# Donnells

CAISO asset profile · https://askthegrid.com/assets/facilities/donnells

Oakdale Irrigation District - Tuolumne County - CAISO

Donnells is a 72-megawatt conventional hydroelectric powerhouse in Tuolumne County, California, operating since June 1957. It sits on the Middle Fork Stanislaus River and is part of the Beardsley/Donnells Hydroelectric Project (FERC No. 2005), built and jointly owned by the Oakdale Irrigation District and South San Joaquin Irrigation District under their Tri-Dam Project partnership. The Donnells generating unit was upgraded from its original size to its current 72 MW rating, a change completed in 1990. FERC issued Tri-Dam a new 40-year operating license for the Beardsley/Donnells Project effective January 2006, giving the project a license horizon to January 30, 2046. The plant sells into the CAISO market and settles at the nearby DONNELLS_7_B1 pricing node. No whole-plant retirement is scheduled; the unit continues to operate under EIA-860.

## Metrics

- **Nameplate capacity:** 72 MW — Canonical EIA plant baseline.
- **Registry anchor:** Plant 415 — plant-415

## Facts

- **Technology:** Conventional Hydroelectric
- **Operator:** Tri-Dam Project

## Related parties

- **Operator / developer / joint venture partner:** Tri-Dam Project — Joint venture entity that developed, operates and maintains the Donnells development. ([source](https://www.tridamproject.com/about-tri-dam))
- **Owner / developer / joint venture partner:** Oakdale Irrigation District — Joint project owner through the Tri-Dam Project with South San Joaquin Irrigation District. ([source](https://www.oakdaleirrigation.com/))
- **Owner / developer / joint venture partner:** South San Joaquin Irrigation District — Joint project owner through the Tri-Dam Project with Oakdale Irrigation District. ([source](https://www.ssjid.gov/))
- **Interconnection counterparty / balancing authority / market operator:** California Independent System Operator — Balancing authority and market operator for Donnells in CAISO. ([source](https://www.caiso.com/))
- **Regulator:** Federal Energy Regulatory Commission — Hydropower licensing regulator; issued Project No. 2005 license for the Beardsley/Donnells project. ([source](https://www.ferc.gov/hydropower))

## Sources

- [api.eia.gov](https://api.eia.gov/v2/electricity/operating-generator-capacity/data?api_key=DEMO_KEY&data%5B0%5D=nameplate-capacity-mw&end=2026-07&facets%5Bplantid%5D%5B%5D=415&frequency=monthly&length=100&start=2026-07) — api.eia.gov · authoritative — Source retained for exact-record publication review.
- [caiso.com](https://www.caiso.com/documents/curtailed-non-operational-generator-am-report-20201130.html) — caiso.com · public_source — Source retained for exact-record publication review.
- [escalontimes.com](https://www.escalontimes.com/news/local-news/tri-dam-project-delivers-water-and-electricity) — escalontimes.com · public_source — Source retained for exact-record publication review.
- [govinfo.gov](https://www.govinfo.gov/content/pkg/FR-1999-10-08/html/99-26259.htm) — govinfo.gov · authoritative — Source retained for exact-record publication review.
- [ssjid.gov](https://www.ssjid.gov/) — ssjid.gov · authoritative — Source retained for exact-record publication review.
- [tridamproject.com](https://www.tridamproject.com/about-tri-dam) — tridamproject.com · public_source — Source retained for exact-record publication review.

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Canonical page: https://askthegrid.com/assets/facilities/donnells
Website: [Oakdale Irrigation District and South San Joaquin Irrigation District (Tri-Dam Project)](https://www.oakdaleirrigation.com/)

Source: Ask the Grid — https://askthegrid.com/