My wife and I found the Sal Elijo Lagoon Ecological Reserve somewhat disappointing. There is a nice 45-60 min walk on a loop trail from the visitor's center - but most of the other trails were closed - apparently due to work on the nearby rail tracks. Although the lagoon is attractive, any serenity is destroyed by the nearby coast highway as well as the extensive construction on the adjacent railroad.
We were also disappointed by the lack of wildlife. Though we visited in December, we only saw 4 ducks during the visit. It seems that many of the birds normally wintering over were disturbed by the construction.
The reserve has potential - but my advice would be to wait until the construction is complete before planning a visit.