TECHNICAL MEMORANDUM #7
WATER QUALITY IN THE LOWER OWENS RIVER:
EXISTING AND FUTURE CONDITIONS

prepared for
Los Angeles Department of Water and Power
and
Inyo County Water Department

prepared by
Mark Hill,
William  Platts,
Ecosystem Sciences

TABLE OF CONTENTS

Introduction
Existing Conditions
Future Conditions
Matrix Analysis - Beneficial Uses
Matrix Analysis - Water Quality Objectives
Anticipated Water Quality Issues
Appendix - Water Quality Monitoring Data
 

Introduction

Purpose

The purpose of this technical memorandum is to describe existing baseline water quality conditions and projected future conditions following implementation of the Lower Owens River Project (LORP), and to compare these conditions with beneficial uses and water quality objectives in the Water Quality Control Plan in the Lahontan Region. In this tech memo we develop a matrix of designated beneficial uses and water quality objectives.

Background

In 1993 the Los Angeles Department of Water and Power (LADWP) performed a controlled flow study in the Lower Owens River to determine the most appropriate flow for rewatering the reach from the LADWP aqueduct intake to Owens Lake, some 65 miles of river channel. This study included HEC-2 hydrologic modeling and QUAL2E water quality modeling based on three calibration flows and empirical sampling (Jackson 1994). Sampling was performed in eight reaches of the river (see Figure 1).

Currently the river channel from the intake to approximately Mazourka Canyon Road is dry and has only received flows in the last fifty years in extremely high water years. (From 1986 to 1990 water was released from Blackrock Ditch to Mazourka Canyon Road as part of the enhancement and mitigation (EM) project.) The lower half of the river, from about Mazourka Canyon Road to the dry lake bed, generally is wetted with variable flows resulting from springs, groundwater, irrigation returns, and releases by LADWP under agreement with Into County.

Following the controlled flow study a monitoring program was initiated to characterize steady state water quality conditions in the wetted reaches of the river. This baseline study was conducted by the Inyo County Water Department from the spring of 1995 to the spring of 1996 (Jackson 1996). Five water quality parameters (dissolved oxygen, pH, temperature, conductivity, and turbidity) were monitored at five river stations (Mazourka Canyon Road, Reinhackle Springs, Lone Pine Ponds, Lone Pine Station Road, and Keeler Bridge; see Figure 1) weekly during the spring of 1995 and biweekly in the winter of 1996. Raw monitoring data, corrected data, and estimates of  total dissolved solids made from electrical conductivity are presented in tables in the Appendix.

Existing Conditions

Summarized water quality monitoring data are presented in Table 1 for 1995 through 1996. Table 1 also shows results of QUAL2E water quality predictions from the controlled flow study of 1993.

In general, dissolved oxygen concentrations decrease downstream in the Lower Owens River for any given time. Over the course of a year dissolved oxygen concentrations are higher in winter, with the accompanying lower temperatures than in summer. All on-river stations drop below 5 mg/l for some period of time. The farther downstream the station, the longer the duration of sub 5 mg/l dissolved oxygen concentrations. The sampling stations at Lone Pine Ponds, Lone Pine Road, and Keeler Bridge all experience dissolved oxygen concentrations near or below 2 mg/l for varying durations during the summer, but all locations (except Lone Pine Road) exhibit dissolved oxygen concentrations above 1 mg/l in the summer.

In general, turbidity decreases downstream from Mazourka Canyon Road to the lake. Over the course of a year, turbidity in the wetted channel is higher in spring, and declines through the summer and fall.

In general, pH decreases downstream for any given time, although exceptions are common in the data. Over the course of a year, pH appears to be slightly higher and be more variable in winter when groundwater conditions contribute to the Lower Owens River flows.

In general, total dissolved solids (TDS, calculated from electrical conductivity (Jackson 1994)) increase downstream for any given time, although exceptions are apparent in the data. Over the course of a year, TDS concentrations are generally higher in winter when evapotranspiration of riparian vegetation slows, surface water supply is reduced, and contributions of groundwater dominate the river. These relatively higher TDS winter periods may be interrupted by runoff from storm events, during which TDS concentrations may be lowered for a short time. During mid-summer surface water contributions dominate the river and TDS concentrations are generally lower than in winter, despite higher summer evapotranspiration rates.

An estimate of dissolved solids transport past Keeler Bridge was developed when LADWP discharge data were available, using both the conductivity relationship to TDS and discharge for the period May 1, 1995 to June 30, 1996 (Jackson 1994). The total dissolved solids transported past Keeler Bridge during this period is estimated to be approximately 7,700 tons. The maximum daily transport for a 24-hour period is estimated to be 57 tons and the minimum is estimated to be approximately 0.2 tons. The average daily transport in total dissolved solids for this period is approximately 18 tons.

In general, temperature exhibits no consistent trend in the Lower Owens River for any given time period. Over the course of a year water temperature varies with ambient air temperature with water temperature being 30 F warmer in summer than in winter.

Future Conditions

Table 1 shows water quality predictions made by the QUAL2E model from the controlled flow study. These predictions are based on calibrations made from empirical data collected at each flow level. Because the controlled flow study mobilized both bottom muck (organic debris collected in sediments) and cattle waste from the floodplain and dry river channels, BOD was extremely high and affected all water quality parameters. Thus, we interpret these data as worst case conditions that do not reflect winter conditions, or those water quality conditions we would expect in the long term of rewatering the river.

In October 1992, prior to the controlled flow study, muck samples were taken to test for total coliform, fecal coliform, fecal streptococci, salmonella, and toxicity (using microtox methods) (Rychert 1992). Results show that all bacteria parameters are well below water quality standards, salmonella is absent, and the sediments are non-toxic.

Even in a worst case scenario, water quality will improve over existing conditions with a base flow of 40 cfs. An example is given in Figure 2 (this figure is not available on the internet) which illustrates existing and predicted dissolved oxygen concentrations by stream mile in the summer (worst case condition). Dissolved oxygen will increase at all points in the river, but will still remain below the 80% saturation level.(80% dissolved oxygen saturation is the standard cited in the Water quality Plan for surface water and at the elevation and summer temperatures of the Lower Owens River this equates to about 6 mg/l.) However, we anticipate that in the long term (>2 to 3 years), with the development of riparian vegetation, steady state flow conditions, improved assimilation capacity, and freshet flows, all water quality parameters will show substantial improvement over present conditions. Increased velocity, depth, and channel width shown in Table 2 for the base flow and freshet flow will improve both riparian conditions and water quality in the Lower Owens River. Most of the constituent values predicted by QUAL2E modelling meet Water Quality Plan water quality objectives. The notable exceptions are dissolved oxygen and BOD.

TABLE 2. HEC-2 modeling results for two flows, LORP.
 

 

 

Matrix Analysis - Beneficial Uses

In the Water Quality Plan, a number of beneficial uses are usually identified for a given body of water. Water quality objectives are established which are sufficiently stringent to protect the most sensitive use. The Lahontan Regional Board reserves the right to resolve any conflicts among beneficial uses, based on the facts in a given case.

Lakes and streams may have potential beneficial uses established because: (1) plans already exist to put the water to those uses, (2) conditions make such future use likely, (3) the water has been
identified as a potential source of drinking water, based on the quality and quantity available, and (4) existing water quality does not support these uses but remedial measures may lead to attainment in the future. Establishment of beneficial uses can have different purposes, such as (1) establishing a water quality goal which must be achieved through control actions in order to re-establish a beneficial use, as in number 4 above, or (2) serving to protect the existing quality of a water source for eventual use.

Table 3 exhibits the beneficial uses currently designated for the Owens River from the LADWP aqueduct intake to Owens Lake. The applicability of these beneficial uses to the Lower Owens River, based on present and future uses, are also discussed in Table 3.

Matrix Analysis - Water Quality Objectives

Water quality objectives are numerical or narrative. Narrative and numerical water quality objectives define the upper concentration of other limits that the Lahontan Regional Board considers protective of beneficial uses.

The general methodology used in establishing water quality objectives involves, first, designating beneficial water uses; and second, selecting and quantifying the water quality parameters necessary to protect the most vulnerable (sensitive) beneficial uses. To comply with the non-degradation goal water quality objectives may be established at levels better than that necessary to protect the most vulnerable beneficial use.

In establishing water quality objectives, factors in addition to designated beneficial uses and the non-degradation goal are considered. These factors include environmental and economic considerations specific to each hydrologic unit, the need to develop and use recycled water, as well as the level of water quality which could be achieved through coordinated control of all factors which affect water quality in an area. Controllable water quality factors are those actions, conditions, or circumstances resulting from human activities that may influence the quality of the waters of the state, and that may be reasonably controlled.

Water quality objectives can be reviewed, and, if appropriate, revised by the Lahontan Regional Board. Revised water quality objectives would then be adopted as part of the Basin Plan by amendment. As a component of the state’s continuing planning process, data may be collected and numerical water quality objectives may be developed for additional water bodies and/or constituents where sufficient information is presently not available for the establishment of objectives.

Table 4 shows the Water Quality Plan objectives for the Owens River from the LADWP aqueduct intake to Owens Lake. This table is presented in matrix form to illustrate the applicability of objectives and the likelihood of compliance in the Lower Owens River as a result of the LORP.

Anticipated Water Quality Issues

We anticipate three principle water quality problems associated with the LORP and rewatering of the river between the intake and Lake Owens. First is the potential for fish kills when water is reintroduced into the river, and second is the need for variances from water quality objectives in the initial years of the restoration. Third is the probable non-compliance of some water quality parameters over the long term.

During the 1993 controlled flow study a substantial fish kill occurred toward the end of the study. The fish killed included both game (largemouth, smallmouth bass, bluegill, and catfish) and non-game (carp, suckers, chubs) species. Field investigations during the fish kill did not find that any endangered fish species (pupfish, tui chub) were killed. As flow was increased during the study, greater quantities of muck and cattle waste from floodplains was mobilized. These organic rich materials caused the dissolved oxygen to drop rapidly and fish experienced both low dissolved oxygen and high flows simultaneously. To reach the desired flow levels for the study water was released from several of the spill gates from the aqueduct to the river. Water in the spill gate channels was high in dissolved oxygen and exhibited low velocities; with the higher water levels the sills between spill channels and the river were inundated. Fish escaped the river’s low dissolved oxygen by moving quickly to the spill channels for refuge. Unfortunately this movement of fish went undetected, and at the end of the controlled flow study the spill gates were closed without ramping down the flows. As a consequence, fish were killed by stranding in the spill channels. Other fish mortalities occurred in the river as a consequence of low dissolved oxygen and possible ammonia toxicity when bottom water from beaver ponds was moved downstream.

We are greatly concerned and cautious that a fish kill not be repeated in the river when flows are reintroduced. To prevent a fish kill and to minimize stress on existing fish populations from rapidly deteriorating water quality conditions, flow introduction must be gradual and carefully monitored. The first year or two of flow release will be "donor" years. Flows will be gradually increased to 40 to 50 cfs beginning in mid-March or the first of April to avoid problems with icing in the channel. Flows will be allowed to fill shallow, near-channel aquifers, wetlands and bank storage areas. Once a near steady-state flow condition is achieved with base flow, out-of-channel (or riparian) flows up to 200 cfs will be released in the following freshet period (typically late May or early June) to recharge upper terrace aquifers.

During the period when the aquifers and bank storage systems are being re-filled, stream water quality and fisheries will be monitored very closely. If water quality conditions begin to deteriorate action plans for emergency recovery of fish (catch and transportation to nearby lakes and ponds) may be implemented. Water can be released simultaneously through spill channels to provide refuge for fish. Water flow in spill channels will be maintained until water quality conditions improve in the river at which time flows will be slowly ramped down (< 10%/day) until all fish have evacuated the spill channels back to the river.

Details of emergency fish recovery and protection plans will be provided in the technical memorandum on fisheries and riverine-riparian habitat.

The second area of concern is with short term water quality conditions. During the early years of channel rewatering it is likely that dissolved oxygen, ammonia, pH, temperature, and turbidity will not meet Water Quality Plan objectives. In time, however, as riparian vegetation matures, stream flows reach equilibrium, beaver ponds disappear, cattle wastes on floodplains diminish, and muck deposits are assimilated most water quality objectives will be met. Nevertheless, in the short term some variances from water quality objectives may be required from the Lahontan Regional Board.

The third area of concern with future water quality conditions is that some parameters may never meet Water Quality Plan objectives. It is possible that dissolved oxygen may always be less than 80% saturation. Temperature, as a result of shading by climax overstory of riparian vegetation, may actually decline to something greater than 0.5F from existing temperatures. The base line water quality data may represent worst case conditions, but, on the other hand, these data may reflect long term, natural conditions for which some parameters may not change too dramatically. In any event, long term affects and changes in water quality parameters will be identified through the intensive, long term monitoring program following start-up of rewatering. During the course of monitoring the Lahontan Regional Board, LADWP, and Inyo County will work closely together to address specific water quality issues.

Appendix - Water Quality Monitoring Data

References

Jackson, R. 1994. Lower Owens River Planning Study: Transient Water Quality in the
    Lower Owens River During Planning Study Flow Releases in July and August of 1993.
    Inyo County Water Dept., Bishop, CA.

Jackson, R. 1996. Lower Owens River Planning Study Water Quality in the Lower Owens
    River Enhancement/Mitigation Project, May 1995 through June 1996. Inyo County
    Water Dept., Bishop, CA.

Rychert, R. 1992. Report on bacteria analysis in the Lower Owens River. LADWP,
    Bishop, CA.