Managing Wastewater in a Changing Climate

Caitrin Chappelle

Research supported by the California Association of Sanitation Agencies, the S. D. Bechtel, Jr. Foundation, and the US Environmental Protection Agency

April 22, 2019

California’s wastewater sector is at a turning point

2

Wastewater management helps protect public health and the environment, is source for recycled water

Shifts in policies, better planning can help sector prepare for drought, changing water demands, climate change

New report based on first-hand information from agencies– Surveyed wastewater managers on experiences before, during,

after latest drought (133 responses) – Focus groups with local and state agencies helped define

challenges, innovations

Drought and changing climate complicate wastewater management

3

Reduced indoor water use reduces volumes into treatment plants Shifts to alternative water sources can affect influent quality Lower flows, higher temperatures in rivers and streams will further

stress ecosystems that depend on treated wastewater More “atmospheric rivers” will increase flood risk to treatment

plants, bring unplanned spills Sea level rise will affect wastewater treatment plants on the coast

A shift is needed in how we manage wastewater

4

Key Challenges: Maintaining water quality in the

face of reduced indoor water use Making smart recycled water

investments Balancing conflicting objectives

within watersheds

Outline

5

Maintaining water quality in the face of reduced indoor water use Making smart recycled water investments Balancing conflicting objectives within watersheds

Maintaining water quality in the face of reduced indoor water use

6

Wastewater managers must adapt to:

– Periodic short-term water conservation in response to droughts

– Long-term increases in urban water use efficiency

The unusually warm drought of 2012–16 was a window into the future

7

Urban water use rapidly declined during mandated conservation period

8

50

75

100

125

150

175

200

225

250

Jun14

Oct14

Feb15

Jun15

Oct15

Feb16

Jun16

Oct16

Feb17

Jun17

Oct17

Feb18

June18

Oct18

Feb19

Wat

er u

se p

er c

apita

(gpc

d)

San Joaquin Valley

Northern California

Statewide

Southern California

Central Coast

San Francisco Bay

Governor'smandate

announced

End of drought emergency declared

Reduced indoor water use led to reduced influent flow, changes to influent quality

9

61

85

0 20 40 60 80 100

Change in influent oreffluent quality

Reduced influent flows

Share of surveyed wastewater agencies (%)

Wastewater agencies experienced problems with collection and treatment during the drought

10

6

37

18

19

27

0 20 40 60 80 100

Damaged infrastructure

Processing issues

Increased odor problem

Increased corrosion

Increased solids deposition

Share of surveyed wastewater agencies (%)

Treatment challenges

Collection challenges

Agencies must adapt to long-term reductions in indoor water use

11

Long-term indoor water use efficiency will impact amount, quality of influent

Per capita water use is declining, further declines likely as a result of state, local policies

Recommendations for building resilience

12

Increase information sharing and coordination with water suppliers

Plan for future droughts Improve understanding of

wastewater system vulnerability

Maintain its current

levels31%

Increase slightly

31%

Increase significantly

38%

“Coordination between water suppliers and wastewater agencies needs to ______.”

Outline

13

Maintaining water quality in the face of reduced indoor water use Making smart recycled water investments Balancing conflicting objectives within watersheds

Wastewater is the source for recycled water, a growing water supply

14

Reduced influent flows during drought cut into recycled water production

Changing influent characteristics creates challenges

Evolving regulations and state policies will change demand

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

1970 1977 1987 2001 2009 2015

Rec

ycle

d W

ater

Use

(acr

e-fe

et)

UrbanAgricultureGroundwater rechargeOther

Recycled water use is growing

Recommendations for building resilience

15

Regional plans for recycled water investments are needed

Focus on flexible recycled water investments

Clovis Water Reuse Facility

Outline

16

Maintaining water quality in the face of reduced indoor water use Making smart recycled water investments Balancing conflicting objectives within watersheds

Most plants discharge treated wastewater into inland watersheds

17

Adapting to declining water use and meeting increased demand for recycled water may mean less treated wastewater for:

– Environmental water needs– Downstream users

Climate change exacerbates these conflicts

Salton Sea

Recommendations for building resilience

18

Identify watersheds vulnerable to changes in wastewater management

Develop science to support management and regulatory decisions

Evaluate tradeoffs caused by the interplay of state policies

LA River

Awareness of these challenges is growing, providing an opportunity for action

19

Thank you!

These slides were created to accompany a presentation. They do not include full documentation of sources, data samples, methods, and interpretations. To avoid misinterpretations, please contact:

Caitrin Chappelle (chappelle@ppic.org; 415-291-4435)

Thank you for your interest in this work.

Managing Wastewater in a Changing Climate

Caitrin Chappelle

Research supported by the California Association of Sanitation Agencies, the S. D. Bechtel, Jr. Foundation, and the US Environmental Protection Agency

April 22, 2019