Statewide Drought Response
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Statewide Drought Response: Stressor Monitoring SUMMARY REPORT • 2014-2017 COVER IMAGES, CLOCKWISE FROM TOP: South Lake Reservoir with low water levels due to drought in California. CDFW staff conducting a salmon carcass survey in the Merced River in 2012. CDFW staff conducting a snorkel survey in Gobernador Creek in 2015. Please direct questions about this report to Ms. Kristine Atkinson, Senior Environmental Scientist (Specialist), at [email protected], CDFW Fisheries Branch, 830 S Street, Sacramento, CA 95811 Contributors FISHERIES BRANCH BAY DELTA REGION Kristine Atkinson NORTH OF SAN FRANCISCO John Kelly Ryan Watanabe Stephen Swales Derek Acomb Melissa Mandrup George Neillands Patrick Mulcahy Lydia Eldridge SOUTH OF SAN FRANCISCO Helen Benson Jennifer Nelson Stephanie Mehalick Michelle Leicester Jon Jankovitz BIOGEOGRAPHIC DATA BRANCH George Neillands Janet Brewster Ryan Hill CENTRAL REGION Kristina White COASTAL Dennis Michniuk OFFICE OF COMMUNICATION, Matthew Michie EDUCATION AND OUTREACH Margaret Paul Meredith Fleener WILD TROUT / INLAND Ken Johnson NORTHERN REGION Eric Guzman COASTAL SAN JOAQUIN BASIN Seth Ricker Pat Ferguson CENTRAL VALLEY Steve Tsao Stacey Alexander Jason Roberts SOUTH COAST REGION WILD TROUT / INLAND COASTAL Andrew Jensen Ben Lakish Jennifer Bull Mary Larson Paul Divine Kyle Evans Steve Baumgartner Marianne Pelletier Mike Dege Bernard Aguilar INLAND Caitlin Bean Jennifer Pareti Tom Christy Tim Hovey Dylan Nickerson NORTH CENTRAL REGION Russell Barabe CENTRAL VALLEY Hans Hansen Tracy McReynolds John O’Brien Mike Healey Jeanine Phillips INLAND DESERTS REGION Colin Purdy NORTH Clint Garman Nick Buckmaster Dawne Emery WILD TROUT / INLAND Steve Parmenter Kevin Thomas John Hanson SOUTH Claire Ingel Contents EXECUTIVE SUMMARY v INTRODUCTION: STATEWIDE DROUGHT STRESSOR MONITORING i CHAPTER 1: NORTHERN REGION 1 1.1 Coastal Watersheds 1 1.2 Central Valley Watersheds 9 1.3 Wild Trout and Inland Watersheds 16 CHAPTER 2: NORTH CENTRAL REGION 28 2.1 Central Valley Watersheds 30 2.2 Wild Trout and Inland Watersheds 38 CHAPTER 3: BAY DELTA REGION 47 3.1 North of San Francisco Bay Watersheds 47 3.2 South of San Francisco Bay Watersheds 60 CHAPTER 4: CENTRAL REGION 72 4.1 Coastal Watersheds 72 4.2 Inland Watersheds 83 4.3 San Joaquin River Basin 91 CHAPTER 5: SOUTH COAST REGION 101 5.1 Coastal Watersheds 101 5.2 Inland Watersheds 115 CHAPTER 6: INLAND DESERTS REGION 131 6.1 North 132 6.2 South 139 CHAPTER 7: DISCUSSION 144 LITERATURE CITED 151 Executive Summary The state of California recently experienced a severe status species, or those that were expected to face drought and one of the warmest and driest periods the greatest risks from drought. To better understand of recorded history. The drought lasted for five years, the extent to which habitats and populations may from 2012 to 2016. On January 17, 2014, Governor Jerry be affected by drought, monitoring focused on the Brown declared the drought a state of emergency. following questions: This proclamation directed all state agencies to act • Were streams drying and was aquatic habitat to prepare for and mitigate drought-related effects becoming fragmented? on water supply and aquatic species. The California • Were streams warming? Department of Fish and Wildlife (CDFW) responded by developing and implementing “Drought Stressor • Was there sufficient dissolved oxygen in the Monitoring”. In late 2016 to early 2017, drought streams to support aquatic life? conditions improved considerably throughout most • What were the effects of the drought on of the state when winter storms delivered higher than aquatic species? average levels of rainfall. This report describes the results from a collaborative monitoring effort carried A direct result of the drought was that many streams out during the period 2014 to 2017 by scientists from dried out throughout the state. As a result of reduced California Department of Fish and Wildlife and other streamflow, streams usually characterized as wet agencies throughout the state. year-round dried out and formed isolated pools. Streams that were typically intermittent during the The purpose of the Drought Stressor Monitoring dry summer months dried earlier in the year and for initiative was to collect information on the status of longer durations. Isolated pools provided temporary populations of fish and other aquatic species, their safe havens for many aquatic species; however, habitats, and the water quality in the streams in which as the drought persisted, water quality in many of they reside. The intent of this project was to provide these pools quickly deteriorated. The effects of the the scientific community and the public with a better drought often resulted in higher water temperatures. understanding of potential drought-related threats In some cases, reduced streamflow, stagnant water, to vulnerable species, and the measures taken by and biological oxygen demand resulted in decreased CDFW, and other agencies, to alleviate these threats. levels of dissolved oxygen. Aquatic species were This information was also necessary to help CDFW frequently stranded as streams dried, and were also make better-informed management decisions. impacted by reduced water quality, which frequently required emergency management actions, such as CDFW scientists monitored habitat conditions for 17 fish rescues. When the drought finally ended in early aquatic species and subspecies in 141 watersheds and 2017, environmental conditions in most areas of the sub-watersheds, spanning 28 counties statewide. state improved markedly. The increased rainfall and Nearly all fish species monitored were listed under the streamflow reduced water temperatures in many state and/or federal Endangered Species Acts (CESA streams, improving fish survival; however, many and ESA, respectively) or were state listed as Species streams still experienced water temperatures high of Special Concern. CDFW focused its monitoring enough to negatively impact the survival of salmon efforts on watersheds that provided habitat to special and steelhead. The drying of streams and increased habitat high elevations, as trout were not able to reach refuge fragmentation experienced during the drought often areas to escape freezing. Increased precipitation resulted in less suitable habitat for native species. during the winter of 2016-2017 restored snowpack Low streamflow prevented salmon and steelhead to most high elevation streams, reducing the risk of from accessing spawning and rearing habitat. anchor ice formation. Increased rainfall in some northern areas of the state in 2016 improved stream connectivity and allowed The information provided by Drought Stressor fish to travel between habitats, decreasing the risk Monitoring helped to maintain adequate streamflows of stranding; however, streams in south central and and water temperatures for fish survival. This southern California continued to experience drying, information also allowed for adequate water supplies with deteriorating water quality. for communities and industry, and for hydroelectric power generation. In May 2014, CDFW and NOAA River estuaries and lagoons were also found to be Fisheries developed a “Voluntary Drought Initiative” impacted by the drought. Tidal influence in these between the two agencies. This provided a framework systems was more pronounced, largely due to for taking collaborative actions with water users to reduced freshwater inputs, allowing saltwater layers protect aquatic species. These actions included fish to extend farther into streams and to persist longer rescue, relocation, monitoring, and habitat restoration. than in previous years. During the summer and early The implementation of suitable environmental fall, the bottom saltwater layer was often warmer and monitoring and management allowed CDFW to had lower dissolved oxygen levels than the upper respond to changing environmental conditions. freshwater layer. This likely placed increased stress on rearing juvenile salmon and steelhead. Conditions The end of the prolonged drought early in 2017 generally improved in 2016 as increased precipitation presented new threats to California’s vulnerable fish led to higher streamflow, resulting in estuaries and populations and their habitat, including increased lagoons remaining open to the ocean for longer frequencies of wildfires, mud slides, flash flooding, periods and receiving more freshwater input. and debris flows. Future climate change predictions suggest that these threats may increase in frequency Wild trout populations in high elevation streams were and severity in the coming years, potentially adversely also at increased survival risk throughout the drought affecting fish and other aquatic resources. These years. In summer, trout faced reduced streamflow threats must be adequately monitored to protect and warming waters, similar to the threats faced by fish and the environment. The knowledge and data salmon and steelhead. In winter, reduced or absent gained through Drought Stressor Monitoring can be snowpack often coupled with low streamflow led used to guide CDFW and other resource managers to the formation of anchor ice on river beds. This, during future droughts. in turn, likely resulted in increased trout mortality at Statewide Drought Response: Stressor Monitoring Introduction To conserve and manage aquatic species, it is The drought lasted for five years, from 2012 to 2016 necessary to collect information on the status and (Figure I-1). Concerns about the adverse effects