water quantity

Existing Conditions and Assessment Conclusions

Irrigation agriculture (primarily pasture and hay production) is the largest water user in the Pit River watershed. Approximately 230,000 acre-feet of surface water is annually diverted for this purpose. These diversions, together with the natural precipitation and stream flow patterns in this area, result in seasonal low flow (or no flow) in the Pit River and some tributaries during the summer and early fall months. This condition is in part mitigated by winter storage of wet season runoff and release of that water through the irrigation season. Seasonal low flow in many of the watercourses impacts water quality, aquatic habitat, recreation, and agricultural uses within the Pit RCD area.

In addition to variations in natural precipitation (which cannot be influenced by the management strategy), the following are factors, influence seasonal instream flow:

  • Entrenched (gullied) stream channels which quickly transport wet season runoff out of the watershed, prevent high flows from accessing and rewatering meadow systems, and act as a drain on those water storing meadow systems. This condition works toward reducing dry season base flow in the River and tributary streams.

  • Proliferation of undesirable and/or overly dense vegetation in the upland areas (e.g. the juniper problem) which use water that would otherwise be available in springs, wet meadows and streams.

  • Inefficient transport and use of water for irrigation resulting in surface water diversions which are in excess of that actually needed for the irrigation use.

Management Strategy

A. The Pit RCD will seek to implement projects which result in augmentation of instream flows, particularly during the critical summer dry season. This includes:

  • projects which improve natural stream and floodplain function resulting in improved water retention during the wet season and slower release of wet meadow storage during the dry season

  • projects which work towards managing timber and other upland vegetation in a more healthy and natural condition resulting in an overall decrease in surface and groundwater demand by these upland species

  • projects which increase irrigation use efficiency and dedicate saved water for instream flow purposes

  • projects which retire existing consumptive uses and dedicate saved water for instream flow purposes

  • projects which increase capacity for wet season storage and dry season release of stored water via instream flow

Created by Prism Designs