Californians have traditionally managed stormwater as both a waste product and an environmental hazard. But extreme droughts and harsh storm events have shifted perceptions over the last few decades. In regions struggling with water security, stormwater capture can increase water resiliency, protect urban developments, and safeguard water quality. Moving forward, stormwater capture will become increasingly important to water conservation efforts. 

The growing importance of stormwater is intrinsically connected to the effects of global climate change on California’s water supplies and precipitation patterns. Global warming is no secret; average air temperatures have increased since 1895 and last year saw a record breaking heat wave. Nowhere is temperature rise more apparent than in the Sierra Nevada Mountains—a vital source of water for the state. The Sierra snowpack provides drinking water to 23 million Californians and feeds into several important state water infrastructure projects. The mountains serve as our frozen reservoirs during the winter, stockpiling water and gradually releasing it as snowmelt during the spring. But rising temperatures mean less snow and more rain in the mountains and an accelerated springtime melting process. Consequently, stormwater floods can overwhelm reservoirs, which are not built to efficiently capture or store large, sudden influxes of water. Snow reserves have declined since the 1950s but another poor winter season has diminished state reservoirs once again to new lows. 

On a larger scale, climate change is intensifying the state’s naturally volatile seasons. Within the last decade, California has experienced the third driest and wettest years on record since 1895. This phenomenon, sometimes dubbed “water whiplash”, indicates that drought periods are growing longer and drier while intermittent wet years are producing heavier rainfall events. 

Diminishing Sierra snowpack and water whiplash are forcing cities to look for alternative water sources. Efficiently capturing and storing stormwater, especially from urban areas, offers a promising solution.

Historically, stormwater was an urban nuisance. Unlike grass or soil, city surfaces such as roads, parking lots, rooftops, sidewalks, and patios do not absorb rainwater. Water instead pools on top of these impervious surfaces and poses a significant flooding hazard. Cities typically managed flood risk by collecting and conveying stormwater to a nearby river, lake, or stream. But this practice brought about different consequences; urban stormwater runoff picks up city pollutants--pesticides, heavy metals, bacteria, oil, grease, and trash---and introduces these pollutants to waterways and ecosystems. 

As a non-point source of pollution, stormwater is difficult to regulate. But creating an effective stormwater capture system can help protect watersheds from polluted runoff while also providing water for municipal use. Cities generally take two approaches to managing stormwater: collecting and conveying stormwater to centralized facilities or implementing decentralized LID (Low Impact Development) strategies.

Many dry regions like Southern California utilize centralized stormwater systems to collect, transfer, filter, and store stormwater. The water can later be used for non-potable purposes, such as irrigation or groundwater recharge. For example, the IEUA (Inland Empire Utilities Agency) operates a stormwater plant in Chino Basin that recharges the local groundwater with 13,600 acre-feet of water per year. Reinvesting water back into natural aquifers helps prevent overdrafting and land subsidence during drought years. 

But large and expensive centralized facilities are not the only method for managing stormwater. Other regions like Los Angeles and San Jose use LID stormwater management to reduce surface water pollution, improve flood protection, and preserve valuable water. Closer to home, Riverside County Flood Control is using its own facility in Riverside to collect information on the effectiveness of various parking lot and hardscape LID techniques. LID strategies include rain gardens, vegetated rooftops, permeable pavement, and other green infrastructure projects. Unlike centralized stormwater management, which uses storm drains, pipes, and storage facilities, LID structures use landscaping to preserve the natural hydrologic processes of a region. 

The largest obstacle to stormwater capture projects is funding. Most communities rely on general funds and state grants to cover stormwater management costs, but one study found these annual funds fell 500 to 800 million dollars short. California tried to address this gap back in 2014, when voters passed Prop 1. The proposition authorized 7 billion dollars in general obligation bonds for multi-benefit stormwater projects. Prop 1, as well as other propositions, try to lower the funding barriers preventing smaller cities from integrating stormwater capture projects into their infrastructure. 

Climate change is radically altering how and where Californians are getting their water. With the Sierra snowpack in critical condition, cities need alternative sources to bolster their water security. Cleaning and reusing our stormwater is an increasingly critical aspect of water conservation.

Babcock Labs offers stormwater testing and reporting to assist our clients with management of this precious water resource. As a leading environmental lab, Babcock is dedicated to safeguarding the public health and protecting our environment. Contact Babcock Labs to learn more.