Lesotho Reservoir Transparency

For the COVERED subset (Katse + Mohale), current storage percentages for both dams are published on the LHDA homepage in near-real time. South Africa's DWS also publishes weekly reservoir levels for these Lesotho dams at dws.gov.za/hydrology/Weekly/ProvinceWeek.aspx?region=L without registration. Third-party aggregators (mydorpie.com, afriwx.co.za) redistribute this DWS data weekly. The typical covered reservoir has weekly structured publication plus near-real-time HTML display.

For the COVERED subset, the dominant access mechanism is scrapable HTML tables. The DWS weekly page offers PDF downloads and HTML tables — no REST API. South Africa's NIWIS portal (niwis.dws.gov.za) provides CSV and Excel exports for surface water storage covering ~5 years of weekly data, but navigation is manual and no documented API endpoint exists. The LHDA website displays live percentages as unstructured HTML with no machine-readable download. No registration barrier exists, which partially offsets the lack of API.

Methodology v1.3.0 (capacity-weighted). Total Lesotho national reservoir storage capacity is approximately 2,888 hm³ — Katse (1,950 hm³ total / 1,519 hm³ live) and Mohale (938 hm³ total / 844 hm³ live). Covered capacity through DWS-SA weekly publication plus LHDA homepage live percentages is the full ~2,888 hm³ — both reservoirs are publicly reported with no gaps. Coverage = round(100 × 2,888 / 2,888) = 100. The Matsoku Weir is a minor run-of-river diversion with negligible storage. Polihali Dam (Phase II, 2,325 hm³) is under construction and not yet operational in 2026. Domestic WASCo small dams are all below operational significance.

MEDIAN historical depth across the 2 covered reservoirs is approximately 5-10 years of machine-readable public data. South Africa's NIWIS portal provides ~5 years of downloadable weekly dam level data (roughly 2021-2026) for Katse and Mohale. Journalistic sources cite LHDA-supplied data going back to January 2014 (~12 years), confirming data exists internally for over a decade. LHDA annual reports from 2007/08 onwards contain operational statistics but as PDFs rather than machine-readable time series. With both reservoirs at roughly the same public depth, median lands in the 5-10 year band.

For the COVERED subset, the typical cadence is WEEKLY. DWS state of reservoirs is updated every week and explicitly lists Katse and Mohale with current week's percentage, prior week, and year-ago comparison. The LHDA homepage displays current dam fill percentages that track closely with the DWS weekly cycle. Weekly is significantly better than regional norms and comparable to mid-tier OECD practice.

For the COVERED subset, the 1986 LHWP Treaty (publicly available on lhda.org.ls) specifies that LHDA and TCTA jointly measure water volumes delivered at the end of each calendar month at the designated outlet point, with disputes resolved by the Lesotho Highlands Water Commission. This establishes a bilateral audit framework. However, no technical document publicly describes the specific gauge types, measurement standards, calibration procedures, or accuracy estimates for reservoir storage at Katse or Mohale. The DWS weekly report does not describe its methodology. Partial transparency through treaty governance, but station-level hydrometric metadata is not publicly disclosed.

All LHDA web content, annual reports, governance documents, and the LHWP Treaty are in English. The DWS weekly reservoir data (the de facto public channel for Katse and Mohale levels) is entirely in English. No language barrier exists for any international researcher. English is the official administrative language of both Lesotho and South Africa in this project's context.