few exceptions do exist. One
exception is for residential properties that use a
well for domestic use purposes, however such
properties must meet several other criteria and apply for a Precipitation Collection System Permit (see
link below). The other exception pertains primarily to new developments and is the result of Colorado
House Bill 09-1129 “Pilot Projects for the Beneficial Use of Captured Precipitation in New Real Estate
Developments”. This Bill allows up to 10 new residential/mixed-use developments in Colorado to be
designed with rainwater harvesting systems. To date, only one development (Sterling Ranch in Douglas
County) has taken advantage of this opportunity, so that means 9 other permits are currently available for
new developments. Rainwater harvesting not only reduces demands on potable water supplies, but also
reduces the amount of stormwater discharged to receiving waters.
Additional information on these topics can be found at the following links:
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Colorado Division of Water Resources: Administrative Approach for Stormwater Management
Colorado Division of Water Resources: Precipitation Collection System Permit
Colorado Water Conservation Board – Memorandum on Pilot Projects for Captured Precipitation
Upcoming Trainings
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October 9, 2013 - EPA Stormwater Calculator - CASFM Lunch-and-Learn - Denver, CO
November 20-21, 2013 - Permanent Stormwater BMP Inspection and Maintenance Workshop CSU Extension Building - Denver, CO
Click here for full descriptions of these training courses.
BMP Inspection and Maintenance Workshop Registration
NOW OPEN!
Be one of the first 20 people in the State to become certified! Upon completion of the two day workshop
and successfully passing the optional exam, you will receive a certificate and be listed on our website.
Cost is $250 for workshop and exam. Click here for more information and registration form.
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Colorado Stormwater Center | Colorado State University | Civil Engineering Department | Fort Collins | CO | 80523